Domain movements of the enhancer-dependent sigma factor drive DNA delivery into the RNA polymerase active site: Insights from single molecule studies

Amit Sharma, Robert N. Leach, Christopher Gell, Nan Zhang, Patricia C. Burrows, Dale A. Shepherd, Sivaramesh Wigneshweraraj, David Alastair Smith, Xiaodong Zhang, Martin Buck, Peter G. Stockley, Roman Tuma

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Recognition of bacterial promoters is regulated by two distinct classes of sequence-specific sigma factors, σ70 or σ54, that differ both in their primary sequence and in the requirement of the latter for activation via enhancer-bound upstream activators. The σ54 version controls gene expression in response to stress, often mediating pathogenicity. Its activator proteins are members of the AAA+ superfamily and use adenosine triphosphate (ATP) hydrolysis to remodel initially auto-inhibited holoenzyme promoter complexes. We have mapped this remodeling using single-molecule fluorescence spectroscopy. Initial remodeling is nucleotide-independent and driven by binding both ssDNA during promoter melting and activator. However, DNA loading into the RNA polymerase active site depends on co-operative ATP hydrolysis by the activator. Although the coupled promoter recognition and melting steps may be conserved between σ70 and σ54, the domain movements of the latter have evolved to require an activator ATPase.

Original languageEnglish (US)
Pages (from-to)5177-5190
Number of pages14
JournalNucleic Acids Research
Volume42
Issue number8
DOIs
StatePublished - Apr 2014

ASJC Scopus subject areas

  • Genetics

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