Sugar transport by the bacterial phosphotransferase system. The glucose receptors of the Salmonella typhimurium phosphotransferase system.
Sugar transport by the bacterial phosphotransferase system. The glucose receptors of the Salmonella typhimurium phosphotransferase system.
复制标题
DOI：
10.1016/s0021-9258(19)45412-4
复制
发表时间：
1982-12
期刊：
影响因子：
--
通讯作者：
J. Stock;E. Waygood;N. Meadow;P. Postma;S. Roseman
中科院分区：
文献类型：
--
作者：
J. Stock;E. Waygood;N. Meadow;P. Postma;S. Roseman
我们以前报道过葡萄糖可以被磷酸hpr和大肠杆菌和鼠伤寒沙门氏菌的磷酸烯醇丙酮酸：糖苷磷酸转移酶系统的两对糖特异性蛋白磷酸化。每种糖特异性复合物包括两种蛋白质，脂质和二价阳离子，每种都存在于从野生型细胞分离的膜中。由于本报告所述的原因，其中一个复合物被指定为IIGlc，另一个被指定为IIMan。IIMan复合体先前已被分离为其蛋白质组分II-A和II-B (Kundig， W., and Roseman， S. (1971) J. Biol。化学，246,1407-1418)，而随附的报告描述了IIGlc复合物解离成其组分，IIIGlc和II-BGlc。Curtis和Epstein （Curtis， S. J, and Epstein， W. (1975) J. Bacteriol. 122, 1189-1199）首次发现全细胞中有两种磷酸转移酶系统负责葡萄糖摄取，并获得了各自的突变体，现在被命名为ptsG和ptsM。当两种活性存在于同一膜制剂中时，本研究为分别测定每种活性（体内和体外）提供了动力学条件。IIGlc系统负责葡萄糖和甲基α -葡萄糖苷的摄取和磷酸化，而IIMan系统的特异性较低，主要利用葡萄糖、甘露糖和2-脱氧葡萄糖。在高糖浓度的体外条件下，IIMan还能磷酸化甲基α -葡萄糖苷、果糖和n -乙酰甘露糖胺，而IIGlc则能磷酸化果糖和甘露糖。体内转运结果与体外磷酸化结果定性一致，几个动力学参数也显示出良好的定量一致性。这两种活性的水平取决于生长条件。此外，转运研究表明，甲基α -葡萄糖苷的初始摄取速率和这种类似物的稳态水平取决于细胞的能量状态，并且当使用代谢抑制剂时，这两个参数不一定在同一方向上改变。一系列大肠杆菌和鼠伤寒沙门氏菌突变体的特征在于它们在体外运输葡萄糖类似物和磷酸化它们的能力。Curtis和Epstein的原突变体ptsG和ptsM分别在II-BGlc和IIMan复合体中存在缺陷。
We have previously reported that glucose can be phosphorylated by phospho-HPr and two sugar-specific pairs of proteins of the Escherichia coli and Salmonella typhimurium phosphoenolpyruvate:glycose phosphotransferase system. Each of the sugar-specific complexes comprises two proteins, lipid, and divalent cation, and each is present in membranes isolated from wild type cells. For reasons described in this report, one of the complexes is designated IIGlc and the other IIMan. The IIMan complex has previously been separated into its protein components, II-A and II-B (Kundig, W., and Roseman, S. (1971) J. Biol. Chem. 246, 1407-1418), while the accompanying reports describe dissociation of the IIGlc complex into its components, IIIGlc and II-BGlc. Curtis and Epstein (Curtis, S. J., and Epstein, W. (1975) J. Bacteriol. 122, 1189-1199) first showed that there are two phosphotransferase systems in whole cells responsible for glucose uptake and obtained the respective mutants, now designated ptsG and ptsM. The present studies provide kinetic conditions for assaying each activity separately (in vivo and in vitro), when both are present in the same membrane preparation. The IIGlc system is responsible for the uptake and phosphorylation of glucose and methyl alpha-glucoside, whereas the IIMan system is less specific and utilizes glucose, mannose, and 2-deoxyglucose. With high sugar concentrations in vitro, IIMan is also capable of phosphorylating methyl alpha-glucoside, fructose, and N-acetylmannosamine, while IIGlc phosphorylates fructose and mannose. The in vivo transport results were qualitatively consistent with the in vitro phosphorylation results, and several of the kinetic parameters also showed good quantitative agreement. The levels of the two activities depended on the growth conditions. In addition, transport studies showed that initial uptake rates of methyl alpha-glucoside and steady state levels of this analogue depended on the energy state of the cells and that these two parameters did not necessarily change in the same direction when metabolic inhibitors were used. A series of E. coli and S. typhimurium mutants were characterized both with respect to their ability to transport the glucose analogues and to phosphorylate them in vitro. The original mutants of Curtis and Epstein, ptsG and ptsM, were found to be defective in II-BGlc and the IIMan complex, respectively.