Molecular basis for substrate recognition by MTMR2, a myotubularin family phosphoinositide phosphatase
Molecular basis for substrate recognition by MTMR2, a myotubularin family phosphoinositide phosphatase
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DOI：
10.1073/pnas.0510006103
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发表时间：
2006-01-24
影响因子：
11.1
通讯作者：
Dixon, JE
中科院分区：
文献类型：
--
作者：
Begley, MJ;Taylor, GS;Dixon, JE
肌管蛋白是一个催化活性和非活性蛋白的大家族，属于蛋白质酪氨酸磷酸酶的一个独特亚类，它使用肌醇磷脂而不是磷蛋白作为生理底物。在这里，通过结合结晶学和氢交换质谱学研究人肌管蛋白相关蛋白-2(MTMR2)与磷脂酰肌醇的络合物，我们定义了这种独特底物专一性的分子基础。磷脂酰肌醇底物结合在位于蛋白质正电荷表面的口袋中，这表明膜靶向的静电机制。一个灵活的疏水螺旋与底物的二酰甘油部分进行了广泛的相互作用，解释了膜结合磷脂酰肌醇的专一性。活性部位口袋内广泛的氢键网络和电荷相互作用决定了磷脂酰肌醇头基的专一性。这些特异性决定因素在活跃的肌小管蛋白中的保守，而不是不活跃的，为深入了解活跃和不活跃成员之间的功能差异提供了洞察力。
Myotubularins, a large family of catalytically active and inactive proteins, belong to a unique subgroup of protein tyrosine phosphatases that use inositol phospholipids, rather than phosphoproteins, as physiological substrates. Here, by integrating crystallographic and deuterium-exchange mass spectrometry studies of human myotubularin-related protein-2 (MTMR2) in complex with phosphoinositides, we define the molecular basis for this unique substrate specificity. Phosphoinositide substrates bind in a pocket located on a positively charged face of the protein, suggesting an electrostatic mechanism for membrane targeting. A flexible, hydrophobic helix makes extensive interactions with the diacylglycerol moieties of substrates, explaining the specificity for membrane-bound phosphoinositides. An extensive H-bonding network and charge-charge interactions within the active site pocket determine phosphoinositide headgroup specificity. The conservation of these specificity determinants within the active, but not the inactive, myotubularins provides insight into the functional differences between the active and inactive members.