Structure of the G60A mutant of Ras
Structure of the G60A mutant of Ras
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DOI：
10.1074/jbc.m502240200
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发表时间：
2005-07-08
影响因子：
4.8
通讯作者：
Nassar, N
中科院分区：
文献类型：
--
作者：
Ford, B;Skowronek, K;Nassar, N
取代丙氨酸甘氨酸在位置60的v-H-Ras产生的显性负突变体，完全废除的能力，v-H-Ras转化NIH 3 T3细胞和诱导的非洲爪蟾卵母细胞的生殖囊泡破裂。GppNp结合形式的RasG 60 A的晶体结构出乎意料地显示开关区域采用开放构象，这让人想起Ras与Sos复合的无核苷酸形式的结构。通常稳定鸟嘌呤核苷酸和Mg 2+离子的关键残基已经发生了相当大的移动。Sos与RasG 60 A结合，但不能催化核苷酸交换。我们的数据表明，RasG 60 A中心点GTP观察到的显性负效应可能是由于在非生产性Ras-GTP-鸟嘌呤核苷酸交换因子三元复合物中的Sos的螯合。
Substituting alanine for glycine at position 60 in v-H-Ras generated a dominant negative mutant that completely abolished the ability of v-H-Ras to transform NIH 3T3 cells and to induce germinal vesicle breakdown in Xenopus oocytes. The crystal structure of the GppNp-bound form of RasG60A unexpectedly shows that the switch regions adopt an open conformation reminiscent of the structure of the nucleotide-free form of Ras in complex with Sos. Critical residues that normally stabilize the guanine nucleotide and the Mg2+ ion have moved considerably. Sos binds to RasG60A but is unable to catalyze nucleotide exchange. Our data suggest that the dominant negative effect observed for RasG60A center dot GTP could result from the sequestering of Sos in a non-productive Ras-GTP-guanine nucleotide exchange factor ternary complex.