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Journal articles on the topic 'Isogenic mutants'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Pathirana, Rishi D., Neil M. O'Brien-Simpson, Gail C. Brammar, Nada Slakeski, and Eric C. Reynolds. "Kgp and RgpB, but Not RgpA, Are Important for Porphyromonas gingivalis Virulence in the Murine Periodontitis Model." Infection and Immunity 75, no. 3 (2007): 1436–42. http://dx.doi.org/10.1128/iai.01627-06.

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ABSTRACT The contributions of three proteinase genes (rgpA, rgpB, and kgp) to the virulence of Porphyromonas gingivalis W50 were investigated in the murine periodontitis model. Mice were orally inoculated with eight doses (1 × 1010 cells per dose) of rgpA, rgpB, kgp, rgpA rgpB, or rgpA rgpB kgp isogenic mutants, and the level of alveolar bone loss, immune response induced, and number of bacterial cells per half maxilla were compared with those of animals inoculated with wild-type P. gingivalis. The kgp, rgpB, rgpA rgpB, and rgpA rgpB kgp isogenic mutants induced significantly (P < 0.05) les

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2

Xu, Xin-J., M. R. Ferguson, V. L. Popov, C. W. Houston, J. W. Peterson, and A. K. Chopra. "Role of a Cytotoxic Enterotoxin in Aeromonas-Mediated Infections: Development of Transposon and Isogenic Mutants." Infection and Immunity 66, no. 8 (1998): 3501–9. http://dx.doi.org/10.1128/iai.66.8.3501-3509.1998.

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ABSTRACT Transposon and marker exchange mutagenesis were used to evaluate the role of Aeromonas cytotoxic enterotoxin (Act) in the pathogenesis of diarrheal diseases and deep wound infections. The transposon mutants were generated by random insertion of Tn5-751 in the chromosomal DNA of a diarrheal isolate SSU of Aeromonas hydrophila. Some of the transposon mutants had dramatically reduced hemolytic and cytotoxic activities, and such mutants exhibited reduced virulence in mice compared to wild-typeAeromonas when injected intraperitoneally (i.p.). Southern blot data indicated that transposition

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3

Luke, Nicole R., and Anthony A. Campagnari. "Construction and Characterization ofMoraxella catarrhalis Mutants Defective in Expression of Transferrin Receptors." Infection and Immunity 67, no. 11 (1999): 5815–19. http://dx.doi.org/10.1128/iai.67.11.5815-5819.1999.

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ABSTRACT We have previously reported the construction of an isogenic mutant defective in expression of OmpB1, the TbpB homologue, inMoraxella catarrhalis 7169. In this report, we have extended these studies by constructing and characterizing two new isogenic mutants in this clinical isolate. One mutant is defective in expression of TbpA, and the other mutant is defective in expression of both TbpA and TbpB. These isogenic mutants were confirmed by using PCR analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sequencing. In vitro growth studies, comparing all three mutants,

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4

Petersen, F. C., S. Assev, H. C. van der Mei, H. J. Busscher, and A. A. Scheie. "Functional Variation of the Antigen I/II Surface Protein in Streptococcus mutans and Streptococcus intermedius." Infection and Immunity 70, no. 1 (2002): 249–56. http://dx.doi.org/10.1128/iai.70.1.249-256.2002.

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ABSTRACT Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commensal microflora of the body, S. intermedius is often associated with deep-seated purulent infections, whereas S. mutans is frequently associated with dental caries. In this study, we investigated the roles of the S. mutans and S. intermedius antigen I/II proteins in adhesion and modulation of cell surface characteristics. By using isogenic mutants, we show that the antigen I/II in S. mutans, but not in S. intermedius, was involved in adhesion to a salivary film under flowing conditions, as

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5

Mishima, Harutaka, Hirokazu Watanabe, Kei Uchigasaki, et al. "L-Alanine Prototrophic Suppressors Emerge from L-Alanine Auxotroph through Stress-Induced Mutagenesis in Escherichia coli." Microorganisms 9, no. 3 (2021): 472. http://dx.doi.org/10.3390/microorganisms9030472.

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In Escherichia coli, L-alanine is synthesized by three isozymes: YfbQ, YfdZ, and AvtA. When an E. coli L-alanine auxotrophic isogenic mutant lacking the three isozymes was grown on L-alanine-deficient minimal agar medium, L-alanine prototrophic mutants emerged considerably more frequently than by spontaneous mutation; the emergence frequency increased over time, and, in an L-alanine-supplemented minimal medium, correlated inversely with L-alanine concentration, indicating that the mutants were derived through stress-induced mutagenesis. Whole-genome analysis of 40 independent L-alanine prototr

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6

Young, Vincent B., Kimberly A. Knox, Jason S. Pratt, et al. "In Vitro and In Vivo Characterization of Helicobacter hepaticus Cytolethal Distending Toxin Mutants." Infection and Immunity 72, no. 5 (2004): 2521–27. http://dx.doi.org/10.1128/iai.72.5.2521-2527.2004.

