title: Substrate specificity of the Escherichia coli 4-aminobutyrate carrier encoded by gabP. Uptake and counterflow of structurally diverse molecules.
abstract: Transport of 4-aminobutyrate into Escherichia coli is catalyzed by gab permease (GabP). Although published studies show that GabP is relatively specific, recognizing the common alpha-amino acids with low affinity, recent work from this laboratory indicates that a number of synthetic compounds are high affinity transport inhibitors (50% inhibition at 5-100 microM). Here we present evidence that many of these structurally heterogeneous compounds not only inhibit transport but also function as alternative GabP substrates (i.e. a set of observations inconsistent with the idea that the core of the GabP transport channel exhibits rigid structural specificity for the native substrate, 4-aminobutyrate.
authors.affiliation: Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555-0641, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Brechtel
authors.forename: L
authors.initials: L
authors.lastname: Hu
authors.forename: S C
authors.initials: SC
authors.lastname: King
mesh_terms: D000613:Aminobutyrates / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D051268:GA-Binding Protein Transcription Factor; D026901:Membrane Transport Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D000613:Aminobutyrates; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D051268:GA-Binding Protein Transcription Factor; D026901:Membrane Transport Proteins; D014157:Transcription Factors