Interaction of the conserved region 4.2 of σE with the RseA anti-sigma factor

Abstract

EσE RNA polymerase transcribes a regulon of folding factors for the bacterial envelope and is induced by physical and chemical stresses. The RseA anti-sigma factor inhibits the activity of EσE RNA polymerase. It is shown here that the N-terminal portion of σE, residues 1-153, binds core RNA polymerase. RseA interacts with residues 154-191 of σE, a site that is homologous to region 4, the sigma factor binding site for promoter DNA. Mutations that reduce transcription of EσE RNA polymerase map to σE residues 178, 181, and 183. Variant σE proteins with amino acid substitutions at residues 178, 181, or 183 do not associate with RseA. A regulatory mechanism is proposed whereby RseA binds to a C-terminal peptide of σE and inhibits the transcription of EσE RNA polymerase by blocking promoter recognition.