SecA suppresses the temperature-sensitive SecY24 defect in protein translocation in Escherichia coli membrane vesicles.
SecA suppresses the temperature-sensitive SecY24 defect in protein translocation in Escherichia coli membrane vesicles.
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SecA 抑制大肠杆菌膜囊泡中蛋白质易位的温度敏感性 SecY24 缺陷。
DOI：
10.1073/pnas.85.23.8953
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发表时间：
1988
影响因子：
11.1
通讯作者：
Tai,PC
中科院分区：
文献类型：
--
作者：
Fandl,JP;Cabelli,R;Oliver,D;Tai,PC
大肠杆菌蛋白质分泌的遗传分析已经鉴定secY/prlA和secA为分泌器的组分。我们已经研究了secY（prlA）基因产物（一种完整的膜蛋白）和可溶性secA基因产物在OmpA和碱性磷酸酶前体在体外系统中的易位中的作用。最近在体外证明了secY 24突变的蛋白质易位缺陷，其被S300提取物抑制。我们在这里表明，提取物基本上是无活性的SecY 24抑制时，SecA蛋白从它通过免疫亲和层析。此外，纯化的SecA蛋白抑制SecY 24缺陷。当在不存在另外的可溶性蛋白质的情况下测定时，用含有SecA的S300或用纯化的SecA蛋白预孵育灭活的SecY 24膜囊泡重建膜并恢复易位活性。这些结果表明SecY 24易位缺陷被SecA直接或间接地与细胞质膜上的SecY 24相互作用所抑制。
Genetic analysis of protein secretion in Escherichia coli has identified secY/prlA and secA as components of the secretory apparatus. We have examined the roles of the secY(prlA) gene product (an integral membrane protein) and the soluble secA gene product in translocation of OmpA and alkaline phosphatase precursors in an in vitro system. The protein translocation defect of the secY24 mutation was recently demonstrated in vitro as was its suppression by an S300 extract. We show here that the extract was essentially inactive in SecY24 suppression when SecA protein was removed from it by immunoaffinity chromatography. Furthermore, purified SecA protein suppressed the SecY24 defect. Preincubation of the inactivated SecY24 membrane vesicles either with S300 containing SecA or with purified SecA protein reconstituted the membranes and restored the translocation activity when assayed in the absence of additional soluble proteins. These results suggest that the SecY24 translocation defect is suppressed by SecA interacting, directly or indirectly, with SecY24 on the cytoplasmic membrane.