Nonconsecutive disulfide bond formation in an essential integral outer membrane protein
Nonconsecutive disulfide bond formation in an essential integral outer membrane protein
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DOI：
10.1073/pnas.1007319107
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发表时间：
2010-07-06
影响因子：
11.1
通讯作者：
Silhavy, Thomas J.
中科院分区：
文献类型：
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作者：
Ruiz, Natividad;Chng, Shu-Sin;Silhavy, Thomas J.
革兰氏阴性菌的被膜由两层膜包围。在这种氧化环境中，二硫键的形成和异构化分别由DsbA和DsbC催化。目前尚不清楚Dsb蛋白何时以及如何参与外膜蛋白的生物合成，外膜蛋白在合成后被转运穿过细胞包膜。大肠杆菌蛋白LptD是与脂蛋白LptE形成必需复合物的完整外膜蛋白。我们表明，氧化LptD是不需要的LptD/E复合物的形成，但它是必不可少的功能。值得注意的是，LptD中没有一个半胱氨酸是必需的，因为两个非连续二硫键中的任何一个都足以发挥功能。DsbA有效催化的LptD的氧化不涉及异构酶DsbC，但它需要LptE。因此，只有在LptD与LptE相互作用后，氧化才完成，这种相互作用发生在外膜上，并且似乎是LptD折叠所必需的。
The Gram-negative bacterial envelope is bounded by two membranes. Disulfide bond formation and isomerization in this oxidizing environment are catalyzed by DsbA and DsbC, respectively. It remains unknown when and how the Dsb proteins participate in the biogenesis of outer membrane proteins, which are transported across the cell envelope after their synthesis. The Escherichia coli protein LptD is an integral outer membrane protein that forms an essential complex with the lipoprotein LptE. We show that oxidation of LptD is not required for the formation of the LptD/E complex but it is essential for function. Remarkably, none of the cysteines in LptD are essential because either of two nonconsecutive disulfide bonds suffices for function. Oxidation of LptD, which is efficiently catalyzed by DsbA, does not involve the isomerase DsbC, but it requires LptE. Thus, oxidation is completed only after LptD interacts with LptE, an interaction that occurs at the outer membrane and seems necessary for LptD folding.