A glutamate switch controls voltage-sensitive phosphatase function
A glutamate switch controls voltage-sensitive phosphatase function
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DOI：
10.1038/nsmb.2289
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发表时间：
2012-06-01
影响因子：
16.8
通讯作者：
Minor, Daniel L., Jr.
中科院分区：
文献类型：
--
作者：
Liu, Lijun;Kohout, Susy C.;Minor, Daniel L., Jr.
玻璃海鞘电压敏感磷酸酶（Ci-VSP）将电压敏感结构域（VSD）偶联到与肿瘤抑制因子PTEN相似的脂质磷酸酶。VSD如何控制酶功能尚不清楚。在这里，我们提出了高分辨率的晶体结构的Ci-VSP酶结构域，揭示构象变化的一个关键的环，称为“门控环”，控制访问的活性位点的机制，其中残基Glu 411直接与基板竞争。限制门控环构象的基于结构的突变损害了催化功能，并证明Glu 411也有助于底物选择性。结构引导的突变进一步定义了门控环和连接磷酸酶与VSD的接头之间的相互作用，用于酶活性的电压控制。总之，这些数据表明，门控环和接头之间的功能耦合形成了控制电压依赖性酶激活的调节机制的核心。
The Ciona intestinalis voltage-sensing phosphatase (Ci-VSP) couples a voltage-sensing domain (VSD) to a lipid phosphatase that is similar to the tumor suppressor PTEN. How the VSD controls enzyme function has been unclear. Here, we present high-resolution crystal structures of the Ci-VSP enzymatic domain that reveal conformational changes in a crucial loop, termed the 'gating loop', that controls access to the active site by a mechanism in which residue Glu411 directly competes with substrate. Structure-based mutations that restrict gating loop conformation impair catalytic function and demonstrate that Glu411 also contributes to substrate selectivity. Structure-guided mutations further define an interaction between the gating loop and linker that connects the phosphatase to the VSD for voltage control of enzyme activity. Together, the data suggest that functional coupling between the gating loop and the linker forms the heart of the regulatory mechanism that controls voltage-dependent enzyme activation.