ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
clpC ofBacillus subtilis is part of an operon containing six genes. Northern blot analysis suggested that all genes are co-transcribed and encode stress-inducible proteins. Two promoters (PA and PB) were mapped upstream of the first gene. PA resembles promoters recognized by the vegetative RNA polymerase EσA. The other promoter (PB) was shown to be dependent on σB, the general stress σ factor in B. subtilis, suggesting that clpC, a potential chaperone, is expressed in a σB-dependent manner. This is the first evidence that σB in B, subtilis is involved in controlling the expression of a gene whose counterpart, clpB, is subject to regulation by σ32 in Escherichia coli, indicating a new function of σB-dependent general stress proteins. PB deviated from the consensus sequence of σB promoters and was only slightly induced by starvation conditions. Nevertheless, strong induction by heat, ethanol, and salt stress occurred at the σB-dependent promoter, whereas the vegetative promoter was only weakly induced under these conditions. However, in a sigB mutant, the σA-like promoter became inducible by heat and ethanol stress, completely compensating for sigB deficiency. Only the downstream σA-like promoter was induced by certain stress conditions such as hydrogen peroxide or puromycin. These results suggest that novel stress-induction mechanisms are acting at a vegetative promoter. Involvement of additional elements in this mode of induction are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2958.1996.tb02511.x
