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Littérature scientifique sur le sujet « Sporulation initiation (Spo0) pathway »
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Articles de revues sur le sujet "Sporulation initiation (Spo0) pathway"
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Quisel, John D., William F. Burkholder et Alan D. Grossman. « In Vivo Effects of Sporulation Kinases on Mutant Spo0A Proteins in Bacillus subtilis ». Journal of Bacteriology 183, no 22 (15 novembre 2001) : 6573–78. http://dx.doi.org/10.1128/jb.183.22.6573-6578.2001.
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ABSTRACT The phosphorylated form of the response regulator Spo0A (Spo0A∼P) is required for the initiation of sporulation in Bacillus subtilis. Phosphate is transferred to Spo0A from at least four histidine kinases (KinA, KinB, KinC, and KinD) by a phosphotransfer pathway composed of Spo0F and Spo0B. Several mutations inspo0A allow initiation of sporulation in the absence ofspo0F and spo0B, but the mechanisms by which these mutations allow bypass of spo0F andspo0B are not fully understood. We measured the ability of KinA, KinB, and KinC to activate sporulation of fivespo0A mutants in the absence of Spo0F and Spo0B. We also determined the effect of Spo0E, a Spo0A∼P-specific phosphatase, on sporulation of strains containing the spo0A mutations. Our results indicate that several of the mutations relax the specificity of Spo0A, allowing Spo0A to obtain phosphate from a broader group of phosphodonors. In the course of these experiments, we observed medium-dependent effects on the sporulation of different mutants. This led us to identify a small molecule, acetoin, that can stimulate sporulation of some spo0A mutants.
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Underwood, Sarah, Shuang Guan, Vinod Vijayasubhash, Simon D. Baines, Luke Graham, Richard J. Lewis, Mark H. Wilcox et Keith Stephenson. « Characterization of the Sporulation Initiation Pathway of Clostridium difficile and Its Role in Toxin Production ». Journal of Bacteriology 191, no 23 (25 septembre 2009) : 7296–305. http://dx.doi.org/10.1128/jb.00882-09.
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ABSTRACT Clostridium difficile is responsible for significant mortality and morbidity in the hospitalized elderly. C. difficile spores are infectious and are a major factor contributing to nosocomial transmission. The Spo0A response regulator is the master regulator for sporulation initiation and can influence many other cellular processes. Using the ClosTron gene knockout system, we inactivated genes encoding Spo0A and a putative sporulation-associated sensor histidine kinase in C. difficile. Inactivation of spo0A resulted in an asporogeneous phenotype, whereas inactivation of the kinase reduced C. difficle sporulation capacity by 3.5-fold, suggesting that this kinase also has a role in sporulation initiation. Furthermore, inactivation of either spo0A or the kinase resulted in a marked defect in C. difficile toxin production. Therefore, Spo0A and the signaling pathway that modulates its activity appear to be involved in regulation of toxin synthesis in C. difficile. In addition, Spo0A was directly phosphorylated by a putative sporulation-associated kinase, supporting the hypothesis that sporulation initiation in C. difficile is controlled by a two-component signal transduction system rather than a multicomponent phosphorelay. The implications of these findings for C. difficile sporulation, virulence, and transmission are discussed.
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Brunsing, Ryan L., Chandra La Clair, Sharon Tang, Christina Chiang, Lynn E. Hancock, Marta Perego et James A. Hoch. « Characterization of Sporulation Histidine Kinases of Bacillus anthracis ». Journal of Bacteriology 187, no 20 (15 octobre 2005) : 6972–81. http://dx.doi.org/10.1128/jb.187.20.6972-6981.2005.
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ABSTRACT The initiation of sporulation in Bacillus species is regulated by the phosphorelay signal transduction pathway, which is activated by several histidine sensor kinases in response to cellular and metabolic signals. Comparison of the protein components of the phosphorelay between Bacillus subtilis and Bacillus anthracis revealed high homology in the phosphorelay orthologs of Spo0F, Spo0B, and Spo0A. The sensor domains of sensor histidine kinases are poorly conserved between species, making ortholog recognition tenuous. Putative sporulation sensor histidine kinases of B. anthracis were identified by homology to the HisKA domain of B. subtilis sporulation sensor histidine kinases, which interacts with Spo0F. Nine possible kinases were uncovered, and their genes were assayed for complementation of kinase mutants of B. subtilis, for ability to drive lacZ expression in B. subtilis and B. anthracis, and for the effect of deletion of each on the sporulation of B. anthracis. Five of the nine sensor histidine kinases were inferred to be capable of inducing sporulation in B. anthracis. Four of the sensor kinases could not be shown to induce sporulation; however, the genes for two of these were frameshifted in all B. anthracis strains and one of these was also frameshifted in the pathogenic pXO1-bearing Bacillus cereus strain G9241. It is proposed that acquisition of plasmid pXO1 and pathogenicity may require a dampening of sporulation regulation by mutational selection of sporulation sensor histidine kinase defects. The sporulation of B. anthracis ex vivo appears to result from any one or a combination of the sporulation sensor histidine kinases remaining.
