Topological analyses of the L-fucose-H+ symport protein, FucP from Escherichia coli.

Francis James Gunn-Moore, CG Tate, CE Sansom, PJF Henderson

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

The transport of L-fucose into Escherichia coli is mediated by the L-fucose-H+ symport protein (FucP). The fucP gene has been sequenced and encodes a hydrophobic protein that contains 438 amino acid residues, with a predicted M(r) of 47773. The hydropathic profile of FucP indicates 10 to 12 hydrophobic regions that could span the membrane as alpha-helices. A 12-helix model with the N- and C-termini located in the cytoplasm was derived from the hydropathic profile and from application of the 'positive inside' rule. This model was tested using beta-lactamase fusion technology. Analyses of 62 different FucP-beta-lactamase fusions suggested that the FucP protein crosses the cytoplasmic membrane of E. coli 12 times, with the N- and C-termini in the cytoplasm. From measurements of [C-14]-L-fucose uptake, it was deduced that the last putative transmembrane region must be complete for transport activity to be retained and that the four C-terminal residues were unnecessary for transport activity. Fourier transform analyses show that all the predicted helices contain a periodicity that enables hydrophobic/hydrophilic faces to be identified; these were particularly evident in putative helices 1, 3, 4, 5, 6, 10 and 11.

Original languageEnglish
Pages (from-to)771-83
Number of pages13
JournalMolecular Microbiology
Volume15
Issue number4
Publication statusPublished - Feb 1995

Keywords

  • MEMBRANE TOPOLOGY
  • BETA-LACTAMASE
  • CYTOPLASMIC MEMBRANE
  • TRANSPORT PROTEINS
  • LACTOSE PERMEASE
  • SEQUENCE
  • ORGANIZATION
  • INSERTION
  • RESIDUES
  • FUSIONS

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