Journal articles: 'LytA'

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Eldholm, Vegard, Ola Johnsborg, Kristine Haugen, Hilde Solheim Ohnstad, and Leiv Sigve Håvarstein. "Fratricide in Streptococcus pneumoniae: contributions and role of the cell wall hydrolases CbpD, LytA and LytC." Microbiology 155, no. 7 (July 1, 2009): 2223–34. http://dx.doi.org/10.1099/mic.0.026328-0.

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Pneumococci that have developed the competent state kill and lyse non-competent sister cells and members of closely related species during co-cultivation in vitro. The key component in this process, called fratricide, is the product of the late competence gene cbpD. In addition, the peptidoglycan hydrolases LytA and LytC are required for efficient lysis of target cells. Here, we have investigated the relative contribution and possible role of each of the proteins mentioned above. Previous studies have shown that CbpD is produced exclusively by competent cells, whereas LytA and LytC can be provided by the competent attackers as well as the non-competent target cells. By using an improved assay to compare the effect of cis- versus trans-acting LytA and LytC, we were able to show that target cells are lysed much more efficiently when LytA and LytC are provided in cis, i.e. by the target cells themselves. Western analysis demonstrated that considerable amounts of LytC are present in the growth medium. In contrast, we were not able to detect any extracellular LytA. This finding indicates that LytA- and LytC-mediated fratricide represent different processes. In the absence of LytA and LytC, only a tiny fraction of the target cells were lysed, demonstrating that CbpD does not function efficiently on its own. However, in the presence of 1 mM EDTA, the fraction of target cells lysed directly by CbpD increased dramatically, indicating that divalent cations are involved in the regulation of fratricide under natural conditions.

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Corsini, Bruno, Leire Aguinagalde, Susana Ruiz, Mirian Domenech, and Jose Yuste. "Vaccination with LytA, LytC, or Pce of Streptococcus pneumoniae Protects against Sepsis by Inducing IgGs That Activate the Complement System." Vaccines 9, no. 2 (February 23, 2021): 186. http://dx.doi.org/10.3390/vaccines9020186.

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The emergence of non-vaccine serotypes of Streptococcus pneumoniae after the use of vaccines based in capsular polysaccharides demonstrates the need of a broader protection vaccine based in protein antigens and widely conserved. In this study, we characterized three important virulence factors of S. pneumoniae namely LytA, LytC, and Pce as vaccine candidates. These proteins are choline-binding proteins that belong to the cell wall hydrolases’ family. Immunization of mice with LytA, LytC, or Pce induced high titers of immunoglobulins G (IgGs) of different subclasses, with IgG1, IgG2a, and IgG2b as the predominant immunoglobulins raised. These antibodies activated the classical pathway of the complement system by increasing the recognition of C1q on the surface of pneumococcal strains of different serotypes. Consequently, the key complement component C3 recognized more efficiently these strains in the presence of specific antibodies elicited by these proteins, activating, therefore, the phagocytosis. Finally, a mouse sepsis model of infection was established, confirming that vaccination with these proteins controlled bacterial replication in the bloodstream, increasing the survival rate. Overall, these results demonstrate that LytA, LytC, and Pce can be protein antigens to be contained in a future universal vaccine against S. pneumoniae.

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De Las Rivas, Blanca, José L. García, Rubens López, and Pedro García. "Purification and Polar Localization of Pneumococcal LytB, a Putative Endo-β-N-Acetylglucosaminidase: the Chain-Dispersing Murein Hydrolase." Journal of Bacteriology 184, no. 18 (September 15, 2002): 4988–5000. http://dx.doi.org/10.1128/jb.184.18.4988-5000.2002.

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ABSTRACT The DNA region encoding the mature form of a pneumococcal murein hydrolase (LytB) was cloned and expressed in Escherichia coli. LytB was purified by affinity chromatography, and its activity was suggested to be the first identified endo-β-N-acetylglucosaminidase of Streptococcus pneumoniae. LytB can remove a maximum of only 25% of the radioactivity from [3H]choline-labeled pneumococcal cell walls in in vitro assays. Inactivation of the lytB gene of wild-type strain R6 (R6B mutant) led to the formation of long chains but did not affect either total cell wall hydrolytic activity at the stationary phase of growth or development of genetic competence. Longer chains were formed when the lytB mutation was introduced into the M31 strain (M31B mutant), which harbors a complete deletion of lytA, which codes for the major autolysin. Furthermore, the use of this mutant revealed that LytB is the first nonautolytic murein hydrolase of pneumococcus. Purified LytB added to pneumococcal cultures of R6B or M31B was capable of dispersing, in a dose-dependent manner, the long chains characteristic of these mutants into diplococci or short chains, the typical morphology of R6 and M31 strains, respectively. In vitro acetylation of purified pneumococcal cell walls did not affect the activity of LytB, whereas that of the LytA amidase was drastically reduced. On the other hand, the use of a translational fusion between the gene (gfp) coding for the green fluorescent protein (GFP) and lytB supports the notion that LytB accumulates in the cell poles of either the wild-type R6, lytB mutants, or ethanolamine-containing cells (EA cells). The GFP-LytB fusion protein was also able to unchain the lytB mutants but not the EA cells. In contrast, translational fusion protein GFP-LytA preferentially bound to the equatorial regions of choline-containing cells but did not affect their average chain length. These observations suggest the existence of specific receptors for LytB that are positioned at the polar region on the pneumococcal surface, allowing localized peptidoglycan hydrolysis and separation of the daughter cells.

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Harkness, Robin E., Wolfgang Kusser, Bei-jing Qi, and Edward E. Ishiguro. "Genetic mapping of the lytA and lytB loci of Escherichia coli, which are involved in penicillin tolerance and control of the stringent response." Canadian Journal of Microbiology 38, no. 9 (September 1, 1992): 975–78. http://dx.doi.org/10.1139/m92-156.

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The mutations in nine independently isolated temperature-sensitive mutants of Escherichia coli, which exhibited penicillin tolerance and induction of the stringent response at the restrictive temperature, were assigned to two new loci designated lytA (7 alleles) and lytB (2 alleles) at 58 and 0.4 min on the linkage map, respectively. Key words: bacteriolysis, penicillin tolerance, stringent response.

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Sakakibara, Shuhei, Keiji Ueda, Jiguo Chen, Toshiomi Okuno, and Koichi Yamanishi. "Octamer-Binding Sequence Is a Key Element for the Autoregulation of Kaposi's Sarcoma-Associated Herpesvirus ORF50/Lyta Gene Expression." Journal of Virology 75, no. 15 (August 1, 2001): 6894–900. http://dx.doi.org/10.1128/jvi.75.15.6894-6900.2001.

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ABSTRACT The expression of the Kaposi's sarcoma-associated herpesvirus (KSHV) open reading frame 50 (ORF50) protein, Lyta (lytic transactivator), marks the switch from latent KSHV infection to the lytic phase. ORF50/Lyta upregulates several target KSHV genes, such as K8 (K-bZip), K9 (vIRF1), and ORF57, finally leading to the production of mature viruses. The auto-upregulation of ORF50/Lyta is thought to be an important mechanism for efficient lytic viral replication. In this study, we focused on this autoregulation and identified the promoter element required for it. An electrophoretic mobility shift assay indicated that the octamer-binding protein 1 (Oct-1) bound to this element. Mutations in the octamer-binding motif resulted in refractoriness of the ORF50/Lyta promoter to transactivation by ORF50/Lyta, and Oct-1 expression enhanced this transactivation. These results suggest that the autoregulation of ORF50/Lyta is mediated by Oct-1.

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Standish, Alistair J., Jonathan J. Whittall, and Renato Morona. "Tyrosine phosphorylation enhances activity of pneumococcal autolysin LytA." Microbiology 160, no. 12 (December 1, 2014): 2745–54. http://dx.doi.org/10.1099/mic.0.080747-0.

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Tyrosine phosphorylation has long been recognized as a crucial post-translational regulatory mechanism in eukaryotes. However, only in the past decade has recognition been given to the crucial importance of bacterial tyrosine phosphorylation as an important regulatory feature of pathogenesis. This study describes the effect of tyrosine phosphorylation on the activity of a major virulence factor of the pneumococcus, the autolysin LytA, and a possible connection to the Streptococcus pneumoniae capsule synthesis regulatory proteins (CpsB, CpsC and CpsD). We show that in vitro pneumococcal tyrosine kinase, CpsD, and the protein tyrosine phosphatase, CpsB, act to phosphorylate and dephosphorylate LytA. Furthermore, this modulates LytA function in vitro with phosphorylated LytA binding more strongly to the choline analogue DEAE. A phospho-mimetic (Y264E) mutation of the LytA phosphorylation site displayed similar phenotypes as well as an enhanced dimerization capacity. Similarly, tyrosine phosphorylation increased LytA amidase activity, as evidenced by a turbidometric amidase activity assay. Similarly, when the phospho-mimetic mutation was introduced in the chromosomal lytA of S. pneumoniae, autolysis occurred earlier and at an enhanced rate. This study thus describes, to our knowledge, the first functional regulatory effect of tyrosine phosphorylation on a non-capsule-related protein in the pneumococcus, and suggests a link between the regulation of LytA-dependent autolysis of the cell and the biosynthesis of capsular polysaccharide.

