The STE12 gene product in C. neoformans regulates the expression of several virulence factors of the fungus. To elucidate its regulatory role on other gene products, the differential expression between a wild type and the ste12 (deletant) strain was analysed. The expression of several genes was altered. Among these the expression of the PLB gene that encodes for an extracellular phospholipase was down regulated. Phospholipases have been attributed an important role in the pathogenesis of several clinically important fungal pathogens, including C. albicans. The existence of a direct correlation between possession or expression of phospholipase activity and virulence in C. neoformans has been reported in mouse models. A cDNA fragment containing the partial phospholipase B gene sequence was recovered from the differential expression screen of a wild-type, serotype D isolate of C. neoformans. This cDNA fragment was used as a probe to isolate and chracterize the genomic and cDNAs of the phospholipase gene. The effects on the expression of the phospholipase B gene, both at the transcriptional and translational levels, influenced by interactions with hypothesized regulatory factors such as STE12alpha, have been studied.
