Structure of the Rad50-Mre11 DNA repair complex from Saccharomyces cerevisiae by electron microscopy
Structure of the Rad50-Mre11 DNA repair complex from Saccharomyces cerevisiae by electron microscopy
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DOI：
10.1074/jbc.m106179200
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发表时间：
2001-10-05
影响因子：
4.8
通讯作者：
Erickson, HP
中科院分区：
文献类型：
--
作者：
Anderson, DE;Trujillo, KM;Erickson, HP
酿酒酵母的RAD50基因是营养生长过程中双链DNA断裂的重组修复和减数分裂重组启动所需要的几个基因之一。Rad50与另外两种蛋白质Mre11和Xrs2形成复合体，该复合体参与双链断裂的形成和加工。Rad50与染色体结构维持（SMC）蛋白家族具有有限的序列同源性，并与SMC具有相同的结构域：N端和c端由两个长卷曲线圈分开的球状结构域。然而，一个显著的区别是两个线圈之间的非线圈铰链区域要小得多。我们在这里报道了一种完整的酿酒酵母Rad50的结构分析，通过电子显微镜，单独和与酵母Mre11复合物。我们的研究结果证实，酵母Rad50确实具有与SMC蛋白相同的反平行线圈结构，但没有检测到球形铰链结构域。然而，分子仍然能够在中间急剧弯曲，使两个催化结构域结合在一起，这表明小铰链结构域是灵活的。我们还证明Mre11作为二聚体结合在Rad50的催化结构域之间，使Mre11的核酸酶活性与Rad50的atp酶和DNA结合活性非常接近。
The RAD50 gene of Saccharomyces cerevisiae is one of several genes required for recombinational repair of double-strand DNA breaks during vegetative growth and for initiation of meiotic recombination. Rad50 forms a complex with two other proteins, Mre11 and Xrs2, and this complex is involved in double-strand break formation and processing. Rad50 has limited sequence homology to the structural maintenance of chromosomes (SMC) family of proteins and shares the same domain structure as SMCs: N- and C-terminal globular domains separated by two long coiled-coils. However, a notable difference is the much smaller non-coil hinge region between the two coiled-coils. We report here a structural analysis of full-length S. cerevisiae Rad50, alone and in a complex with yeast Mre11 by electron microscopy. Our results confirm that yeast Rad50 does have the same antiparallel coiled-coil structure as SMC proteins, but with no detectable globular hinge domain. However, the molecule is still able to bend sharply in the middle to bring the two catalytic domains together, indicating that the small hinge domain is flexible. We also demonstrate that Mre11 binds as a dimer between the catalytic domains of Rad50, bringing the nuclease activities of Mre11 in close proximity to the ATPase and DNA binding activities of Rad50.