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Rodríguez-Cerrato, Violeta, Pedro García, Lorena Huelves, Ernesto García, Gema del Prado, Matilde Gracia, Carmen Ponte, Rubens López, and Francisco Soriano. "Pneumococcal LytA Autolysin, a Potent Therapeutic Agent in Experimental Peritonitis-Sepsis Caused by Highly β-Lactam-Resistant Streptococcus pneumoniae." Antimicrobial Agents and Chemotherapy 51, no. 9 (June 18, 2007): 3371–73. http://dx.doi.org/10.1128/aac.00137-07.

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ABSTRACT The in vitro and in vivo antipneumococcal activities of the main pneumococcal autolysin (LytA) and Cpl-1, a lysozyme encoded by phage Cp-1, were studied. Intraperitoneal therapy with LytA or high-dose Cpl-1 remarkably reduced peritoneal bacterial counts (>5 log10 CFU/ml) compared with those for the controls. After intravenous injection, LytA was the most effective treatment.

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Ramos-Sevillano, Elisa, Ana Urzainqui, Susana Campuzano, Miriam Moscoso, Fernando González-Camacho, Mirian Domenech, Santiago Rodríguez de Córdoba, et al. "Pleiotropic Effects of Cell Wall Amidase LytA on Streptococcus pneumoniae Sensitivity to the Host Immune Response." Infection and Immunity 83, no. 2 (November 17, 2014): 591–603. http://dx.doi.org/10.1128/iai.02811-14.

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The complement system is a key component of the host immune response for the recognition and clearance ofStreptococcus pneumoniae. In this study, we demonstrate that the amidase LytA, the main pneumococcal autolysin, inhibits complement-mediated immunity independently of effects on pneumolysin by a complex process of impaired complement activation, increased binding of complement regulators, and direct degradation of complement C3. The use of human sera depleted of either C1q or factor B confirmed that LytA prevented activation of both the classical and alternative pathways, whereas pneumolysin inhibited only the classical pathway. LytA prevented binding of C1q and the acute-phase protein C-reactive protein toS. pneumoniae, thereby reducing activation of the classical pathway on the bacterial surface. In addition, LytA increased recruitment of the complement downregulators C4BP and factor H to the pneumococcal cell wall and directly cleaved C3b and iC3b to generate degradation products. As a consequence, C3b deposition and phagocytosis increased in the absence of LytA and were markedly enhanced for thelytA plydouble mutant, confirming that a combination of LytA and Ply is essential for the establishment of pneumococcal pneumonia and sepsis in a murine model of infection. These data demonstrate that LytA has pleiotropic effects on complement activation, a finding which, in combination with the effects of pneumolysin on complement to assist with pneumococcal complement evasion, confirms a major role of both proteins for the full virulence of the microorganism during septicemia.

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Suzuki, Nao, Mayumi Yuyama, Sinsaku Maeda, Haruhiko Ogawa, Kazuyuki Mashiko, and Yusuke Kiyoura. "Genotypic identification of presumptive Streptococcus pneumoniae by PCR using four genes highly specific for S. pneumoniae." Journal of Medical Microbiology 55, no. 6 (June 1, 2006): 709–14. http://dx.doi.org/10.1099/jmm.0.46296-0.

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It was previously reported that two oligonucleotide primer sets (spn9802 and spn9828) for discriminating Streptococcus pneumoniae from pneumococcus-like oral streptococcal isolates using PCR had been developed. In this study, PCR amplification of the lytA, ply, spn9802 and spn9828 genes was used to identify presumptive S. pneumoniae. Two genetic groups were identified by analysing sputum samples from 28 patients with community-acquired pneumonia: the lytA-positive, ply-positive, spn9802-positive and spn9828-negative group, and the lytA-positive, ply-positive, spn9802-positive and spn9828-positive group. Isolates of the former group were resistant to optochin, while those of the latter group showed susceptibility to optochin. The lytA-positive, ply-positive, spn9802-negative and spn9828-negative isolates, and lytA-positive, ply-positive, spn9802-negative and spn9828-positive isolates, were not detected in sputum from patients with pneumonia. Subsequently, a total of 92 saliva samples from healthy individuals was screened by PCR using these primer sets. The lytA-positive, ply-positive, spn9802-positive and spn9828-negative group was identified more frequently in saliva from healthy children than in saliva from older healthy individuals and patients with pneumonia. The lytA-positive, ply-positive, spn9802-positive and spn9828-positive group was found frequently in saliva from healthy children, and in saliva and sputum from patients with pneumonia. This study demonstrates a rapid, optimal screening method for the genotypic identification of presumptive S. pneumoniae by PCR using four genes highly specific for S. pneumoniae.

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Romero, Patricia, Rubens López, and Ernesto García. "Characterization of LytA-Like N-Acetylmuramoyl-l-Alanine Amidases from Two New Streptococcus mitis Bacteriophages Provides Insights into the Properties of the Major Pneumococcal Autolysin." Journal of Bacteriology 186, no. 24 (December 15, 2004): 8229–39. http://dx.doi.org/10.1128/jb.186.24.8229-8239.2004.

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ABSTRACT Two new temperate bacteriophages exhibiting a Myoviridae (φB6) and a Siphoviridae (φHER) morphology have been isolated from Streptococcus mitis strains B6 and HER 1055, respectively, and partially characterized. The lytic phage genes were overexpressed in Escherichia coli, and their encoded proteins were purified. The lytA HER and lytA B6 genes are very similar (87% identity) and appeared to belong to the group of the so-called typical LytA amidases (atypical LytA displays a characteristic two-amino-acid deletion signature). although they exhibited several differential biochemical properties with respect to the pneumococcal LytA, e.g., they were inhibited in vitro by sodium deoxycholate and showed a more acidic pH for optimal activity. However, and in sharp contrast with the pneumococcal LytA, a short dialysis of LytAHER or LytAB6 resulted in reversible deconversion to the low-activity state (E-form) of the fully active phage amidases (C-form). Comparison of the amino acid sequences of LytAHER and LytAB6 with that of the pneumococcal amidase suggested that Val317 might be responsible for at least some of the peculiar properties of S. mitis phage enzymes. Site-directed mutagenesis that changed Val317 in the pneumococcal LytA amidase to a Thr residue (characteristic of LytAB6 and LytAHER) produced a fully active pneumococcal enzyme that differs from the parental one only in that the mutant amidase can reversibly recover the low-activity E-form upon dialysis. This is the first report showing that a single amino acid residue is involved in the conversion process of the major S. pneumoniae autolysin. Our results also showed that some lysogenic S. mitis strains possess a lytA-like gene, something that was previously thought to be exclusive to Streptococcus pneumoniae. Moreover, the newly discovered phage lysins constitute a missing link between the typical and atypical pneumococcal amidases known previously.

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Yamamoto, Hiroki, Shin-ichirou Kurosawa, and Junichi Sekiguchi. "Localization of the Vegetative Cell Wall Hydrolases LytC, LytE, and LytF on the Bacillus subtilis Cell Surface and Stability of These Enzymes to Cell Wall-Bound or Extracellular Proteases." Journal of Bacteriology 185, no. 22 (November 15, 2003): 6666–77. http://dx.doi.org/10.1128/jb.185.22.6666-6677.2003.

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ABSTRACT LytF, LytE, and LytC are vegetative cell wall hydrolases in Bacillus subtilis. Immunofluorescence microscopy showed that an epitope-tagged LytF fusion protein (LytF-3xFLAG) in the wild-type background strain was localized at cell separation sites and one of the cell poles of rod-shaped cells during vegetative growth. However, in a mutant lacking both the cell surface protease WprA and the extracellular protease Epr, the fusion protein was observed at both cell poles in addition to cell separation sites. This suggests that LytF is potentially localized at cell separation sites and both cell poles during vegetative growth and that WprA and Epr are involved in LytF degradation. The localization pattern of LytE-3xFLAG was very similar to that of LytF-3xFLAG during vegetative growth. However, especially in the early vegetative growth phase, there was a remarkable difference between the shape of cells expressing LytE-3xFLAG and the shape of cells expressing LytF-3xFLAG. In the case of LytF-3xFLAG, it seemed that the signals in normal rod-shaped cells were stronger than those in long-chain cells. In contrast, the reverse was found in the case of LytE-3xFLAG. This difference may reflect the dependence on different sigma factors for gene expression. The results support and extend the previous finding that LytF and LytE are cell-separating enzymes. On the other hand, we observed that cells producing LytC-3xFLAG are uniformly coated with the fusion protein after the middle of the exponential growth phase, which supports the suggestion that LytC is a major autolysin that is not associated with cell separation.

