Molecular mechanism of protein translocation in Escherichia coli

大肠杆菌蛋白质易位的分子机制

• 批准号: 07408015
• 负责人: SHISHIDO Katsuko
• 金额: $ 18.94万
• 依托单位: Tokyo University of Pharmacy and Life Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07408015/
• 关键词: translocation; secretory protein; Escherichia coli; signal sequence; 膜蛋白質; 小胞体; Stepwise Translocation; SecA; 前駆体タンパク質; 結晶解析; シグナル認識粒子

The protein translocation machinery in Escherichia coli consists of SecA,translocation ATPase, and the membrane-embedded complex comprising SecY,SecE and SecG.Secretory proteins are passed through a hydrophilic tunnel formed by the membrane-embedded complex, and then released into the periplasm via a mechanism involving SecD and SecF.Secretory proteins contain a signal sequence at the amino-terminus. Signal sequences consist of positively charged amino-terminal region and a hydrophobic core region. We analyzed the mechanism of protein translocation in E.coli at the molecular level and obtained the following results.1. SecA interacts with the hydrophobic core region of the signal peptide in the presence of acidic phospholipids and can mediate the translocation of secretory proteins that do not contain positively charged amino acid residues in the signal sequence.2. Short hydrophobic segments consisting of 4-5 amino acid residues in the mature region of a secretory protein, proOmpA,are a determinant for the rate of translocation across the membrane. A duplicated short hydrophobic segment can act as a stop-transfer sequence.3. The amino-terminal region and Asp-133 of SecA are important for the interaction with SecG and ATP hydrolysis, respectively.4. The hydrophobic core of the signal sequence is also important for translocation across the endoplasmic reticulum membrane in animal cells.

大肠杆菌的蛋白质转运机制由SecA、转运ATP酶和由SecY、SecE和SecG组成的膜包埋复合物组成，分泌蛋白通过由膜包埋复合物形成的亲水通道，通过SecD和SecF机制释放到周质中，分泌蛋白的氨基端含有信号序列。信号序列由带正电荷的氨基末端区域和疏水核心区域组成。我们从分子水平上分析了大肠杆菌中蛋白质转位的机制，得到以下结果. SecA在酸性磷脂存在下与信号肽的疏水核心区相互作用，可介导信号序列中不含带正电荷氨基酸残基的分泌蛋白易位.在分泌蛋白proOmpA的成熟区域中由4-5个氨基酸残基组成的短疏水区段是跨膜易位速率的决定因素。重复的短疏水片段可以作为终止转移序列。SecA的氨基端区域和Asp-133分别对SecG和ATP水解起重要作用.信号序列的疏水核心对于动物细胞中跨内质网膜的易位也是重要的。

项目成果

Sato et al.: "In vitro analysis of the stop-transfer process during translocation across the cytoplamic membrane of Escherichis coli." J.Biol.Chem.272. 20082-20087 (1997)

Sato 等人：“大肠杆菌细胞质膜易位过程中停止转移过程的体外分析。”

Sato et al.: "Short hydrophobic segments in the mature domain of proOmpA determine its stepwise movement during translocation across the cytoplasmic membrane of Escherichia coli." J.Biol.Chem.272. 5880-5886 (1997)

Sato 等人：“proOmpA 成熟结构域中的短疏水片段决定了其在穿过大肠杆菌细胞质膜易位过程中的逐步运动。”

Mori et al.: "The hydrophobic region of signal peptides is involved in the interaction with membrane-bound SecA." Biochim.Biophys.Acta. 1326. 23-36 (1997)

Mori 等人：“信号肽的疏水区域参与与膜结合 SecA 的相互作用。”

M. Tagay et al.: "Systaxin 1 (HPC-1)Is Associated with Chromaffin Granules." J. B. C.270. 15930-15933 (1995)

M. Tagay 等人：“Systaxin 1 (HPC-1) 与嗜铬颗粒相关。”

Nishiyama et al.: "Preferential interaction of Sec-G with Sec-E stabilizes an unstable Sec-E derivative in the Escherichis coli cytoplasmic membrane." Biochem.Biophys.Res.Commun.217. 217-223 (1995)

Nishiyama 等人：“Sec-G 与 Sec-E 的优先相互作用可稳定大肠杆菌细胞质膜中不稳定的 Sec-E 衍生物。”