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Mónica Serrano JinXin Gao Jo?o Bota Ashley R. Bate Jeffrey Meisner Patrick Eichenberger Charles P. Moran Jr. Adriano O. Henriques 《PLoS genetics》2015,11(4)
Gene expression during spore development in Bacillus subtilis is controlled by cell type-specific RNA polymerase sigma factors. σFand σE control early stages of development in the forespore and the mother cell, respectively. When, at an intermediate stage in development, the mother cell engulfs the forespore, σF is replaced by σG and σE is replaced by σK. The anti-sigma factor CsfB is produced under the control of σF and binds to and inhibits the auto-regulatory σG, but not σF. A position in region 2.1, occupied by an asparagine in σG and by a glutamate in οF, is sufficient for CsfB discrimination of the two sigmas, and allows it to delay the early to late switch in forespore gene expression. We now show that following engulfment completion, csfB is switched on in the mother cell under the control of σK and that CsfB binds to and inhibits σE but not σK, possibly to facilitate the switch from early to late gene expression. We show that a position in region 2.3 occupied by a conserved asparagine in σE and by a conserved glutamate in σK suffices for discrimination by CsfB. We also show that CsfB prevents activation of σG in the mother cell and the premature σG-dependent activation of σK. Thus, CsfB establishes negative feedback loops that curtail the activity of σE and prevent the ectopic activation of σG in the mother cell. The capacity of CsfB to directly block σE activity may also explain how CsfB plays a role as one of the several mechanisms that prevent σE activation in the forespore. Thus the capacity of CsfB to differentiate between the highly similar σF/σG and σE/σK pairs allows it to rinforce the cell-type specificity of these sigma factors and the transition from early to late development in B. subtilis, and possibly in all sporeformers that encode a CsfB orthologue. 相似文献
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P. A. Fontán M. I. Voskuil M. Gomez D. Tan M. Pardini R. Manganelli L. Fattorini G. K. Schoolnik I. Smith 《Journal of bacteriology》2009,191(18):5628-5633
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Analyses of suppressor mutations have been extremely valuable in understanding gene function. However, techniques for mapping suppressor mutations are not available for most bacterial species. Here, we used high-throughput sequencing technology to identify spontaneously arising suppressor mutations that enabled disruption of rpoE (which encodes σE) in Vibrio cholerae, the agent of cholera. The alternative sigma factor σE, which is activated by envelope stress, promotes expression of factors that help preserve and/or restore cell envelope integrity. In Escherichia coli, rpoE is an essential gene that can only be disrupted in the presence of additional suppressor mutations. Among a panel of independent V. cholerae rpoE mutants, more than 75% contain suppressor mutations that reduce production of OmpU, V. cholerae’s principal outer membrane porin. OmpU appears to be a key determinant of V. cholerae’s requirement for and production of σE. Such dependence upon a single factor contrasts markedly with regulation of σE in E. coli, in which numerous factors contribute to its activation and none is dominant. We also identified a suppressor mutation that differs from all previously described suppressors in that it elevates, rather than reduces, σE’s activity. Finally, analyses of a panel of rpoE mutants shed light on the mechanisms by which suppressor mutations may arise in V. cholerae. 相似文献
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A Spore Coat Protein, CotS, of Bacillus subtilis Is Synthesized under the Regulation of ςK and GerE during Development and Is Located in the Inner Coat Layer of Spores
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Hiromu Takamatsu Yukari Chikahiro Takeko Kodama Hidekatsu Koide Satoshi Kozuka Kunio Tochikubo Kazuhito Watabe 《Journal of bacteriology》1998,180(11):2968-2974
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Expression of the sigmaF-directed csfB locus prevents premature appearance of sigmaG activity during sporulation of Bacillus subtilis
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During sporulation, σG becomes active in the prespore upon the completion of engulfment. We show that the inactivation of the σF-directed csfB locus resulted in premature activation of σG. CsfB exerted control distinct from but overlapping with that exerted by LonA to prevent inappropriate σG activation. The artificial induction of csfB severely compromised spore formation. 相似文献
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