Studies on the E. coli FtsH protein, which has a homologous domain with Sec18p in Yeast.

对大肠杆菌 FtsH 蛋白的研究，该蛋白与酵母中的 Sec18p 具有同源结构域。

基本信息

批准号：
03680222
负责人：
OGURA Teru
金额：
$ 1.41万
依托单位：
KUMAMOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The ftsH gene is essential for cell viability in Escherichia coli. We have shown that FtsH protein is an integral cytoplasmic membrane protein of 70.7 KDa spanning the membrane twice, and that it has a large cytoplasmic carboxy-terminal part with a putative ATP-binding domain. Homology search revealed that a -200-amino-acid domain, including the putative ATP-binding sequence, is highly homologous to the domain found in members of a novel, eukaryotic family of putative ATPases, e.g., Sec18p, Paslp, CDC48p, and TBP-1, which function in protein transport pathways, peroxisome assembly, cell division cycle, and gene expression, respectively. The average number of FtsH molecules per cell was estimated to be approximately 400.A temperature-sensitive ftsHl mutation reduces the amount of a septum-forming enzyme, penicillin-binding protein 3 (PBP3) at 42ﾟC. The post-translational processing of PBP3, at the carboxy-terminal part, is significantly retarded in the ftsHl mutant. Evidence suggested t … More hat the delay of PBP3 processing in the ftsHl cells was due to either slow export or an altered state of pre-PBP3. The ftsHl mutation was also found to cause a marked intracellular accumulation of the precursor form of beta-lactamase. Although the GroE activity was not significantly affected by the ftsHl mutation, overproduction of the chaperonins GroEL/ES stimulated the processing of both PBP3 and beta-lactamase in the ftsHl cells.A mutation that allowed significant export of the PhoA moiety of the SecY-PhoA fusion protein, in which PhoA sequence is attached to the last cytoplasmic domain of SecY, across the membrane was isolated and identified as a single base change in the ftsH gene. The ftsHl mutation as well as a truncated and an ATP-binding sequence variants of ftsH also caused similar phenotypes, the latter two being dominant over the wild type allele. The expression of the ATP-binding site mutation caused significant export defects of beta-lactamase and OmpA. These results suggest that the FtsH protein is a membrane-bound chaperone involved in the localization processes (translocation, folding, and/or assembly) of some envelope proteins. Less

ftsH 基因对于大肠杆菌的细胞活力至关重要。我们已经证明，FtsH 蛋白是一种跨膜两次的 70.7 KDa 完整的细胞质膜蛋白，并且它具有一个大的细胞质羧基末端部分，具有假定的 ATP 结合结构域。同源性搜索显示，-200 个氨基酸结构域（包括推定的 ATP 结合序列）与在 ap 成员中发现的结构域高度同源。假定的新的真核 ATP 酶家族，例如 Sec18p、Paslp、CDC48p 和 TBP-1，它们分别在蛋白质转运途径、过氧化物酶体组装、细胞分裂周期和基因表达中发挥作用。每个细胞的 FtsH 分子的平均数量为。估计约为 400。温度敏感的 ftsHl 突变减少了隔膜形成酶、青霉素结合蛋白 3 的量(PBP3) 在 42°C 时，PBP3 的羧基末端部分的翻译后加工在 ftsHl 突变体中显着延迟。有证据表明 ftsHl 细胞中 PBP3 加工的延迟是由于以下原因之一。还发现 ftsHl 突变导致 β-内酰胺酶前体形式在细胞内显着积累。 GroE 活性并未受到 ftsHl 突变的显着影响，伴侣蛋白 GroEL/ES 的过量产生刺激了 ftsHl 细胞中 PBP3 和 β-内酰胺酶的加工。这种突变允许 SecY-PhoA 融合蛋白的 PhoA 部分显着输出，其中 PhoA 序列附着在 SecY 的最后一个胞质结构域上，跨膜分离并鉴定为 ftsH 基因中的单碱基变化。 ftsHl突变以及ftsH的截短和ATP结合序列变体也引起类似的表型，后两者相对于野生型等位基因占优势。ATP结合位点突变的表达导致β-内酰胺酶的显着输出缺陷。这些结果表明 FtsH 蛋白是参与某些包膜蛋白的定位过程（易位、折叠和/或组装）的膜结合分子伴侣。