Postma P W
J Bacteriol. 1977 Feb;129(2):630-9. doi: 10.1128/jb.129.2.630-639.1977.
We have studied the various systems by which galactose can be transported in Salmonella typhimurium, in particular the specific galactose permease (GP). Mutants that contain GP as the sole galactose transport system have been isolated, and starting from these mutants we have been able to select point mutants that lack GP. The galP mutation maps close to another mutation, which results in the constitutive synthesis of GP, but is not linked to galR. Growth of wild-type strains on glaactose induces GP but not the beta-methylgalactoside permease (MGP). Strains lacking GP are able to grow slowly on galactose, and MGP is induced; however, D-fucose is a much better inducer of MGP. Induction of GP or MGP is not prevented by a pts mutation, although this mutation changes the apparent Km of MGP for galactose. pts mutations have no effect on GP. GP has a rather broad specificity: galactose, glucose, mannose, fucose, 2-deoxygalactose, and 2-deoxyglucose are substrates, but only galactose and fucose can induce this transport system.
我们研究了鼠伤寒沙门氏菌中半乳糖运输的各种系统，特别是特异性半乳糖通透酶（GP）。已分离出以GP作为唯一半乳糖运输系统的突变体，从这些突变体出发，我们能够筛选出缺乏GP的点突变体。galP突变位点靠近另一个突变，该突变导致GP的组成型合成，但不与galR连锁。野生型菌株在半乳糖上生长可诱导GP，但不诱导β-甲基半乳糖苷通透酶（MGP）。缺乏GP的菌株能够在半乳糖上缓慢生长，且MGP被诱导；然而，D-岩藻糖是MGP更好的诱导剂。尽管pts突变会改变MGP对半乳糖的表观Km值，但它不会阻止GP或MGP的诱导。pts突变对GP没有影响。GP具有相当广泛的特异性：半乳糖、葡萄糖、甘露糖、岩藻糖、2-脱氧半乳糖和2-脱氧葡萄糖都是底物，但只有半乳糖和岩藻糖能诱导该运输系统。
