Turning a disulfide isomerase into an oxidase: DsbC mutants that imitate DsbA
Turning a disulfide isomerase into an oxidase: DsbC mutants that imitate DsbA
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DOI：
10.1093/emboj/20.7.1555
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发表时间：
2001-04-02
期刊：
影响因子：
11.4
通讯作者：
Bardwell, JCA
中科院分区：
文献类型：
--
作者：
Bader, MW;Hiniker, A;Bardwell, JCA
在原核生物中有两种不同的二硫键形成途径。DsbA-DsbB途径从头引入二硫键，而DsbC-DsbD途径的功能是异构化二硫键。二硫键生物学中的关键问题之一是如何在体内保持异构酶途径与氧化酶途径分离。这两个系统之间的相互干扰将是相互破坏的。为了迫使这两个系统之间的通信，我们选择了dsbC突变体，补充dsbA无效突变。在这些突变体中，DsbC作为单体存在，与二聚体野生型DsbC相比，基于这些发现，我们合理地设计了DsbC二聚化结构域突变体。所有这些突变体都能够拯救dsbA无效表型。拯救依赖于体内和体外DsbA的天然再氧化剂DsbB的存在。我们的研究结果表明，二聚作用，以保护DsbC的活性位点DsbB介导的氧化。这些结果解释了氧化和还原途径如何共存于大肠杆菌的周质中。
There are two distinct pathways for disulfide formation in prokaryotes. The DsbA-DsbB pathway introduces disulfide bonds de novo, while the DsbC-DsbD pathway functions to isomerize disulfides, One of the key questions in disulfide biology is how the isomerase pathway is kept separate from the oxidase pathway in vivo. Cross-talk between these two systems would be mutually destructive. To force communication between these two systems we have selected dsbC mutants that complement a dsbA null mutation. In these mutants, DsbC is present as a monomer as compared with dimeric wild-type DsbC, Based on these findings we rationally designed DsbC mutants in the dimerization domain. All of these mutants are able to rescue the dsbA null phenotype, Rescue depends on the presence of DsbB, the native re-oxidant of DsbA, both in vivo and in vitro. Our results suggest that dimerization acts to protect DsbC's active sites from DsbB-mediated oxidation. These results explain how oxidative and reductive pathways can co-exist in the periplasm of Escherichia coli.