Light regulation of differentiation through a red- and blue-light sensing light regulator complex in Aspergillus nidulans

• Applicant: Professor Dr. Reinhard Fischer
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2004 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5446481

Phytochromes sense red and far-red light through photo-interconversion between two stable conformations. They were originally thought to be confined to photosynthetic organisms but were recently discovered in heterotrophic eubacteria and in fungi where little is known about their functions. Interestingly, the developmental programs of the filamentous fungus Aspergillus nidulans are triggered by red and far-red light, and the system is thus reminiscent of the phytochrome response. We discovered a crucial role of a putative phytochrome, PhsA, for this response. PhsA shares also homology to prokaryotic twocomponent regulatory systems with a histidine kinase and a response regulator receiver domain. PhsA will be expressed and purified from E. coli and A. nidulans to characterize its chromophore and kinase activity. To unravel the signalling cascade, we are going to study the two previously characterized Zn(II)2Cys6 transcription factors RosA (repressor of sexual development) and NosA (no sexual development), the light regulator VeA and signalosome components as potential targets of PhsA. Their activity or subcellular localization may depend on PhsA. This will be the first phytochrome characterized outside the plant and bacterial kingdoms.

• DFG Programme: Research Grants