4fth

Publication Abstract from PubMed

Transcription initiation by bacterial sigma(54)-polymerase requires the action of a transcriptional activator protein. Activators bind sequence-specifically upstream of the transcription initiation site via a DNA-binding domain (DBD). The structurally characterized DBDs from activators all belong to the Fis (factor for inversion stimulation) family of helix-turn-helix DNA-binding proteins. We report here structures of the free and DNA-bound forms of the DBD of NtrC4 (4DBD) from Aquifex aeolicus, a member of the NtrC family of sigma(54) activators. Two NtrC4-binding sites were identified upstream (-145 and -85bp) from the start of the lpxC gene, which is responsible for the first committed step in lipid A biosynthesis. This is the first experimental evidence for sigma(54) regulation in lpxC expression. 4DBD was crystallized both without DNA and in complex with the -145-binding site. The structures, together with biochemical data, indicate that NtrC4 binds to DNA in a manner that is similar to that of its close homolog, Fis. The greater sequence specificity for the binding of 4DBD relative to Fis seems to arise from a larger number of base-specific contacts contributing to affinity than for Fis.

DNA Recognition by a sigma(54) Transcriptional Activator from Aquifex aeolicus.,Vidangos NK, Heideker J, Lyubimov A, Lamers M, Huo Y, Pelton JG, Ton J, Gralla J, Berger J, Wemmer DE J Mol Biol. 2014 Oct 23;426(21):3553-68. doi: 10.1016/j.jmb.2014.08.009. Epub, 2014 Aug 23. PMID:25158097^[1]

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