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Bongiorni, Cristina, Ricarda Stoessel et Marta Perego. « Negative Regulation of Bacillus anthracis Sporulation by the Spo0E Family of Phosphatases ». Journal of Bacteriology 189, no 7 (26 janvier 2007) : 2637–45. http://dx.doi.org/10.1128/jb.01798-06.
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ABSTRACT The initiation of sporulation in Bacillus species is controlled by the phosphorelay signal transduction system. Multiple regulatory elements act on the phosphorelay to modulate the level of protein phosphorylation in response to cellular, environmental, and metabolic signals. In Bacillus anthracis nine possible histidine sensor kinases can positively activate the system, while two response regulator aspartyl phosphate phosphatases of the Rap family negatively impact the pathway by dephosphorylating the Spo0F intermediate response regulator. In this study, we have characterized the B. anthracis members of the Spo0E family of phosphatases that specifically dephosphorylate the Spo0A response regulator of the phosphorelay and master regulator of sporulation. The products of four genes were able to promote the dephosphorylation of Spo0A∼P in vitro. The overexpression of two of these B. anthracis Spo0E-like proteins from a multicopy vector consistently resulted in a sporulation-deficient phenotype. A third gene was found to be not transcribed in vivo. A fourth gene encoded a prematurely truncated protein due to a base pair deletion that nevertheless was subject to translational frameshift repair in an Escherichia coli protein expression system. A fifth Spo0E-like protein has been structurally and functionally characterized as a phosphatase of Spo0A∼P by R. N. Grenha et al. (J. Biol. Chem. 281:37993-38003, 2006). We propose that these proteins may contribute to maintain B. anthracis in the transition phase of growth during an active infection and therefore contribute to the virulence of this organism.
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Bongiorni, Cristina, Ricarda Stoessel, Dorinda Shoemaker et Marta Perego. « Rap Phosphatase of Virulence Plasmid pXO1 Inhibits Bacillus anthracis Sporulation ». Journal of Bacteriology 188, no 2 (15 janvier 2006) : 487–98. http://dx.doi.org/10.1128/jb.188.2.487-498.2006.
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ABSTRACT This study shows that the Bacillus anthracis pXO1 virulence plasmid carries a Rap-Phr system, BXA0205, which regulates sporulation initiation in this organism. The BXA0205Rap protein was shown to dephosphorylate the Spo0F response regulator intermediate of the phosphorelay signal transduction system that regulates the initiation of the developmental pathway in response to environmental, metabolic, and cell cycle signals. The activity of the Rap protein was shown to be inhibited by the carboxy-terminal pentapeptide generated through an export-import processing pathway from the associated BXA0205Phr protein. Deregulation of the Rap activity by either overexpression or lack of the Phr pentapeptide resulted in severe inhibition of sporulation. Five additional Rap-Phr encoding systems were identified on the chromosome of B. anthracis, one of which, BA3790-3791, also affected sporulation initiation. The results suggest that the plasmid-borne Rap-Phr system may provide a selective advantage to the virulence of B. anthracis.
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Gottig, Natalia, María Eugenia Pedrido, Marcelo Méndez, Esteban Lombardía, Adrián Rovetto, Valeria Philippe, Lelia Orsaria et Roberto Grau. « The Bacillus subtilis SinR and RapA Developmental Regulators Are Responsible for Inhibition of Spore Development by Alcohol ». Journal of Bacteriology 187, no 8 (15 avril 2005) : 2662–72. http://dx.doi.org/10.1128/jb.187.8.2662-2672.2005.
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ABSTRACT Even though there is a large body of information concerning the harmful effects of alcohol on different organisms, the mechanism(s) that affects developmental programs, at a single-cell level, has not been clearly identified. In this respect, the spore-forming bacterium Bacillus subtilis constitutes an excellent model to study universal questions of cell fate, cell differentiation, and morphogenesis. Here, we demonstrate that treatment with subinhibitory concentrations of alcohol that did not affect vegetative growth inhibited the initiation of spore development through a selective blockage of key developmental genes under the control of the master transcription factor Spo0A∼P. Isopropyl-β-d-thiogalactopyranoside-directed expression of a phosphorylation-independent form of Spo0A (Sad67) and the use of an in vivo mini-Tn10 insertional library permitted the identification of the developmental SinR repressor and RapA phosphatase as the effectors that mediated the inhibitory effect of alcohol on spore morphogenesis. A double rapA sinR mutant strain was completely resistant to the inhibitory effects of different-C-length alcohols on sporulation, indicating that the two cell fate determinants were the main or unique regulators responsible for the spo0 phenotype of wild-type cells in the presence of alcohol. Furthermore, treatment with alcohol produced a significant induction of rapA and sinR, while the stationary-phase induction of sinI, which codes for a SinR inhibitor, was completely turned off by alcohol. As a result, a dramatic repression of spo0A and the genes under its control occurred soon after alcohol addition, inhibiting the onset of sporulation and permitting the evaluation of alternative pathways required for cellular survival.
