Plant cell wall degrading enzymes (PCWDEs) produced by filamentous fungi have many industrial applications. Using Aspergillus nidulans as a genetic model system, our group conducts basic research on gene function and regulation as well as the characterization of unconventional protein secretion and sugar uptake/utilization to generate knowledge that could be used for the optimization of the production and secretion of PCWDEs. To this end we are using transcriptomics to elucidate components and regulatory mechanisms involved in the deconstruction and utilization of pectin. Our studies could have implications not only for the production of PCWDEs of utility in manipulating the organoleptic/functional characteristics of foods and beverages but also the revalorisation of agricultural and forestry wastes (biofuels and other products) and phytopathology since pectin-degrading enzymes are some of the first enzymes to be secreted by phytopathogenic fungi in their assault on plant tissues.
1) Identification, cloning and genetic/functional characterization of genes encoding transporters and enzymes involved in the uptake and catabolism of pectic sugars; identification of their orthologues in phytopathogenic fungi. 2) Establish the transcription profiles of genes encoding CAZy family enzymes involved in pectin deconstruction. 3) Characterization of the genes controlled by the transcriptional activators (RhaR and PecR) that mediate induction by rhamnose and pectin, and identification of their orthologues in phytopathogenic fungi. 4) Characterise the mechanism of CreA-independent carbon catabolite repression (CCR) of rhamnosidases and pectin-acting genes. Identification of the putative repressor CriS. 5) Optimization of plant cell wall degrading enzyme (PCWDE) production by manipulation of the genes studied in the previous objectives. 6) Establish the secretion pathway followed by an extracellular rhamnosidase lacking signal peptide (SP) as a model of a PCWDE secreted by the non-classical pathway (UPS).