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Eldholm, Vegard, Beatrice Gutt, Ola Johnsborg, Reinhold Brückner, Patrick Maurer, Regine Hakenbeck, Thorsten Mascher, and Leiv Sigve Håvarstein. "The Pneumococcal Cell Envelope Stress-Sensing System LiaFSR Is Activated by Murein Hydrolases and Lipid II-Interacting Antibiotics." Journal of Bacteriology 192, no. 7 (January 29, 2010): 1761–73. http://dx.doi.org/10.1128/jb.01489-09.

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ABSTRACT In the Firmicutes, two-component regulatory systems of the LiaSR type sense and orchestrate the response to various agents that perturb cell envelope functions, in particular lipid II cycle inhibitors. In the current study, we found that the corresponding system in Streptococcus pneumoniae displays similar properties but, in addition, responds to cell envelope stress elicited by murein hydrolases. During competence for genetic transformation, pneumococci attack and lyse noncompetent siblings present in the same environment. This phenomenon, termed fratricide, increases the efficiency of horizontal gene transfer in vitro and is believed to stimulate gene exchange also under natural conditions. Lysis of noncompetent target cells is mediated by the putative murein hydrolase CbpD, the key effector of the fratricide mechanism, and the autolysins LytA and LytC. To avoid succumbing to their own lysins, competent attacker cells must possess a protective mechanism rendering them immune. The most important component of this mechanism is ComM, an integral membrane protein of unknown function that is expressed only in competent cells. Here, we show that a second layer of self-protection is provided by the pneumococcal LiaFSR system, which senses the damage inflicted to the cell wall by CbpD, LytA, and LytC. Two members of the LiaFSR regulon, spr0810 and PcpC (spr0351), were shown to contribute to the LiaFSR-coordinated protection against fratricide-induced self-lysis.

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Whatmore, Adrian M., and Christopher G. Dowson. "The Autolysin-Encoding Gene (lytA) ofStreptococcus pneumoniae Displays Restricted Allelic Variation despite Localized Recombination Events with Genes of Pneumococcal Bacteriophage Encoding Cell Wall Lytic Enzymes." Infection and Immunity 67, no. 9 (September 1, 1999): 4551–56. http://dx.doi.org/10.1128/iai.67.9.4551-4556.1999.

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ABSTRACT The lytA-encoded autolysin (N-acetylmuramoyl-l-alanine amidase) ofStreptococcus pneumoniae is believed to play an important role in the pathogenesis of pneumococcal infection and has been identified as a putative vaccine target. Allelic diversity oflytA in an extensive collection of clinical isolates was assessed by restriction fragment length polymorphism and confirmatory sequencing studies. Genetic diversity within lytA is limited, especially compared to the high levels of diversity seen in other pneumococcal virulence factor genes, although small blocks generating mosaic structure were identified. Sequence comparisons with genes encoding cell wall lytic enzymes of pneumococcal bacteriophage suggest that localized recombination events have occurred between hostlytA and these bacteriophage genes. These results confirm earlier suggestions that recombination between DNA encoding bacteriophage autolytic enzymes and chromosomally encodedlytA might be important in the evolution oflytA. The implications of these findings for understanding the evolution of lytA and the potential utility of LytA as a vaccine target are discussed.

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MAESTRO, Beatriz, and Jesús M. SANZ. "Accumulation of partly folded states in the equilibrium unfolding of the pneumococcal choline-binding module C-LytA." Biochemical Journal 387, no. 2 (April 5, 2005): 479–88. http://dx.doi.org/10.1042/bj20041194.

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Choline-binding modules are present in some virulence factors and many other proteins of Streptococcus pneumoniae (Pneumococcus). The most extensively studied choline-binding module is C-LytA, the C-terminal moiety of the pneumococcal cell-wall amidase LytA. The three-dimensional structure of C-LytA is built up from six loop-hairpin structures forming a left-handed β-solenoid with four choline-binding sites. The affinity of C-LytA for choline and other structural analogues allows its use as an efficient fusion tag for single-step purification of hybrid proteins. In the present study, we characterize the folding and stability of C-LytA by chemical and thermal equilibrium denaturation experiments. Unfolding experiments using guanidinium chloride at pH 7.0 and 20 °C suggest the existence of two partly folded states (I1 and I2) in the following model: N (native)→I1⇆I2. The N→I1 transition is non-co-operative and irreversible, and is significant even in the absence of a denaturant. In contrast, the I1⇆I2 transition is co-operative and reversible, with an associated freeenergy change (ΔG0) of 30.9±0.8 kJ·mol−1. The residual structure in the I2 state is unusually stable even in 7.4 M guanidinium chloride. Binding of choline stabilizes the structure of the native state, induces its dimerization and prevents the accumulation of the I1 species ([N]2⇆[I2]2, ΔG0=50.1±0.8 kJ·mol−1). Fluorescence and CD measurements, gel-filtration chromatography and limited proteolysis suggest that I1 differs from N in the local unfolding of the N-terminal β-hairpins, and that I2 has a residual structure in the C-terminal region. Thermal denaturation of C-LytA suggests the accumulation of at least the I1 species. These results might pave the way for an effective improvement of its biotechnological applications by protein engineering.

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Ramos-Sevillano, Elisa, Cinthya Rodríguez-Sosa, Roberto Díez-Martínez, María-José Giménez, Eduardo Olmedillas, Pedro García, Ernesto García, Lorenzo Aguilar, and Jose Yuste. "Macrolides and β-Lactam Antibiotics Enhance C3b Deposition on the Surface of Multidrug-Resistant Streptococcus pneumoniae Strains by a LytA Autolysin-Dependent Mechanism." Antimicrobial Agents and Chemotherapy 56, no. 11 (August 13, 2012): 5534–40. http://dx.doi.org/10.1128/aac.01470-12.

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ABSTRACTThe emergence ofStreptococcus pneumoniaestrains displaying high levels of multidrug resistance is of great concern worldwide and a serious threat for the outcome of the infection. Modifications of the bacterial envelope by antibiotics may assist the recognition and clearance of the pathogen by the host immune system. Recognition ofS. pneumoniaeresistant strains by the complement component C3b was increased in the presence of specific anti-pneumococcal antibodies and subinhibitory concentrations of different macrolides and β-lactam antibiotics for all the strains investigated. However, C3b levels were unchanged in the presence of serum containing specific antibodies and sub-MICs of levofloxacin. To investigate whether LytA, the main cell wall hydrolase ofS. pneumoniae, might be involved in this process,lytA-deficient mutants were constructed. In the presence of antibiotics, loss of LytA was not associated with enhanced C3b deposition on the pneumococcal surface, which confirms the importance of LytA in this interaction. The results of this study offer new insights into the development of novel therapeutic strategies using certain antibiotics by increasing the efficacy of the host immune response to efficiently recognize pneumococcal resistant strains.

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Domenech, Mirian, Ernesto García, and Miriam Moscoso. "In VitroDestruction of Streptococcus pneumoniae Biofilms with Bacterial and Phage Peptidoglycan Hydrolases." Antimicrobial Agents and Chemotherapy 55, no. 9 (July 11, 2011): 4144–48. http://dx.doi.org/10.1128/aac.00492-11.

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ABSTRACTHost- and phage-coded cell wall hydrolases have been used to fightStreptococcus pneumoniaegrowing as planktonic cellsin vitroas well as in animal models. Until now, however, the usefulness of these enzymes in biofilm-grown pneumococci has gone untested. The antipneumococcal activity of different cell wall hydrolases produced byS. pneumoniaeand a number of its phages was examined in anin vitrobiofilm model. The major pneumococcal autolysin LytA, anN-acetylmuramoyl-l-alanine amidase, showed the greatest efficiency in disintegratingS. pneumoniaebiofilms. The phage-encoded lysozymes Cpl-1 and Cpl-7 were also very efficient. Biofilms formed by the close pneumococcal relativesStreptococcus pseudopneumoniaeandStreptococcus oraliswere also destroyed by the phage endolysins but not by theS. pneumoniaeautolysin LytA. A cooperative effect of LytA and Cpl-1 in the disintegration ofS. pneumoniaebiofilms was recorded.

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Frias, Maria João, José Melo-Cristino, and Mário Ramirez. "The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus pneumoniae." Journal of Bacteriology 191, no. 17 (July 6, 2009): 5428–40. http://dx.doi.org/10.1128/jb.00477-09.

