title: Functional analysis of skunk cabbage SfUCPB, a unique uncoupling protein lacking the fifth transmembrane domain, in yeast cells.
abstract: Skunk cabbage, Symplocarpus foetidus, expresses two uncoupling proteins (UCPs), termed SfUCPA and SfUCPB, in the thermogenic organ spadix. SfUCPB exhibits unique structural features characterized by the absence of the putative fifth transmembrane domain (TM5) observed in SfUCPA, which is structurally similar to UCP1, and is abundantly expressed in the thermogenic spadix. Here, we conducted a series of comparative analyses of UCPs with six transmembrane domains, SfUCPA and rat UCP1, and TM5-deficient SfUCPB, using a heterologous yeast expression system. All UCPs were successfully expressed and targeted to the mitochondria, although the expression level of SfUCPB protein was approximately 10% of rat UCP1. The growth rate, mitochondrial membrane potential, and ATP content were significantly lower in cells expressing SfUCPB than in those expressing rat UCP1 and SfUCPA. These results suggest that SfUCPB, a novel TM5-deficient UCP, acts as an uncoupling protein in yeast cells.
authors.affiliation: Cryobiosystem Research Center, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan. kikuito@iwate-u.ac.jp
authors.forename: Kikukatsu
authors.initials: K
authors.lastname: Ito
authors.forename: Kazushige
authors.initials: K
authors.lastname: Matsukawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kato
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001937:Brassica; D005822:Genetic Vectors; D007473:Ion Channels / Q000737:chemistry* / Q000502:physiology*; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000502:physiology*; D008969:Molecular Sequence Data; D010101:Oxygen Consumption; D010940:Plant Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D000071256:Uncoupling Protein 1; D015003:Yeasts / Q000378:metabolism
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D010940:Plant Proteins; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D000255:Adenosine Triphosphate