Role of the Cyclin-dependent Kinase PtkA in the Morphogenetic Cycle of Aspergillus Nidulans
Final Report Abstract
Filamentous fungi have an important economic impact in biotechnology and food production, but are also potentially hazardous as human pathogens or producer of mycotoxins. Their life cycle comprises highly differentiated cell types like the extremely polarized hyphae or the asexual conidiospores. The cell biological networks that control the specific morphological and developmental processes of these cell types are complex and of great interest for both, basic and applied research. The filamentous ascomycete Aspergillus nidulans is easy accessible for cultivation and genetic modification and has emerged over the last decades to one of most important fungal model systems. This project focused on the functional role of the newly identified cyclindependent kinase PtkA in A. nidulans. Based on sequence comparisons PtkA was classified as a member of the Cdk9-subfamily, which in complex with T-type cyclins are known to be essential components of the eukaryotic transcription elongation machinery. In accordance to that the deletion of ptkA in A. nidulans had a lethal effect in later stages of vegetative growth and completely impeded spore production. A fluorescently tagged PtkA version was used to examine the subcellular localization of the protein, which turned out to be concentrated in the nucleus, also supporting a possible role in transcription elongation. In addition, a putative cyctin T homolog, PchA, was identified in the A. nidulans genome and its interaction with PtkA was confirmed in vivo. Surprisingly, the Pcl-like cyclin PclA, previously described to be involved In asexual development, was also found to interact with PtkA. This is the first report of a Cdk9 kinase interacting with a canonical rather than a transcriptional cyclin, indicating a possible role of this subfamily in linking transcriptional activity with development and/or morphogenesis in filamentous fungi. Based on these results, RkA might be an important key player in the morphogenetic networks of A. nidulans and in the future could be potentially used to regulate proliferation and productive activity of fungal cells.
Publications
- 2010. Functional Characterization of a new Member of the Cdk9-Familiy in Aspergillus nidulans. Eukaryotic Cell
Bathe, F., C. Kempf, S. A. Osmani, A. H. Osmani, S. Hettinger, E. Wohlmann and R. Fischer
