Protein phosphorylation in mitochondria --a study on fermentative and respiratory growth of Saccharomyces cerevisiae

Phosphorylation as a posttranslational protein modification is a common subject of proteomic studies, but phosphorylation in mitochondria is still poorly investigated. The study presented here applied 2-DE to characterize phosphorylation in the yeast mitochondrial proteome and identified 59 spots corresponding to 34 phosphorylated mitochondrial or mitochondria-associated proteins. Most of these proteins presented putative substrates of mitogen-activated protein and target of rapamycin kinases, cAMP-dependent protein kinase, cyclin-dependent kinases and Snf1p suggesting them as key players in the phosphorylation of mitochondrial or mitochondria-associated proteins. The dynamic behaviour of the phosphoproteome under a major metabolic change, the shift from fermentation to respiration (diauxic shift), was further studied. Eight proteins (Ald4p, Eft1p/2p, Eno1p, Eno2p, Om14p, Pda1p, Qcr2p, Sdh1p) had growth dependent changes in their phosphorylation, indicating a role of phosphorylation-dependent regulation of translation, metabolic pathways (e.g. glucose fermentation, tricarboxylic acid cycle, pyruvate dehydrogenase and its bypass) and respiratory chain.