ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
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 Mr of 47773. The hydropathic profile of FucP indicates 10 to 12 hydrophobic regions that could span the membrane as α-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 β-lactamase fusion technology. Analyses of 62 different FucP-β-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 [14C]-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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2958.1995.tb02384.x
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