title: Evolutionarily distinct residues in the uncoupling protein UCP1 are essential for its characteristic basal proton conductance.
abstract: The uncoupling proteins (UCPs) are mitochondrial transporters that modulate the efficiency of oxidative phosphorylation. Members of this family have been described in many phyla within the animal and plant kingdoms, as well as in fungi. The mammalian uncoupling protein UCP1 is activated by fatty acids and inhibited by nucleotides. In the absence of both regulators, UCP1 presents a high ohmic proton conductance that is a unique property of this carrier. The increasing number of protein sequences available has enabled us to apply a sequence analysis approach to investigate transporter function. We reconstructed a robust phylogeny of UCPs and used comparative sequence analysis to search for phylogenetically shared derived sequence features that may confer distinct properties on UCP1. We assessed the functional relevance of shared derived UCP1 residues by substituting them with their counterparts in UCP2, and expressing the protein chimeras in yeast. We found that substitution of both Glu134 and Met140 abolishes the basal proton permeability of UCP1 while preserving fatty acid activation and its nucleotide inhibition.
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Jiménez-Jiménez
authors.forename: Rafael
authors.initials: R
authors.lastname: Zardoya
authors.forename: Amalia
authors.initials: A
authors.lastname: Ledesma
authors.forename: Mario
authors.initials: M
authors.lastname: García de Lacoba
authors.forename: Pilar
authors.initials: P
authors.lastname: Zaragoza
authors.forename: M
authors.initials: M
authors.lastname: Mar González-Barroso
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rial
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006639:Histidine / Q000235:genetics; D007473:Ion Channels; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D011522:Protons; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2; D015003:Yeasts / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011522:Protons; D011994:Recombinant Proteins; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2; D006639:Histidine