Sequence of the Bacillus subtilis genome region in the vicinity of the lev operon reveals two new extracytoplasmic function RNA polymerase sigma factors SigV and SigZ

Abstract

Summary: Two regions with sizes 18 900 and 25400 bp, which join previously known contigs containing levRDEFG, aadK and bit genes near 235δ of the Bacillus subtilis chromosome, were sequenced. Among others, two genes, which encode proteins homologous to RNA polymerase σ-factors, were identified within this region. The gene products designated SigV and SigZ, show the highest homology with σ-factors encoded by the gene carQ of Myxococcus xanthus and sigX (formerly orfX20) of B. subtilis, correspondingly. All σ-factors which show statistically significant homology to SigV and SigZ, belong to the ECF (extracytoplasmic functions) subfamily. SigV and SigZ do not have N-terminal sequence which prevents such proteins from binding to DNA without RNA polymerase core enzyme.