Studies in the model eukaryote Saccharomyces cerevisiae have revealed that homologous recombination provides a major mechanism for eliminating DNA double- stranded breaks (DSBs) induced by ionizing radiation or are associated with injured DNA replication forks. During the repair process, the ends of the DNA breaks are processed nucleolytically to yield 3'ssDNA tails, which are bound by recombination factors. The nucleoprotein complex thus formed then conducts a search to locate an undamaged DNA homologue, and catalyzes the formation of a DNA joint, called D-loop, with the homologue. Resolution of the D-loop can proceed via at least three mechanistically distinct pathways, two of which generate only non-crossover recombinants and are therefore more adept at genome preservation, with the remaining pathway able to produce crossovers frequently. Proteins encoded by evolutionarily conserved genes of the RAD52 epistasis group catalyze the HR reaction. Our studies have provided insights into the mechanistic underpinnings of the HR machinery that harbors proteins of this gene group. In this renewal project, a combination of biochemical, genetic, and other cell-based approaches will be employed to (i) define the mechanism of action of the DNA motor-driven path of DSB end resection, and (ii) delineate the roles of two novel protein complexes in subsequent stages of the HR reaction. Knowing that the structure and function of the RAD52 group of genes and proteins have been conserved highly, the results from our endeavors will allow us to formulate detailed models to elucidate HR mechanisms in other eukaryotes, including humans. Given the importance of HR-mediated chromosome damage repair in tumor suppression, our work also has direct relevance to cancer biology.

Public Health Relevance

Cancers are characterized by genomic instability and rearrangements, which can be induced by exposure of cells to DNA damaging agents such as ionizing radiation or are associated with the stalling or collapse of DNA replication forks. The proposed studies will continue to delineate the mechanism by which cells avoid deleterious genome rearrangements via the process of homologous recombination. The results from our research endeavors have direct relevance to understanding the role of homologous recombination in cancer suppression.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES007061-21
Application #
8449095
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Mcallister, Kimberly A
Project Start
1995-01-01
Project End
2015-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
21
Fiscal Year
2013
Total Cost
$387,126
Indirect Cost
$153,213
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
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Xue, Xiaoyu; Papusha, Alma; Choi, Koyi et al. (2016) Differential regulation of the anti-crossover and replication fork regression activities of Mph1 by Mte1. Genes Dev 30:687-99
Chen, Xuefeng; Niu, Hengyao; Yu, Yang et al. (2016) Enrichment of Cdk1-cyclins at DNA double-strand breaks stimulates Fun30 phosphorylation and DNA end resection. Nucleic Acids Res 44:2742-53
Cassani, Corinne; Gobbini, Elisa; Wang, Weibin et al. (2016) Tel1 and Rif2 Regulate MRX Functions in End-Tethering and Repair of DNA Double-Strand Breaks. PLoS Biol 14:e1002387
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Xue, Xiaoyu; Choi, Koyi; Bonner, Jaclyn N et al. (2015) Selective modulation of the functions of a conserved DNA motor by a histone fold complex. Genes Dev 29:1000-5
Xue, Xiaoyu; Sung, Patrick; Zhao, Xiaolan (2015) Functions and regulation of the multitasking FANCM family of DNA motor proteins. Genes Dev 29:1777-88
Zhao, Weixing; Sung, Patrick (2015) Significance of ligand interactions involving Hop2-Mnd1 and the RAD51 and DMC1 recombinases in homologous DNA repair and XX ovarian dysgenesis. Nucleic Acids Res 43:4055-66
Puddu, Fabio; Oelschlaegel, Tobias; Guerini, Ilaria et al. (2015) Synthetic viability genomic screening defines Sae2 function in DNA repair. EMBO J 34:1509-22
Zhao, Weixing; Vaithiyalingam, Sivaraja; San Filippo, Joseph et al. (2015) Promotion of BRCA2-Dependent Homologous Recombination by DSS1 via RPA Targeting and DNA Mimicry. Mol Cell 59:176-87

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