Institut Pasteur, Université Paris Cité, CNRS UMR3528, Unité de Microbiologie Structurale, F-75015, Paris, France.
Wuhan Institute of Biological Products Co. Ltd., Wuhan, 430207, PR China.
Nat Commun. 2023 Aug 10;14(1):4851. doi: 10.1038/s41467-023-40253-6.
Actinobacteria possess unique ways to regulate the oxoglutarate metabolic node. Contrary to most organisms in which three enzymes compose the 2-oxoglutarate dehydrogenase complex (ODH), actinobacteria rely on a two-in-one protein (OdhA) in which both the oxidative decarboxylation and succinyl transferase steps are carried out by the same polypeptide. Here we describe high-resolution cryo-EM and crystallographic snapshots of representative enzymes from Mycobacterium smegmatis and Corynebacterium glutamicum, showing that OdhA is an 800-kDa homohexamer that assembles into a three-blade propeller shape. The obligate trimeric and dimeric states of the acyltransferase and dehydrogenase domains, respectively, are critical for maintaining the overall assembly, where both domains interact via subtle readjustments of their interfaces. Complexes obtained with substrate analogues, reaction products and allosteric regulators illustrate how these domains operate. Furthermore, we provide additional insights into the phosphorylation-dependent regulation of this enzymatic machinery by the signalling protein OdhI.
放线菌拥有独特的方式来调节草酰戊二酸代谢节点。与大多数生物体中由三种酶组成的 2- 氧戊二酸脱氢酶复合物（ODH）不同，放线菌依赖于一种二合一蛋白（OdhA），其中氧化脱羧和琥珀酰转移酶步骤由同一多肽完成。在这里，我们描述了来自耻垢分枝杆菌和谷氨酸棒杆菌的代表性酶的高分辨率冷冻电镜和晶体快照，结果表明 OdhA 是一个 800kDa 的同六聚体，组装成三叶推进器形状。酰基转移酶和脱氢酶结构域的必需三聚体和二聚体状态对于维持整体组装至关重要，其中两个结构域通过其界面的细微调整相互作用。用底物类似物、反应产物和变构调节剂获得的复合物说明了这些结构域的工作方式。此外，我们提供了更多关于信号蛋白 OdhI 对这种酶机制的磷酸化依赖性调节的见解。
