Published online June 30, 2008
doi:10.1083/jcb.200711146
The Journal of Cell Biology, Vol. 181, No. 7, 1083-1093
The Rockefeller University Press, 0021-9525 $30.00
© 2008 Banerjee et al.
Mph1p promotes gross chromosomal rearrangement through partial inhibition of homologous recombination
Soma Banerjee1,
Stephanie Smith1,
Ji-Hyun Oum2,
Hung-Jiun Liaw1,
Ji-Young Hwang1,
Nilabja Sikdar1,
Akira Motegi1,
Sang Eun Lee2, and
Kyungjae Myung1
1 Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
2 Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78245
Correspondence to Kyungjae Myung: kmyung{at}nhgri.nih.gov
Gross chromosomal rearrangement (GCR) is a type of genomic instability associated with many cancers. In yeast, multiple pathways cooperate to suppress GCR. In a screen for genes that promote GCR, we identified MPH1, which encodes a 3'–5' DNA helicase. Overexpression of Mph1p in yeast results in decreased efficiency of homologous recombination (HR) as well as delayed Rad51p recruitment to double-strand breaks (DSBs), which suggests that Mph1p promotes GCR by partially suppressing HR. A function for Mph1p in suppression of HR is further supported by the observation that deletion of both mph1 and srs2 synergistically sensitize cells to methyl methanesulfonate-induced DNA damage. The GCR-promoting activity of Mph1p appears to depend on its interaction with replication protein A (RPA). Consistent with this observation, excess Mph1p stabilizes RPA at DSBs. Furthermore, spontaneous RPA foci at DSBs are destabilized by the mph1
mutation. Therefore, Mph1p promotes GCR formation by partially suppressing HR, likely through its interaction with RPA.
S. Banerjee's present address is Center for Liver Research, School of Digestive and Liver Diseases, Institute of Post-Graduate Medical Education and Research, Kolkata, India.
J.-Y. Hwang's present address is Cell Biology Team, Bio Technology Research Center, Korean German Institute of Technology, Mapo-Gu, 121-270 Seoul, South Korea.
A. Motegi's present address is Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku Kyoto 606-8501, Japan.
Abbreviations used in this paper: 5-FOA, 5-fluoroorotic acid; ChIP, chromatin immunoprecipitation; DSB, double-strand break; FA, Fanconi anemia; GCR, gross chromosomal rearrangement; HR, homologous recombination; MMS, methyl methanesulfonate; NHEJ, nonhomologous end joining; RPA, replication protein A; YPD, yeast extract peptone-dextrose.

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