1sc5
From Proteopedia
Sigma-28(FliA)/FlgM complex
Overview
The key regulators of bacterial transcription initiation are the sigma factors, which direct promoter recognition and melting but only after binding to the core RNA polymerase to form the holoenzyme. X-ray crystal structures of the flagellar sigma, sigma(28), in complex with its anti-sigma, FlgM, explain the inhibition mechanism of FlgM, including its ability to attack and destabilize the sigma(28)-holoenzyme. The sigma domains (sigma(2), sigma(3), and sigma(4)) pack together in a compact unit with extensive interdomain interfaces that bury the promoter binding determinants, including the -35 element recognition helix of sigma(4), which fits in an acidic groove on the surface of sigma(3). The structure illustrates the large rearrangements that sigma(28) must undergo to form the holoenzyme and provides insights into the regulation of sigma(28) promoter binding activity that may extend, at least in principle, to other sigmas.
About this Structure
1SC5 is a Protein complex structure of sequences from Aquifex aeolicus. Full crystallographic information is available from OCA.
Reference
Crystal structure of the flagellar sigma/anti-sigma complex sigma(28)/FlgM reveals an intact sigma factor in an inactive conformation., Sorenson MK, Ray SS, Darst SA, Mol Cell. 2004 Apr 9;14(1):127-38. PMID:15068809 Page seeded by OCA on Sat May 3 08:32:06 2008
