Protease-deficient DegP suppresses lethal effects of a mutant OmpC protein by its capture
Protease-deficient DegP suppresses lethal effects of a mutant OmpC protein by its capture
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DOI：
10.1128/jb.185.1.148-154.2003
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发表时间：
2003-01-01
影响因子：
3.2
通讯作者：
Misra, R
中科院分区：
文献类型：
--
作者：
CastilloKeller, M;Misra, R
组装缺陷的外膜蛋白的表达可以赋予致命性，如果它们不被包膜蛋白酶降解。我们在这里报告的突变OmpC蛋白，OmpC（2Cys），由于存在两个非天然的半胱氨酸残基，在周质中形成二硫键的表达，是致命的细胞缺乏主要的周质蛋白酶，DegP。在形成周质二硫键的能力减弱的dsbA菌株中未观察到这种致死性。我们的数据表明，在degP：：Km（r）dsbA（+）背景下，这种OmpC（2Cys）介导的致死性可以被DegP变体DegP（S210 A）逆转，该变体缺乏蛋白水解活性，但保留了报告的伴侣蛋白活性。然而，DegP（S210A）并不通过纠正OmpC（2Cys）的组装来逆转OmpC（2Cys）的致死作用，而是通过捕获错误折叠的突变OmpC多肽并因此将它们从组装途径中移除来逆转OmpC（2Cys）的致死作用。DegP（S210A）对OmpC（2Cys）的置换也证实了突变OmpC蛋白对野生型OmpF的负面影响。
The expression of assembly-defective outer membrane proteins can confer lethality if they are not degraded by envelope proteases. We report here that the expression of a mutant OmpC protein, OmpC(2Cys), which forms disulfide bonds in the periplasm due to the presence of two non-native cysteine residues, is lethal in cells lacking the major periplasmic protease, DegP. This lethality is not observed in dsbA strains that have diminished ability to form periplasmic disulfide bonds. Our data show that this OmpC(2Cys)-mediated lethality in a degP::Km(r)dsbA(+) background can be reversed by a DegP variant, DegP(S210A), that is devoid of its proteolytic activity but retains its reported chaperone activity. However, DegP(S210A) does not reverse the lethal effect of OmpC(2Cys) by correcting its assembly but rather by capturing misfolded mutant OmpC polypeptides and thus removing them from the assembly pathway. Displacement of OmpC(2Cys) by DegP(S210A) also alleviates the negative effect that the mutant OmpC protein has on wild-type OmpF.