Author:
SKELLY P. J.,PFEIFFER R.,VERREY F.,SHOEMAKER C. B.
Abstract
The Schistosoma mansoni protein, SPRM1lc, is a light chain member of a new family of heterodimeric amino acid
permeases. These proteins require covalent association with a type II glycoprotein (like h4F2hc) for functional surface
localization when expressed in Xenopus oocytes. We previously reported that, when co-expressed with h4F2hc, the
transport properties of SPRM1lc resemble system y and y+ while its human homologue, E16, functions as an L-type
permease. Here we extend the functional characterization of SPRM1lc in oocytes and show by competitor studies that its
amino acid transport capacity is similar to that of whole adult schistosomes. We demonstrate by Northern and Western
analysis that SPRM1lc is expressed within both larval and adult schistosomes. In all stages, SPRM1lc is associated into
a high molecular weight complex that can be disrupted by reducing agents, consistent with the hypothesis that a significant
fraction of the endogenous SPRM1lc is linked by a disulphide bond to an uncharacterized schistosome amino acid
transporter heavy chain. Immunofluorescence localization detects SPRM1lc in miracidia, daughter sporocysts and adult
worms. Confocal microscopy demonstrates that SPRM1lc is found in the apical membrane of the syncytial, double-lipid
bilayer tegument which surrounds adult worms. Aqueous biotinylation studies on living worms show that SPRM1lc is
exposed on the host-interactive surface of this tegumental membrane. Host exposed, functionally important surface
proteins such as SPRM1lc could form the basis of an effective schistosomiasis vaccine. These studies are the first to
describe a helminth amino acid transporter, and the first to characterize an invertebrate heterodimeric amino acid
transporter.
Publisher
Cambridge University Press (CUP)
Subject
Infectious Diseases,Animal Science and Zoology,Parasitology
Cited by
31 articles.
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