title: Enzymatic activity and immunolocalization of Schistosoma mansoni and Schistosoma haematobium neutral sphingomyelinase.
abstract: We predicted, and provided evidence for, the existence of a schistosome tegument-associated Mg(2+)-dependent neutral sphingomyelinase (nSMase), which controls hydrolysis of surface membrane sphingomyelin molecules, thus allowing nutrients, but not host antibodies, to access proteins at the host-parasite interface. While a putative nSMase was identified in a recent Schistosoma mansoni genome sequencing and analysis study, our report is the first to measure nSMase enzymatic activity in Triton X-100-solubilized surface membrane (Sup 1) and whole worm soluble (SWAP) molecules of male and female S. mansoni and Schistosoma haematobium. Neutral, but no acidic, sphingomyelinase activity was readily detectable by the amplex red sphingomyelinase assay, and increased with incubation time and protein amount. Like nSMase family members, the schistosome nSMase activity was significantly (P<0.05 to <0.0001) enhanced by unsaturated fatty acids and phosphatidyl serine and significantly (P<0.01) decreased following exposure to the nSMase specific inhibitor GW4869. Peptides based on the published sequence of S. mansoni putative nSMase and used in a multiple antigen peptide form induced the generation of specific antibodies, which readily bound to the immunogen and to the cognate protein in Sup 1 and SWAP. Immunofluorescence studies suggested the parasite nSMase is located in the worm tegument and gut lining. Studies using RNA interference are in progress to define nSMase role in larval and adult worm surface membrane antigen exposure and unsaturated fatty acid-mediated attrition.
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt.
authors.forename: Hatem
authors.initials: H
authors.lastname: Tallima
authors.forename: Mohammad Farhan
authors.initials: MF
authors.lastname: Al-Halbosiy
authors.forename: Rashika
authors.initials: R
authors.lastname: El Ridi
mesh_terms: D000825:Animal Structures / Q000201:enzymology; D000818:Animals; D003067:Coenzymes / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D007814:Larva / Q000737:chemistry / Q000201:enzymology; D008274:Magnesium / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010718:Phosphatidylserines / Q000378:metabolism; D012548:Schistosoma haematobium / Q000737:chemistry / Q000201:enzymology*; D012550:Schistosoma mansoni / Q000737:chemistry / Q000201:enzymology*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism
chemical_list: D003067:Coenzymes; D005231:Fatty Acids, Unsaturated; D010718:Phosphatidylserines; D013109:Sphingomyelins; D013108:Sphingomyelin Phosphodiesterase; D008274:Magnesium