Two conformational states of Ras GTPase exhibit differential GTP-binding kinetics
Two conformational states of Ras GTPase exhibit differential GTP-binding kinetics
复制标题
DOI：
10.1016/j.bbrc.2008.01.169
复制
发表时间：
2008-05-02
影响因子：
3.1
通讯作者：
Kataoka, Tohru
中科院分区：
文献类型：
--
作者：
Liao, Jingling;Shima, Fumi;Kataoka, Tohru
先前的P-31 NMR研究表明，小GTP酶H-Ras和K-Ras与GTP复合，呈现两种相互转换的构象状态，状态I和状态2。虽然状态2对应于活性构象，但对状态1的功能知之甚少，状态1是一种不能与效应物结合的非活性构象。为了解决状态1的生物化学性质，我们测量了五个Ras家族小GTP酶的P-31 NMR谱; H-Ras，M-Ras，Rap 1A，Rap 2A和Ra 1A，并发现它们表现出独特的状态2/状态1群体，其比例范围从M-Ras的0.072到Rap 2A的16。此外，我们表明，具有较高的人口状态I的GTP酶表现出较高的解离和缔合速率常数的GTP。这些结果表明，GTP加载到无核苷酸的小GTP酶优先产生状态1，随后转化为状态2，使GTP结合形式的功能。(c)2008年爱思唯尔公司All rights reserved.
Previous P-31 NMR studies revealed that small GTPases H-Ras and K-Ras in complex with GTP assume two interconverting conformational states, state I and state 2. While state 2 corresponds to an active conformation, little is known about the function of state 1, an inactive conformation incapable of effector binding. To address the biochemical properties of state 1, we measured the P-31 NMR spectra of five Ras family small GTPases; H-Ras, M-Ras, Rap1A, Rap2A and Ra1A, and find that they exhibit distinctive state 2/state 1 populations with the ratios ranging from 0.072 for M-Ras to 16 for Rap2A. Further, we show that GTPases with higher populations of state I exhibit higher dissociation and association rate constants for GTP. These results imply that GTP loading to the nucleotide-free small GTPases preferentially yields state 1, which is subsequently converted to state 2, rendering the GTP-bound form functional. (c) 2008 Elsevier Inc. All rights reserved.