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 #
5R01ES007061-20
Application #
8245741
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
2012-04-01
Budget End
2013-03-31
Support Year
20
Fiscal Year
2012
Total Cost
$395,353
Indirect Cost
$156,469
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Gibb, Bryan; Ye, Ling F; Kwon, YoungHo et al. (2014) Protein dynamics during presynaptic-complex assembly on individual single-stranded DNA molecules. Nat Struct Mol Biol 21:893-900
Gibb, Bryan; Ye, Ling F; Gergoudis, Stephanie C et al. (2014) Concentration-dependent exchange of replication protein A on single-stranded DNA revealed by single-molecule imaging. PLoS One 9:e87922
Liu, Yan; Gaines, William A; Callender, Tracy et al. (2014) Down-regulation of Rad51 activity during meiosis in yeast prevents competition with Dmc1 for repair of double-strand breaks. PLoS Genet 10:e1004005
Zhao, Weixing; Saro, Dorina; Hammel, Michal et al. (2014) Mechanistic insights into the role of Hop2-Mnd1 in meiotic homologous DNA pairing. Nucleic Acids Res 42:906-17
Potenski, Catherine J; Niu, Hengyao; Sung, Patrick et al. (2014) Avoidance of ribonucleotide-induced mutations by RNase H2 and Srs2-Exo1 mechanisms. Nature 511:251-4
Daley, James M; Niu, Hengyao; Sung, Patrick (2013) Roles of DNA helicases in the mediation and regulation of homologous recombination. Adv Exp Med Biol 767:185-202
Busygina, Valeria; Gaines, William A; Xu, Yuanyuan et al. (2013) Functional attributes of the Saccharomyces cerevisiae meiotic recombinase Dmc1. DNA Repair (Amst) 12:707-12
Daley, James M; Sung, Patrick (2013) RIF1 in DNA break repair pathway choice. Mol Cell 49:840-1
Wilson, Marenda A; Kwon, YoungHo; Xu, Yuanyuan et al. (2013) Pif1 helicase and Polýý promote recombination-coupled DNA synthesis via bubble migration. Nature 502:393-6
Adkins, Nicholas L; Niu, Hengyao; Sung, Patrick et al. (2013) Nucleosome dynamics regulates DNA processing. Nat Struct Mol Biol 20:836-42

Showing the most recent 10 out of 62 publications