ATP Binding and a Second Reduction Enables a Conformationally Gated Uphill Electron Transfer
ATP Binding and a Second Reduction Enables a Conformationally Gated Uphill Electron Transfer
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DOI：
10.1021/acscatal.1c01038
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发表时间：
2021-06-30
期刊：
影响因子：
12.9
通讯作者：
Dobbek，Holger
中科院分区：
文献类型：
--
作者：
Neumann，Felix;Dobbek，Holger
上坡电子转移可以减少惰性代谢物并激活低电位金属酶。克服上坡电子转移障碍的一种方法是与ATP水解偶联。这些过程是如何耦合的，以及它们如何产生单向转移，从而阻止了热力学上有利的反向电子转移，目前还不清楚。在这里，我们研究了CoFeSP的金属- atp酶还原激活剂（RACo）与其b12依赖的伴侣蛋白CoFeSP之间依赖atp的电子转移。我们发现电子转移是由ATP结合触发的，克服了ΔE0 '大于- 250 mV。快速电子转移是构象门控的，需要钾离子或铵离子。缓慢的ATP水解延迟了最后一个反应步骤，以允许氧化活化剂的还原，将电子转移平衡转移到产物。这些对机制的见解为我们提供了一个蓝图，以有效地利用ATP的能量与构象变化的耦合方案来产生单向上坡电子转移。
Uphill electron transfers allow reducing inert metabolites and activating low potential metalloenyzmes. One way to overcome the barrier of an uphill electron transfer is coupling to ATP hydrolysis. How the processes are coupled and how they produce a unidirectional transfer preventing the thermodynamically favorable back electron transfer is not understood. Here, we investigated the ATP-dependent electron transfer between the metallo-ATPase reductive activator of CoFeSP (RACo) and its B12-dependent partner protein CoFeSP. We show that electron transfer is triggered by ATP binding, overcoming a ΔE0′ of more than −250 mV. Rapid electron transfer is conformationally gated and requires potassium or ammonium ions. Slow ATP hydrolysis delays the last reaction step to allow rereduction of the oxidized activator, shifting the electron-transfer equilibrium to the products. These insights into the mechanism provide us with a blueprint to efficiently harness the energy of ATP in a coupling scheme with conformational changes to generate a unidirectional uphill electron transfer.