Roles of a conserved arginine residue of DsbB in linking protein disulfide-bond-formation pathway to the respiratory chain of Escherichia coli
Roles of a conserved arginine residue of DsbB in linking protein disulfide-bond-formation pathway to the respiratory chain of Escherichia coli
复制标题
DsbB 的一个保守精氨酸残基在连接蛋白质二硫键形成途径和大肠杆菌呼吸链中的作用
DOI：
10.1073/pnas.97.20.10884
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发表时间：
2000-09-26
影响因子：
11.1
通讯作者：
Beckwith, J
中科院分区：
文献类型：
--
作者：
Kadokura, H;Bader, M;Beckwith, J
DsbA是大肠杆菌的周质二硫键形成酶，其活性部位的半胱氨酸被细胞质膜蛋白DsbB氧化。DsbB又被电子传递链中的两种苯醌(用于好氧生长的泛醌和用于厌氧生长的孟喹酮)氧化。我们描述了dsbB错义突变的分离，该突变将第48位高度保守的精氨酸残基改变为组氨酸或半胱氨酸。在这些变种人身上。DsbB的有氧功能相当好，但厌氧功能较差。与这一条件表型一致。纯化的R48H对麦喹酮的活性很低，对泛醌的表观米氏常数(K-m)是野生型DsbB的7倍。同时保持DsbA的表观K-m与野生型酶相似。根据这些结果，我们认为DsbB的这种高度保守的精氨酸残基通过它在DsbB与苯二酚的相互作用中的作用，在催化二硫键的形成中起着重要的作用。
The active-site cysteines of DsbA, the periplasmic disulfide-bond-forming enzyme of Escherichia coli, are kept oxidized by the cytoplasmic membrane protein DsbB. DsbB, in turn, is oxidized by two kinds of quinones (ubiquinone for aerobic and menaquinone for anaerobic growth) in the electron-transport chain. We describe the isolation of dsbB missense mutations that change a highly conserved arginine residue at position 48 to histidine or cysteine. In these mutants. DsbB functions reasonably well aerobically but poorly anaerobically. Consistent with this conditional phenotype. purified R48H exhibits very low activity with menaquinone and an apparent Michaelis constant (K-m) for ubiquinone seven times greater than that of the wild-type DsbB. while keeping an apparent K-m for DsbA similar to that of wild-type enzyme. From these results, we propose that this highly conserved arginine residue of DsbB plays an important role in the catalysis of disulfide bond formation through its role in the interaction of DsbB with quinones.