of Work: Rare replication errors are corrected by the cell's spellchecking machinery, post-replication DNA mismatch repair (MMR). The goal of this project is to understand the biochemistry and genetics of MMR in normal and mutant eukaryotic cells. This year we had three main accomplishments. To test the hypothesis that MSH3 is important for MMR and for reducing cancer incidence, we studied mice deficient in MSH3 alone or in combination MSH6. The (-/-) mice were found to have an increased incidence of cancer and extracts of cells derived from these mice are deficient in MMR activity. To test the hypothesis that polymorphisms in the MSH2 coding sequence may be functionally important, we studied three different polymorphisms that are reported at 1-8% allele frequency. We provided evidence that all three MSH2 gene sequence changes partially reduced MMR, suggesting that people harboring these polymorphisms may be at increased risk of developing cancer. To investigate the function of the Mlh1oPms1 heterodimer in MMR, we are developing a procedure to purify this complex. As part of this effort, we used mass spectroscopy to identify protein contaminants in the partially purified protein preparation. This permitted redesign of the purification procedure to remove the contaminants, thus providing highly purified MutL alpha heterodimer for ongoing biochemical characterizations. These studies are important for understanding the genetics and biochemistry of DNA mismatch repair, the functions of mismatch repair genes, the molecular genetic basis for the initiating events in cancer and its subsequent treatment, and the risk posed to individuals in the population by exposure to DNA damaging agents.
| Burgers, Peter M J; Kunkel, Thomas A (2017) Eukaryotic DNA Replication Fork. Annu Rev Biochem 86:417-438 |
| Kunkel, Thomas A; Erie, Dorothy A (2015) Eukaryotic Mismatch Repair in Relation to DNA Replication. Annu Rev Genet 49:291-313 |
| St Charles, Jordan A; Liberti, Sascha E; Williams, Jessica S et al. (2015) Quantifying the contributions of base selectivity, proofreading and mismatch repair to nuclear DNA replication in Saccharomyces cerevisiae. DNA Repair (Amst) 31:41-51 |
| Liu, Songbai; Lu, Guojun; Ali, Shafat et al. (2015) Okazaki fragment maturation involves ?-segment error editing by the mammalian FEN1/MutS? functional complex. EMBO J 34:1829-43 |
| Makarova, Alena V; Nick McElhinny, Stephanie A; Watts, Brian E et al. (2014) Ribonucleotide incorporation by yeast DNA polymerase ?. DNA Repair (Amst) 18:63-7 |
| Schaetzlein, Sonja; Chahwan, Richard; Avdievich, Elena et al. (2013) Mammalian Exo1 encodes both structural and catalytic functions that play distinct roles in essential biological processes. Proc Natl Acad Sci U S A 110:E2470-9 |
| Sparks, Justin L; Chon, Hyongi; Cerritelli, Susana M et al. (2012) RNase H2-initiated ribonucleotide excision repair. Mol Cell 47:980-6 |
| Lujan, Scott A; Williams, Jessica S; Pursell, Zachary F et al. (2012) Mismatch repair balances leading and lagging strand DNA replication fidelity. PLoS Genet 8:e1003016 |
| Kunkel, Thomas A (2011) Balancing eukaryotic replication asymmetry with replication fidelity. Curr Opin Chem Biol 15:620-6 |
| Jirawatnotai, Siwanon; Hu, Yiduo; Michowski, Wojciech et al. (2011) A function for cyclin D1 in DNA repair uncovered by protein interactome analyses in human cancers. Nature 474:230-4 |
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