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ABSTRACT Most bacteriophages (phages) release their progeny through the action of holins that form lesions in the cytoplasmic membrane and lysins that degrade the bacterial peptidoglycan. Although the function of each protein is well established in phages infecting Streptococcus pneumoniae, the role—if any—of the powerful bacterial autolysin LytA in virion release is currently unknown. In this study, deletions of the bacterial and phage lysins were done in lysogenic S. pneumoniae strains, allowing the evaluation of the contribution of each lytic enzyme to phage release through the monitoring of bacterial-culture lysis and phage plaque assays. In addition, we assessed membrane integrity during phage-mediated lysis using flow cytometry to evaluate the regulatory role of holins over the lytic activities. Our data show that LytA is activated at the end of the lytic cycle and that its triggering results from holin-induced membrane permeabilization. In the absence of phage lysin, LytA is able to mediate bacterial lysis and phage release, although exclusive dependence on the autolysin results in reduced virion egress and altered kinetics that may impair phage fitness. Under normal conditions, activation of bacterial LytA, together with the phage lysin, leads to greater phage progeny release. Our findings demonstrate that S. pneumoniae phages use the ubiquitous host autolysin to accomplish an optimal phage exiting strategy.

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Ramirez, Mario, Elena Severina, and Alexander Tomasz. "A High Incidence of Prophage Carriage among Natural Isolates of Streptococcus pneumoniae." Journal of Bacteriology 181, no. 12 (June 15, 1999): 3618–25. http://dx.doi.org/10.1128/jb.181.12.3618-3625.1999.

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ABSTRACT The majority (591 of 791, or 76%) of Streptococcus pneumoniae clinical isolates examined showed the presence of two or more chromosomal SmaI fragments that hybridized with thelytA-specific DNA probe. Only one of these fragments, frequently having an approximate molecular size of 90 kb, was shown to carry the genetic determinant of the pneumococcal autolysin (N-acetylmuramic acid-l-alanine amidase). Strains carrying multiple copies of lytA homologues included both antibiotic-susceptible and -resistant isolates as well as a number of different serotypes and strains recovered from geographic sites on three continents. Mitomycin C treatment of strains carrying several lytA-hybridizing fragments caused the appearance of extrachromosomal DNA hybridizing to the lytA gene, followed by lysis of the bacteria. Such lysates contained phage particles detectable by electron microscopy. The findings suggest that thelytA-hybridizing fragments in excess of the hostlytA represent components of pneumococcal bacteriophages. The high proportion of clinical isolates carrying multiple copies oflytA indicates the widespread occurrence of lysogeny, which may contribute to genetic variation in natural populations of pneumococci.

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Olivares, Alma. "pep27 and lytA in Vancomycin-Tolerant Pneumococci." Journal of Microbiology and Biotechnology 21, no. 12 (December 28, 2011): 1345–51. http://dx.doi.org/10.4014/jmb.1105.05045.

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Moscoso, Miriam, Ernesto García, and Rubens López. "Biofilm Formation by Streptococcus pneumoniae: Role of Choline, Extracellular DNA, and Capsular Polysaccharide in Microbial Accretion." Journal of Bacteriology 188, no. 22 (August 25, 2006): 7785–95. http://dx.doi.org/10.1128/jb.00673-06.

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ABSTRACTStreptococcus pneumoniaecolonizes the human upper respiratory tract, and this asymptomatic colonization is known to precede pneumococcal disease. In this report, chemically defined and semisynthetic media were used to identify the initial steps of biofilm formation by pneumococcus during growth on abiotic surfaces such as polystyrene or glass. Unencapsulated pneumococci adhered to abiotic surfaces and formed a three-dimensional structure about 25 μm deep, as observed by confocal laser scanning microscopy and low-temperature scanning electron microscopy. Choline residues of cell wall teichoic acids were found to play a fundamental role in pneumococcal biofilm development. The role in biofilm formation of choline-binding proteins, which anchor to the teichoic acids of the cell envelope, was determined using unambiguously characterized mutants. The results showed that LytA amidase, LytC lysozyme, LytB glucosaminidase, CbpA adhesin, PcpA putative adhesin, and PspA (pneumococcal surface protein A) mutants had a decreased capacity to form biofilms, whereas no such reduction was observed in Pce phosphocholinesterase or CbpD putative amidase mutants. Moreover, encapsulated, clinical pneumococcal isolates were impaired in their capacity to form biofilms. In addition, a role for extracellular DNA and proteins in the establishment ofS. pneumoniaebiofilms was demonstrated. Taken together, these observations provide information on conditions that favor the sessile mode of growth byS. pneumoniae. The experimental approach described here should facilitate the study of bacterial genes that are required for biofilm formation. Those results, in turn, may provide insight into strategies to prevent pneumococcal colonization of its human host.

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Berry, Anne M., and James C. Paton. "Additive Attenuation of Virulence ofStreptococcus pneumoniae by Mutation of the Genes Encoding Pneumolysin and Other Putative Pneumococcal Virulence Proteins." Infection and Immunity 68, no. 1 (January 1, 2000): 133–40. http://dx.doi.org/10.1128/iai.68.1.133-140.2000.

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ABSTRACT Although the polysaccharide capsule of Streptococcus pneumoniae has been recognized as a sine qua non of virulence, much recent attention has focused on the role of pneumococcal proteins in pathogenesis, particularly in view of their potential as vaccine antigens. The individual contributions of pneumolysin (Ply), the major neuraminidase (NanA), autolysin (LytA), hyaluronidase (Hyl), pneumococcal surface protein A (PspA), and choline-binding protein A (CbpA) have been examined by specifically mutagenizing the respective genes in the pneumococcal chromosome and comparing the impact on virulence in a mouse intraperitoneal challenge model. Mutagenesis of either the ply, lytA, or pspA gene in S. pneumoniae D39 significantly reduced virulence, relative to that of the wild-type strain, indicating that the respective gene products contribute to pathogenesis. On the other hand, mutations in nanA, hyl, or cbpA had no significant impact. The virulence of D39 derivatives carrying aply deletion mutation as well as an insertion-duplication mutation in one of the other genes was also examined. Mutagenesis of either nanA or lytA did not result in an additional attenuation of virulence in the ply deletion background. However, significant additive attenuation in virulence was observed for the strains with ply-hyl,ply-pspA, and ply-cbpA double mutations.

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Chen, Rui, Sarah B. Guttenplan, Kris M. Blair, and Daniel B. Kearns. "Role of the σD-Dependent Autolysins in Bacillus subtilis Population Heterogeneity." Journal of Bacteriology 191, no. 18 (June 19, 2008): 5775–84. http://dx.doi.org/10.1128/jb.00521-09.

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ABSTRACT Exponentially growing populations of Bacillus subtilis contain two morphologically and functionally distinct cell types: motile individuals and nonmotile multicellular chains. Motility differentiation arises because RNA polymerase and the alternative sigma factor σD activate expression of flagellin in a subpopulation of cells. Here we demonstrate that the peptidoglycan-remodeling autolysins under σD control, LytC, LytD, and LytF, are expressed in the same subpopulation of cells that complete flagellar synthesis. Morphological heterogeneity is explained by the expression of LytF that is necessary and sufficient for cell separation. Moreover, LytC is required for motility but not at the level of cell separation or flagellum biosynthesis. Rather, LytC appears to be important for flagellar function, and motility was restored to a LytC mutant by mutation of either lonA, encoding the LonA protease, or a gene encoding a previously unannotated swarming motility inhibitor, SmiA. We conclude that heterogeneous activation of σD-dependent gene expression is sufficient to explain both the morphological heterogeneity and functional heterogeneity present in vegetative B. subtilis populations.

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Li, Qiong, Wang Cheng, Cécile Morlot, Xiao-Hui Bai, Yong-Liang Jiang, Wenjia Wang, David I. Roper, et al. "Full-length structure of the major autolysin LytA." Acta Crystallographica Section D Biological Crystallography 71, no. 6 (May 23, 2015): 1373–81. http://dx.doi.org/10.1107/s1399004715007403.

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LytA is responsible for the autolysis of manyStreptococcusspecies, including pathogens such asS. pneumoniae,S. pseudopneumoniaeandS. mitis. However, how this major autolysin achieves full activity remains unknown. Here, the full-length structure of theS. pneumoniaeLytA dimer is reported at 2.1 Å resolution. Each subunit has an N-terminal amidase domain and a C-terminal choline-binding domain consisting of six choline-binding repeats, which form five canonical and one single-layered choline-binding sites. Site-directed mutageneses combined with enzymatic activity assays indicate that dimerization and binding to choline are two independent requirements for the autolytic activity of LytAin vivo. Altogether, it is suggested that dimerization and full occupancy of all choline-binding sites through binding to choline-containing TA chains enable LytA to adopt a fully active conformation which allows the amidase domain to cleave two lactyl-amide bonds located about 103 Å apart on the peptidoglycan.

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Martner, Anna, Claes Dahlgren, James C. Paton, and Agnes E. Wold. "Pneumolysin Released during Streptococcus pneumoniae Autolysis Is a Potent Activator of Intracellular Oxygen Radical Production in Neutrophils." Infection and Immunity 76, no. 9 (June 16, 2008): 4079–87. http://dx.doi.org/10.1128/iai.01747-07.