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Devi, Seram Nganbiton, Brittany Kiehler, Lindsey Haggett et Masaya Fujita. « Evidence that Autophosphorylation of the Major Sporulation Kinase in Bacillus subtilis Is Able To Occur in trans ». Journal of Bacteriology 197, no 16 (8 juin 2015) : 2675–84. http://dx.doi.org/10.1128/jb.00257-15.
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ABSTRACTEntry into sporulation inBacillus subtilisis governed by a multicomponent phosphorelay, a complex version of a two-component system which includes at least three histidine kinases (KinA to KinC), two phosphotransferases (Spo0F and Spo0B), and a response regulator (Spo0A). Among the three histidine kinases, KinA is known as the major sporulation kinase; it is autophosphorylated with ATP upon starvation and then transfers a phosphoryl group to the downstream components in a His-Asp-His-Asp signaling pathway. Our recent study demonstrated that KinA forms a homotetramer, not a dimer, mediated by the N-terminal domain, as a functional unit. Furthermore, when the N-terminal domain was overexpressed in the starving wild-type strain, sporulation was impaired. We hypothesized that this impairment of sporulation could be explained by the formation of a nonfunctional heterotetramer of KinA, resulting in the reduced level of phosphorylated Spo0A (Spo0A∼P), and thus, autophosphorylation of KinA could occur intrans. To test this hypothesis, we generated a series ofB. subtilisstrains expressing homo- or heterogeneous KinA protein complexes consisting of various combinations of the phosphoryl-accepting histidine point mutant protein and the catalytic ATP-binding domain point mutant protein. We found that the ATP-binding-deficient protein was phosphorylated when the phosphorylation-deficient protein was present in a 1:1 stoichiometry in the tetramer complex, while each of the mutant homocomplexes was not phosphorylated. These results suggest that ATP initially binds to one protomer within the tetramer complex and then the γ-phosphoryl group is transmitted to another in atransfashion. We further found that the sporulation defect of each of the mutant proteins is complemented when the proteins are coexpressedin vivo. Taken together, thesein vitroandin vivoresults reinforce the evidence that KinA autophosphorylation is able to occur in atransfashion.IMPORTANCEAutophosphorylation of histidine kinases is known to occur by either thecis(one subunit of kinase phosphorylating itself within the multimer) or thetrans(one subunit of the multimer phosphorylates the other subunit) mechanism. The present study provided directin vivoandin vitroevidence that autophosphorylation of the major sporulation histidine kinase (KinA) is able to occur intranswithin the homotetramer complex. While the physiological and mechanistic significance of thetransautophosphorylation reaction remains obscure, understanding the detailed reaction mechanism of the sporulation kinase is the first step toward gaining insight into the molecular mechanisms of the initiation of sporulation, which is believed to be triggered by unknown factors produced under conditions of nutrient depletion.
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de Jong, Imke G., Jan-Willem Veening et Oscar P. Kuipers. « Heterochronic Phosphorelay Gene Expression as a Source of Heterogeneity in Bacillus subtilis Spore Formation ». Journal of Bacteriology 192, no 8 (12 février 2010) : 2053–67. http://dx.doi.org/10.1128/jb.01484-09.
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ABSTRACT In response to limiting nutrient sources and cell density signals, Bacillus subtilis can differentiate and form highly resistant endospores. Initiation of spore development is governed by the master regulator Spo0A, which is activated by phosphorylation via a multicomponent phosphorelay. Interestingly, only part of a clonal population will enter this developmental pathway, a phenomenon known as sporulation bistability or sporulation heterogeneity. How sporulation heterogeneity is established is largely unknown. To investigate the origins of sporulation heterogeneity, we constructed promoter-green fluorescent protein (GFP) fusions to the main phosphorelay genes and perturbed their expression levels. Using time-lapse fluorescence microscopy and flow cytometry, we showed that expression of the phosphorelay genes is distributed in a unimodal manner. However, single-cell trajectories revealed that phosphorelay gene expression is highly dynamic or “heterochronic” between individual cells and that stochasticity of phosphorelay gene transcription might be an important regulatory mechanism for sporulation heterogeneity. Furthermore, we showed that artificial induction or depletion of the phosphorelay phosphate flow results in loss of sporulation heterogeneity. Our data suggest that sporulation heterogeneity originates from highly dynamic and variable gene activity of the phosphorelay components, resulting in large cell-to-cell variability with regard to phosphate input into the system. These transcriptional and posttranslational differences in phosphorelay activity appear to be sufficient to generate a heterogeneous sporulation signal without the need of the positive-feedback loop established by the sigma factor SigH.
