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Publication Abstract from PubMed

The bacterial sigma factors confer promoter specificity to the RNA polymerase (RNAP). One alternative sigma factor, sigmaN, is unique in its structure and functional mechanism, forming transcriptionally inactive promoter complexes that require activation by specialized AAA+ ATPases. We report a 3.4-A resolution X-ray crystal structure of a sigmaN fragment in complex with its cognate promoter DNA, revealing the molecular details of promoter recognition by sigmaN The structure allowed us to build and refine an improved sigmaN-holoenzyme model based on previously published 3.8-A resolution X-ray data. The improved sigmaN-holoenzyme model reveals a conserved interdomain interface within sigmaN that, when disrupted by mutations, leads to transcription activity without activator intervention (so-called bypass mutants). Thus, the structure and stability of this interdomain interface are crucial for the role of sigmaN in blocking transcription activity and in maintaining the activator sensitivity of sigmaN.

Crystal structure of Aquifex aeolicus sigmaN bound to promoter DNA and the structure of sigmaN-holoenzyme.,Campbell EA, Kamath S, Rajashankar KR, Wu M, Darst SA Proc Natl Acad Sci U S A. 2017 Feb 21. pii: 201619464. doi:, 10.1073/pnas.1619464114. PMID:28223493^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.