The Bacillus subtilis rsbU gene product is necessary for RsbX-dependent regulation of sigma B.
sigma B is a secondary sigma factor of Bacillus subtilis. sigma B-dependent transcription is induced when B. subtilis enters the stationary phase of growth or is exposed to any of a number of different environmental stresses. Three genes (rsbV, rsbW, and rsbX), which are cotranscribed with the sigma B structural gene (sigB), encode regulators of sigma B-dependent gene expression. RsbW and RsbV have been shown to control sigma B activity, functioning as an inhibitory sigma B binding protein and its antagonist, respectively. Using the SPAC promoter (PSPAC) to control the expression of the sigB operon, a ctc::lacZ reporter system to monitor sigma B activity, and monoclonal antibodies to determine the levels of sigB operon products, we have now obtained evidence that RsbX is an indirect regulator of sigma B activity. Genetic data and in vivo measurements argue that RsbX negatively regulates an extension of the RsbV-RsbW pathway that requires the product of an additional regulatory gene (rsbU) which lies immediately upstream of the sigB operon. The results are consistent with RsbU, or a process dependent on RsbU, being able to facilitate the RsbV-dependent release of sigma B from RsbW but normally prevented from doing this by RsbX.
Voelker
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Department of Microbiology, University of Texas Health Science Center at San Antonio 78284-7758.
Dufour
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A
Haldenwang
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WG
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D005809:Genes, Regulator / Q000235:genetics; D007613:Kanamycin Resistance; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D010744:Phosphoric Monoester Hydrolases; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D012808:Sigma Factor / Q000096:biosynthesis*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D010744:Phosphoric Monoester Hydrolases; C091162:RsbU protein, Bacillus subtilis