The C-Terminal RpoN Domain of sigma54 Forms an unpredictedHelix-Turn-Helix Motif Similar to domains of sigma70
The ''{delta}'' subunit of prokaryotic RNA-polymerase allows gene-specific transcription initiation. Two {sigma} families have been identified, {sigma}{sup 70} and {sigma}{sup 54}, which use distinct mechanisms to initiate transcription and share no detectable sequence homology. Although the {sigma}{sup 70}-type factors have been well characterized structurally by x-ray crystallography, no high-resolution structural information is available for the {sigma}{sup 54}-type factors. Here we present the NMR derived structure of the C-terminal domain of {sigma}{sup 54} from Aquifex aeolicus. This domain (Thr323 to Gly389), 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 {sigma}{sup 70}-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. This structure's homology with other DNA binding proteins, combined with previous biochemical data, suggest how the C-terminal domain of {sigma}{sup 54} binds to DNA.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science; National Institutes ofHealth
- DOE Contract Number:
- DE-AC02-05CH11231; NIH:864P1B
- OSTI ID:
- 889887
- Report Number(s):
- LBNL-59078; JBCHA3; R&D Project: 864P1B; BnR: 400412000; TRN: US200620%%71
- Journal Information:
- Journal of Biological Chemistry, Vol. 280, Issue 50; Related Information: Journal Publication Date: 12/16/2005; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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