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ABSTRACT Helicobacter hepaticus expresses a member of the cytolethal distending toxin (CDT) family of bacterial cytotoxins. To investigate the role of CDT in the pathogenesis of H. hepaticus, transposon mutagenesis was used to generate a series of isogenic mutants in and around the cdtABC gene cluster. An H. hepaticus transposon mutant with a disrupted cdtABC coding region no longer produced CDT activity. Conversely, a transposon insertion outside of the cluster did not affect the CDT activity. An examination of these mutants demonstrated that CDT represents the previously described granulatin

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7

Schäbler, Stefan, Kelechi M. Amatobi, Melanie Horn, et al. "Loss of function in the Drosophila clock gene period results in altered intermediary lipid metabolism and increased susceptibility to starvation." Cellular and Molecular Life Sciences 77, no. 23 (2020): 4939–56. http://dx.doi.org/10.1007/s00018-019-03441-6.

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Abstract The fruit fly Drosophila is a prime model in circadian research, but still little is known about its circadian regulation of metabolism. Daily rhythmicity in levels of several metabolites has been found, but knowledge about hydrophobic metabolites is limited. We here compared metabolite levels including lipids between period01 (per01) clock mutants and Canton-S wildtype (WTCS) flies in an isogenic and non-isogenic background using LC–MS. In the non-isogenic background, metabolites with differing levels comprised essential amino acids, kynurenines, pterinates, glycero(phospho)lipids, a

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8

O'Brien-Simpson, Neil M., Rita A. Paolini, Brigitte Hoffmann, Nada Slakeski, Stuart G. Dashper, and Eric C. Reynolds. "Role of RgpA, RgpB, and Kgp Proteinases in Virulence of Porphyromonas gingivalis W50 in a Murine Lesion Model." Infection and Immunity 69, no. 12 (2001): 7527–34. http://dx.doi.org/10.1128/iai.69.12.7527-7534.2001.

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ABSTRACT Extracellular Arg-x- and Lys-x-specific cysteine proteinases are considered important virulence factors and pathogenic markers forPorphyromonas gingivalis, a bacterium implicated as a major etiological agent of chronic periodontitis. Three genes.rgpA, rgpB, and kgp,encode an Arg-x-specific proteinase and adhesins (RgpA), an Arg-x-specific proteinase (RgpB), and a Lys-x-specific proteinase and adhesins (Kgp), respectively. The contribution to pathogenicity of each of the proteinase genes of P. gingivalis W50 was investigated in a murine lesion model using isogenic mutants lacking RgpA,

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9

Harrington, D. J., and R. R. Russell. "Multiple changes in cell wall antigens of isogenic mutants of Streptococcus mutans." Journal of Bacteriology 175, no. 18 (1993): 5925–33. http://dx.doi.org/10.1128/jb.175.18.5925-5933.1993.

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10

Sha, Jian, E. V. Kozlova, and A. K. Chopra. "Role of Various Enterotoxins in Aeromonas hydrophila-Induced Gastroenteritis: Generation of Enterotoxin Gene-Deficient Mutants and Evaluation of Their Enterotoxic Activity." Infection and Immunity 70, no. 4 (2002): 1924–35. http://dx.doi.org/10.1128/iai.70.4.1924-1935.2002.

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ABSTRACT Three enterotoxins from the Aeromonas hydrophila diarrheal isolate SSU have been molecularly characterized in our laboratory. One of these enterotoxins is cytotoxic in nature, whereas the other two are cytotonic enterotoxins, one of them heat labile and the other heat stable. Earlier, by developing an isogenic mutant, we demonstrated the role of a cytotoxic enterotoxin in causing systemic infection in mice. In the present study, we evaluated the role of these three enterotoxins in evoking diarrhea in a murine model by developing various combinations of enterotoxin gene-deficient mutan

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11

Vanterpool, Elaine, Francis Roy, Lawrence Sandberg, and Hansel M. Fletcher. "Altered Gingipain Maturation in vimA- and vimE-Defective Isogenic Mutants of Porphyromonas gingivalis." Infection and Immunity 73, no. 3 (2005): 1357–66. http://dx.doi.org/10.1128/iai.73.3.1357-1366.2005.

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ABSTRACT We have previously shown that gingipain activity in Porphyromonas gingivalis is modulated by the unique vimA and vimE genes. To determine if these genes had a similar phenotypic effect on protease maturation and activation, isogenic mutants defective in those genes were further characterized. Western blot analyses with antigingipain antibodies showed RgpA-, RgpB-, and Kgp-immunoreactive bands in membrane fractions as well as the culture supernatant of both P. gingivalis W83 and FLL93, the vimE-defective mutant. In contrast, the membrane of P. gingivalis FLL92, the vimA-defective mutan

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12

Ormonde, Patricia, Per Hörstedt, Ronan O'Toole, and Debra L. Milton. "Role of Motility in Adherence to and Invasion of a Fish Cell Line by Vibrio anguillarum." Journal of Bacteriology 182, no. 8 (2000): 2326–28. http://dx.doi.org/10.1128/jb.182.8.2326-2328.2000.