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ABSTRACT Streptococcus pneumoniae is a major cause of otitis media, pneumonia, meningitis, and septicemia in humans. The host defense against this pathogen largely depends on bacterial killing by neutrophils. A peculiar property of pneumococci is their tendency to undergo autolysis, i.e., autoinduced disruption of the bacterial cell wall mediated by activation of the enzyme LytA, under stationary growth conditions. LytA is a virulence factor, but the molecular background for this has not been fully clarified. Here we examine how bacterial compounds released upon autolysis affect the production of reactive oxygen species (ROS) in neutrophils. We found that the S. pneumoniae strains A17 and D39 induced activation of the NADPH oxidase and the production of ROS in human neutrophils and that this activation was blocked when LytA was inactivated. The ROS-inducing bacterial substance released from autolyzed bacteria was identified as the cytoplasmic toxin pneumolysin. Further screening of clinical pneumococcal strains of various sero- and genotypes revealed that selected strains expressing toxins with reduced pneumolysin-dependent hemolytic activity had decreased abilities to induce ROS in neutrophils. Furthermore, a mutated form of purified pneumolysin lacking hemolytic and complement binding functions (PdT) did not induce any oxygen radical production. The ROS produced in response to pneumolysin formed mainly intracellularly, which may explain why this production was not detected previously. ROS released intracellularly may function as signaling molecules, modifying the function of neutrophils in bacterial defense.

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Simões, Alexandra S., Débora A. Tavares, Dora Rolo, Carmen Ardanuy, Herman Goossens, Birgitta Henriques-Normark, Josefina Linares, Hermínia de Lencastre, and Raquel Sá-Leão. "lytA-based identification methods can misidentify Streptococcus pneumoniae." Diagnostic Microbiology and Infectious Disease 85, no. 2 (June 2016): 141–48. http://dx.doi.org/10.1016/j.diagmicrobio.2016.03.018.

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Bon, Jon, Nagraj Mani, and R. K. Jayaswal. "Molecular analysis of lytic genes of bacteriophage 80α ofStaphylococcus aureus." Canadian Journal of Microbiology 43, no. 7 (July 1, 1997): 612–16. http://dx.doi.org/10.1139/m97-087.

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Nucleotide sequencing of a 3779-bp fragment of the Staphylococcus aureus bacteriophage 80α revealed two open reading frames: ORF1, designated as lytA, which encodes a polypeptide of 481 amino acids with an apparent Mrof 53.81 kDa; and ORF2, designated as holin, which encodes for a hydrophobic polypeptide of 145 amino acids with an apparent Mrof 15.58 kDa and exhibits two putative transmembrane helices. Both genes showed 100% sequence homology to that of the peptidoglycan hydrolase and holin genes of the S. aureus phage [Formula: see text] reported earlier. In addition, the downstream sequences of the lytA gene were homologous to the phage attachment site (attP) of the phage [Formula: see text]. Based on our data we propose that the lytic system of the phage 80α evolved from that of phage [Formula: see text].Key words: attachment site, bacteriophage 80α, holin, peptidoglycan hydrolase, Staphylococcus aureus.

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Hutabarat, Mustika Sari, Firdaus Hamid, Irawaty Djaharuddin, Alfian Zainuddin, Rossana Agus, and Muhammad Nassrum Massi. "Detection of LytA Genes in Streptococcus pneumoniae Isolated from sputum pneumonia patients." Biomedika 13, no. 1 (July 9, 2020): 23–30. http://dx.doi.org/10.31001/biomedika.v13i1.718.

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Streptococcus pneumoniae (pneumococcus) is a Gram-positive facultative anaerobic bacterium that is a major cause of morbidity and mortality worldwide. But the lack of reporting of disease by this bacterium in Indonesia, one of the causes is because the diagnosis of pneumococcal infection is often clinically not typical and conventional methods which are still the standard gold method often give false-negative results. So the purpose of this study was to evaluate the performance of culture and molecular diagnostic methods using the Polymerase Chain Reaction (PCR) technique in detecting Streptococcus pneumoniae in sputum clinical samples using the Autolysin (LytA) gene which is a virulence factor of this bacterium. 57 isolates from 60 samples were confirmed as Streptococcus sp through microscopic identification, culture, and biochemical tests. Then the sensitivity test with an optochin test of 9 (9%) compared the results descriptively with the PCR technique using the Autolysin A (LytA) gene which was obtained more sensitive by 15 (25%).

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Monterroso, Begoña, Consuelo López-Zumel, José L. García, José L. Sáiz, Pedro García, Nuria E. Campillo, and Margarita Menéndez. "Unravelling the structure of the pneumococcal autolytic lysozyme." Biochemical Journal 391, no. 1 (September 26, 2005): 41–49. http://dx.doi.org/10.1042/bj20050612.

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The LytC lysozyme of Streptococcus pneumoniae forms part of the autolytic system of this important pathogen. This enzyme is composed of a C-terminal CM (catalytic module), belonging to the GH25 family of glycosyl hydrolases, and an N-terminal CBM (choline-binding module), made of eleven homologous repeats, that specifically recognizes the choline residues that are present in pneumococcal teichoic and lipoteichoic acids. This arrangement inverts the general assembly pattern of the major pneumococcal autolysin, LytA, and the lytic enzymes encoded by pneumococcal bacteriophages that place the CBM (made of six repeats) at the C-terminus. In the present paper, a three-dimensional model of LytC built by homology modelling of each module and consistent with spectroscopic and hydrodynamic studies is shown. In addition, the putative catalytic-pair residues are identified. Despite the inversion in the modular arrangement, LytC and the bacteriophage-encoded Cpl-1 lysozyme most probably adopt a similar global fold. However, the distinct choline-binding ability and their substrate-binding surfaces may reflect a divergent evolution directed by the different roles played by them in the host (LytC) or in the bacteriophage (Cpl-1). The tight binding of LytC to the pneumococcal envelope, mediated by the acquisition of additional choline-binding repeats, could facilitate the regulation of the potentially suicidal activity of this autolysin. In contrast, a looser attachment of Cpl-1 to the cell wall and the establishment of more favourable interactions between its highly negatively charged catalytic surface and the positively charged chains of pneumococcal murein could enhance the lytic activity of the parasite-encoded enzyme and therefore liberation of the phage progeny.

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Llull, Daniel, Luis Rivas, and Ernesto García. "In Vitro Bactericidal Activity of the Antiprotozoal Drug Miltefosine against Streptococcus pneumoniae and Other Pathogenic Streptococci." Antimicrobial Agents and Chemotherapy 51, no. 5 (March 12, 2007): 1844–48. http://dx.doi.org/10.1128/aac.01428-06.

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ABSTRACT Miltefosine (hexadecylphosphocholine), the first oral drug against visceral leishmaniasis, triggered pneumococcal autolysis at concentrations higher than 2.5 μM. Bactericidal activity was also observed in cultures of other streptococci, although these failed to undergo lysis. The autolysis elicited by miltefosine can be attributed to triggering of the pneumococcal autolysin LytA.

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Morales, María, Pedro García, Adela G. de la Campa, Josefina Liñares, Carmen Ardanuy, and Ernesto García. "Evidence of Localized Prophage-Host Recombination in the lytA Gene, Encoding the Major Pneumococcal Autolysin." Journal of Bacteriology 192, no. 10 (March 19, 2010): 2624–32. http://dx.doi.org/10.1128/jb.01501-09.

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ABSTRACT According to a highly polymorphic region in the lytA gene, encoding the major autolysin of Streptococcus pneumoniae, two different families of alleles can be differentiated by PCR and restriction digestion. Here, we provide evidence that this polymorphic region arose from recombination events with homologous genes of pneumococcal temperate phages.

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Whatmore, Adrian M., Samantha J. King, Neil C. Doherty, Daniel Sturgeon, Neil Chanter, and Christopher G. Dowson. "Molecular Characterization of Equine Isolates ofStreptococcus pneumoniae: Natural Disruption of Genes Encoding the Virulence Factors Pneumolysin and Autolysin." Infection and Immunity 67, no. 6 (June 1, 1999): 2776–82. http://dx.doi.org/10.1128/iai.67.6.2776-2782.1999.

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ABSTRACT Although often considered a strict human pathogen,Streptococcus pneumoniae has been reported to infect and cause pneumonia in horses, although the pathology appears restricted compared to that of human infections. Here we report on the molecular characterization of a group of S. pneumoniae isolates obtained from horses in England and Ireland. Despite being obtained from geographically distinct locations, the isolates were found to represent a tight clonal group, virtually identical to each other but genetically distinguishable from more than 120 divergent isolates of human S. pneumoniae. A comprehensive analysis of known pneumococcal virulence determinants was undertaken in an attempt to understand the pathogenicity of equine pneumococci. Surprisingly, equine isolates appear to lack activities associated with both the hemolytic cytotoxin pneumolysin, often considered a major virulence factor of pneumococci, and the major autolysin gene lytA, also considered an important virulence factor. In support of phenotypic data, molecular studies demonstrated a deletion of parts of the coding sequences of both lytA and ply genes in equine pneumococci. The implications of these findings for the evolution and pathogenicity of equine S. pneumoniae are discussed.

