RAD51C和XRCC3在基因重组及DNA修复中的作用。
Role of RAD51C and XRCC3 in genetic recombination and DNA repair.
作者信息
Liu Yilun, Tarsounas Madalena, O'regan Paul, West Stephen C
机构信息
Clare Hall Laboratories, London Research Institute, Cancer Research UK, South Mimms, Hertfordshire EN6 3LD, United Kingdom.
出版信息
J Biol Chem. 2007 Jan 19;282(3):1973-9. doi: 10.1074/jbc.M609066200. Epub 2006 Nov 17.
In germ line cells, recombination is required for gene reassortment and proper chromosome segregation at meiosis, whereas in somatic cells it provides an important mechanism for the repair of DNA double-strand breaks. Five proteins (RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3) that share homology with RAD51 recombinase and are known as the RAD51 paralogs are important for recombinational repair, as paralog-defective cell lines exhibit spontaneous chromosomal aberrations, defective DNA repair, and reduced gene targeting. The paralogs form two distinct protein complexes, RAD51B-RAD51C-RAD51D-XRCC2 and RAD51C-XRCC3, but their precise cellular roles remain unknown. Here, we show that, like MLH1, RAD51C localized to mouse meiotic chromosomes at pachytene/diplotene. Using immunoprecipitation and gel filtration analyses, we found that Holliday junction resolvase activity associated tightly and co-eluted with the 80-kDa RAD51C-XRCC3 complex. Taken together, these data indicate that the RAD51C-XRCC3-associated Holliday junction resolvase complex associates with crossovers and may play an essential role in the resolution of recombination intermediates prior to chromosome segregation.
在生殖系细胞中,减数分裂时基因重排和正确的染色体分离需要重组,而在体细胞中,重组为DNA双链断裂的修复提供了一种重要机制。五种与RAD51重组酶具有同源性且被称为RAD51旁系同源物的蛋白质(RAD51B、RAD51C、RAD51D、XRCC2和XRCC3)对重组修复很重要,因为旁系同源物缺陷的细胞系表现出自发性染色体畸变、DNA修复缺陷和基因打靶减少。这些旁系同源物形成两种不同的蛋白质复合物,即RAD51B-RAD51C-RAD51D-XRCC2和RAD51C-XRCC3,但其确切的细胞作用仍不清楚。在这里,我们表明,与MLH1一样,RAD51C在粗线期/双线期定位于小鼠减数分裂染色体。通过免疫沉淀和凝胶过滤分析,我们发现霍利迪连接体解离酶活性与80 kDa的RAD51C-XRCC3复合物紧密相关并共同洗脱。综上所述,这些数据表明,与RAD51C-XRCC3相关的霍利迪连接体解离酶复合物与交叉相关,可能在染色体分离前重组中间体的解离中起重要作用。