The mae1 gene of Schizosaccharomyces pombe encodes a permease for malate and other C-4 dicarboxylic acids

The mael gene of the yeast Schizosaccharomyces pombe was identified on the basis of its ability to complement a mutant defective in the transport of malic acid. Analysis of the DNA sequence revealed an open reading frame of 1314 base pairs, encoding a polypeptide of 438 amino acids with a predicted molecular weight of 49 kDa. A hydropathy profile of the predicted amino acid sequence revealed a protein with ten membrane-spanning or associated domains and hydrophilic N- and C- termini. The predicted secondary structure of the protein is similar to models proposed for other integral mambrane proteins from both prokaryotes and eukaryotes. The S. pombe mael gene encodes a single mRNA of 1.5 kb. The mael gene is expressed constitutively and is not subject to catabolite repression as was previously reported for the malate permease systems of Candida utilis and Hansenula anomala. The mael gene was mapped 2842 bp 5' to the MFml gene on chromosome I. Transport assays revealed that the mael gene encodes a permease involved in the uptake of L-malate, succinate and malonic acid. The sequence of the S. pombe mael gene is available in GenBank under Accession Number U21002.