Download MendeleyThe C-terminal RpoN domain of sigma54 forms an unpredicted helix-turn-helix motif similar to domains of sigma70.
Doucleff, M., Malak, L.T., Pelton, J.G., Wemmer, D.E.(2005) J Biol Chem 280: 41530-41536
- PubMed: 16210314
- DOI: https://doi.org/10.1074/jbc.M509010200
- Primary Citation of Related Structures:
2AHQ - PubMed Abstract:
The "sigma" subunit of prokaryotic RNA polymerase allows gene-specific transcription initiation. Two sigma families have been identified, sigma70 and sigma54, which use distinct mechanisms to initiate transcription and share no detectable sequence homology. Although the sigma70-type factors have been well characterized structurally by x-ray crystallography, no high resolution structural information is available for the sigma54-type factors. Here we present the NMR-derived structure of the C-terminal domain of sigma54 from Aquifex aeolicus. This domain (Thr-323 to Gly-389), which contains the highly conserved RpoN box sequence, consists of a poorly structured N-terminal tail followed by a three-helix bundle, which is surprisingly similar to domains of the sigma70-type proteins. Residues of the RpoN box, which have previously been shown to be critical for DNA binding, form the second helix of an unpredicted helix-turn-helix motif. The homology of this structure with other DNA-binding proteins, combined with previous biochemical data, suggests how the C-terminal domain of sigma54 binds to DNA.
Organizational Affiliation:
Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