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Thangamony, Helen Hencida, Ravindran Kumar, Chinnappan Palaniappan Thangavelu, Mani Mariappa, Berlin Grace Viswanathan Mariammal, and Kootallur Narayanan Brahmadathan. "Nonspecific Amplification of Human DNA by Streptococcus pneumoniae LytA Primer." Indian Journal of Medical Microbiology 36, no. 1 (January 2018): 65–69. http://dx.doi.org/10.4103/ijmm.ijmm_17_342.

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Mellroth, Peter, Robert Daniels, Alice Eberhardt, Daniel Rönnlund, Hans Blom, Jerker Widengren, Staffan Normark, and Birgitta Henriques-Normark. "LytA, Major Autolysin ofStreptococcus pneumoniae, Requires Access to Nascent Peptidoglycan." Journal of Biological Chemistry 287, no. 14 (February 9, 2012): 11018–29. http://dx.doi.org/10.1074/jbc.m111.318584.

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Rubin, Lorry G., and Atqia Rizvi. "PCR-based assays for detection of Streptococcus pneumoniae serotypes 3, 14, 19F and 23F in respiratory specimens." Journal of Medical Microbiology 53, no. 7 (July 1, 2004): 595–602. http://dx.doi.org/10.1099/jmm.0.45550-0.

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Current culture-based assays are insensitive for detection of simultaneous respiratory tract colonization by more than one pneumococcal serotype. Separate single-tube, nested PCR-based assays have been developed to detect Streptococcus pneumoniae serotypes 3, 14, 19F and 23F by amplifying unique DNA sequences in the capsular polysaccharide gene cluster of each serotype. Pairs of 27–32-base outer primers and 20–21-base inner primers and a 20–22-base probe were designed to amplify and detect a 200–221-base sequence by dot blotting using the labelled probe. Sensitivity of the assays was 0.01–10 fg using chromosomal DNA and ⩽ 1 viable cell using DNA extracted from exponential-phase bacteria. Each serotype-specific assay detected chromosomal DNA from all of five to ten clinical isolates of the homologous type and did not detect DNA sequences from any of 190–204 strains from 51–52 different serotypes or 28 non-pneumococcal bacterial strains. Sixteen throat swabs from children that had been cultured for S. pneumoniae were tested in PCR assays following DNA extraction. All of six that grew S. pneumoniae serotype 3, 14, 19F or 23F were positive in the PCR assay for the homologous serotype (and in a PCR assay for sequences in lytA, present in all pneumococci) and were negative in assays for other serotypes. Of eight culture-negative specimens in children not receiving antimicrobials, three were positive for both the lytA assay and an assay for one of the four serotypes, suggesting true positive results; in three others all five PCR assays were negative and, in the remaining two, the lytA assay was positive but each of the four assays for individual serotypes was negative, suggesting either false-positive results or presence of DNA sequences from an S. pneumoniae serotype other than 3, 14, 19F or 23F. These preliminary clinical data suggest that these PCR-based assays are sensitive and specific for detection of individual serotypes of pneumococci and may be used with respiratory tract specimens.

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Chi, Fang, Michaela Leider, Fabian Leendertz, Carina Bergmann, Christophe Boesch, Svenja Schenk, Georg Pauli, Heinz Ellerbrok, and Regine Hakenbeck. "New Streptococcus pneumoniae Clones in Deceased Wild Chimpanzees." Journal of Bacteriology 189, no. 16 (June 22, 2007): 6085–88. http://dx.doi.org/10.1128/jb.00468-07.

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ABSTRACT In wild chimpanzees in the Taï National Park, Côte d'Ivoire, sudden deaths which were preceded by respiratory problems had been observed since 1999. Two new clones of Streptococcus pneumoniae were identified in deceased apes on the basis of multilocus sequence typing analysis and ply, lytA, and pbp2x sequences. The findings suggest that virulent S. pneumoniae occurs in populations of wild chimpanzees with the potential to cause infections similar to those observed in humans.

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Hernandez-Rocamora, V. M., B. Maestro, A. Molla-Morales, and J. M. Sanz. "Rational stabilization of the C-LytA affinity tag by protein engineering." Protein Engineering Design and Selection 21, no. 12 (September 29, 2008): 709–20. http://dx.doi.org/10.1093/protein/gzn046.

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Hernández-Rocamora, Víctor M., Beatriz Maestro, Almudena Mollá-Morales, and Jesús M. Sanz. "Rational stabilization of the C-LytA affinity tag by protein engineering." Protein Engineering, Design and Selection 24, no. 6 (March 17, 2011): 531. http://dx.doi.org/10.1093/protein/gzr010.

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Roberts, Matthew, Tania Sadlon, and Geoff D. Higgins. "2135. Streptococcus pneumoniae DNA (lytA) Detection in Clinical Samples Sent for a Respiratory Viral Polymerase Chain Reaction: Is There Bacterial-Viral Association?" Open Forum Infectious Diseases 6, Supplement_2 (October 2019): S723. http://dx.doi.org/10.1093/ofid/ofz360.1815.

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Abstract Background Streptococcus pneumoniae (SPNEU) is a major cause of community-acquired pneumonia and frequently complicates respiratory viral infections. Clinical differentiation of viral and bacterial respiratory tract infection can be difficult, as can predicting which patients with respiratory viral infection will develop bacterial infection. A SPNEU polymerase chain reaction (PCR) to specific DNA region lytA may be able to determine which patients with viral infections may develop bacterial infection. Methods Stored nucleic acid extracts from clinical samples collected and tested for respiratory viral PCR (RVP) in 2015 and 2016 were tested for SPNEU lytA DNA using standard laboratory procedure. Analyses of demographic data, RVP and SPNEU PCR result were performed to determine relevant associations. Results 1581 stored clinical RVP samples were tested for SPNEU DNA with PCR to lytA, 1550 of these had complete RVP panel results available for analysis. RVP samples from patients 0–5 years old were more likely to have a viral or bacterial pathogen detected than > 5 years old (78% vs. 45%, P < 0.001). Of 1,550 samples analyzed with SPNEU PCR, 19% were positive for SPNEU, this was more likely in those 0–5 years old than > 5 years old (50% vs. 10%, P < 0.0001). In 0–5 years old, SPNEU was more frequently detected when multiple pathogens were detected on RVP vs. those with no pathogen (63% vs. 43%, P = 0.031). In > 5 years old, compared with no pathogen samples, the presence of multiple pathogens, any single pathogen, influenza, rhinovirus and Bordetella pertussis were significantly associated with higher SPNEU positivity rates. Median SPNEU PCR DNA load was higher in multiple pathogen and single pathogen samples than in no pathogen RVP samples. Conclusion We have demonstrated an association between common respiratory pathogens and detection of SPNEU DNA via PCR. This association is strongest in samples with multiple RVP pathogens, suggesting additional nasopharyngeal inflammation may contribute to SPNEU presence in the nasopharynx. Previous data have focused on those 0–5 years old, we have demonstrated an SPNEU-viral association in those > 5 years old. This tool may be clinically useful to determine which individuals with viral respiratory tract infection will progress to bacterial pneumonia and warrants further investigation. Disclosures All authors: No reported disclosures.

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Wyllie, Anne L., Yvonne Pannekoek, Sandra Bovenkerk, Jody van Engelsdorp Gastelaars, Bart Ferwerda, Diederik van de Beek, Elisabeth A. M. Sanders, Krzysztof Trzciński, and Arie van der Ende. "Sequencing of the variable region of rpsB to discriminate between Streptococcus pneumoniae and other streptococcal species." Open Biology 7, no. 9 (September 2017): 170074. http://dx.doi.org/10.1098/rsob.170074.

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The vast majority of streptococci colonizing the human upper respiratory tract are commensals, only sporadically implicated in disease. Of these, the most pathogenic is Mitis group member, Streptococcus pneumoniae . Phenotypic and genetic similarities between streptococci can cause difficulties in species identification. Using ribosomal S2-gene sequences extracted from whole-genome sequences published from 501 streptococci, we developed a method to identify streptococcal species. We validated this method on non-pneumococcal isolates cultured from cases of severe streptococcal disease ( n = 101) and from carriage ( n = 103), and on non-typeable pneumococci from asymptomatic individuals ( n = 17) and on whole-genome sequences of 1157 pneumococcal isolates from meningitis in the Netherlands. Following this, we tested 221 streptococcal isolates in molecular assays originally assumed specific for S. pneumoniae , targeting cpsA , lytA , piaB , ply , Spn9802, zmpC and capsule-type-specific genes. Cluster analysis of S2-sequences showed grouping according to species in line with published phylogenies of streptococcal core genomes. S2-typing convincingly distinguished pneumococci from non-pneumococcal species (99.2% sensitivity, 100% specificity). Molecular assays targeting regions of lytA and piaB were 100% specific for S. pneumoniae , whereas assays targeting cpsA , ply , Spn9802, zmpC and selected serotype-specific assays (but not capsular sequence typing) showed a lack of specificity. False positive results were over-represented in species associated with carriage, although no particular confounding signal was unique for carriage isolates.

