Inhibition of Escherichia coli RNA polymerase by bacteriophage T7 gene 2 protein

Sergei Nechaev, Konstantin Severinov

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72 Citations (Scopus)


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 β' 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 σ70 holoenzyme (Eσ70) prevents promoter recognition at -10/-35 promoters. Once open promoter complexes are formed, however, Eσ70 transcription is resistant to gp2, since gp2 can no longer bind RNA polymerase. Surprisingly, transcription inhibition by gp2 is both σ and promoter-specific. gp2 has little effect on Eσ70 transcription from an extended -10 promoter, which does not depend on σ70 region 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 σ70 region 4 with the -35 consensus promoter element is the primary target of gp2 inhibition.

Original languageEnglish
Pages (from-to)815-826
Number of pages12
JournalJournal of Molecular Biology
Issue number4
Publication statusPublished - 18 Jun 1999
Externally publishedYes


  • Bacteriophage T7
  • Promoter complex
  • RNA polymerase
  • Sigma subunit
  • Transcription regulation


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