Biochemical and genetic analysis of an alpha-mannosidase mutant from Saccharomyces cerevisiae.

A yeast mutant lacking non-specific alpha-mannosidase activity was found as a background marker during our search for dap2 mutants (Suárez-Rendueles, P. and Wolf, D. H. (1987) J. Bacteriol. 169, 4041-4048). The mutant (DPS-15) is characterized in detail. The mutation called amd1 segregates 2:2 in meiotic tetrads, indicating a single chromosomal gene mutation which is recessive. Diploids heterozygous for amd1 show gene dosage. Thus, it appears that AMD1 might be the structural gene for alpha-mannosidase. Results obtained with this mutant show that alpha-mannosidase is not a vital component of the vegetative cell cycle. The differentiation process of sporulation is not disturbed in homozygous mutant diploids. Mannose turnover does not seem to be altered in mutant cells.