Saccharomyces cerevisiae Dmc1 protein promotes renaturation of single-strand DNA (ssDNA) and assimilation of ssDNA into homologous super-coiled duplex DNA

Dmc1 and Rad51 are eukaryotic RecA homologues that are involved in meiotic recombination. The expression of Dmc1 is limited to meiosis, whereas Rad51 is expressed in mitosis and meiosis. Dmc1 and Ptad51 have unique and overla pping functions during meiotic recombination. Here we report the purificati on of the Dmc1 protein from the budding yeast Saccharomyces cerevisiae and present basic characterization of its biochemical activity. The protein has a weak DNA-dependent ATPase activity and binds both single-strand DNA (ssD NA) and double-strand DNA. Electrophoretic mobility shift assays suggest th at DNA binding by Dmc1 is cooperative. Dmc1 renatures linearized plasmid DN A with first order reaction kinetics and without requiring added nucleotide cofactor. In addition, Dmc1 catalyzes strand assimilation of ssDNA oligonu cleotides into homologous supercoiled duplex DNA in a reaction promoted by ATP or the non-hydrolyzable ATP analogue AMP-PNP.