Two cysteines in each periplasmic domain of the membrane protein DsbB are required for its function in protein disulfide bond formation.
Two cysteines in each periplasmic domain of the membrane protein DsbB are required for its function in protein disulfide bond formation.
复制标题
膜蛋白 DsbB 的每个周质结构域中的两个半胱氨酸是其在蛋白质二硫键形成中发挥功能所必需的。
作者：
Georg Jander;Nancy L. Martin;Jon Beckwith
DsbB是导致大肠杆菌周质蛋白中二硫键形成的途径的蛋白质组分。以前的研究已经导致了这样的假设，即DsbB氧化周质蛋白DsbA，这反过来又氧化其他周质蛋白中的半胱氨酸以形成二硫键。使用基因融合方法来显示（i）DsbB是跨膜四次的膜蛋白，以及（ii）蛋白的N-和C-末端都在细胞质中。突变分析表明，在DsbB中的六个半胱氨酸中，有四个是DsbB在体内正常功能所必需的。蛋白质的每个周质结构域具有两个必需的半胱氨酸。第一周质结构域中的两个半胱氨酸呈Cys-X-Y-Cys构型，这是参与二硫键形成的其他蛋白质（包括DsbA和蛋白质二硫键异构酶）的活性位点的特征。
DsbB is a protein component of the pathway that leads to disulfide bond formation in periplasmic proteins of Escherichia coli. Previous studies have led to the hypothesis that DsbB oxidizes the periplasmic protein DsbA, which in turn oxidizes the cysteines in other periplasmic proteins to make disulfide bonds. Gene fusion approaches were used to show that (i) DsbB is a membrane protein which spans the membrane four times and (ii) both the N‐ and C‐termini of the protein are in the cytoplasm. Mutational analysis shows that of the six cysteines in DsbB, four are necessary for proper DsbB function in vivo. Each of the periplasmic domains of the protein has two essential cysteines. The two cysteines in the first periplasmic domain are in a Cys‐X‐Y‐Cys configuration that is characteristic of the active site of other proteins involved in disulfide bond formation, including DsbA and protein disulfide isomerase.