A critical tyrosine residue determines the uncoupling protein-like activity of the yeast mitochondrial oxaloacetate carrier.

Luis A Luévano-Martínez, Carlos Barba-Ostria, Daniela Araiza-Olivera, Natalia Chiquete-Félix, Sergio Guerrero-Castillo, Eduardo Rial, Dimitris Georgellis, Salvador Uribe-Carvajal

Department of Molecular Genetics, Instituto de Fisiología Celular, UNAM, México.

The Biochemical journal 2012 Apr 1

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The mitochondrial Oac (oxaloacetate carrier) found in some fungi and plants catalyses the uptake of oxaloacetate, malonate and sulfate. Despite their sequence similarity, transport specificity varies considerably between Oacs. Indeed, whereas ScOac (Saccharomyces cerevisiae Oac) is a specific anion-proton symporter, the YlOac (Yarrowia lipolytica Oac) has the added ability to transport protons, behaving as a UCP (uncoupling protein). Significantly, we identified two amino acid changes at the matrix gate of YlOac and ScOac, tyrosine to phenylalanine and methionine to leucine. We studied the role of these amino acids by expressing both wild-type and specifically mutated Oacs in an Oac-null S. cerevisiae strain. No phenotype could be associated with the methionine to leucine substitution, whereas UCP-like activity was dependent on the presence of the tyrosine residue normally expressed in the YlOac, i.e. Tyr-ScOac mediated proton transport, whereas Phe-YlOac lost its protonophoric activity. These findings indicate that the UCP-like activity of YlOac is determined by the tyrosine residue at position 146.

Citation

Luis A Luévano-Martínez, Carlos Barba-Ostria, Daniela Araiza-Olivera, Natalia Chiquete-Félix, Sergio Guerrero-Castillo, Eduardo Rial, Dimitris Georgellis, Salvador Uribe-Carvajal. A critical tyrosine residue determines the uncoupling protein-like activity of the yeast mitochondrial oxaloacetate carrier. The Biochemical journal. 2012 Apr 1;443(1):317-25