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McCurdy, Sandra, Kara Keedy, Laura Lawrence, Amanda Sheets, and Megan Quintas. "2230. Analysis of the Microbiological Data from the Delafloxacin (DLX) Phase 3 Community-acquired Bacterial Pneumonia (CABP) Trial." Open Forum Infectious Diseases 6, Supplement_2 (October 2019): S761—S762. http://dx.doi.org/10.1093/ofid/ofz360.1908.

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Abstract Background DLX is a novel fluoroquinolone (FQ) antibiotic with Gram-positive/MRSA, Gram-negative and atypical activity. It offers IV and oral treatment with no QT restrictions. In a Phase 3 study in CABP patients, DLX was non-inferior to moxifloxacin (MOX) in the primary endpoint, early clinical response at 96 ± 24 hours (88.9 vs. 89.0; 95% CI: −4.4, 4.1) in the intent-to-treat (ITT) population. A detailed microbiological analysis was conducted. Methods CABP pathogens were identified by culture/non-culture methods. Pathogens identified by non-culture methods included Streptococcus pneumoniae (Sp; culture, urinary antigen [UA], nasopharyngeal [NP] swab lytA PCR), Legionella pneumophila (Lp) (culture, UA, serology), Mycoplasma pneumoniae (Mp; culture, serology), and Chlamydia pneumoniae (Cp; serology). All other pathogens were identified using culture only. For Sp cultured from NP, a concomitant lytA PCR value of ≥ 1000 gene copies/mL was required. All isolates underwent susceptibility testing, and a subset of isolates underwent molecular or phenotypic characterization including whole-genome sequencing for FQ resistance mechanisms, PCR for PVL/mecA genes (S. aureus), β-lactamases (Haemophilus/Moraxella spp), and serotyping (Sp). Results Included in submitted image. Conclusion DLX demonstrated potent in vitro and clinical activity against CABP pathogens, including Sp [MRSP, MDRSP, PRSP], MRSA, Haemophilus species, Enterobacteriaceae, P. aeruginosa, and the atypical pathogens Cp, Mp, and Lp. Disclosures All authors: No reported disclosures.

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Lewis, Kim. "Programmed Death in Bacteria." Microbiology and Molecular Biology Reviews 64, no. 3 (September 1, 2000): 503–14. http://dx.doi.org/10.1128/mmbr.64.3.503-514.2000.

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SUMMARY Programmed cell death (PCD) in bacteria plays an important role in developmental processes, such as lysis of the mother cell during sporulation of Bacillus subtilis and lysis of vegetative cells in fruiting body formation of Myxococcus xanthus. The signal transduction pathway leading to autolysis of the mother cell includes the terminal sporulation sigma factor EςK, which induces the synthesis of autolysins CwlC and CwlH. An activator of autolysin in this and other PCD processes is yet to be identified. Autolysis plays a role in genetic exchange in Streptococcus pneumoniae, and the gene for the major autolysin, lytA, is located in the same operon with recA. DNA from lysed cells is picked up by their neighbors and recombined into the chromosome by RecA. LytA requires an unknown activator controlled by a sensory kinase, VncS. Deletion of vncS inhibits autolysis and also decreases killing by unrelated antibiotics. This observation suggests that PCD in bacteria serves to eliminate damaged cells, similar to apoptosis of defective cells in metazoa. The presence of genes affecting survival without changing growth sensitivity to antibiotics (vncS, lytA, hipAB, sulA, and mar) indicates that bacteria are able to control their fate. Elimination of defective cells could limit the spread of a viral infection and donate nutrients to healthy kin cells. An altruistic suicide would be challenged by the appearance of asocial mutants without PCD and by the possibility of maladaptive total suicide in response to a uniformly present lethal factor or nutrient depletion. It is proposed that a low rate of mutation serves to decrease the probability that asocial mutants without PCD will take over the population. It is suggested that PCD is disabled in persistors, rare cells that are resistant to killing, to ensure population survival. It is suggested that lack of nutrients leads to the stringent response that suppresses PCD, producing a state of tolerance to antibiotics, allowing cells to discriminate between nutrient deprivation and unrepairable damage. High levels of persistors are apparently responsible for the extraordinary survival properties of bacterial biofilms, and genes affecting persistence appear to be promising targets for development of drugs aimed at eradicating recalcitrant infections. PCD in unicellular eukaryotes is also considered, including aging in Saccharomyces cerevisiae. Apoptosis-like elimination of defective cells in S. cerevisiae and protozoa suggests that all unicellular life forms evolved altruistic programmed death that serves a variety of useful functions.

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Regev-Yochay, Gili, Krzysztof Trzcinski, Claudette M. Thompson, Marc Lipsitch, and Richard Malley. "SpxB Is a Suicide Gene of Streptococcus pneumoniae and Confers a Selective Advantage in an In Vivo Competitive Colonization Model." Journal of Bacteriology 189, no. 18 (July 13, 2007): 6532–39. http://dx.doi.org/10.1128/jb.00813-07.

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ABSTRACT The human bacterial pathogen Streptococcus pneumoniae dies spontaneously upon reaching stationary phase. The extent of S. pneumoniae death at stationary phase is unusual in bacteria and has been conventionally attributed to autolysis by the LytA amidase. In this study, we show that spontaneous pneumococcal death is due to hydrogen peroxide (H2O2), not LytA, and that the gene responsible for H2O2 production (spxB) also confers a survival advantage in colonization. Survival of S. pneumoniae in stationary phase was significantly prolonged by eliminating H2O2 in any of three ways: chemically by supplementing the media with catalase, metabolically by growing the bacteria under anaerobic conditions, or genetically by constructing ΔspxB mutants that do not produce H2O2. Likewise, addition of H2O2 to exponentially growing S. pneumoniae resulted in a death rate similar to that of cells in stationary phase. While ΔlytA mutants did not lyse at stationary phase, they died at a rate similar to that of the wild-type strain. Furthermore, we show that the death process induced by H2O2 has features of apoptosis, as evidenced by increased annexin V staining, decreased DNA content, and appearance as assessed by transmission electron microscopy. Finally, in an in vivo rat model of competitive colonization, the presence of spxB conferred a selective advantage over the ΔspxB mutant, suggesting an explanation for the persistence of this gene. We conclude that a suicide gene of pneumococcus is spxB, which induces an apoptosis-like death in pneumococci and confers a selective advantage in nasopharyngeal cocolonization.

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Sadowy, Ewa, Agnieszka Bojarska, Alicja Kuch, Anna Skoczyńska, Keith A. Jolley, Martin C. J. Maiden, Andries J. van Tonder, Sven Hammerschmidt, and Waleria Hryniewicz. "Relationships among streptococci from the mitis group, misidentified as Streptococcus pneumoniae." European Journal of Clinical Microbiology & Infectious Diseases 39, no. 10 (May 14, 2020): 1865–78. http://dx.doi.org/10.1007/s10096-020-03916-6.

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Abstract The aim of our study was to investigate phenotypic and genotypic features of streptococci misidentified (misID) as Streptococcus pneumoniae, obtained over 20 years from hospital patients in Poland. Sixty-three isolates demonstrating microbiological features typical for pneumococci (optochin susceptibility and/or bile solubility) were investigated by phenotypic tests, lytA and 16S rRNA gene polymorphism and whole-genome sequencing (WGS). All isolates had a 6-bp deletion in the lytA 3′ terminus, characteristic for Mitis streptococc and all but two isolates lacked the pneumococcal signature cytosine at nucleotide position 203 in the 16S rRNA genes. The counterparts of psaA and ply were present in 100% and 81.0% of isolates, respectively; the spn9802 and spn9828 loci were characteristic for 49.2% and 38.1% of isolates, respectively. Phylogenetic trees and networks, based on the multilocus sequence analysis (MLSA) scheme, ribosomal multilocus sequence typing (rMLST) scheme and core-genome analysis, clearly separated investigated isolates from S. pneumoniae and demonstrated the polyclonal character of misID streptococci, associated with the Streptococcus pseudopneumoniae and Streptococcus mitis groups. While the S. pseudopneumoniae clade was relatively well defined in all three analyses, only the core-genome analysis revealed the presence of another cluster comprising a fraction of misID streptococci and a strain proposed elsewhere as a representative of a novel species in the Mitis group. Our findings point to complex phylogenetic and taxonomic relationships among S. mitis-like bacteria and support the notion that this group may in fact consist of several distinct species.