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ABSTRACT To understand further the role of the flagellum of Vibrio anguillarum in virulence, invasive and adhesive properties of isogenic motility mutants were analyzed by using a chinook salmon embryo cell line. Adhesion was unaffected but invasion of the cell line was significantly decreased in nonmotile or partially motile mutants, and the chemotactic mutant was hyperinvasive. These results suggest that active motility aids invasion by V. anguillarum, both in vivo and in vitro.

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13

Gulig, Paul a. "Use of isogenic mutants to study bacterial virulence factors." Journal of Microbiological Methods 18, no. 3 (1993): 275–87. http://dx.doi.org/10.1016/0167-7012(93)90042-g.

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14

Aebi, Christoph, Eric R. Lafontaine, Leslie D. Cope, et al. "Phenotypic Effect of Isogenic uspA1 anduspA2 Mutations on Moraxella catarrhalis 035E." Infection and Immunity 66, no. 7 (1998): 3113–19. http://dx.doi.org/10.1128/iai.66.7.3113-3119.1998.

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ABSTRACT The UspA surface antigen of Moraxella catarrhalis was recently shown to be comprised of two different proteins (UspA1 and UspA2) which share an internal region containing 140 amino acids with 93% identity (C. Aebi, I. Maciver, J. L. Latimer, L. D. Cope, M. K. Stevens, S. E. Thomas, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 65:4367–4377, 1997). Isogenic uspA1, uspA2, and uspA1 uspA2 mutants were tested in a number of in vitro systems to determine what effect these mutations, either individually or together, might exert on the phenotype of M. catarrhalis 035E. Monoclonal an

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15

Tsuda, Hiromasa, Yoshihisa Yamashita, Kuniaki Toyoshima, et al. "Role of Serotype-Specific Polysaccharide in the Resistance of Streptococcus mutans to Phagocytosis by Human Polymorphonuclear Leukocytes." Infection and Immunity 68, no. 2 (2000): 644–50. http://dx.doi.org/10.1128/iai.68.2.644-650.2000.

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ABSTRACT To clarify the role of cell surface components ofStreptococcus mutans in resistance to phagocytosis by human polymorphonuclear leukocytes (PMNs), several isogenic mutants ofS. mutans defective in cell surface components were studied with a luminol-enhanced chemiluminescence (CL) assay, a killing assay, and a transmission electron microscope. The CL responses of human PMNs to mutant Xc11 defective in a major cell surface antigen, PAc, and mutant Xc16 defective in two surface glucosyltransferases (GTF-I and GTF-SI) were the same as the response to the wild-type strain, Xc. In contrast,

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16

Whitacre, Johanna L., Dana A. Davis, Kurt A. Toenjes, Sharon M. Brower, and Alison E. M. Adams. "Generation of an Isogenic Collection of Yeast Actin Mutants and Identification of Three Interrelated Phenotypes." Genetics 157, no. 2 (2001): 533–43. http://dx.doi.org/10.1093/genetics/157.2.533.

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Abstract A large collection of yeast actin mutations has been previously isolated and used in numerous studies of actin cytoskeletal function. However, the various mutations have been in congenic, rather than isogenic, backgrounds, making it difficult to compare the subtle phenotypes that are characteristic of these mutants. We have therefore placed 27 mutations in an isogenic background. We used a subset of these mutants to compare the degree to which different actin alleles are defective in sporulation, endocytosis, and growth on NaCl-containing media. We found that the three phenotypes are

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17

Perez, M. D., S. J. Chambers, J. R. Bacon, N. Lambert, C. L. Hedley, and T. L. Wang. "Seed protein content and composition of near-isogenic and induced mutant pea lines." Seed Science Research 3, no. 3 (1993): 187–94. http://dx.doi.org/10.1017/s096025850000177x.

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AbstractTotal protein content and amounts of albumin, legumin and vicilin have been determined for pea seeds from lines near-isogenic except for genes at the rugosus loci, r and rb (RR/RbRb; rr/RbRb; RR/rbrb; rr/rbrb). Seeds with the wildtype, round-seeded phenotype (RR/RbRb) had less protein on a total seed dry-weight basis than any of the wrinkled-seeded lines and this protein had a lower proportion of albumin. The lines which had recessive alleles at both r and rb loci had the highest proportion of protein and the highest proportion of albumin. The roundseeded peas possessed nearly two-fold

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18

Chen, Yu-Chung, Yin-Ching Chuang, Chun-Chin Chang, Chii-Ling Jeang, and Ming-Chung Chang. "A K+ Uptake Protein, TrkA, Is Required for Serum, Protamine, and Polymyxin B Resistance in Vibrio vulnificus." Infection and Immunity 72, no. 2 (2004): 629–36. http://dx.doi.org/10.1128/iai.72.2.629-636.2004.

