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Mus81-Mms4 functions as a single heterodimer to cleave nicked intermediates in recombinational DNA repair

Schwartz, Erin K. and Wright, William D. and Ehmsen, Kirk T. and Evans, James E. and Stahlberg, Henning and Heyer, Wolf-Dietrich. (2012) Mus81-Mms4 functions as a single heterodimer to cleave nicked intermediates in recombinational DNA repair. Molecular and cellular biology, Vol. 32, H. 15. pp. 3065-3080.

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Official URL: http://edoc.unibas.ch/dok/A6056071

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Abstract

The formation of crossovers is a fundamental genetic process. The XPF-family endonuclease Mus81-Mms4 (Eme1) contributes significantly to crossing over in eukaryotes. A key question is whether Mus81-Mms4 can process Holliday junctions that contain four uninterrupted strands. Holliday junction cleavage requires the coordination of two active sites, necessitating the assembly of two Mus81-Mms4 heterodimers. Contrary to this expectation, we show that Saccharomyces cerevisiae Mus81-Mms4 exists as a single heterodimer both in solution and when bound to DNA substrates in vitro. Consistently, immunoprecipitation experiments demonstrate that Mus81-Mms4 does not multimerize in vivo. Moreover, chromatin-bound Mus81-Mms4 does not detectably form higher-order multimers. We show that Cdc5 kinase activates Mus81-Mms4 nuclease activity on 3' flaps and Holliday junctions in vitro but that activation does not induce a preference for Holliday junctions and does not induce multimerization of the Mus81-Mms4 heterodimer. These data support a model in which Mus81-Mms4 cleaves nicked recombination intermediates such as displacement loops (D-loops), nicked Holliday junctions, or 3' flaps but not intact Holliday junctions with four uninterrupted strands. We infer that Mus81-dependent crossing over occurs in a noncanonical manner that does not involve the coordinated cleavage of classic Holliday junctions.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Stahlberg)
UniBasel Contributors:Stahlberg, Henning
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society for Microbiology
ISSN:1098-5549
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Feb 2013 08:46
Deposited On:01 Feb 2013 08:41

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