Defining the roles of the periplasmic chaperones SurA, Skp, and DegP in Escherichia coli
Defining the roles of the periplasmic chaperones SurA, Skp, and DegP in Escherichia coli
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DOI：
10.1101/gad.1581007
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发表时间：
2007-10-01
影响因子：
10.5
通讯作者：
Silhavy, Thomas J.
中科院分区：
文献类型：
--
作者：
Sklar, Joseph G.;Wu, Tao;Silhavy, Thomas J.
整合β-桶蛋白（Integral beta-barrel proteins，OMPs）是革兰氏阴性菌中一类主要的外膜蛋白。在大肠杆菌中，这些蛋白质在细胞质中合成，通过Sec机制跨内膜易位，并通过需要外膜YaeT复合物和周质伴侣SurA、DegP和Skp的未知机制在外膜中组装。在这里，我们已经建立了这三个分子伴侣之间的关系，提供深入了解OMP生物合成的机制，使用耗尽分析。单独消耗SurA会导致外膜密度显着降低，而DegP和Skp的损失对外膜组成没有影响。此外，我们证明，SurA和YaeT直接在体内相互作用。基于这些结果，我们认为，SurA是主要的伴侣负责周质过境的散装质量的外膜蛋白的YaeT复合物。在不存在SurA的情况下，Skp和DegP的作用被放大。提出的证据表明，DegP/Skp的功能是拯救从SurA途径脱落的OMP。看似多余的周质分子伴侣确实平行发挥作用，但每个途径的主要功能的相对重要性取决于细胞是否处于应激状态。
Integral beta-barrel proteins (OMPs) are a major class of outer membrane proteins in Gram-negative bacteria. In Escherichia coli, these proteins are synthesized in the cytoplasm, translocated across the inner membrane via the Sec machinery, and assembled in the outer membrane through an unknown mechanism that requires the outer membrane YaeT complex and the periplasmic chaperones SurA, DegP, and Skp. Here, we have established the relationship between these three chaperones providing insight into the mechanism of OMP biogenesis using depletion analysis. Depletion of SurA alone results in a marked decrease in outer membrane density, while the loss of DegP and Skp has no effect on outer membrane composition. Furthermore, we demonstrate that SurA and YaeT interact directly in vivo. Based on these results, we suggest that SurA is the primary chaperone responsible for the periplasmic transit of the bulk mass of OMPs to the YaeT complex. The role of Skp and DegP is amplified in the absence of SurA. Evidence presented suggests that DegP/Skp function to rescue OMPs that fall off the SurA pathway. The seemingly redundant periplasmic chaperones do function in parallel, but the relative importance of the primary function of each pathway depends on whether or not cells are under stress.