Proteomic analysis reveals a novel function of the kinase Sat4p in Saccharomyces cerevisiae mitochondria.

Proteomic analysis reveals a novel function of the kinase Sat4p in Saccharomyces cerevisiae mitochondria.

Blog Article

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 cubs foam finger 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 read more 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.