title: Abundance of tegument surface proteins in the human blood fluke Schistosoma mansoni determined by QconCAT proteomics.
abstract: The schistosome tegument provides a major interface with the host blood stream in which it resides. Our recent proteomic studies have identified a range of proteins present in the complex tegument structure, and two models of protective immunity have implicated surface proteins as mediating antigens. We have used the QconCAT technique to evaluate the relative and absolute amounts of tegument proteins identified previously. A concatamer comprising R- or K-terminated peptides was generated with [(13)C(6)] lysine/arginine amino acids. Two tegument surface preparations were each spiked with the purified SmQconCAT as a standard, trypsin digested, and subjected to MALDI ToF-MS. The absolute amounts of protein in the biological samples were determined by comparing the areas under the pairs of peaks, separated by 6m/z units, representing the light and heavy peptides derived from the biological sample and SmQconCAT, respectively. We report that aquaporin is the most abundant transmembrane protein, followed by two phosphohydrolases. Tetraspanin Tsp-2 and Annexin-2 are also abundant but transporters are scarce. Sm200 surface protein comprised the bulk of the GPI-anchored fraction and likely resides in the secreted membranocalyx. Two host IgGs were identified but in amounts much lower than their targets. The findings are interpreted in relation to the models of protective immunity.
authors.affiliation: Centre for Immunology & Infection, Department of Biology, University of York, Heslington, York, YO10 5DD, UK. williamcborges@hotmail.com
authors.forename: William
authors.initials: W
authors.lastname: Castro-Borges
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Simpson
authors.forename: Adam
authors.initials: A
authors.lastname: Dowle
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Curwen
authors.forename: Jane
authors.initials: J
authors.lastname: Thomas-Oates
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Beynon
authors.forename: R Alan
authors.initials: RA
authors.lastname: Wilson
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000032:analysis; D015801:Helminth Proteins / Q000032:analysis*; D006801:Humans; D007109:Immunity; D008565:Membrane Proteins / Q000032:analysis* / Q000276:immunology; D040901:Proteomics / Q000379:methods*; D012550:Schistosoma mansoni / Q000737:chemistry* / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D020346:Aquaporins; D015801:Helminth Proteins; D008565:Membrane Proteins