Possible intermediate steps in the evolution of a prokaryotic developmental system.
Sigma factors (sigma) are transcription factors that operate global switches in gene expression in prokaryotes. They work by directing core RNA polymerase to specific cis-acting promoter sequences; each sigma has a cognate class of promoters with specific sequence characteristics. In Bacillus subtilis four different sigma factors have been implicated in the regulation of gene expression during spore formation, which is a simple differentiation system involving two cell types. In this review I show how the modern developmental system may have arisen from a primitive organism that used only two sigma factors, by a series of steps involving gene duplication and divergence. The increasing sophistication of eukaryotic developmental systems may reflect similar evolutionary processes.
Errington
J
J
Sir William Dunn School of Pathology, University of Oxford, U.K.
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology; D005075:Biological Evolution; D008969:Molecular Sequence Data; D005810:Multigene Family; D011387:Prokaryotic Cells / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology; D013171:Spores, Bacterial / Q000235:genetics / Q000502:physiology
D012808:Sigma Factor