Isolation and characterization of the Cryptococcus neoformans MATa pheromone gene

Cryptococcus neoformans is a heterothallic basidiomycete with two mating types, MATa and MATα. The mating pathway of this fungus has a number of conserved genes, including a MATα-specific pheromone (MFα1). A modified differential display strategy was used to identify a gene encoding the MATa pheromone. The gene, designated MFa1, is 42 amino acids in length and contains a conserved farnesylation motif. MFa1 is present in three linked copies that span a 20-kb fragment of MATa-specific DNA and maps to the MAT-containing chromosome. Transformation studies showed that MFal induced filament formation only in MATα cells, demonstrating that MFa1 is functionally conserved. Sequence analysis of the predicted Mfa1 and Mfα1 proteins revealed that, in contrast to other fungi such as Saccharomyces cerevisiae, the C. neoformans pheromone genes are structurally and functionally conserved. However, unlike the MFα1 gene, which is found in MATα strains of both varieties of C. neoformans, MFa1 is specific for the neoformans variety of C. neoformans.