Ruickoldt Jakob, Kreibich Julian, Bick Thomas, Jeoung Jae-Hun, Duffus Benjamin R, Leimkühler Silke, Dobbek Holger, Wendler Petra
Department of Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany.
Department of Biology, Humboldt-Universität zu Berlin, Berlin, Germany.
Nat Catal. 2025;8(7):657-667. doi: 10.1038/s41929-025-01365-y. Epub 2025 Jul 11.
Catalytic metal clusters play critical roles in important enzymatic pathways such as carbon fixation and energy conservation. However, how ligand binding to the active-site metal regulates conformational changes critical for enzyme function is often not well understood. One carbon fixation pathway that relies heavily on metalloenzymes is the reductive acetyl-coenzyme A (acetyl-CoA) pathway. In this study, we investigated the catalysis of the last step of the reductive acetyl-CoA pathway by the CO-dehydrogenase (CODH)-acetyl-CoA synthase (ACS) complex from , focusing on how ligand binding to the nickel atom in the active site affects the conformational equilibrium of the enzyme. We captured six intermediate states of the enzyme by cryo-electron microscopy, with resolutions of 2.5-1.9 Å, and visualized reaction products bound to cluster A (an Ni,Ni-[4Fe4S] cluster) and identified several previously uncharacterized conformational states of CODH-ACS. The structures demonstrate how substrate binding controls conformational changes in the ACS subunit to prepare for the next catalytic step.
催化金属簇在诸如碳固定和能量守恒等重要的酶促途径中发挥着关键作用。然而，配体与活性位点金属的结合如何调节对酶功能至关重要的构象变化，人们通常并不十分清楚。一种严重依赖金属酶的碳固定途径是还原性乙酰辅酶A（acetyl-CoA）途径。在本研究中，我们研究了来自[具体来源未给出]的一氧化碳脱氢酶（CODH）-乙酰辅酶A合酶（ACS）复合物对还原性乙酰辅酶A途径最后一步的催化作用，重点关注配体与活性位点镍原子的结合如何影响酶的构象平衡。我们通过冷冻电子显微镜捕获了该酶的六个中间状态，分辨率为2.5 - 1.9 Å，并观察到与簇A（一个Ni,Ni-[4Fe4S]簇）结合的反应产物，还鉴定出了几种以前未表征的CODH-ACS构象状态。这些结构展示了底物结合如何控制ACS亚基中的构象变化，为下一个催化步骤做好准备。
