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Involvement of the phosphotransferase system in galactose transport in Salmonella typhimurium
Author(s) -
Postma P.W.
Publication year - 1976
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(76)80169-x
Subject(s) - citation , pep group translocation , phosphotransferase , library science , salmonella , chemistry , computer science , information retrieval , biochemistry , biology , genetics , enzyme , bacteria , phosphoenolpyruvate carboxykinase
At least four different transport systems for galactose are known in Escherichiu coli [ 1 ] . Two of those, TMG I and TMG II, are the lactose and melibiose transport systems, respectively, while a third, the fl-methylgalactoside system, involves the galactose binding protein and is induced by D-fucose. The fourth system, the galactose permease, seems to be rather specific for galactose (and glucose) as compared to the first three systems. In all cases galactose is accumulated as the free sugar and the first step in its metabolism is a phosphorylation to galactose-lphosphate, catalyzed by galactokinase. It has been reported that galactose can also be phosphorylated in vitro to galactose 6-phosphate [2,3]. This reaction is catalyzed by the phosphoenolpyruvate-dependent phosphotransferase system (F’TS)* Since no pathway for galactose 6-phosphate metabolism is known in E. coli, it is not clear whether this reaction plays a role in galactose metabolism. I here report data that suggest that the membranebound Enzyme II of the PTS is able to catalyze the transport of galactose in a strain of Salmonella typhimurium which lacks all other galactose transport systems [4,5]. The soluble components of the PTS, Enzyme I and HPr, are not involved in this process.