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ABSTRACT Vibrio vulnificus, a highly virulent marine bacterium, is the causative agent of both serious wound infections and fatal septicemia in many areas of the world. To identify the genes required for resistance to human serum, we constructed a library of transposon mutants of V. vulnificus and screened them for hypersensitivity to human serum. Here we report that one of the isolated serum-susceptible mutants had a mutation in an open reading frame identified as trkA, a gene encoding an amino acid sequence showing high identity to that of TrkA of Vibrio alginolyticus, a protein required for

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19

Hansen, E. J., J. L. Latimer, S. E. Thomas, M. Helminen, W. L. Albritton, and J. D. Radolf. "Use of electroporation to construct isogenic mutants of Haemophilus ducreyi." Journal of Bacteriology 174, no. 16 (1992): 5442–49. http://dx.doi.org/10.1128/jb.174.16.5442-5449.1992.

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20

Rivera, Mildred, Anne Bertasso, Catherine McCaffrey, and Nafsika H. Georgopapadakou. "Porins and lipopolysaccharide ofEscherichia coliATCC 25922 and isogenic rough mutants." FEMS Microbiology Letters 108, no. 2 (1993): 183–87. http://dx.doi.org/10.1111/j.1574-6968.1993.tb06096.x.

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21

Murphy, George L., and Lisa C. Whitworth. "Construction of isogenic mutants of Pasteurella haemolytica by allelic replacement." Gene 148, no. 1 (1994): 101–5. http://dx.doi.org/10.1016/0378-1119(94)90241-0.

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22

Ottemann, Karen M., and Andrew C. Lowenthal. "Helicobacter pylori Uses Motility for Initial Colonization and To Attain Robust Infection." Infection and Immunity 70, no. 4 (2002): 1984–90. http://dx.doi.org/10.1128/iai.70.4.1984-1990.2002.

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ABSTRACT Helicobacter pylori has been shown to require flagella for infection of the stomach. To analyze whether flagella themselves or motility is needed by these pathogens, we constructed flagellated nonmotile mutants. This was accomplished by using both an insertion mutant and an in-frame deletion of the motB gene. In vitro, these mutants retain flagella (Fla+) but are nonmotile (Mot−). By using FVB/N mice, we found that these mutants had reduced ability to infect mice in comparison to that of their isogenic wild-type counterparts. When these mutants were coinfected with wild type, we were

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23

Mack, Dietrich, Holger Rohde, Sabine Dobinsky, et al. "Identification of Three Essential Regulatory Gene Loci Governing Expression of Staphylococcus epidermidis Polysaccharide Intercellular Adhesin and Biofilm Formation." Infection and Immunity 68, no. 7 (2000): 3799–807. http://dx.doi.org/10.1128/iai.68.7.3799-3807.2000.

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ABSTRACT The formation of adherent multilayered biofilms embedded into a glycocalyx represents an essential factor in the pathogenesis ofStaphylococcus epidermidis biomaterial-related infections. Using biofilm-producing S. epidermidis 1457 and transposon Tn917 carried on plasmid pTV1ts, we isolated nine isogenic biofilm-negative transposon mutants. Transduction byS. epidermidis phage 71 was used to prove the genetic linkage of transposon insertions and altered phenotypes. Mapping of the different transposon insertions by Southern hybridization and pulsed-field gel electrophoresis indicated tha

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24

Balzer, Grant J., and Robert J. C. McLean. "NoteThe stringent response genes relA and spoT are important for Escherichia coli biofilms under slow-growth conditions." Canadian Journal of Microbiology 48, no. 7 (2002): 675–80. http://dx.doi.org/10.1139/w02-060.

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In order to see whether the stringent response was involved in biofilm formation, Escherichia coli DS291 (MG1655), and its isogenic relA spoT derivative were grown for 48 h in a chemostat at dilution rates of 0.025 and 0.25 h1 under serine limitation. The absence of the stringent response genes relA and spoT had little effect on the planktonic cell concentrations. However, a significant (P < 0.001) reduction in biofilm cell density of the relA spoT mutants was seen at a doubling time of 40 h. At a doubling time of 4 h, differences in biofilm cell density were not significant. Scanning conf

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25

Hopper, Sylvia, J. Scott Wilbur, Brandi L. Vasquez, et al. "Isolation of Neisseria gonorrhoeaeMutants That Show Enhanced Trafficking across Polarized T84 Epithelial Monolayers." Infection and Immunity 68, no. 2 (2000): 896–905. http://dx.doi.org/10.1128/iai.68.2.896-905.2000.

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ABSTRACT Initiation of a gonococcal infection involves attachment ofNeisseria gonorrhoeae to the plasma membrane of an epithelial cell in the mucosal epithelium and its internalization, transepithelial trafficking, and exocytosis from the basal membrane. Piliation and expression of certain Opa proteins and the immunoglobulin A1 protease influence the transcytosis process. We are interested in identifying other genetic determinants of N. gonorrhoeaethat play a role in transcellular trafficking. Using polarized T84 monolayers as a model epithelial barrier, we have assayed an N. gonorrhoeae FA109

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26

Smith, Hilde E., Marloes Damman, Joeke van der Velde, et al. "Identification and Characterization of thecps Locus of Streptococcus suis Serotype 2: the Capsule Protects against Phagocytosis and Is an Important Virulence Factor." Infection and Immunity 67, no. 4 (1999): 1750–56. http://dx.doi.org/10.1128/iai.67.4.1750-1756.1999.

