Two-domain reconstitution of a functional protein histidine kinase
Two-domain reconstitution of a functional protein histidine kinase
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DOI：
10.1073/pnas.95.12.6728
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发表时间：
1998-06-09
影响因子：
11.1
通讯作者：
Inouye, M
中科院分区：
文献类型：
--
作者：
Park, H;Saha, SK;Inouye, M
在原核生物中，在缺乏蛋白丝氨酸/苏氨酸/酪氨酸激酶的情况下，蛋白组氨酸激酶在细胞适应各种环境变化和胁迫的信号转导中起着重要作用，组氨酸激酶在特定的天冬氨酸残基上磷酸化其同源反应调节因子，并与ATP一起响应特定的环境信号。在His-Asp磷酸化信号转导系统中，组氨酸激酶如何发挥其酶促功能尚不清楚。在这里，我们证明了大肠杆菌的跨膜渗透传感器EnvZ的细胞质激酶结构域可以进一步分为两个不同的功能亚结构域：亚结构域a [EnvZ(C).(223-289)]；67个残基]和子结构域B [EnvZ(C).(290-450)]；161残留]。亚结构域A螺旋含量高，包含自磷酸化位点H-243，形成稳定的二聚体，具有EnvZ同源反应调节因子OmpR的识别位点。子结构域B是一种α / β蛋白，以单体形式存在。当两个子结构域混合时，它们重建激酶功能，在ATP存在下使a子结构域的His-243磷酸化。随后，磷酸化的亚结构域A能够将其磷酸基团转移到OmpR中。这种组氨酸激酶的双结构域结构提供了对酶的结构排列及其转磷酸化机制的深入了解。
In prokaryotes, in the absence of protein serine/threonine/tyrosine kinases, protein histidine kinases play a major role in signal transduction invoked in cellular adaptation to various environmental changes and stresses, Histidine kinases phosphorylate their cognate response regulators at a specific aspartic acid residue with ATP in response to particular environmental signals. In this His-Asp phosphorelay signal transduction system, it is still unknown how the histidine kinase exerts its enzymatic function. Here we demonstrate that the cytoplasmic kinase domain of EnvZ, a transmembrane osmo-sensor of Escherichia coli can be further divided into two distinct functional subdomains: subdomain A [EnvZ(C).(223-289); 67 residues] and subdomain B [EnvZ(C).(290-450); 161 residues]. Subdomain A, with a high helical content, contains the autophosphorylation site, H-243, and forms a stable dimer having the recognition site for OmpR, the cognate response regulator of EnvZ. Subdomain B, an alpha/beta-protein, exists as a monomer, When mixed, the two subdomains reconstitute the kinase function to phosphorylate subdomain A at His-243 in the presence of ATP. Subsequently, the phosphorylated subdomain A is able to transfer its phosphate group to OmpR The two-domain structure of this histidine kinase provides an insight into the structural arrangement of the enzyme and its transphosphorylation mechanism.