title: Identification of G protein-coupled receptors in Schistosoma haematobium and S. mansoni by comparative genomics.
abstract: BACKGROUND
  Schistosomiasis is a parasitic disease affecting ~200 million people worldwide. Schistosoma haematobium and S. mansoni are two relatively closely related schistosomes (blood flukes), and the causative agents of urogenital and hepatointestinal schistosomiasis, respectively. The availability of genomic, transcriptomic and proteomic data sets for these two schistosomes now provides unprecedented opportunities to explore their biology, host interactions and schistosomiasis at the molecular level. A particularly important group of molecules involved in a range of biological and developmental processes in schistosomes and other parasites are the G protein-coupled receptors (GPCRs). Although GPCRs have been studied in schistosomes, there has been no detailed comparison of these receptors between closely related species. Here, using a genomic-bioinformatic approach, we identified and characterised key GPCRs in S. haematobium and S. mansoni (two closely related species of schistosome).
  
  
  METHODS
  Using a Hidden Markov Model (HMM) and Support Vector Machine (SVM)-based pipeline, we classified and sub-classified GPCRs of S. haematobium and S. mansoni, combined with phylogenetic and transcription analyses.
  
  
  RESULTS
  We identified and classified classes A, B, C and F as well as an unclassified group of GPCRs encoded in the genomes of S. haematobium and S. mansoni. In addition, we characterised ligand-specific subclasses (i.e. amine, peptide, opsin and orphan) within class A (rhodopsin-like).
  
  
  CONCLUSIONS
  Most GPCRs shared a high degree of similarity and conservation, except for members of a particular clade (designated SmGPR), which appear to have diverged between S. haematobium and S. mansoni and might explain, to some extent, some of the underlying biological differences between these two schistosomes. The present set of annotated GPCRs provides a basis for future functional genomic studies of cellular GPCR-mediated signal transduction and a resource for future drug discovery efforts in schistosomes.
authors.forename: Tulio D L
authors.initials: TD
authors.lastname: Campos
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia. nyoung@unimelb.edu.au.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Young
authors.forename: Pasi K
authors.initials: PK
authors.lastname: Korhonen
authors.forename: Ross S
authors.initials: RS
authors.lastname: Hall
authors.forename: Stefano
authors.initials: S
authors.lastname: Mangiola
authors.forename: Andrew
authors.initials: A
authors.lastname: Lonie
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D023281:Genomics; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012548:Schistosoma haematobium / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000378:metabolism*
chemical_list: D000871:Anthelmintics; D015801:Helminth Proteins; D019476:Insect Proteins; D043562:Receptors, G-Protein-Coupled