Recombination hotspots and single-stranded DNA binding proteins couple DNA translocation to DNA unwinding by the AddAB helicase-nuclease

Joseph Yeeles, Kara van Aelst, Mark S Dillingham, F Moreno-Herrero

Research output: Contribution to journalArticle (Academic Journal)

28 Citations (Scopus)

Abstract

AddAB is a helicase-nuclease that processes double-stranded DNA breaks for repair by homologous recombination. This process is modulated by Chi recombination hotspots: specific DNA sequences that attenuate the nuclease activity of the translocating AddAB complex to promote downstreamrecombination. Using a combination of kinetic and imaging techniques, we show that AddAB translocation is not coupled to DNA unwinding in the absence of single-stranded DNA binding proteins because nascent single-stranded DNA immediately re-anneals behind the moving enzyme. However, recognition of recombination hotspot sequences during translocation activates unwinding by coupling these activities, thereby ensuring the downstream formation of single-stranded DNA that is required for RecA-mediated recombinational repair. In addition to their implications for the mechanism of double-stranded DNA break repair, these observations may affect our implementation and interpretation of helicase assays and our understanding of helicase mechanisms in general.
Translated title of the contributionRecombination hotspots and single-stranded DNA binding proteins couple DNA translocation to DNA unwinding by the AddAB helicase-nuclease
Original languageEnglish
Pages (from-to)806 - 816
Number of pages11
JournalMolecular Cell
Volume42
Issue number6
DOIs
Publication statusPublished - Jun 2011

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