1tlh
From Proteopedia
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T4 AsiA bound to sigma70 region 4
Overview
Bacteriophage T4 AsiA is a versatile transcription factor capable of, inhibiting host gene expression as an 'anti-sigma' factor while, simultaneously promoting gene-specific expression of T4 middle genes in, conjunction with T4 MotA. To accomplish this task, AsiA engages conserved, region 4 of Eschericia coli sigma70, blocking recognition of most host, promoters by sequestering the DNA-binding surface at the AsiA/sigma70, interface. The three-dimensional structure of an AsiA/region 4 complex, reveals that the C-terminal alpha helix of region 4 is unstructured, while, four other helices adopt a completely different conformation relative to, the canonical structure of unbound region 4. That AsiA induces, rather, than merely stabilizes, this rearrangement can be realized by comparison, to the homologous structures of region 4 solved in a variety of contexts, including the structure of Thermotoga maritima sigmaA region 4 described, herein. AsiA simultaneously occupies the surface of region 4 that, ordinarily contacts core RNA polymerase (RNAP), suggesting that an, AsiA-bound sigma70 may also undergo conformational changes in the context, of the RNAP holoenzyme.
About this Structure
1TLH is a Protein complex structure of sequences from Bacteriophage t4 and Escherichia coli. Full crystallographic information is available from OCA.
Reference
T4 AsiA blocks DNA recognition by remodeling sigma70 region 4., Lambert LJ, Wei Y, Schirf V, Demeler B, Werner MH, EMBO J. 2004 Aug 4;23(15):2952-62. Epub 2004 Jul 15. PMID:15257291
Page seeded by OCA on Wed Nov 21 03:22:46 2007
