DsbB elicits a red-shift of bound ubiquinone during the catalysis of DsbA oxidation
DsbB elicits a red-shift of bound ubiquinone during the catalysis of DsbA oxidation
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DOI：
10.1074/jbc.m310765200
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发表时间：
2004-02-20
影响因子：
4.8
通讯作者：
Ito, K
中科院分区：
文献类型：
--
作者：
Inaba, K;Takahashi, YH;Ito, K
DsbB是大肠杆菌质膜蛋白，其再氧化DsbA的Cys（30）-Pro-His-Cys（33）活性位点，DsbA是周质中的主要二硫醇氧化剂。在这里，我们描述了一种新的活动DsbB诱导电子跃迁的绑定泛醌分子。该转变的特征在于在500 nm处显著出现吸收峰，产生可见的粉红色。泛醌红移被观察到稳定的DsbA（C33 S）-DsbB复合物，以及瞬态的停流快速扫描光谱在野生型DsbA和DsbB之间的反应。突变和重建实验证实，DsbB第44位的未配对Cys主要负责泛醌的显色转变，并且该性质与Cys附近氨基酸残基的功能排列相关（44）。我们认为Cys（44）诱导的泛醌异常代表其激活状态，这驱动了DsbB介导的电子转移。
DsbB is an Escherichia coli plasma membrane protein that reoxidizes the Cys(30)-Pro-His-Cys(33) active site of DsbA, the primary dithiol oxidant in the periplasm. Here we describe a novel activity of DsbB to induce an electronic transition of the bound ubiquinone molecule. This transition was characterized by a striking emergence of an absorbance peak at 500 nm giving rise to a visible pink color. The ubiquinone red-shift was observed stably for the DsbA(C33S)-DsbB complex as well as transiently by stopped flow rapid scanning spectroscopy during the reaction between wild-type DsbA and DsbB. Mutation and reconstitution experiments established that the unpaired Cys at position 44 of DsbB is primarily responsible for the chromogenic transition of ubiquinone, and this property correlates with the functional arrangement of amino acid residues in the neighborhood Of Cys(44). We propose that the Cys(44)-induced anomaly in ubiquinone represents its activated state, which drives the DsbB-mediated electron transfer.