Changes in conserved region 2 of Escherichia coli sigma 70 affecting promoter recognition

Academic Program

Not applicable

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Biological Sciences

Publication Date


Document Type



Life Sciences | Medicine and Health Sciences


We describe a mutation in rpoD, the gene encoding the sigma 70 subunit of RNA polymerase, which alters the promoter specificity of the holoenzyme in vivo. The mutant sigma causes a substantial and specific increase in the activity of mutant ant and lac promoters with a T.A to C.G substitution at position -12, the first position of the -10 hexamer. The rpoD mutation is a single base-pair substitution causing a Gln----His change at position 437, which is in a domain of conserved region 2.4 that is predicted to form an alpha-helix. Gln437 would lie one turn of the alpha-helix away from Thr440, which was previously implicated in recognition of position -12. The rpoD-QH437 mutation described here lends further support to the model that region 2.4 of sigma is involved in recognition of the 5' end of the -10 hexamer. In addition, two rpoD mutations with non-specific effects on promoter recognition are described.

DOI of Published Version



J Mol Biol. 1990 Sep 20;215(2):267-76.

Journal/Book/Conference Title

Journal of molecular biology

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Link to Article in PubMed

PubMed ID