Regulated communication between the upstream face of RNA polymerase and the β′ subunit jaw domain

We used bacteriophage T7-encoded transcription inhibitor gene protein 2 (gp2) as a probe to study the contribution of the Escherichia coli RNA polymerase ( RNAP) beta' subunit jaw domain - the site of gp2 binding - to activator and ATP hydrolysis-dependent open complex formation by the sigma(54)-RNAP. We show that, unlike sigma(70)-dependent transcription, activated transcription by sigma(54)-RNAP is resistant to gp2. In contrast, activator and ATP hydrolysis-independent transcription by sigma(54)-RNAP is highly sensitive to gp2. We provide evidence that an activator- and ATP hydrolysis-dependent conformational change involving the beta' jaw domain and promoter DNA is the basis for gp2-resistant transcription by sigma(54)-RNAP. Our results establish that accessory factors bound to the upstream face of the RNAP, communicate with the beta' jaw domain, and that such communication is subjected to regulation.