The ghrelin O-acyltransferase structure reveals a catalytic channel for transmembrane hormone acylation
The ghrelin O-acyltransferase structure reveals a catalytic channel for transmembrane hormone acylation
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DOI：
10.1074/jbc.ac119.009749
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发表时间：
2019-09-27
影响因子：
4.8
通讯作者：
Hougland, James L.
中科院分区：
文献类型：
--
作者：
Campana, Maria B.;Irudayanathan, Flaviyan Jerome;Hougland, James L.
整体膜蛋白代表了蛋白质组的一个很大且多样化的部分，并且通常难以纯化，阻碍了对蛋白质结构和功能的理解所必需的研究。通过结合共同进化约束和计算建模，以及通过定点诱变和酶活性分析进行的生化验证，我们在这里展示了一种协同方法来构建抗纯化拓扑复杂整体膜蛋白的结构模型。我们报道了真核生物膜结合o -酰基转移酶（MBOAT），胃饥饿素o -酰基转移酶（GOAT）的第一个结构模型，它可以修饰代谢调节激素胃饥饿素。我们的结构是在没有任何实验结构数据的情况下生成的，揭示了一种意想不到的跨膜蛋白酰化策略，催化发生在连接内质网管腔和细胞质的内部通道中。这一发现验证了我们的方法在为其他具有实验挑战性的整体膜蛋白生成预测结构模型方面的能力。我们的结果阐明了膜蛋白功能的新方面，并代表了推进结构导向抑制剂设计的关键步骤，以靶向治疗上重要但实验上难以处理的膜蛋白。
Integral membrane proteins represent a large and diverse portion of the proteome and are often recalcitrant to purification, impeding studies essential for understanding protein structure and function. By combining co-evolutionary constraints and computational modeling with biochemical validation through site-directed mutagenesis and enzyme activity assays, we demonstrate here a synergistic approach to structurally model purification-resistant topologically complex integral membrane proteins. We report the first structural model of a eukaryotic membrane-bound O-acyltransferase (MBOAT), ghrelin O-acyltransferase (GOAT), which modifies the metabolism-regulating hormone ghrelin. Our structure, generated in the absence of any experimental structural data, revealed an unanticipated strategy for transmembrane protein acylation with catalysis occurring in an internal channel connecting the endoplasmic reticulum lumen and cytoplasm. This finding validated the power of our approach to generate predictive structural models for other experimentally challenging integral membrane proteins. Our results illuminate novel aspects of membrane protein function and represent key steps for advancing structure-guided inhibitor design to target therapeutically important but experimentally intractable membrane proteins.