title: Proteomic analysis reveals a novel function of the kinase Sat4p in Saccharomyces cerevisiae mitochondria.
abstract: The Saccharomyces cerevisiae kinase Sat4p has been originally identified as a protein involved in salt tolerance and stabilization of plasma membrane transporters, implicating a cytoplasmic localization. Our study revealed an additional mitochondrial (mt) localization, suggesting a dual function for Sat4p. While no mt related phenotype was observed in the absence of Sat4p, its overexpression resulted in significant changes of a specific mitochondrial subproteome. As shown by a comparative two dimensional difference gel electrophoresis (2D-DIGE) approach combined with mass spectrometry, particularly two groups of proteins were affected: the iron-sulfur containing aconitase-type proteins (Aco1p, Lys4p) and the lipoamide-containing subproteome (Lat1p, Kgd2p and Gcv3p). The lipoylation sites of all three proteins could be assigned by nanoLC-MS/MS to Lys75 (Lat1p), Lys114 (Kgd2p) and Lys102 (Gcv3p), respectively. Sat4p overexpression resulted in accumulation of the delipoylated protein variants and in reduced levels of aconitase-type proteins, accompanied by a decrease in the activities of the respective enzyme complexes. We propose a regulatory role of Sat4p in the late steps of the maturation of a specific subset of mitochondrial iron-sulfur cluster proteins, including Aco1p and lipoate synthase Lip5p. Impairment of the latter enzyme may account for the observed lipoylation defects.
authors.affiliation: Institute of Genetics, Technische Universität Dresden, Dresden, Germany.
authors.forename: Uta
authors.initials: U
authors.lastname: Gey
authors.affiliation: Biotechnological Center, Technische Universität Dresden, Dresden, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Czupalla
authors.affiliation: Biotechnological Center, Technische Universität Dresden, Dresden, Germany.
authors.forename: Bernard
authors.initials: B
authors.lastname: Hoflack
authors.affiliation: Institute of Genetics, Technische Universität Dresden, Dresden, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Krause
authors.affiliation: Institute of Genetics, Technische Universität Dresden, Dresden, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Rödel
mesh_terms: D003593:Cytoplasm / Q000378:metabolism; D015870:Gene Expression; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D020543:Proteome; D040901:Proteomics / Q000379:methods; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D046912:Multiprotein Complexes; D020543:Proteome; D029701:Saccharomyces cerevisiae Proteins; C072246:SAT4 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases