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Trigger loop folding determines transcription rate of <i>Escherichia coli’s</i> RNA polymerase [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 2014.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
pages 743-748 : digital, PDF file
Additional Creators
Lawrence Berkeley National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Two components of the RNA polymerase (RNAP) catalytic center, the bridge helix and the trigger loop (TL), have been linked with changes in elongation rate and pausing. Here, single molecule experiments with the WT and two TL-tip mutants of the Escherichia coli enzyme reveal that tip mutations modulate RNAP’s pause-free velocity, identifying TL conformational changes as one of two rate-determining steps in elongation. Consistent with this observation, we find a direct correlation between helix propensity of the modified amino acid and pause-free velocity. Moreover, nucleotide analogs affect transcription rate, suggesting that their binding energy also influences TL folding. A kinetic model in which elongation occurs in two steps, TL folding on nucleoside triphosphate (NTP) binding followed by NTP incorporation/pyrophosphate release, quantitatively accounts for these results. The TL plays no role in pause recovery remaining unfolded during a pause. The model suggests a finely tuned mechanism that balances transcription speed and fidelity.
Report Numbers
E 1.99:1221838
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Note
Published through SciTech Connect.
12/31/2014.
Proceedings of the National Academy of Sciences of the United States of America 112 3 ISSN 0027-8424 AM
Mejia, Yara; Nudler, Evgeny; Bustamante, Carlos.
Funding Information
AC03-76SF00098(MSD KC261).
R01-GM107329
R01-GM0325543
View MARC record | catkey: 23500572