title: UCP3 is associated with Hax-1 in mitochondria in the presence of calcium ion.
abstract: Uncoupling protein 3 (UCP3) is known to regulate energy dissipation, proton leakage, fatty acid oxidation, and oxidative stress. To identify the putative protein regulators of UCP3, we performed yeast two-hybrid screens. Here we report that UCP3 interacted with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that was localized in the mitochondria, and is involved in cellular responses to Ca(2+). The hydrophilic sequences within loop 2, and the matrix-localized hydrophilic domain of mouse UCP3, were necessary for binding to Hax-1 at the C-terminal domain, adjacent to the mitochondrial inner membrane. Interestingly, interaction of these proteins occurred in a calcium-dependent manner. Moreover, the NMR spectrum of the C-terminal domain of Hax-1 was dramatically changed by removal of Ca(2+), suggesting that the C-terminal domain of Hax-1 underwent a Ca(2+)-induced conformational change. In the Ca(2+)-free state, the C-terminal Hax-1 tended to unfold, suggesting that Ca(2+) binding may induce protein folding of the Hax-1 C-terminus. These results suggested that the UCP3-Hax-1 complex may regulate mitochondrial functional changes caused by mitochondrial Ca(2+).
authors.affiliation: Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan; Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan. Electronic address: hirasaka@nagasaki-u.ac.jp.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Hirasaka
authors.affiliation: Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX, USA.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Mills
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Marie
authors.initials: M
authors.lastname: Haruna
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Aki
authors.initials: A
authors.lastname: Bando
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Ikeda
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Abe
authors.affiliation: Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX, USA.
authors.forename: Shohei
authors.initials: S
authors.lastname: Kohno
authors.affiliation: Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Nowinski
authors.affiliation: Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Cory U
authors.initials: CU
authors.lastname: Lago
authors.affiliation: Section of Laboratory Equipment, National Institute of Biomedical Innovation, Osaka, Japan.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Akagi
authors.affiliation: Graduate School of Engineering, Kyoto University, Kyoto, Japan.
authors.forename: Hidehito
authors.initials: H
authors.lastname: Tochio
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Ohno
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Shigetada
authors.initials: S
authors.lastname: Teshima-Kondo
authors.affiliation: Department of Nutrition and Health, Sagami Woman's University, Kanagawa, Japan.
authors.forename: Yuushi
authors.initials: Y
authors.lastname: Okumura
authors.affiliation: Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nikawa
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D000071247:Uncoupling Protein 3
chemical_list: C491295:Hs1bp1 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D024101:Mitochondrial Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C000604392:UCP3 protein, human; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3; D002118:Calcium
keywords: Calcium ion; Folding; Mitochondria; Uncoupling protein 3