title: Genomic characterization of the European sea bass Dicentrarchus labrax reveals the presence of a novel uncoupling protein (UCP) gene family member in the teleost fish lineage.
abstract: BACKGROUND
  Uncoupling proteins (UCP) are evolutionary conserved mitochondrial carriers that control energy metabolism and therefore play important roles in several physiological processes such as thermogenesis, regulation of reactive oxygen species (ROS), growth control, lipid metabolism and regulation of insulin secretion. Despite their importance in various physiological processes, their molecular function remains controversial. The evolution and phylogenetic distribution may assist to identify their general biological function and structure-function relationships. The exact number of uncoupling protein genes in the fish genome and their evolution is unresolved.
  
  
  RESULTS
  Here we report the first characterisation of UCP gene family members in sea bass, Dicentrarchus labrax, and then retrace the evolution of the protein family in vertebrates. Four UCP genes that are shared by five other fish species were identified in sea bass genome. Phylogenetic reconstitution among vertebrate species and synteny analysis revealed that UCP1, UCP2 and UCP3 evolved from duplication events that occurred in the common ancestor of vertebrates, whereas the novel fourth UCP originated specifically in the teleost lineage. Functional divergence analysis among teleost species revealed specific amino acid positions that have been subjected to altered functional constraints after duplications.
  
  
  CONCLUSIONS
  This work provides the first unambiguous evidence for the presence of a fourth UCP gene in teleost fish genome and brings new insights into the evolutionary history of the gene family. Our results suggest functional divergence among paralogues which might result from long-term and differential selective pressures, and therefore, provide the indication that UCP genes may have diverse physiological functions in teleost fishes. Further experimental analysis of the critical amino acids identified here may provide valuable information on the physiological functions of UCP genes.
authors.affiliation: Max Planck Institute for Molecular Genetics, Ihnestresse 63-73, 14195, Berlin, Germany. tine@mpipz.mpg.de
authors.forename: Mbaye
authors.initials: M
authors.lastname: Tine
authors.forename: Heiner
authors.initials: H
authors.lastname: Kuhl
authors.forename: Martin
authors.initials: M
authors.lastname: Jastroch
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass / Q000235:genetics*; D019143:Evolution, Molecular; D020440:Gene Duplication; D023281:Genomics; D007473:Ion Channels / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics*; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment; D026801:Synteny; D000071256:Uncoupling Protein 1
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1