Homology sensing via non-linear amplification of sequence-dependent pausing by RecQ helicase

eLife

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[1] Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Budapest, Hungary;Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Budapest, Hungary;Department of Biochemistry, MTA-ELTE Motor Pharmacology Research Group, Eötvös Loránd University, Budapest, Hungary;Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States;

关键词: single molecule biophysics;    homologous recombination;    unwinding mechanism;    magnetic tweezers;    genome stability;    helicase;    E. coli;   

DOI  :  10.7554/eLife.45909

来源: publisher

【 摘 要 】

10.7554/eLife.45909.001RecQ helicases promote genomic stability through their unique ability to suppress illegitimate recombination and resolve recombination intermediates. These DNA structure-specific activities of RecQ helicases are mediated by the helicase-and-RNAseD like C-terminal (HRDC) domain, via unknown mechanisms. Here, employing single-molecule magnetic tweezers and rapid kinetic approaches we establish that the HRDC domain stabilizes intrinsic, sequence-dependent, pauses of the core helicase (lacking the HRDC) in a DNA geometry-dependent manner. We elucidate the core unwinding mechanism in which the unwinding rate depends on the stability of the duplex DNA leading to transient sequence-dependent pauses. We further demonstrate a non-linear amplification of these transient pauses by the controlled binding of the HRDC domain. The resulting DNA sequence- and geometry-dependent pausing may underlie a homology sensing mechanism that allows rapid disruption of unstable (illegitimate) and stabilization of stable (legitimate) DNA strand invasions, which suggests an intrinsic mechanism of recombination quality control by RecQ helicases.

【 授权许可】

CC BY