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ABSTRACT To study the role of the capsule of Streptococcus suisserotype 2 in virulence, we generated two isogenic mutants disturbed in capsule production. For that purpose, we first cloned and characterized a major part of the capsular polysaccharide biosynthesis (cps) locus of S. suis serotype 2. Based on the established sequence, 14 open reading frames (ORFs), designated Orf2Z, Orf2Y, Orf2X, and Cps2A to Cps2K, were identified. Twelve ORFs belonged to a single transcriptional unit. The gene products of 11 of these ORFs showed similarity to proteins involved in polysaccharide biosynthesis of

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27

Thaler, David S., Elizabeth Sampson, Imran Siddiqi та ін. "Recombination of bacteriophage λ in recD mutants of Escherichia coli". Genome 31, № 1 (1989): 53–67. http://dx.doi.org/10.1139/g89-013.

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RecBCD enzyme is centrally important in homologous recombination in Escherichia coli and is the source of ExoV activity. Null alleles of either the recB or the recC genes, which encode the B and C subunits, respectively, manifest no recombination and none of the nuclease functions characteristic of the holoenzyme. Loss of the D subunit, by a recD mutation, likewise results in loss of ExoV activity. However, mutants lacking the D subunit are competent for homologous recombination. We report that the distribution of exchanges along the chromosome of Red−Gam−phage λ is strikingly altered by recD

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28

Callegan, Michelle C., Daniel C. Cochran, Scott T. Kane, Michael S. Gilmore, Myriam Gominet, and Didier Lereclus. "Contribution of Membrane-Damaging Toxins to Bacillus Endophthalmitis Pathogenesis." Infection and Immunity 70, no. 10 (2002): 5381–89. http://dx.doi.org/10.1128/iai.70.10.5381-5389.2002.

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ABSTRACT Membrane-damaging toxins are thought to be responsible for the explosive clinical course of Bacillus endophthalmitis. This study analyzed the contribution of phosphatidylinositol-specific phospholipase C (PI-PLC) and phosphatidylcholine-specific phospholipase C (PC-PLC) to the pathogenesis of experimental Bacillus endophthalmitis. Isogenic mutants were constructed by insertion of lacZ into Bacillus thuringiensis genes encoding PI-PLC (plcA) and PC-PLC (plcB). Rabbit eyes were injected intravitreally with 2 log10 CFU of strain BT407 (wild type), the PI-PLC mutant (BTplcA::lacZ), or the

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29

J Danon, Stephen, and Kathryn A. Eaton. "Isogenic flagella mutants of Helicobacter pylori: Candidates for an attenuated vaccine?" Gastroenterology 114 (April 1998): A958. http://dx.doi.org/10.1016/s0016-5085(98)83903-6.

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Jousset, Alexandre, Enrique Lara, Luis G. Wall, and Claudio Valverde. "Secondary Metabolites Help Biocontrol Strain Pseudomonas fluorescens CHA0 To Escape Protozoan Grazing." Applied and Environmental Microbiology 72, no. 11 (2006): 7083–90. http://dx.doi.org/10.1128/aem.00557-06.

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ABSTRACT In soil ecosystems, bacteria must cope with predation activity, which is attributed mainly to protists. The development of antipredation strategies may help bacteria maintain higher populations and persist longer in the soil. We analyzed the interaction between the root-colonizing and biocontrol strain Pseudomonas fluorescens CHA0 and three different protist isolates (an amoeba, a flagellate, and a ciliate). CHA0 produces a set of antibiotics, HCN, and an exoprotease. We observed that protists cannot grow on CHA0 but can multiply on isogenic regulatory mutants that do not produce the

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Sha, Jian, E. V. Kozlova, A. A. Fadl, et al. "Molecular Characterization of a Glucose-Inhibited Division Gene, gidA, That Regulates Cytotoxic Enterotoxin of Aeromonas hydrophila." Infection and Immunity 72, no. 2 (2004): 1084–95. http://dx.doi.org/10.1128/iai.72.2.1084-1095.2004.

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ABSTRACT By using a mini-transposon, we obtained two mutated strains of a diarrheal isolate, SSU, of Aeromonas hydrophila that exhibited a 50 to 53% reduction in the hemolytic activity and 83 to 87% less cytotoxic activity associated with the cytotoxic enterotoxin (Act). Act is a potent virulence factor of A. hydrophila and has been shown to contribute significantly to the development of both diarrhea and septicemia in animal models. Subsequent cloning and DNA sequence analysis revealed that transposon insertion occurred at different locations in these two mutants within the same 1,890-bp open

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Saldaña, Zeus, Ayşen L. Erdem, Stephanie Schüller, et al. "The Escherichia coli Common Pilus and the Bundle-Forming Pilus Act in Concert during the Formation of Localized Adherence by Enteropathogenic E. coli." Journal of Bacteriology 191, no. 11 (2009): 3451–61. http://dx.doi.org/10.1128/jb.01539-08.

