POST-TRANSLATIONAL MODIFICATION AND PROCESSING OF ESCHERICHIA-COLI PRO-LIPOPROTEIN INVITRO
POST-TRANSLATIONAL MODIFICATION AND PROCESSING OF ESCHERICHIA-COLI PRO-LIPOPROTEIN INVITRO
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DOI：
10.1073/pnas.79.7.2255
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发表时间：
1982-01-01
期刊：
影响因子：
--
通讯作者：
WU, HC
中科院分区：
文献类型：
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作者：
TOKUNAGA, M;TOKUNAGA, H;WU, HC
E.大肠杆菌MM 18细胞含有malE-lacZ杂合蛋白，经麦芽糖诱导后，可积累脂蛋白原。(Ito，K.，例如，1981年）。在麦芽糖诱导的MM 18细胞中积累的前脂蛋白未被修饰，缺乏共价连接的甘油酯。当含有未修饰的前脂蛋白的MM 18的细胞包膜在去污剂存在下与[2- 3 H]甘油标记的缺乏胞壁素脂蛋白的菌株JE 5505的细胞包膜一起孵育时，观察到[2- 3 H]甘油放射性掺入前脂蛋白和加工的成熟脂蛋白中。同样，当[3 H]-棕榈酸酯标记的JE 5505细胞包膜与含有未修饰前脂蛋白的MM 18细胞包膜在存在去污剂的情况下孵育时，[3 H]棕榈酸酯放射性通过酯键结合到前脂蛋白中，并通过酯键和酰胺键结合到成熟脂蛋白中。该体外系统显然含有前脂蛋白修饰和加工酶的活性，包括甘油基转移酶、O-酰基转移酶、信号肽酶和N-酰基转移酶。在体外系统中，信号肽酶活性被球霉素完全抑制。在pH 5.0时，甘油基转移酶无活性。信号肽酶在pH 5.0时是活性的，前提是前脂蛋白在pH 9.1的预先孵育期间已被甘油基转移酶（和O-酰基转移酶）修饰。甘油基转移酶（和O-酰基转移酶）对前脂蛋白的修饰先于信号肽酶对前脂蛋白的加工，事实上可能是信号肽酶对前脂蛋白加工的先决条件。
E. coli strain MM18 cells containing malE-lacZ hybrid protein was reported to accumulate prolipoprotein when induced with maltose. (Ito, K., et al., 1981). The proplipoprotein accumulated in maltose-induced MM18 cells is not modified, lacking covalently linked glyceride. When the cell envelope of MM18 containing unmodified prolipoprotein was incubated in the presence of detergent with [2-3H]glycerol-labeled cell envelope of strain JE5505 lacking murein lipoprotein, incorporation of [2-3H]glycerol radioactivity into both prolipoprotein and processed mature lipoprotein was observed. Likewise, when [3H]-palmitate-labeled JE5505 cell envelope was incubated with the MM18 cell envelope containing unmodified prolipoprotein in the presence of detergent, [3H]palmitate radioactivity was incorporated into prolipoprotein by ester linkage and into mature lipoprotein by both ester and amide linkages. This in vitro system apparently contains activities of prolipoprotein modification and processing enzymes, including glyceryltransferase, O-acyltransferase, signal peptidase and N-acyltransferase. The signal peptidase activity in the in vitro system was completely inhibited by globomycin. At pH 5.0, glyceryltransferase was inactive. Signal peptidase was active at pH 5.0, provided that prolipoprotein had been modified by glyceryltransferase (and O-acyltransferase) during a prior incubation at pH 9.1. The modification of prolipoprotein by glyceryltransferase (and O-acyltransferase) precedes, and may in fact be a prerequisite for, the processing of prolipoprotein by signal peptidase.