A Full-Length Group 1 Bacterial Sigma Factor Adopts a Compact Structure Incompatible with DNA Binding

Edmund C. Schwartz, Alexander Shekhtman, Kaushik Dutta, Matthew R. Pratt, David Cowburn, Seth Darst, Tom W. Muir

Research output: Contribution to journalArticle

39 Scopus citations


The σ factors are the key regulators of bacterial transcription initiation. Through direct read-out of promoter DNA sequence, they recruit the core RNA polymerase to sites of initiation, thereby dictating the RNA polymerase promoter-specificity. The group 1 σ factors, which direct the vast majority of transcription initiation during log phase growth and are essential for viability, are autoregulated by an N-terminal sequence known as σ1.1. We report the solution structure of Thermotoga maritima σA σ1.1. We additionally demonstrate by using chemical crosslinking strategies that σ1.1 is in close proximity to the promoter recognition domains of σA. We therefore propose that σ1.1 autoinhibits promoter DNA binding of free σA by stabilizing a compact organization of the σ factor domains that is unable to bind DNA.

Original languageEnglish (US)
Pages (from-to)1091-1103
Number of pages13
JournalChemistry and Biology
Issue number10
Publication statusPublished - Oct 20 2008



  • DNA

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmacology
  • Drug Discovery
  • Clinical Biochemistry

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