The nucleotide addition cycle of RNA polymerase is controlled by two molecular hinges in the Bridge Helix domainReportar como inadecuado




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BMC Biology

, 8:134

First Online: 29 October 2010Received: 20 September 2010Accepted: 29 October 2010

Abstract

BackgroundCellular RNA polymerases RNAPs are complex molecular machines that combine catalysis with concerted conformational changes in the active center. Previous work showed that kinking of a hinge region near the C-terminus of the Bridge Helix BH-HC plays a critical role in controlling the catalytic rate.

ResultsHere, new evidence for the existence of an additional hinge region in the amino-terminal portion of the Bridge Helix domain BH-HN is presented. The nanomechanical properties of BH-HN emerge as a direct consequence of the highly conserved primary amino acid sequence. Mutations that are predicted to influence its flexibility cause corresponding changes in the rate of the nucleotide addition cycle NAC. BH-HN displays functional properties that are distinct from BH-HC, suggesting that conformational changes in the Bridge Helix control the NAC via two independent mechanisms.

ConclusionsThe properties of two distinct molecular hinges in the Bridge Helix of RNAP determine the functional contribution of this domain to key stages of the NAC by coordinating conformational changes in surrounding domains.

AbbreviationsBH-Hcmolecular hinge located within the carboxy-terminal portion of the Bridge Helix

BH-HNmolecular hinge located within the amino-terminal portion of the Bridge Helix

NACnucleotide addition cycle

rNTPribonucleotide triphosphate

pspicosecond

RNAPRNA polymerase

TCAtrichloroacetic acid.

Electronic supplementary materialThe online version of this article doi:10.1186-1741-7007-8-134 contains supplementary material, which is available to authorized users.

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Autor: Robert OJ Weinzierl

Fuente: https://link.springer.com/article/10.1186/1741-7007-8-134







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