Regulation of transcription of the cel1 gene in Agaricus bisporus.

Northern analysis showed that accumulation of Agaricus bisporus cel1 mRNA was regulated by two independent mechanisms: (i) induction by cellulose; and (ii) repression by glucose and other sugars. Isolated A. bisporus nuclei were transcriptionally active. Nuclei isolated from cellulose-grown mycelium synthesized six times more cel1 mRNA than nuclei from glucose-grown mycelium. The start point of transcription (tsp) was identified by primer extension and S1 nuclease analysis. Putative glucose-, and cAMP-responsive elements as well as regions with homology to promoter regions of other fungal cellulase genes were detected both upstream and downstream from the tsp of the cel1 gene.