The MAT1 Locus of Histoplasma capsulatum Is Responsive in a Mating Type-Specific Manner

Recombination events associated with sexual replication in pathogens may generate new strains with altered virulence. Histoplasma capsulatum is a mating-competent, pathogenic fungus with two described phenotypic mating types, + and -. The mating (MAT) locus of H. capsulatum was identified to facilitate molecular studies of mating in this organism. Through syntenic analysis of the H. capsulatum genomic sequence databases, a MAT1-1 idiomorph region was identified in H. capsulatum strains G217B and WU24, and a MAT1-2 idiomorph region was identified in the strain G186AR. A mating type-specific PCR assay was developed, and two clinical isolates of opposite genotypic mating type, UH1 and VA1, were identified. A known--mating type strain, T-3-1 (ATCC 22635), was demonstrated to be of MAT1-2 genotypic mating type. The clinical isolates UH1 and VA1 were found to be mating compatible and also displayed mating-type-dependent regulation of the MAT transcription factors in response to extracts predicted to contain mating pheromones. These studies support a role for the identified MAT1 locus in determining mating type in H. capsulatum.