title: On the evolution of the bacterial major sigma factors.
abstract: The existence of internal sequence homologies between the N-terminal halves of the gram-negative bacterial major sigma factors and their C-terminal halves, which correspond to minor factors, is reported. In the case of Escherichia-Salmonella sigma-70, an apparent homology was even found between the C-terminal helix-turn-helix DNA-binding motif and the corresponding region of the peptide N half, which, however, is not directly engaged in promoter recognition. It is proposed that major sigma factors may have originated by duplication and fusion of a DNA unit related to the ancestral gene for the whole sigma family. Coevolution of major sigma structures and complex promoters is suggested.
authors.forename: P
authors.initials: P
authors.lastname: Szafrański
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D001665:Binding Sites; D005075:Biological Evolution; D002692:Chlamydia trachomatis / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D012808:Sigma Factor / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor