Structural basis for phosphatidylinositol-phosphate biosynthesis.
Structural basis for phosphatidylinositol-phosphate biosynthesis.
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DOI：
10.1038/ncomms9505
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发表时间：
2015-10-16
影响因子：
16.6
通讯作者：
Mancia F
中科院分区：
文献类型：
--
作者：
Clarke OB;Tomasek D;Jorge CD;Dufrisne MB;Kim M;Banerjee S;Rajashankar KR;Shapiro L;Hendrickson WA;Santos H;Mancia F
磷脂酰肌醇对于细胞内信号传导以及碳水化合物和蛋白质锚定到细胞外膜至关重要。磷脂酰肌醇生物合成中的限定步骤由CDP-醇磷酸转移酶催化，所述跨膜酶使用CDP-二酰基甘油作为该反应的供体底物，并且真核生物中的肌醇或原核生物中的磷酸肌醇作为受体醇。在这里，我们报告的结构相关的酶，磷脂酰肌醇磷酸合成酶从Renibacterium salmoninarum，有和没有结合CDP-二酰甘油，分别为3.6和2.5 μ m的分辨率。这些结构揭示了受体位点的位置，以及底物特异性和催化作用的分子决定因素。来自结核分枝杆菌（Mycobacterium tuberculosis）的40%相同的直系同源物的功能表征支持所提出的底物结合和催化机制，所述直系同源物是开发新型抗结核药物的潜在靶点。因此，这项工作提供了一个结构和功能框架，以了解磷脂酰肌醇磷酸生物合成的机制。 CDP-醇磷酸转移酶（CDP-AP）是甘油磷脂生物合成的关键酶。在这里，Clarke等人提出了在结合的脂质底物存在下具有酶活性的CDP-AP的第一种结构，并提出了底物结合和催化的机制。
Phosphatidylinositol is critical for intracellular signalling and anchoring of carbohydrates and proteins to outer cellular membranes. The defining step in phosphatidylinositol biosynthesis is catalysed by CDP-alcohol phosphotransferases, transmembrane enzymes that use CDP-diacylglycerol as donor substrate for this reaction, and either inositol in eukaryotes or inositol phosphate in prokaryotes as the acceptor alcohol. Here we report the structures of a related enzyme, the phosphatidylinositol-phosphate synthase from Renibacterium salmoninarum, with and without bound CDP-diacylglycerol to 3.6 and 2.5 Å resolution, respectively. These structures reveal the location of the acceptor site, and the molecular determinants of substrate specificity and catalysis. Functional characterization of the 40%-identical ortholog from Mycobacterium tuberculosis, a potential target for the development of novel anti-tuberculosis drugs, supports the proposed mechanism of substrate binding and catalysis. This work therefore provides a structural and functional framework to understand the mechanism of phosphatidylinositol-phosphate biosynthesis. CDP-alcohol phosphotransferases (CDP-APs) are critical for the biosynthesis of glycerophospholipids. Here, Clarke et al. present the first structure of an enzymatically active CDP-AP in the presence of a bound lipid substrate and propose a mechanism for substrate binding and catalysis.