Identification and Characterization of MFA1, the Gene Encoding Candida albicans a-Factor Pheromone

摘要

In the opaque state, MTL>a and MTLα strains of Candida albicans are able to mate, and this mating is directed by a pheromone-mediated signaling process. We have used comparisons of genome sequences to identify a C. albicans gene encoding a candidate >a-specific mating factor. This gene is conserved in Candida dubliniensis and is similar to a three-gene family in the related fungus Candida parapsilosis but has extremely limited similarity to the Saccharomyces cerevisiae MFA1 (ScMFA1) and ScMFA2 genes. All these genes encode C-terminal CAAX box motifs characteristic of prenylated proteins. The C. albicans gene, designated CaMFA1, is found on chromosome 2 between ORF19.2165 and ORF19.2219. MFA1 encodes an open reading frame of 42 amino acids that is predicted to be processed to a 14-amino-acid prenylated mature pheromone. Microarray analysis shows that MFA1 is poorly expressed in opaque MTL>a cells but is induced when the cells are treated with α-factor. Disruption of this C. albicans gene blocks the mating of MTL>a cells but not MTLα cells, while the reintegration of the gene suppresses this cell-type-specific mating defect.