In spite of its exceptional biotechnological importance, the autolytic phase of growth is a poorly understood and underexploited area in fungal biology. Nutrient limitation initiates the release of a wide array of cell wall degrading hydrolases (chitinases, glucanases and proteinases) to feed surviving hyphal cells in submerged cultures. Among the autolytic hydrolases produced by the model filamentous fungus Aspergillus nidulans, ChiB endochitinase, EngA beta-1,3-endoglucanase, PrtA serine proteinase and PepJ metalloproteinase play a major role in the decomposition of cell wall biopolymers. Importantly, all these autolytic enzymes are regulated by the FluG-BrlA developmental signaling pathway, suggesting that conidiogenesis and autolysis are inherently coupled physiological processes and, hence, share common upstream regulatory elements. The biosyntheses of autolytic hydrolases are sophistically and inter-dependently coordinated to avoid either the early and uncontrolled decomposition of intact hyphae or the inefficient degradation of cell wall biopolymers. Considering cell wall constituents, the enzymatic disruption of the polysaccharide (chitin, glucan) layers seems to be a decisive step in fungal autolysis because the chiB and engA gene deletion mutants possessed non-autolytic phenotypes.
Full conference title:
26th Fungal Genetics Conference
- Fungal Genetics Conference 26th (2005)