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ABSTRACT Although the bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) mediates microcolony formation on epithelial cells, the adherence of BFP-deficient mutants is significantly abrogated, but the mutants are still adherent due to the presence of intimin and possibly other adhesins. In this study we investigated the contribution of the recently described E. coli common pilus (ECP) to the overall adherence properties of EPEC. We found that ECP and BFP structures can be simultaneously observed in the course (between zero time and 7 h during infection) of formation of local

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33

Fontaine, Michael C., Jeong Jin Lee, and Michael A. Kehoe. "Combined Contributions of Streptolysin O and Streptolysin S to Virulence of Serotype M5 Streptococcus pyogenes Strain Manfredo." Infection and Immunity 71, no. 7 (2003): 3857–65. http://dx.doi.org/10.1128/iai.71.7.3857-3865.2003.

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ABSTRACT Streptolysin O (SLO) and streptolysin S (SLS) are potent cytolytic toxins produced by almost all clinical isolates of group A streptococci (GAS). Allele-replacement mutagenesis was used to construct nonpolar (in-frame) deletion mutations in the slo and sagB genes of the serotype M5 GAS strain Manfredo, producing isogenic single and double SLO- and SLS-defective mutants. In contrast to recent reports on SLS-defective insertion mutants (I. Biswas, P. Germon, K. McDade, and J. Scott, Infect. Immun. 69:7029-7038, 2001; Z. Li, D. Sledjeski, B. Kreikemeyer, A.Podbielski, and M. Boyle, J. Ba

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Clyne, Marguerite, Tadhg Ocroinin, Sebastian Suerbaum, Christine Josenhans, and Brendan Drumm. "Adherence of Isogenic Flagellum-Negative Mutants ofHelicobacter pylori and Helicobacter mustelae to Human and Ferret Gastric Epithelial Cells." Infection and Immunity 68, no. 7 (2000): 4335–39. http://dx.doi.org/10.1128/iai.68.7.4335-4339.2000.

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ABSTRACT Isogenic flagellum-negative mutants of Helicobacter pylori and Helicobacter mustelae were screened for their ability to adhere to primary human and ferret gastric epithelial cells, respectively. We also evaluated the adherence of an H. pylori strain with a mutation in theflbA gene, a homologue of the flbF/lcrD family of genes known to be involved in the regulation of H. pylori flagellar biosynthesis. H. pylori and H. mustelae mutants deficient in production of FlaA or FlaB and mutants deficient in the production of both FlaA and FlaB showed no reduction in adherence to primary human o

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Vaudaux, Pierre, Patrice Francois, Carmelo Bisognano, et al. "Increased Expression of Clumping Factor and Fibronectin-Binding Proteins by hemB Mutants of Staphylococcus aureus Expressing Small Colony Variant Phenotypes." Infection and Immunity 70, no. 10 (2002): 5428–37. http://dx.doi.org/10.1128/iai.70.10.5428-5437.2002.

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ABSTRACT Small colony variants (SCVs) of Staphylococcus aureus are slow-growing subpopulations that cause persistent and relapsing infections. The altered phenotype of SCV can arise from defects in menadione or hemin biosynthesis, which disrupt the electron transport chain and decrease ATP concentrations. With SCVs, virulence is altered by a decrease in exotoxin production and susceptibility to various antibiotics, allowing their intracellular survival. The expression of bacterial adhesins by SCVs is poorly documented. We tested fibrinogen- and fibronectin-mediated adhesion of a hemB mutant of

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Hu, Rouh-Mei, Kuang-Jay Huang, Lii-Tzu Wu, Ying-Ju Hsiao та Tsuey-Ching Yang. "Induction of L1 and L2 β-Lactamases of Stenotrophomonas maltophilia". Antimicrobial Agents and Chemotherapy 52, № 3 (2007): 1198–200. http://dx.doi.org/10.1128/aac.00682-07.

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ABSTRACT Isogenic L1 and L2 gene knockout mutants of Stenotrophomonas maltophilia KJ (KJΔL1 and KJΔL2, respectively) were constructed by xylE gene replacement. Induction kinetics of the L1 and L2 genes were evaluated by testing catechol 2,3-dioxygenase activity in the mutants. The results suggested that the induction of the L1 and L2 genes was differentially regulated.

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Takata, Tohru, Emad El-Omar, Margarita Camorlinga, et al. "Helicobacter pylori Does Not Require Lewis X or Lewis Y Expression To Colonize C3H/HeJ mice." Infection and Immunity 70, no. 6 (2002): 3073–79. http://dx.doi.org/10.1128/iai.70.6.3073-3079.2002.

