An open conformation of switch I revealed by the crystal structure of a Mg2+-free form of RHOA complexed with GDP -: Implications for the GDP/GTP exchange mechanism
An open conformation of switch I revealed by the crystal structure of a Mg2+-free form of RHOA complexed with GDP -: Implications for the GDP/GTP exchange mechanism
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DOI：
10.1074/jbc.m910274199
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发表时间：
2000-06-16
影响因子：
4.8
通讯作者：
Hakoshima, T
中科院分区：
文献类型：
--
作者：
Shimizu, T;Ihara, K;Hakoshima, T
Mg2+离子是鸟苷三磷酸酶（GTPase）活性所必需的，在鸟嘌呤核苷酸结合和保持gtp结合蛋白结构完整性中起关键作用。我们在2.0埃的分辨率下测定了一个小的GTPase RHOA在没有Mg2+的情况下与GDP络合的晶体结构，消除Mg2+离子会在打开核苷酸结合位点的开关I区引起显着的构象变化。在Ha Ras与其鸟嘌呤核苷酸交换因子Sos结合的开关区域也观察到类似的结构变化。这种RHOA-GDP结构揭示了Mg2+的重要调控作用，表明鸟嘌呤核苷酸交换因子可能利用开关I的这一特征在GDP/GTP交换中产生开放构象。
Mg2+ ions are essential for guanosine triphosphatase (GTPase) activity and play key roles in guanine nucleotide binding and preserving the structural integrity of GTP-binding proteins. We determined the crystal structure of a small GTPase RHOA complexed with GDP in the absence of Mg2+ at 2.0-Angstrom resolution Elimination of a Mg2+ ion induces significant conformational changes in the switch I region that opens up the nucleotide-binding site. Similar structural changes have been observed in the switch regions of Ha Ras bound to its guanine nucleotide exchange factor, Sos. This RHOA-GDP structure reveals an important regulatory role for Mg2+ and suggests that guanine nucleotide exchange factor may utilize this feature of snitch I to produce an open conformation in GDP/GTP exchange.