Specificity and topology of the Escherichia coli xanthosine permease, a representative of the NHS subfamily of the major facilitator superfamily

J Bacteriol. 2001 Aug;183(16):4900-4. doi: 10.1128/JB.183.16.4900-4904.2001.

Abstract

The specificity of XapB permease was compared with that of the known nucleoside transporters NupG and NupC. XapB-mediated xanthosine uptake is abolished by 2,4-dinitrophenol and exhibits saturation kinetics with an apparent K(m) of 136 microM. A 12-transmembrane-segment model was confirmed by translational fusions to alkaline phosphatase and the alpha fragment of beta-galactosidase.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism*
  • Carrier Proteins / chemistry*
  • Carrier Proteins / metabolism*
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins*
  • Kinetics
  • Membrane Proteins / metabolism
  • Membrane Transport Proteins*
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Conformation
  • Protein Structure, Secondary
  • Ribonucleosides / metabolism*
  • Software
  • Substrate Specificity
  • Xanthines

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Escherichia coli Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • NupC protein, Bacteria
  • NupC protein, E coli
  • NupG protein, E coli
  • Ribonucleosides
  • Xanthines
  • XapB protein, E coli
  • xanthosine