Studies in the model eukaryote Saccharomyces cerevisiae have revealed that homologous recombination (HR) 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 resected nucleolytically to yield 3' ssDNA tails, which are bound by HR factors. The nucleoprotein complex thus formed then conducts a search to locate an undamaged DNA homolog, and catalyzes the formation of a DNA joint, called D-loop, with the homolog. 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 being 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 its functional crosstalk with Exo1-mediated resection in both yeast and human cells, and (ii) delineate the roles that the conserved Rad51 paralogs fulfill in the assembly of Rad51-ssDNA nucleoprotein filaments. The results from our endeavors will allow us to formulate detailed models to elucidate HR mechanisms in eukaryotes. Given the importance of HR-mediated chromosome damage repair in tumor suppression, our work also has direct, strong 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 eukaryotic cells avoid deleterious genome rearrangements via the process of homologous recombination. The results from our research endeavors have direct relevance to radiation and cancer biology.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES007061-24
Application #
9276685
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Mcallister, Kimberly A
Project Start
1995-01-01
Project End
2021-05-31
Budget Start
2017-06-01
Budget End
2018-05-31
Support Year
24
Fiscal Year
2017
Total Cost
$376,875
Indirect Cost
$151,875
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
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
Ma, Chu Jian; Kwon, Youngho; Sung, Patrick et al. (2017) Human RAD52 interactions with replication protein A and the RAD51 presynaptic complex. J Biol Chem 292:11702-11713
Zhao, Weixing; Steinfeld, Justin B; Liang, Fengshan et al. (2017) BRCA1-BARD1 promotes RAD51-mediated homologous DNA pairing. Nature 550:360-365
Lee, Ja Yil; Steinfeld, Justin B; Qi, Zhi et al. (2017) Sequence imperfections and base triplet recognition by the Rad51/RecA family of recombinases. J Biol Chem 292:11125-11135
Adkins, Nicholas L; Swygert, Sarah G; Kaur, Parminder et al. (2017) Nucleosome-like, Single-stranded DNA (ssDNA)-Histone Octamer Complexes and the Implication for DNA Double Strand Break Repair. J Biol Chem 292:5271-5281
Xu, Jingfei; Zhao, Lingyun; Xu, Yuanyuan et al. (2017) Cryo-EM structures of human RAD51 recombinase filaments during catalysis of DNA-strand exchange. Nat Struct Mol Biol 24:40-46
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
Liang, Fengshan; Longerich, Simonne; Miller, Adam S et al. (2016) Promotion of RAD51-Mediated Homologous DNA Pairing by the RAD51AP1-UAF1 Complex. Cell Rep 15:2118-2126

Showing the most recent 10 out of 81 publications