 Paul L. ModrichJames B. Duke Professor of Biochemistry and Investigator, Howard Hughes Medical InstituteResearch interests include Medical Biology, Nucleic Acids Biochemistry, Replication and Stabilization of Genes. Contact InformationOffice Number: (919) 684-2775 Fax: (919) 684-8885 e-mail modrich@biochem.duke.edu Lab Location Room 157A Nanaline Duke Building Mailing Address Department of Biochemistry Nanaline H. Duke Box 3711, DUMC Durham, NC 27710 Education
Research InterestsWe study mismatch repair, a mutation avoidance system that provides several genetic stabilization functions: it corrects DNA biosynthetic errors, ensures the fidelity of genetic recombination, and participates in the earliest steps of checkpoint and apoptotic responses to several classes of DNA damage. We have reconstituted E. coli mismatch repair in a pure system comprised of eleven activities, including the MutH, MutL, MutS, and MutU proteins. Current work on the bacterial system addresses the mechanism of this complex reaction. We have shown that human cells also support mismatch repair and that this reaction is defective in tumors from patients with hereditary nonpolyposis colon cancer (HNPCC). A number of activities have been implicated in human mismatch repair, and we have recently reconstituted the reaction in a purified system comprised of MutSα (MSH2-MSH6 heterodimer), MutLα (MLH1-PMS2 heterodimer), exonuclease 1, the human single-stranded DNA binding protein RPA, the PCNA replication clamp, the clamp loader RFC, and DNA polymerase δ. Hereditary defects in the subunits of MutSα or MutLα are the cause of HNPCC. We have shown that MutSα is responsible for most mismatch recognition events in human cells and that MutLα functions as an endonuclease that is activated in a mismatch-, MutSα–, RFC-, PCNA-, and ATP-dependent manner. MutLα endonuclease incises heteroduplex DNA in a strand-specific fashion. The resulting strand breaks serve as entry sites for MutSα-activated exonuclease I, which removes the mismatch. We are currently exploring the nature of protein-protein and protein-DNA interactions that occur during the course of this reaction. In addition to conferral of strong cancer predisposition, genetic inactivation of MutSα or MutLα also renders cells resistant to some chemotherapeutic agents that kill by triggering an apoptotic respose. We have shown that the cytotoxic DNA lesions produced by these drugs are recognized by the human mismatch repair system, and that recognition/processing of these lesions by the mismatch repair system is necessary for activation of damage signaling kinase(s) that activate the cellular damage response. We are studying the molecular nature of this link between human repair system and the DNA damage signaling cascade. Selected Publications1. Genschel, J. and Modrich, P. (2009) Functions of MutLα, RPA, and HMGB1 in 5’-directed mismatch repair, J. Biol. Chem. 284(32):21536-44. More… 2. Kadyrov, F. A., Genschel, J., Fang, Y., Penland, E., Edelmann, W, and Modrich, P. (2009) A possible mechanism for exonuclease 1-independent eukaryotic mismatch repair, Proc. Natl. Acad. Sci. U. S. A. 106, 8495-8500. More… 3. Iyer, R. R., Pohlhaus, T. J., Chen, S., Hura, G. L., Dzantiev, L., Beese, L. S. and Modrich, P. (2008) The MutSα-PCNA Interaction in Human DNA Mismatch Repair, J. Biol. Chem. 283, 13310-13319. More… 4. Kadyrov, F. A., Holmes, S. F., Arana, M. E., Lukianova, O. A., O’Donnell, M., Kunkel, T. A., and Modrich, P. (2007) Saccharomyces cerevisiae MutLα is a mismatch repair endonuclease, J. Biol. Chem. 282, 37181–37190. More… 5. Pluciennik, A. and Modrich, P. (2007) Protein roadblocks and helix discontinuities are barriers to the initiation of mismatch repair, Proc. Natl. Acad. Sci. U. S. A. 104, 12709-12713. More… 6. Warren, J. J., Pohlhaus, T. J., Changela, A., Iyer, R. R., Modrich, P. L., and Beese, L. S. (2007) Structure of the human MutS DNA lesion recognition complex, Mol. Cell 26, 579-592. More… 7. Iyer, R. R., Pluciennik, A., Burdett, V., and Modrich, P. L. (2006) Mismatch repair: functions and mechanisms, Chem. Rev. 106, 302-323. More… 8. Kadyrov, F. A., Dzantiev, L., Constantin, N., and Modrich, P. (2006) Endonucleolytic function of MutLa in human mismatch repair, Cell 126, 297-308. More… 9. York, S. J. and Modrich, P. (2006) Mismatch repair-dependent iterative excision at irreparable O6-methylguanine lesions in human nuclear extracts, J. Biol. Chem. 281, 22674-22683. More… 10. Constantin, N., Dzantiev, L., Kadyrov, F. A., and Modrich P. (2005) Human mismatch repair: reconstitution of a nick-directed bidirectional reaction, J. Biol. Chem. 280, 39752-39761. More… 11. Martik, D., Baitinger, C. and Modrich, P. (2004) Differential Specificities and Simultaneous Occupancy of Human MutSa Nucleotide Binding Sites, J. Biol. Chem. 279, 28402-28410. More… 12. Dzantiev, L., Constantin, N., Genschel, J., Iyer, R. R., Burgers, P. M., and Modrich, P. (2004) A Defined Human System That Supports Bidirectional Mismatch-Provoked Excision, Mol. Cell, 15, 31-41. More… 13. Genschel, J. and Modrich, P. (2003) Mechanism of 5’-directed excision in human mismatch repair, Mol. Cell 12, 1077-1086. More… 14. Genschel, J., Bazemore, L. R., and Modrich, P. (2002) Human Exonuclease I is Required for 5’ and 3’ Mismatch Repair, J. Biol. Chem. 277, 13302-13311. More… 15. Chen, S., Bigner, S. H., and Modrich, P. (2001) High rate of CAD gene amplification in human cells deficient in MLH1 or MSH6, Proc. Natl. Acad. Sci. U. S. A. 98, 13802-13807. More… 16. Blackwell, L. J., Wang, S., and Modrich, P. (2001) DNA Chain Length Dependence of Formation and Dynamics of hMutSa•hMutLa•Heteroduplex Complexes, J. Biol. Chem. 276, 33233-33240. More… 17. Burdett, V., Baitinger, C., Viswanathan, M., Lovett, S., and Modrich, P. (2001) In vivo requirement for RecJ, ExoVII, ExoI and ExoX in methyl-directed mismatch repair, Proc. Natl. Acad. Sci. U. S. A. 98, 6765-6770. More… 18. Spampinato, C. and Modrich, P. (2000) The MutL ATPase is required for mismatch repair, J. Biol. Chem. 275, 9863-9869. More… 19. Bjornson, K. P., Allen, D. J., and Modrich, P. (2000) Modulation of MutS ATP hydrolysis by DNA cofactors, Biochemistry, 39, 3176-3183. More… 20. Duckett, D. R., Bronstein, S. M., Taya, Y., and Modrich, P. (1999) hMutSa- and hMutLa-dependent phosphorylation of p53 in response to DNA methylator damage, Proc. Natl. Acad. Sci. U. S. A. 96, 12384-12388. More… 21. Yamaguchi, M., Dao, V., and Modrich, P. (1998) MutS and MutL activate DNA helicase II in a mismatch-dependent manner, J. Biol. Chem. 273, 9197-9201. More… 22. Genschel, J., Littman, S. J., Drummond, J. T., and Modrich P. (1998) Isolation of hMutS? from human cells and comparison of the mismatch specificities of hMutSb and hMutSa, J. Biol. Chem. 273, 19895-19901. More… 23. Veigl, M. L., Kasturi, L., Olechnowicz, J., Ma, A., Lutterbaugh, J. D., Periyasamy, S., Li, G.-M., Drummond, J., Modrich, P., Sedwick, W. D., and Markowitz, S. D. (1998) Biallelic inactivation of hMLH1 by epigenetic gene silencing, a novel mechanism causing human MSI cancers, Proc. Natl. Acad. Sci. U. S. A. 95, 8698-8702. More… 24. Drummond, J. T., Genschel, J., Wolf, E., and Modrich, P. (1997) DHFR/MSH3 amplification in methotrexate-resistant cells alters the hMutSa:hMutSb ratio and reduces the efficiency of base-base mismatch repair, Proc. Natl. Acad. Sci. U. S. A. 94, 10144-10149. More… 25. Duckett, D. R., Drummond, J. T., Murchie, A. I. H., Reardon, J. T., Sancar. A., Lilley, D. M. J., and Modrich, P. (1996) Human MutSa recognizes damaged DNA base pairs containing O6-methylguanine, O4-methylthymine or the cisplatin-d(GpG) adduct, Proc. Natl. Acad. Sci. U. S. A. 93, 6443-6447. More… 26. Li, G.-M. and Modrich, P. (1995) Restoration of mismatch repair to nuclear extracts of H6 colorectal tumor cells by a heterodimer of human MutL homologs, Proc. Natl. Acad. Sci. U. S. A. 92, 1950-1954. More… 27. Drummond, J. T., Li, G.-M., Longley, M. J., and Modrich, P. (1995), Isolation of an hMSH2•p160 heterodimer that restores DNA mismatch repair to tumor cells, Science 268, 1909-1912. More… 28. Worth, L., Clark, S., Radman, M., and Modrich, P. (1994) Mismatch repair proteins MutS and MutL inhibit RecA-catalyzed strand transfer between diverged DNAs, Proc. Natl. Acad. Sci. U. S. A. 91, 3238-3241. More… 29. Kat, A., Thilly, W., Fang, W.-h., Longley, M., Li, G.-M., and Modrich, P. (1993) An alkylation-tolerant, mutator human cell line is deficient in strand-specific mismatch repair, Proc. Natl. Acad. Sci. U. S. A. 90, 6424-6428. More… 30. Parsons, R., Li, G.-M., Longley, M. J., Fang, W.-h., Papadopoulos, N., Jen, J., de la Chapelle, A., Kinzler, K.W., Vogelstein, B. and Modrich, P. (1993) Hypermutability and mismatch repair deficiency in RER+ tumor cells, Cell 75, 1227-1236. More… 31. Holmes, J., Clark, S. and Modrich, P. (1990) Strand-specific mismatch correction in nuclear extracts of human and Drosophila melanogaster cell lines, Proc. Natl. Acad. Sci. U. S. A. 87, 5837-5841. More… 32. Lahue, R. S., Au, K. G., and Modrich, P. (1989) DNA mismatch correction in a defined system, Science, 245, 160-164. More… 33. Au, K. G., Clark, S., Miller, J. H., and Modrich, P. (1989) Escherichia coli mutY gene encodes an adenine glycosylase active on G-A mispairs, Proc. Natl. Acad. Sci. U. S. A. 86, 8877-8881. More… 34. Su, S.-S. and Modrich, P. (1986) Escherichia coli mutS-encoded protein binds to mismatched DNA base pairs, Proc. Natl. Acad. Sci. U. S. A. 83, 5057-5061. More… |
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