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Soufiane, Brahim, Marc Sirois, and Jean-Charles Côté. "Mutually exclusive distribution of the sap and eag S-layer genes and the lytB/lytA cell wall hydrolase genes in Bacillus thuringiensis." Antonie van Leeuwenhoek 100, no. 3 (May 25, 2011): 349–64. http://dx.doi.org/10.1007/s10482-011-9590-1.

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45

Sandalova, Tatyana, Birgitta Henriques-Normark, Dusan Hesek, Mijoon Lee, Shahriar Mobashery, Alexey Kikhney, Dmitri Svergun, Peter Mellroth, and Adnane Achour. "Structural basis of the peptidoglycan binding to LytA, the major pneumococcal autolysin." Acta Crystallographica Section A Foundations and Advances 71, a1 (August 23, 2015): s225. http://dx.doi.org/10.1107/s2053273315096606.

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46

Romao, Susana, Guido Memmi, Marco R. Oggioni, and Marie-Claude Trombe. "LuxS impacts on LytA-dependent autolysis and on competence in Streptococcus pneumoniae." Microbiology 152, no. 2 (February 1, 2006): 333–41. http://dx.doi.org/10.1099/mic.0.28406-0.

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The ubiquitous protein LuxS with S-ribosylhomocysteinase activity is involved in S-adenosyl methionine detoxification, C-1 unit recycling and the production of autoinducers that allow the cell to sense and respond to cell density. Independent reports describe the impact of LuxS deficiency on Streptococcus pneumoniae virulence in the mouse. In vitro, LuxS deficiency confers discrete phenotypes. A combined approach using genetic dissection and mixed-culture experiments allowed the involvement of LuxS in the developmental physiology of S. pneumoniae to be investigated. Functional LuxS was found to be related on the one hand to down-regulation of competence, and on the other hand to attenuation of autolysis in cultures entering stationary phase. The competence phenotype of luxS mutant bacteria was complemented by media conditioned by competence-defective ComAB0 bacteria, but not by BSA. The autolytic phenotype was complemented by BSA, but not by conditioned supernatants. It is suggested that the impact of LuxS on competence, but not on autolysis, involves cell–cell communication. The phenotype of luxS mutant strains reveals a hierarchy in the competence regulatory networks of S. pneumoniae.

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Fukushima, Tatsuya, Anahita Afkham, Shin-ichirou Kurosawa, Taichi Tanabe, Hiroki Yamamoto, and Junichi Sekiguchi. "A New d,l-Endopeptidase Gene Product, YojL (Renamed CwlS), Plays a Role in Cell Separation with LytE and LytF in Bacillus subtilis." Journal of Bacteriology 188, no. 15 (August 1, 2006): 5541–50. http://dx.doi.org/10.1128/jb.00188-06.

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ABSTRACT A new peptidoglycan hydrolase, Bacillus subtilis YojL (cell wall-lytic enzyme associated with cell separation, renamed CwlS), exhibits high amino acid sequence similarity to LytE (CwlF) and LytF (CwlE), which are associated with cell separation. The N-terminal region of CwlS has four tandem repeat regions (LysM repeats) predicted to be a peptidoglycan-binding module. The C-terminal region exhibits high similarity to the cell wall hydrolase domains of LytE and LytF at their C-terminal ends. The C-terminal region of CwlS produced in Escherichia coli could hydrolyze the linkage of d-γ-glutamyl-meso-diaminopimelic acid in the cell wall of B. subtilis, suggesting that CwlS is a d,l-endopeptidase. β-Galactosidase fusion experiments and Northern hybridization analysis suggested that the cwlS gene is transcribed during the late vegetative and early stationary phases. A cwlS mutant exhibited a cell shape similar to that of the wild type; however, a lytE lytF cwlS triple mutant exhibited aggregated microfiber formation. Moreover, immunofluorescence microscopy showed that FLAG-tagged CwlS was localized at cell separation sites and cell poles during the late vegetative phase. The localization sites are similar to those of LytF and LytE, indicating that CwlS is involved in cell separation with LytF and LytE. These specific localizations may be dependent on the LysM repeats in their N-terminal domains. The roles of CwlS, LytF, and LytE in cell separation are discussed.

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Ktari, Sonia, Nour El Houda Ben Ayed, Sonda Maalej, Basma Mnif, Faouzia Rhimi, and Adnene Hammami. "Clinical optochin resistant Streptococcus pneumoniae and Streptococcus pseudopneumoniae strains in Tunisia." Journal of Infection in Developing Countries 15, no. 05 (May 31, 2021): 672–77. http://dx.doi.org/10.3855/jidc.13106.

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Introduction: Streptococcus pneumoniae can be responsible for severe human infections. Optochin resistance has been a potential cause of misidentification of pneumococcus and other members of the mitis group. Hence, rapid and easy optochin resistant (Optr) S. pneumoniae identification is essential. Methodology: Atypical pneumococci were characterized using optochin susceptibility, bile solubility based on spectrophotometric reading, serotyping, pulsed field gel electrophoresis (PFGE), 16S rRNA sequencing and PCR-based assays targeting pneumococcal genes lytA, ply, pspA, cpsA, Spn9802 and Spn9828. Results: Optical density values for the bile solubility test suggest the identification of four Optr S. pneumoniae and one Streptococcus pseudopneumoniae. All Optr pneumococci harbored cpsA, lytA, ply, Spn9802, Spn9828 and pspA genes. Only ply, spn9802 and Spn9828 genes were detected in S. pseudopneumoniae. The 16S rRNA sequencing differentiates between these two species. Optr S. pneumoniae strains belonged to different genotypes and serotypes (14, 19A, 3 and 9V). Three Optr S. pneumoniae isolates were typed as pspA family 2, while one belonged to pspA family 1. Sequencing of the atpA and atpC gene of the Optr variants revealed three mutations in the ATPase a-subunit (L99I, M23V and V52I) and one mutation in ATPase c-subunit (V48I). Conclusions: Our data indicate that bile OD-values provides an accurate, fast and easy method to discriminate between Optr S. pneumoniae and other Streptococcus mitis group. Moreover molecular techniques, confirming the bile test, can be used in order to prevent these atypical pneumococci and alert clinical microbiologists of the presence of these strains in the community.

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Aggarwal, Surya D., Adrian J. Lloyd, Saigopalakrishna S. Yerneni, Ana Rita Narciso, Jennifer Shepherd, David I. Roper, Christopher G. Dowson, Sergio R. Filipe, and N. Luisa Hiller. "A molecular link between cell wall biosynthesis, translation fidelity, and stringent response in Streptococcus pneumoniae." Proceedings of the National Academy of Sciences 118, no. 14 (March 30, 2021): e2018089118. http://dx.doi.org/10.1073/pnas.2018089118.

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Survival in the human host requires bacteria to respond to unfavorable conditions. In the important Gram-positive pathogen Streptococcus pneumoniae, cell wall biosynthesis proteins MurM and MurN are tRNA-dependent amino acyl transferases which lead to the production of branched muropeptides. We demonstrate that wild-type cells experience optimal growth under mildly acidic stressed conditions, but ΔmurMN strain displays growth arrest and extensive lysis. Furthermore, these stress conditions compromise the efficiency with which alanyl-tRNAAla synthetase can avoid noncognate mischarging of tRNAAla with serine, which is toxic to cells. The observed growth defects are rescued by inhibition of the stringent response pathway or by overexpression of the editing domain of alanyl-tRNAAla synthetase that enables detoxification of tRNA misacylation. Furthermore, MurM can incorporate seryl groups from mischarged Seryl-tRNAAlaUGC into cell wall precursors with exquisite specificity. We conclude that MurM contributes to the fidelity of translation control and modulates the stress response by decreasing the pool of mischarged tRNAs. Finally, we show that enhanced lysis of ΔmurMN pneumococci is caused by LytA, and the murMN operon influences macrophage phagocytosis in a LytA-dependent manner. Thus, MurMN attenuates stress responses with consequences for host–pathogen interactions. Our data suggest a causal link between misaminoacylated tRNA accumulation and activation of the stringent response. In order to prevent potential corruption of translation, consumption of seryl-tRNAAla by MurM may represent a first line of defense. When this mechanism is overwhelmed or absent (ΔmurMN), the stringent response shuts down translation to avoid toxic generation of mistranslated/misfolded proteins.

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Patel, Kevin, and Dasantila Golemi-Kotra. "Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS." F1000Research 4 (March 22, 2016): 79. http://dx.doi.org/10.12688/f1000research.6213.2.

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The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of cidABC and lrgAB operons, the gene products of which are involved in programmed cell death and lysis. In vivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the in vivo observations that regulation of the lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS.

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Journal articles on the topic 'LytA'

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