Gene encoding the sigma 37 species of RNA polymerase sigma factor from Bacillus subtilis.

Abstract

.sigma.37 is a minor species of RNA polymerase .sigma. factor found in the Gram-positive bacterium Bacillus subtilis. .sigma.37 governs the transcription in vitro of genes that are turned on at an early stage in spore formation, as well as other genes that are switched on at the end of the exponential phase of growth but that are not under sporulation control. To study the role of .sigma.37 in B. subtilis gene expression, we have cloned the gene for this minor species of .sigma. factor in Escherichia coli by using as a hybridization probe a synthetic oligonucleotide that was designed on the basis of the NH2-terminal amino acid sequence of .sigma.37 protein. We determined the nucleotide sequence of the entire .sigma.37 gene, which was found to encode a 262-amino acid residue polypeptide of 29.9 kDa. The predicted amino acid sequence of .sigma.37 showed significant homology to that of other .sigma. proteins in a region that has been proposed to be the site of binding of these factors to core RNA polymerase. Genetic mapping experiments placed the gene for .sigma.37, herein designated sigB, at 40.degree. on the genetic map of Piggot and Hoch [Piggot, P and Hoch, J. A. (1985) Microbiol. Rev. 49, 158-179]. An insertion mutation was constructed in sigB and found not to impair growth or sporulation.