title: Structure of a T7 RNA polymerase elongation complex at 2.9 A resolution.
abstract: 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.
authors.affiliation: High Throughput Factory, RIKEN Harima Institute at SPring-8, 1-1-1 Kouto, Mikazuki-cho, Sayo, Hyogo 679-5148, Japan.
authors.forename: Tahir H
authors.initials: TH
authors.lastname: Tahirov
authors.forename: Dmitry
authors.initials: D
authors.lastname: Temiakov
authors.forename: Michael
authors.initials: M
authors.lastname: Anikin
authors.forename: Vsevolod
authors.initials: V
authors.lastname: Patlan
authors.forename: William T
authors.initials: WT
authors.lastname: McAllister
authors.forename: Dmitry G
authors.initials: DG
authors.lastname: Vassylyev
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D000595:Amino Acid Sequence; D017123:Bacteriophage T7 / Q000201:enzymology*; D020029:Base Pairing; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity; D014158:Transcription, Genetic; D014764:Viral Proteins
chemical_list: D014764:Viral Proteins; D012313:RNA; D004247:DNA; C062210:bacteriophage T7 RNA polymerase; D012321:DNA-Directed RNA Polymerases