Controls of the expression of aspA, the aspartyl protease gene from Penicillium roqueforti.

The gene (aspA) encoding the extracellular aspartyl protease from Penicillium roqueforti was cloned and characterized. Northern hybridization analyses and beta-casein degradation assays revealed that aspA was strongly induced by casein in the medium and efficiently repressed by ammonia. External alkaline pH overrides casein induction, resulting in aspA repression. Cis-acting motifs known to mediate nitrogen and pH regulation of fungal gene expression are present in the aspA promoter and protein-DNA binding experiments showed that mycelial proteins interact with various regions of the promoter. Due to the efficient environmental controls on aspA expression, the promoter of aspA is an attractive candidate for the development of a controllable gene expression system in P. roqueforti.