Mechanism of substrate specificity of phosphatidylinositol phosphate kinases
Mechanism of substrate specificity of phosphatidylinositol phosphate kinases
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DOI：
10.1073/pnas.1522112113
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发表时间：
2016-08-02
影响因子：
11.1
通讯作者：
Ha, Ya
中科院分区：
文献类型：
--
作者：
Muftuoglu, Yagmur;Xue, Yi;Ha, Ya
磷脂酰肌醇磷酸激酶（PIPK）家族酶主要负责将单磷酸化的磷脂酰肌醇衍生物转化为磷脂酰肌醇二磷酸。因此，这些激酶是真核细胞中许多信号传导和膜运输过程的中心。这三种类型的磷脂酰肌醇磷酸激酶在序列上是同源的，但在催化活性和生物学功能上不同。I型和II型激酶分别从磷脂酰肌醇4-磷酸和磷脂酰肌醇5-磷酸产生磷脂酰肌醇4，5-二磷酸，而III型激酶从磷脂酰肌醇3-磷酸产生磷脂酰肌醇3，5-二磷酸。基于对斑马鱼I型激酶PIP 5 K（α）的晶体学分析，我们确定了该激酶家族特有的结构基序，该结构基序用于识别底物上的单磷酸。我们的数据表明，底物识别和磷酸化的复杂模式的结果之间的相互作用的单磷酸结合位点和特异性环：特异性环的功能，以识别不同的方向的肌醇环，而残基侧翼的磷酸结合Arg 244确定是否磷脂酰肌醇3-磷酸是专门结合和磷酸化的5-位置。这项工作提供了一个完整的图片如何PIPKs实现其精致的底物特异性。
The phosphatidylinositol phosphate kinase (PIPK) family of enzymes is primarily responsible for converting singly phosphorylated phosphatidylinositol derivatives to phosphatidylinositol bisphosphates. As such, these kinases are central to many signaling and membrane trafficking processes in the eukaryotic cell. The three types of phosphatidylinositol phosphate kinases are homologous in sequence but differ in catalytic activities and biological functions. Type I and type II kinases generate phosphatidylinositol 4,5-bisphosphate from phosphatidylinositol 4-phosphate and phosphatidylinositol 5-phosphate, respectively, whereas the type III kinase produces phosphatidylinositol 3,5-bisphosphate from phosphatidylinositol 3-phosphate. Based on crystallographic analysis of the zebrafish type I kinase PIP5K(alpha), we identified a structural motif unique to the kinase family that serves to recognize the monophosphate on the substrate. Our data indicate that the complex pattern of substrate recognition and phosphorylation results from the interplay between the monophosphate binding site and the specificity loop: the specificity loop functions to recognize different orientations of the inositol ring, whereas residues flanking the phosphate binding Arg244 determine whether phosphatidylinositol 3-phosphate is exclusively bound and phosphorylated at the 5-position. This work provides a thorough picture of how PIPKs achieve their exquisite substrate specificity.