Hikiba Juri, Hirota Kouji, Kagawa Wataru, Ikawa Shukuko, Kinebuchi Takashi, Sakane Isao, Takizawa Yoshimasa, Yokoyama Shigeyuki, Mandon-Pépin Béatrice, Nicolas Alain, Shibata Takehiko, Ohta Kunihiro, Kurumizaka Hitoshi
Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
Nucleic Acids Res. 2008 Jul;36(12):4181-90. doi: 10.1093/nar/gkn362. Epub 2008 Jun 19.
The M200V polymorphism of the human DMC1 protein, which is an essential, meiosis-specific DNA recombinase, was found in an infertile patient, raising the question of whether this homozygous human DMC1-M200V polymorphism may cause infertility by affecting the function of the human DMC1 protein. In the present study, we determined the crystal structure of the human DMC1-M200V variant in the octameric-ring form. Biochemical analyses revealed that the human DMC1-M200V variant had reduced stability, and was moderately defective in catalyzing in vitro recombination reactions. The corresponding M194V mutation introduced in the Schizosaccharomyces pombe dmc1 gene caused a significant decrease in the meiotic homologous recombination frequency. Together, these structural, biochemical and genetic results provide extensive evidence that the human DMC1-M200V mutation impairs its function, supporting the previous interpretation that this single-nucleotide polymorphism is a source of human infertility.
人类DMC1蛋白是一种必需的、减数分裂特异性DNA重组酶，在一名不育患者中发现了其M200V多态性，这就引发了一个问题，即这种纯合的人类DMC1 - M200V多态性是否可能通过影响人类DMC1蛋白的功能而导致不育。在本研究中，我们确定了八聚体环形式的人类DMC1 - M200V变体的晶体结构。生化分析表明，人类DMC1 - M200V变体稳定性降低，在催化体外重组反应方面存在中度缺陷。在粟酒裂殖酵母dmc1基因中引入的相应M194V突变导致减数分裂同源重组频率显著降低。这些结构、生化和遗传学结果共同提供了大量证据，证明人类DMC1 - M200V突变损害了其功能，支持了先前的解释，即这种单核苷酸多态性是人类不育的一个原因。
