On the evolution of the bacterial major sigma factors

✍ Scribed by Przemysław Szafrański

• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 255 KB
• Volume: 34
• Category: Article
• ISSN: 0022-2844
• DOI: 10.1007/bf00163000

✦ Synopsis

The existence of internal sequence homologies between the N-terminal halves of the gramnegative 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.