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ABSTRACT Helicobacter pylori strains frequently express Lewis X (Lex) and/or Ley on their cell surfaces as constituents of the O antigens of their lipopolysaccharide molecules. To assess the effect of Lex and Ley expression on the ability of H. pylori to colonize the mouse stomach and to adhere to epithelial cells, isogenic mutants were created in which fucT1 alone or fucT1 and fucT2, which encode the fucosyl transferases necessary for Lex and Ley expression, were deleted. C3H/HeJ mice were experimentally challenged with either wild-type 26695 H. pylori or its isogenic mutants. All strains, wh

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Öling, David, Rehan Masoom, and Kristian Kvint. "Loss of Ubp3 increases silencing, decreases unequal recombination in rDNA, and shortens the replicative life span in Saccharomyces cerevisiae." Molecular Biology of the Cell 25, no. 12 (2014): 1916–24. http://dx.doi.org/10.1091/mbc.e13-10-0591.

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Ubp3 is a conserved ubiquitin protease that acts as an antisilencing factor in MAT and telomeric regions. Here we show that ubp3∆ mutants also display increased silencing in ribosomal DNA (rDNA). Consistent with this, RNA polymerase II occupancy is lower in cells lacking Ubp3 than in wild-type cells in all heterochromatic regions. Moreover, in a ubp3∆ mutant, unequal recombination in rDNA is highly suppressed. We present genetic evidence that this effect on rDNA recombination, but not silencing, is entirely dependent on the silencing factor Sir2. Further, ubp3∆ sir2∆ mutants age prematurely at

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Marlink, Katie L., Kathy D. Bacon, Brett C. Sheppard, et al. "Effects ofHelicobacter pylorion intracellular Ca2+signaling in normal human gastric mucous epithelial cells." American Journal of Physiology-Gastrointestinal and Liver Physiology 285, no. 1 (2003): G163—G176. http://dx.doi.org/10.1152/ajpgi.00257.2002.

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In stomach, Helicobacter pylori ( Hp) adheres to gastric mucous epithelial cells (GMEC) and initiates several different signal transduction events. Alteration of intracellular Ca2+concentration ([Ca2+]i) is an important signaling mechanism in numerous bacteria-host model systems. Changes in [Ca2+]iinduced by Hp in normal human GMEC have not yet been described; therefore, we examined effects of Hp on [Ca2+]iin normal human GMEC and a nontransformed GMEC line (HFE-145). Cultured cells were grown on glass slides, porous filters, or 96-well plates and loaded with fura 2 or fluo 4. Hp wild-type str

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Aruni, Wilson, Elaine Vanterpool, Devon Osbourne, et al. "Sialidase and Sialoglycoproteases Can Modulate Virulence in Porphyromonas gingivalis." Infection and Immunity 79, no. 7 (2011): 2779–91. http://dx.doi.org/10.1128/iai.00106-11.

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ABSTRACTThePorphyromonas gingivalisrecombinant VimA can interact with the gingipains and several other proteins, including a sialidase. Sialylation can be involved in protein maturation; however, its role in virulence regulation inP. gingivalisis unknown. The three sialidase-related proteins inP. gingivalisshowed the characteristic sialidase Asp signature motif (SXDXGXTW) and other unique domains. To evaluate the roles of the associated genes, randomly chosenP. gingivalisisogenic mutants created by allelic exchange and designated FLL401 (PG0778::ermF), FLL402 (PG1724::ermF), and FLL403 (PG0352

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Sonneborn, Anja, Dirk P. Bockmühl, and Joachim F. Ernst. "Chlamydospore Formation in Candida albicans Requires the Efg1p Morphogenetic Regulator." Infection and Immunity 67, no. 10 (1999): 5514–17. http://dx.doi.org/10.1128/iai.67.10.5514-5517.1999.

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ABSTRACT Chlamydospore formation of the fungal pathogen Candida albicans was found to depend on the Efg1 protein, which regulates the yeast-hyphal transition. Isogenic mutants lacking EFG1or encoding T206A and T206E variants did not differentiate chlamydospores, while cek1, cph1, ortpk2 mutations had no effect. Furthermore, filamentation ofefg1 cph1 double mutants in microaerophilic conditions suggests a novel Efg1p/Cph1p-independent filamentation pathway inC. albicans.

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Engels-Deutsch, Marc, Annelise Pini, Yoshihisa Yamashita, et al. "Insertional Inactivation of pac and rmlB Genes Reduces the Release of Tumor Necrosis Factor Alpha, Interleukin-6, and Interleukin-8 Induced by Streptococcus mutans in Monocytic, Dental Pulp, and Periodontal Ligament Cells." Infection and Immunity 71, no. 9 (2003): 5169–77. http://dx.doi.org/10.1128/iai.71.9.5169-5177.2003.

