Lactose permeation via the arabinose transport system in Escherichia coli K-12.
This paper describes the isolation and characterization of a mutant of Escherichia coli that transports lactose and its analog thiomethylgalactoside via the arabinose permeation system. Unlike transport via the lactose permease, this transport is not inhibited by thiodigalactoside, but was inhibited by arabinose, xylose, and fucose. The site of the mutation was in the arabinose C gene and confers constitutivity on the entire arabinose operon. Furthermore, this transport was found in 24 independently isolated arabinose-constitutive strains, and in strains which had been induced with arabinose and then starved to remove all traces of it. It was therefore concluded that lactose and thiomethylgalactoside are low-affinity substrates of at least one component of the normal arabinose permeation system.
D001089:Arabinose / Q000378:metabolism*; D001693:Biological Transport, Active; D002238:Carbohydrate Epimerases / Q000378:metabolism; D002250:Carbon Radioisotopes; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D005696:Galactosidases / Q000378:metabolism; D005796:Genes; D007785:Lactose / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D008756:Methylgalactosides / Q000378:metabolism; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D009876:Operon; D009995:Osmosis; D014161:Transduction, Genetic
D002250:Carbon Radioisotopes; D026901:Membrane Transport Proteins; D008756:Methylgalactosides; D009153:Mutagens; D009604:Nitrosoguanidines; D001089:Arabinose; D005696:Galactosidases; D002238:Carbohydrate Epimerases; D007785:Lactose