Involvement of the central loop of the lactose permease of Escherichia coli in its allosteric regulation by the glucose-specific enzyme IIA of the phosphoenolpyruvate-dependent phosphotransferase system.
Allosteric regulation of several sugar transport systems such as those specific for lactose, maltose and melibiose in Escherichia coli (inducer exclusion) is mediated by the glucose-specific enzyme IIA (IIAGlc) of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Deletion mutations in the cytoplasmic N and C termini of the lactose permease protein, LacY, and replacement of all cysteine residues in LacY with other residues did not prevent IIAGlc-mediated inhibition of lactose uptake, but several point and insertional mutations in the central cytoplasmic loop of this permease abolished transport regulation and IIAGlc binding. The results substantiate the conclusion that regulation of the lactose permease in E. coli by the PTS is mediated by a primary interaction of IIAGlc with the central cytoplasmic loop of the permease.
Hoischen
C
C
Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA.
Levin
J
J
Pitaknarongphorn
S
S
Reizer
J
J
Saier
M H
MH
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001665:Binding Sites; D001692:Biological Transport; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007785:Lactose / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D016254:Mutagenesis, Insertional; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D027981:Symporters
D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C021499:lactose permease; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C031629:phosphoenolpyruvate-glucose phosphotransferase; D007785:Lactose