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
Sung, Patrick (2018) Introduction to the Thematic Minireview Series: DNA double-strand break repair and pathway choice. J Biol Chem 293:10500-10501
Crickard, J Brooks; Kaniecki, Kyle; Kwon, YoungHo et al. (2018) Spontaneous self-segregation of Rad51 and Dmc1 DNA recombinases within mixed recombinase filaments. J Biol Chem 293:4191-4200
Crickard, J Brooks; Kaniecki, Kyle; Kwon, YoungHo et al. (2018) Regulation of Hed1 and Rad54 binding during maturation of the meiosis-specific presynaptic complex. EMBO J 37:
Wang, Weibin; Daley, James M; Kwon, Youngho et al. (2018) A DNA nick at Ku-blocked double-strand break ends serves as an entry site for exonuclease 1 (Exo1) or Sgs1-Dna2 in long-range DNA end resection. J Biol Chem 293:17061-17069
Crickard, J Brooks; Kaniecki, Kyle; Kwon, Youngho et al. (2018) Meiosis-specific recombinase Dmc1 is a potent inhibitor of the Srs2 antirecombinase. Proc Natl Acad Sci U S A 115:E10041-E10048
Rao, Timsi; Longerich, Simonne; Zhao, Weixing et al. (2018) Importance of homo-dimerization of Fanconi-associated nuclease 1 in DNA flap cleavage. DNA Repair (Amst) 64:53-58
Kaniecki, Kyle; De Tullio, Luisina; Gibb, Bryan et al. (2017) Dissociation of Rad51 Presynaptic Complexes and Heteroduplex DNA Joints by Tandem Assemblies of Srs2. Cell Rep 21:3166-3177
Daley, James M; Jimenez-Sainz, Judit; Wang, Weibin et al. (2017) Enhancement of BLM-DNA2-Mediated Long-Range DNA End Resection by CtIP. Cell Rep 21:324-332
De Tullio, Luisina; Kaniecki, Kyle; Kwon, Youngho et al. (2017) Yeast Srs2 Helicase Promotes Redistribution of Single-Stranded DNA-Bound RPA and Rad52 in Homologous Recombination Regulation. Cell Rep 21:570-577
Miller, Adam S; Daley, James M; Pham, Nhung Tuyet et al. (2017) A novel role of the Dna2 translocase function in DNA break resection. Genes Dev 31:503-510

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