title: 14-3-3 proteins in Schistosoma mansoni; identification of a second epsilon isoform.
abstract: A new member of the 14-3-3 protein family in Schistosoma mansoni has been identified. Sequence analysis demonstrated that this protein is a member of the epsilon sub-group and is the orthologue of Schistosoma japonicum 14-3-3epsilon. Since we had previously identified a 14-3-3epsilon protein from S. mansoni, we termed the original protein 14-3-3epsilon-1 and this second epsilon protein 14-3-3epsilon-2. Schistosoma mansoni encodes at least four different 14-3-3 isoforms: the two epsilon proteins and 14-3-3 protein 1 and protein 2, which are zeta-like isoforms. Phylogenetic analysis demonstrated the early divergence of the epsilon isoforms, and that schistosome proteins 1 and 2 are among the oldest non-epsilon 14-3-3 proteins yet identified. Schistosoma mansoni 14-3-3epsilon-1, 14-3-3epsilon-2, and protein 1 are stage specifically expressed in a similar manner, being absent in cercariae and schistosomula, and abundant in lung stage and adult male and female worms. Protein 2 transcript was not detected at any of the life cycle stages examined. All three detected 14-3-3 isoforms elicit an immune response during infection, with the greatest response directed against protein 1. Binding studies with S. mansoni receptor kinase-1 (SmRK1) and human Raf kinase revealed that the three 14-3-3epsilon isoforms exhibit a preference for target protein binding. Although all three isoforms do bind to both targets, 14-3-3 protein 1 interacts most strongly with Raf, whereas the 14-3-3-1 isoform binds SmRK1 preferentially. These results suggest that the individual 14-3-3 proteins may have evolved to play isoform-specific roles in the development and survival of S. mansoni within its host.
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, NY 14853, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: McGonigle
authors.forename: Maria
authors.initials: M
authors.lastname: Loschiavo
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Pearce
mesh_terms: D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004791:Enzyme Inhibitors / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D015151:Immunoblotting; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms; D016053:RNA, Protozoan / Q000737:chemistry / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012550:Schistosoma mansoni / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics* / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D004791:Enzyme Inhibitors; D020033:Protein Isoforms; D016053:RNA, Protozoan; D011993:Recombinant Fusion Proteins; D014446:Tyrosine 3-Monooxygenase