The Werner syndrome helicase/exonuclease (WRN) disrupts and degrades D-loops in vitro

David K. Orren, Shaji Theodore, Amrita Machwe

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


The loss of function of WRN, a DNA helicase and exonuclease, causes the premature aging disease Werner syndrome. A hallmark feature of cells lacking WRN is genomic instability typified by elevated illegitimate recombination events and accelerated loss of telomeric sequences. In this study, the activities of WRN were examined on a displacement loop (D-loop) DNA substrate that mimics an intermediate formed during the strand invasion step of many recombinational processes. Our results indicate that this model substrate is specifically bound by WRN and efficiently disrupted by its helicase activity. In addition, the 3′ end of the inserted strand of this D-loop structure is readily attacked by the 3′-5′ exonuclease function of WRN. These results indicate that D-loop structures are favored sites for WRN action. Thus, WRN may participate in DNA metabolic processes that utilize these structures, such as recombination and telomere maintenance pathways.

Original languageEnglish
Pages (from-to)13483-13488
Number of pages6
Issue number46
StatePublished - Nov 19 2002

ASJC Scopus subject areas

  • Biochemistry


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