Evaluation of SCO1 deletion on Saccharomyces cerevisiae metabolism through a proteomic approach

The Saccharomyces cerevisiae gene SCO1 has been shown to play an essential role in copper delivery to cytochrome c oxidase. Biochemical studies demonstrated specific transfer of copper from Cox17p to Sco1p, and physical interactions between the Sco1p and Cox2p. Deletion of SCO1 yeast gene results in a respiratory deficient phenotype. This study aims to gain a more detailed insight on the effects of SCO1 deletion on S. cerevisiae metabolism. We compared, using a proteomic approach, the protein pattern of SCO1 null mutant strain and wild-type BY4741 strain grown on fermentable and on nonfermentable carbon sources. The analysis showed that on nonfermentable medium, the SCO1 mutant displayed a protein profile similar to that of actively fermenting yeast cells. Indeed, on 3% glycerol, this mutant displayed an increase of some glycolytic and fermentative enzymes such as glyceraldehyde-3-phosphate dehydrogenase 1, enolase 2, pyruvate decarboxylase 1, and alcohol dehydrogenase 1. These data were supported by immunoblotting and enzyme activity assay. Moreover, the ethanol assay and the oxygen consumption measurement demonstrated a fermentative activity in SCO1 mutant on respiratory medium. Our results suggest that on nonfermentable carbon source, the lack of Sco1p causes a metabolic shift from respiration to fermentation.