Gonzy-Tréboul G, de Waard J H, Zagorec M, Postma P W
Institut Jacques Monod, Université Paris VII, France.
Mol Microbiol. 1991 May;5(5):1241-9. doi: 10.1111/j.1365-2958.1991.tb01898.x.
Glucose is taken up in Bacillus subtilis via the phosphoenolpyruvate:glucose phosphotransferase system (glucose PTS). Two genes, orfG and ptsX, have been implied in the glucose-specific part of this PTS, encoding an Enzyme IIGlc and an Enzyme IIIGlc, respectively. We now show that the glucose permease consists of a single, membrane-bound, polypeptide with an apparent molecular weight of 80,000, encoded by a single gene which will be designated ptsG. The glucose permease contains domains that are 40-50% identical to the IIGlc and IIIGlc proteins of Escherichia coli. The B. subtilis IIIGlc domain can replace IIIGlc in E. coli crr mutants in supporting growth on glucose and transport of methyl alpha-glucoside. Mutations in the IIGlc and IIIGlc domains of the B. subtilis ptsG gene impaired growth on glucose and in some cases on sucrose. ptsG mutants lost all methyl alpha-glucoside transport but retained part of the glucose-transport capacity. Residual growth on glucose and transport of glucose in these ptsG mutants suggested that yet another uptake system for glucose existed, which is either another PT system or regulated by the PTS. The glucose PTS did not seem to be involved in the regulation of the uptake or metabolism of non-PTS compounds like glycerol. In contrast to ptsl mutants in members of the Enterobacteriaceae, the defective growth of B. subtilis ptsl mutants on glycerol was not restored by an insertion in the ptsG gene which eliminated IIGlc. Growth of B. subtilis ptsG mutants, lacking IIGlc, was not impaired on glycerol. From this we concluded that neither non-phosphorylated nor phosphorylated IIGlc was acting as an inhibitor or an activator, respectively, of glycerol uptake and metabolism.
葡萄糖磷酸转移酶系统（葡萄糖磷酸转移酶系统）在枯草芽孢杆菌中被摄取。两个基因，orfG和ptsX，已被认为参与了该磷酸转移酶系统的葡萄糖特异性部分，分别编码一种葡萄糖特异性酶IIGlc和一种葡萄糖特异性酶IIIGlc。我们现在表明，葡萄糖通透酶由一种单一的、膜结合的多肽组成，其表观分子量为80,000，由一个将被命名为ptsG的单一基因编码。葡萄糖通透酶包含与大肠杆菌的IIGlc和IIIGlc蛋白有40-50%同源性的结构域。枯草芽孢杆菌的IIIGlc结构域可以替代大肠杆菌crr突变体中的IIIGlc，以支持在葡萄糖上的生长和α-甲基葡萄糖苷的转运。枯草芽孢杆菌ptsG基因的IIGlc和IIIGlc结构域中的突变损害了在葡萄糖上的生长，在某些情况下也损害了在蔗糖上的生长。ptsG突变体失去了所有的α-甲基葡萄糖苷转运能力，但保留了部分葡萄糖转运能力。这些ptsG突变体在葡萄糖上的残余生长和葡萄糖转运表明，还存在另一种葡萄糖摄取系统，它要么是另一种磷酸转移酶系统，要么受磷酸转移酶系统调节。葡萄糖磷酸转移酶系统似乎不参与非磷酸转移酶系统化合物如甘油的摄取或代谢的调节。与肠杆菌科成员中的ptsl突变体不同，枯草芽孢杆菌ptsl突变体在甘油上的缺陷生长不会因ptsG基因中的插入而恢复，该插入消除了IIGlc。缺乏IIGlc的枯草芽孢杆菌ptsG突变体在甘油上的生长没有受到损害。由此我们得出结论，无论是未磷酸化的还是磷酸化的IIGlc都分别不作为甘油摄取和代谢的抑制剂或激活剂。
