Background:
Uncoupling proteins (UCP) are evolutionary conserved mitochondrial carriers that controlenergy metabolism and therefore play important roles in several physiological processes suchas thermogenesis, regulation of reactive oxygen species (ROS), growth control, lipidmetabolism and regulation of insulin secretion. Despite their importance in variousphysiological processes, their molecular function remains controversial. The evolution andphylogenetic distribution may assist to identify their general biological function andstructure-function relationships. The exact number of uncoupling protein genes in the fishgenome 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. FourUCP genes that are shared by five other fish species were identified in sea bass genome.Phylogenetic reconstitution among vertebrate species and synteny analysis revealed thatUCP1, UCP2 and UCP3 evolved from duplication events that occurred in the commonancestor of vertebrates, whereas the novel fourth UCP originated specifically in the teleostlineage. Functional divergence analysis among teleost species revealed specific amino acidpositions 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 inteleost 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 longtermand differential selective pressures, and therefore, provide the indication that UCP genesmay have diverse physiological functions in teleost fishes. Further experimental analysis ofthe critical amino acids identified here may provide valuable information on the physiologicalfunctions of UCP genes.
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