A new heat-shock gene, ppiD, encodes a peptidyl-prolyl isomerase required for folding of outer membrane proteins in Escherichia coli
A new heat-shock gene, ppiD, encodes a peptidyl-prolyl isomerase required for folding of outer membrane proteins in Escherichia coli
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DOI：
10.1093/emboj/17.14.3968
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发表时间：
1998-07-15
期刊：
影响因子：
11.4
通讯作者：
Raina, S
中科院分区：
文献类型：
--
作者：
Dartigalongue, C;Raina, S
我们在大肠杆菌的周质中发现了一种新的折叠催化剂PPID，编码PPID的基因是严重损害外膜蛋白(OMPS)折叠的突变SurA的多拷贝抑制因子，PPID基因也是基于它被CpxR-CpxA双组分系统转录的能力而被鉴定的，PPID被纯化到均一，并在体外证明具有肽基-丙酰异构酶(PPIase)的活性。该蛋白通过一个跨膜片段固定在内膜上，其催化结构域面向周质，此外，我们还通过定点突变鉴定了其PPIase活性所必需的一些残基，PPID零突变导致OMPS水平和折叠的整体下降，并诱导周质应激反应，PPID零突变和SurA零突变的组合是致命的。这是第一次有两个周质折叠催化剂被证明是必需的，PPID的另一个独特的方面是它的基因同时受CPX双组分系统和西格玛(32)热休克因子的调节，后者已知调节细胞质伴侣的表达。
We have identified a new folding catalyst, PpiD, in the periplasm of Escherichia coli, The gene encoding PpiD was isolated as a multicopy suppressor of surA, a mutation which severely impairs the folding of outer membrane proteins (OMPs), The ppiD gene was also identified based on its ability to be transcribed by the two-component system CpxR-CpxA, PpiD was purified to homogeneity and shown to have peptidyl-prolyl isomerase (PPIase) activity in vitro. The protein is anchored to the inner membrane via a single transmembrane segment, and its catalytic domain faces the periplasm, In addition, we have identified by site-directed mutagenesis some of the residues essential for its PPIase activity, A null mutation in ppiD leads to an overall reduction in the level and folding of OMPs and to the induction of the periplasmic stress response, The combination of ppiD and surA null mutations is lethal. This is the first time two periplasmic folding catalysts have been shown to be essential, Another unique aspect of PpiD is that its gene is regulated by both the Cpx two-component system and the sigma(32) heat shock factor, known to regulate the expression of cytoplasmic chaperones.