Bacillus subtilis operon under the dual control of the general stress transcription factor sigma B and the sporulation transcription factor sigma H.
The sigma B transcription factor of Bacillus subtilis is activated in response to a variety of environmental stresses, including those imposed by entry into the stationary-growth phase, and by heat, salt or ethanol challenge to logarithmically growing cells. Although sigma B is thought to control a general stress regulon, the range of cellular functions it directs remains largely unknown. Our approach to understand the physiological role of sigma B is to characterize genes that require this factor for all or part of their expression, i.e. the csb genes. In this study, we report that the transposon insertion csb40::Tn917lac identifies an operon with three open reading frames, the second of which resembles plant proteins induced by desiccation stress. Primer-extension and operon-fusion experiments showed that the csb40 operon has a sigma B-dependent promoter which is strongly induced by the addition of salt to logarithmically growing cells. The csb40 operon also has a second, sigma H-dependent promoter that is unaffected by salt addition. These results provide support for the hypothesis that sigma B controls a general stress regulon, and indicate that the sigma B and sigma H regulons partly overlap. We suggest that in addition to its acknowledged role in the sporulation process, sigma H is also involved in controlling a subclass of genes that are broadly involved in a general stress response.
Varón
D
D
Department of Food Science and Technology, University of California, Davis 95616, USA.
Brody
M S
MS
Price
C W
CW
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D009876:Operon; D010641:Phenotype; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000378:metabolism*; D013171:Spores, Bacterial; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C079011:SigB protein, Bacteria; D012808:Sigma Factor; C087737:Spo0H protein, Bacillus subtilis; D014157:Transcription Factors