title: A calcium-activated apyrase from Teladorsagia circumcincta: an excretory/secretory antigen capable of modulating host immune responses?
abstract: A cDNA representing the gene Teladorsagia circumcincta apyrase-1 (Tci-apy-1) was isolated, by PCR, from a T. circumcincta fourth-stage larval (L4) cDNA library. The closest orthologue of this gene is a Ca(2+)-dependent apyrase from Ostertagia ostertagi, with 92% amino acid identity across all 339 residues. Tci-apy-1 is transcribed in a stage-specific manner, the transcript being predominant in L4, detectable in the adult cDNA, but absent from eggs and infective third-stage larvae (L3). The protein, Tci-APY-1, was detected by immunoblotting in extracts of L4 nematodes and was present in excretory/secretory products from the same developmental stage. A recombinant version of Tci-APY-1 was expressed in bacteria as an active enzyme that hydrolysed nucleoside triphosphate substrates with a preference of ATP over other nucleoside triphosphates. Recombinant Tci-APY-1 hydrolysed ATP and ADP but not AMP. Apyrase activity was divalent cation-dependent, with no hydrolysis in the presence of Mg(2+), but activation in the presence of Ca(2+). Recombinant Tci-APY-1 was bound by IgG present in serum and both IgG and IgA present in abomasal mucus from trickle-infected, immune sheep but not in material derived from lambs exposed to a single infection. The potential immunomodulatory roles of this Tci-APY-1 are discussed in relation to purinergic signalling.
authors.affiliation: Parasitology Division, Moredun Research Institute, Penicuik, Scotland, UK. Alasdair.Nisbet@moredun.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Nisbet
authors.forename: D S
authors.initials: DS
authors.lastname: Zarlenga
authors.forename: D P
authors.initials: DP
authors.lastname: Knox
authors.forename: L I
authors.initials: LI
authors.lastname: Meikle
authors.forename: L A
authors.initials: LA
authors.lastname: Wildblood
authors.forename: J B
authors.initials: JB
authors.lastname: Matthews
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics; D001081:Apyrase / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D018509:DNA, Helminth / Q000235:genetics; D020536:Enzyme Activators / Q000378:metabolism; D020869:Gene Expression Profiling; D015801:Helminth Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010028:Ostertagia / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology; D014251:Trichostrongyloidea / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D014252:Trichostrongyloidiasis / Q000276:immunology / Q000662:veterinary
chemical_list: D000947:Antigens, Helminth; D002413:Cations, Divalent; D018076:DNA, Complementary; D018509:DNA, Helminth; D020536:Enzyme Activators; D015801:Helminth Proteins; D011994:Recombinant Proteins; C097418:excretory-secretory protein, Ostertagia; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001081:Apyrase; D002118:Calcium