Reduced capacity of alternative sigmas to melt promoters ensures stringent promoter recognition.

Full Abstract

In bacteria, multiple sigmas direct RNA polymerase to distinct sets of promoters. Housekeeping sigmas direct transcription from thousands of promoters, whereas most alternative sigmas are more selective, recognizing more highly conserved promoter motifs. For sigma(32) and sigma(28), two Escherichia coli Group 3 sigmas, altering a few residues in Region 2.3, the portion of sigma implicated in promoter melting, to those universally conserved in housekeeping sigmas relaxed their stringent promoter requirements and significantly enhanced melting of suboptimal promoters. All Group 3 sigmas and the more divergent Group 4 sigmas have nonconserved amino acids at these positions and rarely transcribe >100 promoters. We suggest that the balance of "melting" and "recognition" functions of sigmas is critical to setting the stringency of promoter recognition. Divergent sigmas may generally use a nonoptimal Region 2.3 to increase promoter stringency, enabling them to mount a focused response to altered conditions.

Author information

Author/s: Koo, Byoung-Mo (BM); Rhodius, Virgil A (VA); Nonaka, Gen (G); deHaseth, Pieter L (PL); Gross, Carol A (CA);

Affiliation: Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA.

Grants: GM057755 (Agency:NIGMS NIH HHS) ; GM31808 (Agency:NIGMS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural

Journal: Genes & development (Genes Dev), published in United States. (Language: eng)

Reference: 2009-Oct; vol 23 (issue 20) : pp 2426-36

Dates: Created 2009/10/16; Completed 2009/11/03;

PMID: 19833768, status: MEDLINE (last retrieval date: 11/3/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

Comments and Corrections

CommentIn: Genes Dev. 2009 Oct 15;23(20):2371-5. (PMID: 19833764)

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