title: Inhibition of Escherichia coli RNA polymerase by bacteriophage T7 gene 2 protein.
abstract: The 64 amino acid residue product of bacteriophage T7 gene 2 (gp2) binds the Escherichia coli RNA polymerase and inhibits transcription. We localized the gp2 binding site to within 53 amino acid residues in the functionally dispensable region of the RNA polymerase beta' subunit. We investigated the effect of gp2 on transcription at a -10/-35 promoter and at an "extended -10" promoter. Our results indicate that binding of gp2 to the sigma70holoenzyme (Esigma70) prevents promoter recognition at -10/-35 promoters. Once open promoter complexes are formed, however, Esigma70transcription is resistant to gp2, since gp2 can no longer bind RNA polymerase. Surprisingly, transcription inhibition by gp2 is both sigma and promoter-specific. gp2 has little effect on Esigma70transcription from an extended -10 promoter, which does not depend on sigma70region 4 interactions with the -35 promoter box for its activity. gp55-dependent phage T4 late promoter transcription is also resistant to gp2. From these results, we conclude that the interaction of the sigma70region 4 with the -35 consensus promoter element is the primary target of gp2 inhibition.
authors.affiliation: Rutgers, The State University, Piscataway, NJ, 08854, USA.
authors.forename: S
authors.initials: S
authors.lastname: Nechaev
authors.forename: K
authors.initials: K
authors.lastname: Severinov
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D017123:Bacteriophage T7; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D012097:Repressor Proteins; D012808:Sigma Factor; D014764:Viral Proteins; C120334:gene 2 product, bacteriophage T7; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases