Doug Bishop, Ph.D.

Responses to DNA Damage in S. cerevisiae; Recombinational Repair and Cell Cycle Regulation

Research Summary

Homologous recombination of DNA repairs DNA damage and also creates the physical connections between chromosomes needed for reductional chromosome segregation during meiosis. We study two recombination proteins, Dmc1 and Rad51 that are related to the bacterial repair protein, RecA. The mechanisms of recombinational repair of damage induced double strand breaks in DNA (DSBs) and the mechanism of meiotic recombination are very closely related in terms of the DNA intermediates that form; DSBs are normal intermediates in most or all meiotic recombination. There are, however critical differences in how meiotic recombination is regulated as compared to mitotic recombinational repair. Our research is directed at understanding how Dmc1's function is specialized for meiosis, how the functions of Rad51 and Dmc1 differ, how the two proteins interact with one another during meiosis, and how the two proteins interact with components of the synaptonemal complex. Our studies have shown that while the functions of Rad51 and Dmc1 overlap, they are also functionally distinct.

Using biochemical techniques we recently showed that, like yeast Rad51 protein, yeast Dmc1 protein promotes strand exchange. These results open the door to future efforts to reconstitute regulated homologous recombination reactions in vitro.

We were first to show that recombination proteins can be detected at multiple subnuclear sites during recombination using immunostaining techniques. We have used this method to identify proteins trequired for recruitment of recombinase to double strand break sites in mitotic and meiotic cells. Among such regulators is the breast cancer susceptibility gene BRCA1. We have shown that BRCA1 promotes recombinase assembly and we are currently working to determine the mechanism through which BRCA1 mediates this effect

Selected Papers

Bishop, D.K. (1994). RecA homologues Dmc1 and Rad51 interact to form multiple nuclear complexes before meiotic chromosome synapsis. Cell 79:1081-1092.

Bhattacharyya A, Ear U, Koller B, Weichselbaum R and Bishop DK (2000). The breast cancer-susceptibility gene BRCA1 is required for subnuclear assembly of Rad51 and survival following treatment with the DNA crosslinking agent cisplatin. J. Biol. Chem. 60: 2520-2526.

Hsu J-Y, Sun Z-W, Li X, Reuben M, Tatchell K, Bishop DK, Grushcow JM, Lin R, Smith MM, and Allis CD (2000). Mitotic Phosphorlation of Histone H3 is goverened by Ipl1/aurora kinase and Glc7/PP1 phosphatase in budding yeast and nematodes. Cell 102: 279-291.

Shinohara M, Gasior SL, Bishop DK, Shinohara A (2000). Tid1/Rdh54 and Red1 promote colocalization of RecA homologs Rad51 and Dmc1 during meiotic recombination. Proc. Natl. Acad. Sci, USA, 97:10814-10819.

Orelli B, Logsdon JM, Bishop DK (2001). Nine novel conserved motifs in BRCA1 identified by the chicken orthologue. Oncogene 20: 4433-4438.

Gasior SL, Olivares H, Ear U, Hari DM, Weichselbaum RR, and Bishop DK (2001). Assembly of RecA-like recombinases: Distinct roles for mediator proteins in mitosis and meiosis. Proc. Natl. Acad. Sci. USA 98:8411-8418.

Hong EL, Shinohara A, and Bishop DK (2001). S. cerevisiae Dmc1 protein promotes renaturation of ssDNA and assimilation of ssDNA into homologous super-coiled duplex DNA. J. Biol. Chem. 276:41906-41912.

Connell, P. P., Siddiqui, N., Hoffman, S., Kuang, A., Khatipov, E.-A., Weichselbaum, R. R., and Bishop, D.K. (2004). A hotspot for RAD51C interactions revealed by a peptide that sensitizes cells to cisplatin. Cancer Research 64, 3002-3005

Chen, Y.-K., Leng, C.-H., Olivares, H., Lee, M.-H.,, Chang, Y.-C., Ti, S.-C.,Lo, Y.-H., Wang, A. H.-J., Chang, C.-S., Bishop, D.K., Hsueh, Y.-P., and Twang, T.-F.(2004). Heterodimeric Complexes of Hop2p and Mnd1p Function with Dmc1 to Promote Meiotic Homolog Juxtaposition and Strand-Assimilation. Proc. Natl. Acad. Sci. USA 101: 10572-10577.
Bishop, D.K. and Zickler, D. (2004) Early Decision: Meiotic Crossover Interference prior to stable strand exchange and synapsis (Review) Cell 117, 117, 9-15.

Holzen, T. Shah, P., Olivares, H. and Bishop D. K. (2006). Tid1 promotes dissociation of Dmc1 from non-recombinogenic sites on meiotic chromatin. Genes Dev 20: 2593-2604