Cleavage mechanism of human Mus81–Eme1 acting on Holliday-junction structures

doi:10.1073/pnas.0710291105

Cleavage mechanism of human Mus81–Eme1 acting on Holliday-junction structures

Ewan R. Taylor* and
Clare H. McGowan*,^†,^‡

Departments of *Molecular Biology and
^†Cell Biology, The Scripps Research Institute, La Jolla, CA 92037

Edited by Stephen J. Elledge, Harvard Medical School, Boston, MA, and approved January 10, 2008 (received for review October 29, 2007)

Abstract

Recombination-mediated repair plays a central role in maintaining genomic integrity during DNA replication. The human Mus81–Eme1 endonuclease is involved in recombination repair, but the exact structures it acts on in vivo are not known. Using kinetic and enzymatic analysis of highly purified recombinant enzyme, we find that Mus81–Eme1 catalyzes coordinate bilateral cleavage of model Holliday-junction structures. Using a self-limiting, cruciform-containing substrate, we demonstrate that bilateral cleavage occurs sequentially within the lifetime of the enzyme–substrate complex. Coordinate bilateral cleavage is promoted by the highly cooperative nature of the enzyme and results in symmetrical cleavage of a cruciform structure, thus, Mus81–Eme1 can ensure coordinate, bilateral cleavage of Holliday junction-like structures.

Footnotes

^‡To whom correspondence should be addressed. E-mail: chmcg{at}scripps.edu
Author contributions: E.R.T. and C.H.M. designed research; E.R.T. performed research; E.R.T. and C.H.M. analyzed data; and E.R.T. and C.H.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0710291105/DC1.