The active-site cysteines of the periplasmic thioredoxin-like protein CcmG of Escherichia coli are important but not essential for cytochrome c maturation in vivo
The active-site cysteines of the periplasmic thioredoxin-like protein CcmG of Escherichia coli are important but not essential for cytochrome c maturation in vivo
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DOI：
10.1128/jb.180.7.1947-1950.1998
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发表时间：
1998-04-01
影响因子：
3.2
通讯作者：
Thöny-Meyer, L
中科院分区：
文献类型：
--
作者：
Fabianek, RA;Hennecke, H;Thöny-Meyer, L
二硫键氧化还原酶(CCMG，又称DsbE)是周质蛋白硫醇家族中的一个新成员，研究了它在大肠杆菌细胞色素c成熟过程中的作用。CCMG蛋白是膜结合型的，面向周质，具有C-末端的亲水性结构域。CCMG的染色体非极性框内缺失导致所有c型细胞色素完全缺失。CCMG(WCPTC)中预测活性部位的两个半胱氨酸残基中的一个或两个的替换导致了低水平但可检测到的日本慢根瘤菌全细胞色素c(550)在大肠杆菌中的表达。这一缺陷，但不是CCMG零突变体的缺陷，可以通过向生长细胞中添加低分子硫醇化合物来补充，这与CCMG的还原功能一致。
A new member of the family of periplasmic protein thiol:disulfide oxidareductases, CcmG (also called DsbE), was characterized with regard to its role in cytochrome c maturation in Escherichia coli. The CcmG protein was shown to be membrane bound, facing the periplasm with its C-terminal, hydrophilic domain. A chromosomal, nonpolar in-frame deletion in ccmG resulted in the complete absence of all c-type cytochromes. Replacement of either one or both of the two cysteine residues of the predicted active site in CcmG (WCPTC) led to low but detectable levels of Bradyrhizobium japonicum holocytochrome c(550) expressed in E. coli. This defect, but not that of the ccmG null mutant, could be complemented by adding low-molecular-weight thiol compounds to growing cells, which is in agreement with a reducing function for CcmG.