The highly processive transcription by multi-subunit RNA polymerases (RNAP) can be interrupted by misincorporation or backtracking events that may stall transcription or lead to erroneous transcripts. Backtracked/misincorporated complexes can be resolved via hydrolysis of the transcript. Here, we show that, in response to misincorporation and/or backtracking, the catalytic domain of RNAP active centre, the trigger loop (TL), is substituted by transcription factor Gre. This substitution turns off the intrinsic TL-dependent hydrolytic activity of RNAP active centre, and exchanges it to a far more efficient Gre-dependent mechanism of RNA hydrolysis. Replacement of the TL by Gre factor occurs only in backtracked/misincorporated complexes, and not in correctly elongating complexes. This controlled switching of RNAP activities allows the processivity of elongation to be unaffected by the hydrolytic activity of Gre, while ensuring efficient proofreading of transcription and resolution of backtracked complexes.
PubMed ID: 21266474
Publication type: Not specified
Date Published: 27th Jan 2011
Registered Mode: Not specified
Created: 10th Feb 2011 at 11:28
Last updated: 10th Feb 2011 at 11:28