Identification of the alpha-galactosidase MEL genes in some populations of Saccharomyces cerevisiae: A new gene MEL11

In this report we mapped a new MEL11 gene and summarize our population studies of the alpha-galactosidase MEL genes of S. cerevisiae. The unique family of structural MEL genes has undergone rapid translocations to the telomeres of most chromosomes in some specific Saccharomyces cerevisiae populations inhabiting olive oil processing waste (alpechin) and animal intestines. A comparative study of MEL genes in wine, pathogenic and alpechin populations of S. cerevisiae was conducted using genetic hybridization analysis, molecular karyotyping and Southern hybridization with the MEL1 probe. Five polymeric genes for the fermentation of melibiose, MEL3, MEL4, MEL6, MEL7, MEL11, were identified in an alpechin strain CBS 3081. The new MEL11 gene was mapped by tetrad analysis to the left telomeric region of chromosome I. In contrast, in wine and pathogenic populations of S. cerevisiae, MEL genes have been apparently eliminated. Their rare Mel(+) strains carry only one of the MEL1, MEL2, or MEL8 genes. One clinical strain YJM273 was heterozygotic on the MEL1 gene; its mel1(0) allele did not have a sequence of the gene.