Feucht B U, Saier M H
J Bacteriol. 1980 Feb;141(2):603-10. doi: 10.1128/jb.141.2.603-610.1980.
Inhibition of cellular adenylate cyclase activity by sugar substrates of the phosphoenolpyruvate-dependent phosphotransferase system was reliant on the activities of the protein components of this enzyme system and on a gene designated crrA. In bacterial strains containing very low enzyme I activity, inhibition could be elicited by nanomolar concentrations of sugar. An antagonistic effect between methyl alpha-glucoside and phosphoenolpyruvate was observed in permeabilized Escherichia coli cells containing normal activities of the phosphotransferase system enzymes. In contrast, phosphoenolpyruvate could not overcome the inhibitory effect of this sugar in strains deficient for enzyme I or HPr. Although the in vivo sensitivity of adenylate cyclase to inhibition correlated with sensitivity of carbohydrate permease function to inhibition in most strains studied, a few mutant strains were isolated in which sensitivity of carbohydrate uptake to inhibition was lost and sensitivity of adenylate cyclase to regulation was retained. These results are consistent with the conclusions that adenylate cyclase and the carbohydrate permeases were regulated by a common mechanism involving phosphorylation of a cellular constituent by the phosphotransferase system, but that bacterial cells possess mechanisms for selectively uncoupling carbohydrate transport from regulation.
磷酸烯醇丙酮酸依赖性磷酸转移酶系统的糖类底物对细胞腺苷酸环化酶活性的抑制作用依赖于该酶系统蛋白质组分的活性以及一个名为crrA的基因。在酶I活性极低的细菌菌株中，纳摩尔浓度的糖类就能引发抑制作用。在含有正常磷酸转移酶系统酶活性的透化大肠杆菌细胞中，观察到α-甲基葡萄糖苷和磷酸烯醇丙酮酸之间存在拮抗作用。相比之下，在酶I或HPr缺陷的菌株中，磷酸烯醇丙酮酸无法克服这种糖类的抑制作用。尽管在大多数研究的菌株中，腺苷酸环化酶在体内对抑制的敏感性与碳水化合物通透酶功能对抑制的敏感性相关，但仍分离出了一些突变菌株，其中碳水化合物摄取对抑制的敏感性丧失，而腺苷酸环化酶对调节的敏感性得以保留。这些结果与以下结论一致：腺苷酸环化酶和碳水化合物通透酶通过一种共同机制进行调节，该机制涉及磷酸转移酶系统对细胞成分的磷酸化作用，但细菌细胞拥有选择性地使碳水化合物转运与调节解偶联的机制。
