title: Expression of Saccharomyces cerevisiae Sdh3p and Sdh4p paralogs results in catalytically active succinate dehydrogenase isoenzymes.
abstract: Succinate dehydrogenase (SDH), also known as complex II, is required for respiratory growth; it couples the oxidation of succinate to the reduction of ubiquinone. The enzyme is composed of two domains. A membrane-extrinsic catalytic domain composed of the Sdh1p and Sdh2p subunits harbors the flavin and iron-sulfur cluster cofactors. A membrane-intrinsic domain composed of the Sdh3p and Sdh4p subunits interacts with ubiquinone and may coordinate a b-type heme. In many organisms, including Saccharomyces cerevisiae, possible alternative SDH subunits have been identified in the genome. S. cerevisiae contains one paralog of the Sdh3p subunit, Shh3p (YMR118c), and two paralogs of the Sdh4p subunit, Shh4p (YLR164w) and Tim18p (YOR297c). We cloned and expressed these alternative subunits. Shh3p and Shh4p were able to complement Δsdh3 and Δsdh4 deletion mutants, respectively, and support respiratory growth. Tim18p was unable to do so. Microarray and proteomics data indicate that the paralogs are expressed under respiratory and other more restrictive growth conditions. Strains expressing hybrid SDH enzymes have distinct metabolic profiles that we distinguished by (1)H NMR analysis of metabolites. Surprisingly, the Sdh3p subunit can form SDH isoenzymes with Sdh4p or with Shh4p as well as be a subunit of the TIM22 mitochondrial protein import complex.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Samuel S W
authors.initials: SS
authors.lastname: Szeto
authors.forename: Stacey N
authors.initials: SN
authors.lastname: Reinke
authors.forename: Kayode S
authors.initials: KS
authors.lastname: Oyedotun
authors.forename: Brian D
authors.initials: BD
authors.lastname: Sykes
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Lemire
mesh_terms: D000595:Amino Acid Sequence; D017920:Antiporters / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002384:Catalysis; D042963:Electron Transport Complex II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055432:Metabolomics / Q000379:methods; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000201:enzymology; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D010641:Phenotype; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D017920:Antiporters; D007527:Isoenzymes; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C102549:TIM22 protein, S cerevisiae; C403803:Tim18 protein, S cerevisiae; D014451:Ubiquinone; C060262:2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase