Biochemistry of Meiotic Recombination
Analysis of the structural architecture of meiotic recombination complexes
Characterization of the mechanism of homolog bias in meiosis
Role of Rad51 in genome stability and cancer
Small molecule stimulators of Rad51-DNA binding
Most eukaryotes have two structurally related strand exchange proteins, Rad51 and Dmc1, which are required for meiotic recombination. Our biochemical and in vivo experiments provided evidence that these proteins have very different meiotic functions. Dmc1 has the direct catalytic role in the central stage of meiotic recombination: it promotes homology search and strand exchange. Although Rad51 provides homology search and strand exchange activity during mitosis, we showed its role is altered in meiosis where it serves as an accessory factor to Dmc1 (Cloud et al. 2012). Rad51 enhances the ability of Dmc1 to assemble at the programmed DNA breaks that initiate meiotic recombination.
We are working towards full biochemical reconstruction of meiotic recombination. To this end, we have purified several recombination proteins and showed they are active in Dmc1-mediated recombination reactions. We are also working to better define the mechanism of action of individual strand exchange protein accessory factors (e.g. Chan et al. 2014). These studies complement our efforts to understand the functions of the same proteins in vivo using molecular, genetic, and cell biological approaches.
Rad51 stimulates Dmc1’s D-loop activity (Figure from Cloud et al. 2012). Rad51-II3A is a mutant form that retains DNA binding, but not strand exchange activity.
Working model for the interaction between Rad51, Dmc1 and factors involved in promoting their assembly on tracts of ssDNA (Bishop 2012). Pink arrows represent homology search activity.
Cloud, V., Chan, Y.-L., Grubb, J., Budke, B., and Bishop D. K. (2012) Rad51 is an Accessory Factor for Dmc1-Mediated Joint Molecule Formation During Meiosis. Science 337, 1222-1225
Chan Y.-L., Brown, M.S., Qin, D., Handa, N., and Bishop, D.K. (2014) The Third Exon of the Budding Yeast Meiotic Recombination Gene HOP2 Is Required for Calcium-dependent and Recombinase Dmc1-specific Stimulation of Homologous Strand Assimilation J. Biol. Chem. 89, 18076–18086.
Bishop, D.K., (2012) Rad51, The Lead In Mitotic Recombinational DNA Repair, Plays a Supporting Role in Budding Yeast Meiosis. Cell Cycle 11, 4104-4106