Tsukamoto Yasumasa, Mitsuoka Chikako, Terasawa Masahiro, Ogawa Hideyuki, Ogawa Tomoko
Iwate College of Nursing, Iwate 020-0151, Japan.
Mol Biol Cell. 2005 Feb;16(2):597-608. doi: 10.1091/mbc.e04-09-0782. Epub 2004 Nov 17.
The Mre11-Rad50-Xrs2 (MRX) protein complex plays pivotal roles in meiotic recombination, repair of damaged DNA, telomere elongation, and cell cycle checkpoint control. Xrs2p is known to be essential for all the functions of the complex, but its role in the complex has not been clearly elucidated. A 32-amino acid region near the C terminus of Xrs2p was identified as an Mre11p-binding site. No more function of Xrs2p than translocation of Mre11p from the cytoplasm to the nucleus is necessary for response to DNA damage. However, domains in Xrs2p located both 49 amino acids upstream and 104 amino acids downstream of the Mre11p binding site are required for meiotic recombination and telomere elongation, respectively, in addition to the 32-amino acid region. These findings demonstrate that Xrs2p acts as a specificity factor that allows the MRX complex to function in meiotic recombination and in telomere elongation.
Mre11-Rad50-Xrs2（MRX）蛋白复合物在减数分裂重组、受损DNA修复、端粒延长和细胞周期检查点控制中发挥着关键作用。已知Xrs2p对该复合物的所有功能至关重要，但其在复合物中的作用尚未得到明确阐明。Xrs2p C末端附近的一个32个氨基酸的区域被确定为Mre11p结合位点。对于DNA损伤的应答，Xrs2p的功能只需将Mre11p从细胞质转运到细胞核即可。然而，除了这个32个氨基酸的区域外，位于Mre11p结合位点上游49个氨基酸和下游104个氨基酸处的Xrs2p结构域分别是减数分裂重组和端粒延长所必需的。这些发现表明，Xrs2p作为一种特异性因子，使MRX复合物能够在减数分裂重组和端粒延长中发挥作用。
