Hong E L, Shinohara A, Bishop D K
Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA.
J Biol Chem. 2001 Nov 9;276(45):41906-12. doi: 10.1074/jbc.M105563200. Epub 2001 Sep 10.
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 Rad51 have unique and overlapping functions during meiotic recombination. Here we report the purification 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 (ssDNA) and double-strand DNA. Electrophoretic mobility shift assays suggest that DNA binding by Dmc1 is cooperative. Dmc1 renatures linearized plasmid DNA with first order reaction kinetics and without requiring added nucleotide cofactor. In addition, Dmc1 catalyzes strand assimilation of ssDNA oligonucleotides into homologous supercoiled duplex DNA in a reaction promoted by ATP or the non-hydrolyzable ATP analogue AMP-PNP.
Dmc1和Rad51是参与减数分裂重组的真核RecA同源物。Dmc1的表达仅限于减数分裂，而Rad51在有丝分裂和减数分裂中均有表达。在减数分裂重组过程中，Dmc1和Rad51具有独特且重叠的功能。在此，我们报道了从小芽殖酵母酿酒酵母中纯化Dmc1蛋白，并展示了其生化活性的基本特征。该蛋白具有较弱的依赖DNA的ATP酶活性，且能结合单链DNA（ssDNA）和双链DNA。电泳迁移率变动分析表明，Dmc1与DNA的结合具有协同性。Dmc1以一级反应动力学使线性化质粒DNA复性，且无需添加核苷酸辅因子。此外，在ATP或不可水解的ATP类似物AMP-PNP促进的反应中，Dmc1催化ssDNA寡核苷酸与同源超螺旋双链DNA的链同化作用。