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ABSTRACT Streptococcus mutans possesses different cell wall molecules, such as protein of the I/II family, the serotype f polysaccharide rhamnose glucose polymer (RGP), and lipoteichoic acid (LTA), which act as adhesins and modulins, allowing S. mutans to colonize teeth and cause dental caries and pulpitis. We tested several isogenic mutants of S. mutans defective in protein I/II and/or RGP, as well as purified modulins such as protein I/II, RGP, and LTA, for their binding and activation abilities on monocytic, dental pulp (DP), and periodontal ligament (PDL) cells. Our results demonstrate tha

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Rioux, Stéphane, Catherine Galarneau, Josée Harel, et al. "Isolation and characterization of mini-Tn10lipopolysaccharide mutants ofActinobacillus pleuropneumoniaeserotype 1." Canadian Journal of Microbiology 45, no. 12 (1999): 1017–26. http://dx.doi.org/10.1139/w99-107.

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Lipopolysaccharide (LPS) has previously been identified as the major adhesin of Actinobacillus pleuropneumoniae involved in adherence to porcine respiratory tract cells. The purpose of the present study was to isolate and characterize mutants in LPS biosynthesis by using a mini-Tn10 transposon mutagenesis system. Seven mutants appeared to possess a rough LPS (among which two had similar Southern blot profiles) while one mutant (#5.1) expressed the high-molecular-mass LPS, but as visualized by Tricine SDS-PAGE, showed an additional band in the core-lipid A region. The LPS mutants showed sensiti

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Liang, Weili, Anisia J. Silva, and Jorge A. Benitez. "The Cyclic AMP Receptor Protein Modulates Colonial Morphology in Vibrio cholerae." Applied and Environmental Microbiology 73, no. 22 (2007): 7482–87. http://dx.doi.org/10.1128/aem.01564-07.

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ABSTRACT Inactivation of the quorum-sensing regulator HapR causes Vibrio cholerae El Tor biotype strain C7258 to adopt a rugose colonial morphology that correlates with enhanced biofilm formation. V. cholerae mutants lacking the cyclic AMP (cAMP) receptor protein (CRP) produce very little HapR, which results in elevated expression of Vibrio exopolysaccharide (vps) genes and biofilm compared to the wild type. However, Δcrp mutants still exhibited smooth colonial morphology and expressed reduced levels of vps genes compared to isogenic hapR mutants. In this study we demonstrate that deletion of

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Lin, Chi-Chang, Sheng-Kai Li, Bor-Shyang Sheu, and Hsien-Chang Chang. "RAPID CHARACTERIZATION AND SEPARATION OF ISOGENIC MUTANTS OF H. PYLORI BY DIELECTROPHORESIS." Biomedical Engineering: Applications, Basis and Communications 21, no. 06 (2009): 433–36. http://dx.doi.org/10.4015/s101623720900157x.

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A simple, fast, real-time, and nondestructive analysis of protein expression in biological samples, such as membranes, based on dielectrophoresis is described. On the basis of the distinct differences in the dielectrophoretic properties of individual cell types, the wild-type BabA-positive Helicobacter pylori isolates and its BabA-negative isogenic mutant can be identified and separated. The herein-presented approach of using microelectrodes should be an easy-to-use, cheap, and rapid alternative to separate and distinguish the presence or absence of important outer-membrane proteins.

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Jack, D. L., A. Dodds, N. Anwar, et al. "C4 Activation by Mannose-binding lectin on isogenic mutants of Neisseria meningitidis." Immunology Letters 56 (May 1997): 18. http://dx.doi.org/10.1016/s0165-2478(97)85070-5.

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Jack, D. "C4 Activation by Mannose-binding lectin on isogenic mutants of Neisseria meningitidis." Immunology Letters 56, no. 1-3 (1997): 18. http://dx.doi.org/10.1016/s0165-2478(97)86908-8.

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Ferrero, R. L., V. Cussac, P. Courcoux, and A. Labigne. "Construction of isogenic urease-negative mutants of Helicobacter pylori by allelic exchange." Journal of Bacteriology 174, no. 13 (1992): 4212–17. http://dx.doi.org/10.1128/jb.174.13.4212-4217.1992.

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Kilár, Anikó, Ágnes Dörnyei, Annamária Bui, Zoltán Szabó, Béla Kocsis, and Ferenc Kilár. "Structural variability of endotoxins from R-type isogenic mutants of Shigella sonnei." Journal of Mass Spectrometry 46, no. 1 (2010): 61–70. http://dx.doi.org/10.1002/jms.1863.

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Garcia, Erin C., Ariel R. Brumbaugh, and Harry L. T. Mobley. "Redundancy and Specificity ofEscherichia coliIron Acquisition Systems during Urinary Tract Infection." Infection and Immunity 79, no. 3 (2011): 1225–35. http://dx.doi.org/10.1128/iai.01222-10.

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ABSTRACTUropathogenicEscherichia coli(UPEC), the predominant cause of uncomplicated urinary tract infection (UTI), utilizes an array of outer membrane iron receptors to facilitate siderophore and heme import from within the iron-limited urinary tract. While these systems are required for UPECin vivofitness and are assumed to be functionally redundant, the relative contributions of specific receptors to pathogenesis are unknown. To delineate the relative roles of distinct UPEC iron acquisition systems in UTI, isogenic mutants in UPEC strain CFT073 or 536 lacking individual receptors were compet

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