Recombinogenic flap ligation pathway for intrinsic repair of topoisomerase IB-induced double-strand breaks

C. Cheng, S. Shuman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Topoisomerase IB catalyzes recombinogenic DNA strand transfer reactions in vitro and in vivo. Here we characterize a new pathway of topoisomerase-mediated DNA ligation in vitro (flap ligation) in which vaccinia virus topoisomerase bound to a blunt-end DNA joins the covalently held strand to a 5' resected end of a duplex DNA containing a 3' tail. The joining reaction occurs with high efficiency when the sequence of the 3' tail is complementary to that of the scissile strand immediately 5' of the cleavage site. A 6-nucleotide segment of complementarity suffices for efficient flap ligation. Invasion of the flap into the duplex apparently occurs while topoisomerase remains bound to DNA, thereby implying a conformational flexibility of the topoisomerase clamp around the DNA target site. The 3' flap acceptor DNA mimics a processed end in the double-strand-break-repair recombination pathway. Our findings suggest that topoisomerase-induced breaks may be rectified by flap ligation, with ensuing genomic deletions or translocations.

Original languageEnglish (US)
Pages (from-to)8059-8068
Number of pages10
JournalMolecular and cellular biology
Volume20
Issue number21
DOIs
StatePublished - 2000

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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