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Stephenson, Sophie, Christian Mueller, Min Jiang et Marta Perego. « Molecular Analysis of Phr Peptide Processing in Bacillus subtilis ». Journal of Bacteriology 185, no 16 (15 août 2003) : 4861–71. http://dx.doi.org/10.1128/jb.185.16.4861-4871.2003.
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ABSTRACT In Bacillus subtilis, an export-import pathway regulates production of the Phr pentapeptide inhibitors of Rap proteins. Processing of the Phr precursor proteins into the active pentapeptide form is a key event in the initiation of sporulation and competence development. The PhrA (ARNQT) and PhrE (SRNVT) peptides inhibit the RapA and RapE phosphatases, respectively, whose activity is directed toward the Spo0F∼P intermediate response regulator of the sporulation phosphorelay. The PhrC (ERGMT) peptide inhibits the RapC protein acting on the ComA response regulator for competence with regard to DNA transformation. The structural organization of PhrA, PhrE, and PhrC suggested a role for type I signal peptidases in the processing of the Phr preinhibitor, encoded by the phr genes, into the proinhibitor form. The proinhibitor was then postulated to be cleaved to the active pentapeptide inhibitor by an additional enzyme. In this report, we provide evidence that Phr preinhibitor proteins are subject to only one processing event at the peptide bond on the amino-terminal end of the pentapeptide. This processing event is most likely independent of type I signal peptidase activity. In vivo and in vitro analyses indicate that none of the five signal peptidases of B. subtilis (SipS, SipT, SipU, SipV, and SipW) are indispensable for Phr processing. However, we show that SipV and SipT have a previously undescribed role in sporulation, competence, and cell growth.
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Chibazakura, T., F. Kawamura, K. Asai et H. Takahashi. « Effects of spo0 mutations on spo0A promoter switching at the initiation of sporulation in Bacillus subtilis. » Journal of bacteriology 177, no 15 (1995) : 4520–23. http://dx.doi.org/10.1128/jb.177.15.4520-4523.1995.
Texte intégralThèses sur le sujet "Sporulation initiation (Spo0) pathway"
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Davidson, Philip. « Evolutionary Remodeling of the Sporulation Initiation Pathway ». Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1026.
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Signal transduction pathways allow organisms to sense and respond appropriately to a complex bouquet of environmental cues. The molecular determinants of specificity are constrained by the demands of signaling fidelity, yet flexible enough to allow pathway remodeling to meet novel environmental challenges. A detailed picture of how these forces shape bacterial two-component signaling systems has emerged over the last decade. However, the tension between constraint and flexibility in more complex architectures has not been well-studied. In this thesis, I combine comparative genomics and in vitro phosphotransfer experiments to investigate pathway remodeling using the Firmicutes sporulation initiation (Spo0) pathway as a model. The present-day Spo0 pathways in Bacilli and Clostridia share common ancestry, but possess different architectures. In Clostridia, a sensor kinase phosphorylates Spo0A, the master regulator of the sporulation, directly. In Bacilli, Spo0 is phosphorylated/activated indirectly via a four-protein phosphorelay. The presence in sister lineages of signaling pathways that activate the same response regulator and control analogous phenotypes, yet possess with different architectures, suggests a common ancestral pathway that evolved through interaction remodeling. The prevailing theory is that the ancestral pathway was a simpler, direct phosphorylation architecture; the more complex phosphorelay emerged within the Bacillar lineage. In contrast to this prevailing view, my analysis of 84 representative genomes supports a novel hypothesis for the evolution of Spo0 architectures, wherein the two protein, direct phosphorylation architecture is a derived state, which arose from an ancestral Spo0 phosphorelay. The combination of my bioinformatic analysis and the first experimental characterization of a Clostridial phosphorelay provide evidence for the presence of functional phosphorelays in both classes Bacilli and Clostridia. Further, a cross-species complementation assay between phosphorelays from each class suggests that interaction specificity has been conserved since the divergence of this phylum, 2.7 BYA. My results reveal a patchy phylogenetic distribution of both Spo0 pathway architectures, consistent with repeated remodeling events, in which a phosphorelay was replaced with a two protein, direct phosphorylation pathway. This remodeling likely occurred via acquisition of a sensor kinase with direct specificity for Spo0A. Further, my analysis suggests that the unusual architectures of the Spo0 pathway and its striking tendency to gain and lose interactions may be due to the juxtaposition of three key properties: the maintenance of interaction specificity through molecular recognition; the ecological role of endosporulation; and the degeneracy of interaction space that permits the ongoing recruitment of kinases to recognize novel environmental signals.