Light-dependent coordination of development and secondary metabolism in the filamentous fungus Aspergillus nidulans

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Secondary metabolism activities and developmental programs are interwoven in fungi and respond to numerous external stimuli. The focus of the proposed project is on the signal ‘light’. Illumination coordinately decreases in the filamentous model mold Aspergillus nidulans the production of sexual tissue and the synthesis of the secondary metabolite sterigmatocystin, a precursor of the highly cancerogenic aflatoxin. We will identify the proteins interacting to the UVA/blue light sensor CryA, a combined photolyase and cryptochrome. This includes the question, whether CryA communicates to other fungal light sensors via physical interaction. Transduction of the light signal reduces the amount of VeA within the nucleus, which is a component of the heterotrimeric nuclear velvet complex VelB/VeA/LaeA. This complex coordinates differentiation and secondary metabolite synthesis in the dark. The light-dependent VeA cis-located signal sequences and the trans-acting factors will be defined. Changes in the composition of the velvet complex during development will be monitored. We will also address, whether there are other interacting proteins to VelB and LaeA in strains lacking VeA in the absence or presence of light. The understanding of the developmental regulation of fungal secondary metabolism will help to control mycotoxin formation or increase the production of beneficial fungi-derived drugs.