Cysteine 295 indirectly affects Ni coordination of carbon monoxide dehydrogenase-II C-cluster

A unique [Ni-Fe-S] cluster (C-cluster) constitutes the active center of Ni-containing carbon monoxide dehydrogenases (CODHs). His(261), which coordinates one of the Fe atoms with Cys(295), is suggested to be the only residue required for Ni coordination in the C-cluster. To evaluate the role of Cys(295), we constructed CODH-II variants. Ala substitution for the Cys(295) substitution resulted in the decrease of Ni content and didn't result in major change of Fe content. In addition, the substitution had no effect on the ability to assemble a full complement of [Fe-S] clusters. This strongly suggests Cys(295) indirectly and His(261) together affect Ni-coordination in the C-cluster. (C) 2013 Elsevier Inc. All rights reserved..

一种独特的[镍 - 铁 - 硫]簇（C - 簇）构成了含镍一氧化碳脱氢酶（CODHs）的活性中心。组氨酸（261）与半胱氨酸（295）共同配位其中一个铁原子，被认为是C - 簇中镍配位所必需的唯一残基。为了评估半胱氨酸（295）的作用，我们构建了CODH - II变体。半胱氨酸（295）被丙氨酸替代后，镍含量降低，而铁含量没有重大变化。此外，这种替代对组装完整的[铁 - 硫]簇的能力没有影响。这有力地表明半胱氨酸（295）间接与组氨酸（261）共同影响C - 簇中镍的配位。（C）2013爱思唯尔公司。保留所有权利。