Aspergillus (Emericella) nidulans is a well-established model organism to study elementary processes of differentiation. A Negative Subtraction Screening procedure was performed with the aim to isolate transcripts that are expressed at elevated levels during cleistothecia formation. Among them, one EST that is specifically up-regulated at the end of fruit body development could be identified. The deduced amino acid sequence of the equivalent full-length cDNA shows similarity to the S. cerevisiae F-box protein Grr1p and the A. nidulans GrrA protein complements the morphology defect of a yeast grr1D mutant strain. The grrA locus was deleted in a wild-type background and the resulting mutant strain was characterised thoroughly: whereas no specific phenotype is obvious with respect to growth capacities, mitosis, asexual sporulation or cleistothecia development, there are no ascospores to be found within the ripe fruiting bodies of the grrAD mutant. As specificity factors of so-called SCF ubiquitin ligase complexes, F-box proteins influence protein stability and turnover. Conclusively, the grrA gene product links ascosporogenesis in A. nidulans to proteasome-executed protein degradation mediated by the SCFGrrA complex.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)