Identification and Characterization of Two Alternative σ Factors of RNA Polymerase in the Deep-Sea Piezophilic Bacterium Shewanella violacea, Strain DSS12

Two genes for alternative σ factors, σE2 and σE3, classified in the extracytoplasmic function σ family for RNA polymerases, were identified in the deep-sea piezophilic bacterium Shewanella violacea DSS12. Amino acid alignments revealed that the domains for transcriptional functions were comparatively conserved compared with Escherichia coli σE in both proteins. Core-binding analysis suggested that both proteins function as σ factors.