Department of Plant Biochemistry, Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
Angew Chem Int Ed Engl. 2023 Feb 6;62(7):e202216903. doi: 10.1002/anie.202216903. Epub 2023 Jan 10.
Hydrogenases are H converting enzymes that harbor catalytic cofactors in which iron (Fe) ions are coordinated by biologically unusual carbon monoxide (CO) and cyanide (CN ) ligands. Extrinsic CO and CN , however, inhibit hydrogenases. The mechanism by which CN binds to [FeFe]-hydrogenases is not known. Here, we obtained crystal structures of the CN -treated [FeFe]-hydrogenase CpI from Clostridium pasteurianum. The high resolution of 1.39 Å allowed us to distinguish intrinsic CN and CO ligands and to show that extrinsic CN binds to the open coordination site of the cofactor where CO is known to bind. In contrast to other inhibitors, CN treated crystals show conformational changes of conserved residues within the proton transfer pathway which could allow a direct proton transfer between E279 and S319. This configuration has been proposed to be vital for efficient proton transfer, but has never been observed structurally.
氢化酶是一种将氢气转化为能量的酶，它含有催化辅因子，其中铁（Fe）离子由生物上不常见的一氧化碳（CO）和氰化物（CN ）配体配位。然而，外源性的 CO 和 CN 会抑制氢化酶。CN 与 [FeFe]-氢化酶结合的机制尚不清楚。在这里，我们获得了来自巴氏梭菌的 CN 处理的 [FeFe]-氢化酶 CpI 的晶体结构。分辨率高达 1.39Å，使我们能够区分内在的 CN 和 CO 配体，并表明外源性的 CN 结合在辅因子的开放配位位点上，已知 CO 结合在此处。与其他抑制剂不同，CN 处理的晶体显示出质子转移途径中保守残基的构象变化，这可能允许 E279 和 S319 之间直接质子转移。这种构象被认为对有效的质子转移至关重要，但从未在结构上观察到。
