1h38

File:1h38.gif

STRUCTURE OF A T7 RNA POLYMERASE ELONGATION COMPLEX AT 2.9A RESOLUTION

OverviewOverview

The single-subunit bacteriophage T7 RNA polymerase carries out the transcription cycle in an identical manner to that of bacterial and eukaryotic multisubunit enzymes. Here we report the crystal structure of a T7 RNA polymerase elongation complex, which shows that incorporation of an 8-base-pair RNA-DNA hybrid into the active site of the enzyme induces a marked rearrangement of the amino-terminal domain. This rearrangement involves alternative folding of about 130 residues and a marked reorientation (about 130 degrees rotation) of a stable core subdomain, resulting in a structure that provides elements required for stable transcription elongation. A wide opening on the enzyme surface that is probably an RNA exit pathway is formed, and the RNA-DNA hybrid is completely buried in a newly formed, deep protein cavity. Binding of 10 base pairs of downstream DNA is stabilized mostly by long-distance electrostatic interactions. The structure implies plausible mechanisms for the various phases of the transcription cycle, and reveals important structural similarities with the multisubunit RNA polymerases.

About this StructureAbout this Structure

1H38 is a Protein complex structure of sequences from Enterobacteria phage t7. Full crystallographic information is available from OCA.

ReferenceReference

Structure of a T7 RNA polymerase elongation complex at 2.9 A resolution., Tahirov TH, Temiakov D, Anikin M, Patlan V, McAllister WT, Vassylyev DG, Yokoyama S, Nature. 2002 Nov 7;420(6911):43-50. Epub 2002 Oct 9. PMID:12422209 Page seeded by OCA on Fri May 2 18:22:26 2008