The putative monocarboxylate permeases of the yeast Saccharomyces cerevisiae do not transport monocarboxylic acids across the plasma membrane

• Published in: Yeast (Chichester, England) Vol. 18; no. 12; pp. 1131 - 1143
• Main Authors: Makuc, Judita, Paiva, Sandra, Schauen, Matthias, Krämer, Reinhard, André, Bruno, Casal, Margarida, Leão, Cecília, Boles, Eckhard
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.09.2001
• Subjects: acetate; beta-Galactosidase - analysis; Biomass; Carboxylic Acids - metabolism; Cell Membrane - enzymology; Cell Membrane - metabolism; functional analysis; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal - physiology; Genes, Fungal; Glucose - metabolism; JEN1 gene; Kinetics; lactate; MCH1 gene; MCH2 gene; MCH3 gene; MCH4 gene; MCH5 gene; MCT genes; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; mitochondria; Mitochondria - metabolism; Mitochondria - physiology; monocarboxylate permease; monocarboxylate transport; Monocarboxylic Acid Transporters - genetics; Monocarboxylic Acid Transporters - metabolism; Mutagenesis; Open Reading Frames; Oxygen Consumption; pyruvate; Pyruvic Acid - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; yeast; YHL008 gene
• ISSN: 0749-503X; 1097-0061
• DOI: 10.1002/yea.763

We have characterized the monocarboxylate permease family of Saccharomyces cerevisiae comprising five proteins. We could not find any evidence that the monocarboxylate transporter‐homologous (Mch) proteins of S. cerevisiae are involved in the uptake or secretion of monocarboxylates such as lactate, pyruvate or acetate across the plasma membrane. A yeast mutant strain deleted for all five MCH genes exhibited no growth defects on monocarboxylic acids as the sole carbon and energy sources. Moreover, the uptake and secretion rates of monocarboxylic acids were indistinguishable from the wild‐type strain. Additional deletion of the JEN1 lactate transporter gene completely blocked uptake of lactate and pyruvate. However, uptake of acetate was not even affected after the additional deletion of the gene YHL008c, which had been proposed to code for an acetate transporter. The mch1–5 mutant strain showed strongly reduced biomass yields in aerobic glucose‐limited chemostat cultures, pointing to the involvement of Mch transporters in mitochondrial metabolism. Indeed, intracellular localization studies indicated that at least some of the Mch proteins reside in intracellular membranes. However, pyruvate uptake into isolated mitochondria was not affected in the mch1–5 mutant strain. It is concluded that the yeast monocarboxylate transporter‐homologous proteins perform other functions than do their mammalian counterparts. Copyright © 2001 John Wiley & Sons, Ltd.