Amino-sugar transport systems of Escherichia coli K12.

Glucosamine, mannose and 2-deoxyglucose enter Escherichia coli by the phosphotransferase system coded for by the gene ptsM. The glucosamine- and mannose-negative, deoxyglucose-resistant phenotype of ptsM mutants can be suppressed by a mutation mapping near ptsG that allows constitutive expression of the glucose phosphotransferase coded for by the gene ptsG. N-Acetylglucosamine enters E. coli by two distinct phosphotransferase systems (White, 1970). One of these is the PtsM system, the other is coded for by a gene which maps near the nagA,B genes at about min 15 on the E. coli chromosome. We propose that this gene be designated ptsN. Strains with either of these components of the phosphotransferase system will utilize N-acetylglucosamine as sole carbon source.