Central role of the RNA polymerase trigger loop in intrinsic RNA hydrolysis


The active center of RNA polymerase can hydrolyze phosphodiester bonds in nascent RNA, a reaction thought to be important for proofreading of transcription. The reaction proceeds via a general two Mg(2+) mechanism and is assisted by the 3' end nucleotide of the transcript. Here, by using Thermus aquaticus RNA polymerase, we show that the reaction also requires the flexible domain of the active center, the trigger loop (TL). We show that the invariant histidine (beta' His1242) of the TL is essential for hydrolysis/proofreading and participates in the reaction in two distinct ways: by positioning the 3' end nucleotide of the transcript that assists catalysis and/or by directly participating in the reaction as a general base. We also show that participation of the beta' His1242 of the TL in phosphodiester bond hydrolysis does not depend on the extent of elongation complex backtracking. We obtained similar results with Escherichia coli RNA polymerase, indicating that the function of the TL in phosphodiester bond hydrolysis is conserved among bacteria.

SEEK ID: https://fairdomhub.org/publications/110

PubMed ID: 20534498

Projects: Noisy-Strep

Publication type: Not specified

Journal: Proc. Natl. Acad. Sci. U.S.A.


Date Published: 1st Jun 2010

Registered Mode: Not specified

Authors: Yulia Yuzenkova,

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Views: 2812

Created: 17th Feb 2011 at 18:22

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