DNA strand breaks are induced by ionizing radiation and mutagenic chemicals, and they also arise during replication of a damaged DNA template. If not handled properly, these strand breaks often lead to gross chromosome rearrangements. Homologous recombination is a major means for DNA strand break repair in eukaryotes. Importantly, there is compelling evidence that homology-directed DNA repair is needed for cancer avoidance in humans. In the homologous repair of a double-stranded break, the ends of the break are subjected to exonucleolytic processing to yield 3' single-stranded DNA tails a few hundred bases in length. Nucleation of various recombination factors onto these DNA tails renders them recombinogenic, leading to a search for the chromosomal homolog and the stable pairing of the DNA tails with the homolog to form a DNA joint called """"""""D-loop"""""""". In the later stages, DNA synthesis occurs, followed by the resolution of DNA intermediates to yield mature recombinants and restore the integrity of the injured chromosome. Extensive genetic evidence indicates that the evolutionarily conserved genes of the RAD52 epistasis group, of which RAD54 and RDH54 are key members, mediate homologous recombination and DNA strand break repair by recombination. Rad54 and Rdh54 proteins have been purified to near homogeneity from yeast cells and found to possess DNA-dependent ATPase and ATP-hydrolysis-driven DNA supercoiling activities. Both Rad54 and Rdh54 dramatically stimulate the Rad51/RPA-mediated D-loop reaction. Further studies are proposed to delineate the action mechanism of Rad54 and Rdh54 proteins in DNA supercoiling and heteroduplex DNA formation, and also to define the role of Rad54 and Rdh54 in chromatin remodeling. In addition, we will examine the functional and physical interactions between Rdh54 and the Rad50-Mrel 1-Xrs2 complex germane for understanding the break-induced replication mode of recombination. The studies should provide insights about the mechanisms of the major recombination pathways in eukaryotic cells.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-CPA (05))
Program Officer
Portnoy, Matthew
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Yale University
Schools of Medicine
New Haven
United States
Zip Code
Black, Paul J; Miller, Adam S; Hayes, Jeffrey J (2016) Radioresistance of GGG sequences to prompt strand break formation from direct-type radiation damage. Radiat Environ Biophys 55:411-422
Bonner, Jaclyn N; Choi, Koyi; Xue, Xiaoyu et al. (2016) Smc5/6 Mediated Sumoylation of the Sgs1-Top3-Rmi1 Complex Promotes Removal of Recombination Intermediates. Cell Rep 16:368-378
Niu, Hengyao; Potenski, Catherine J; Epshtein, Anastasiya et al. (2016) Roles of DNA helicases and Exo1 in the avoidance of mutations induced by Top1-mediated cleavage at ribonucleotides in DNA. Cell Cycle 15:331-6
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
Krasner, Danielle S; Daley, James M; Sung, Patrick et al. (2015) Interplay between Ku and Replication Protein A in the Restriction of Exo1-mediated DNA Break End Resection. J Biol Chem 290:18806-16
Daley, James M; Niu, Hengyao; Miller, Adam S et al. (2015) Biochemical mechanism of DSB end resection and its regulation. DNA Repair (Amst) 32:66-74
Daley, James M; Gaines, William A; Kwon, YoungHo et al. (2014) Regulation of DNA pairing in homologous recombination. Cold Spring Harb Perspect Biol 6:a017954
Xue, Xiaoyu; Choi, Koyi; Bonner, Jaclyn et al. (2014) Restriction of replication fork regression activities by a conserved SMC complex. Mol Cell 56:436-45
Zhao, Qi; Saro, Dorina; Sachpatzidis, Aristidis et al. (2014) The MHF complex senses branched DNA by binding a pair of crossover DNA duplexes. Nat Commun 5:2987

Showing the most recent 10 out of 51 publications