Present address: Leiden University, Institute of Biology, Research group Molecular Microbiology, Wassenaarseweg 64, NL-2333 AL Leiden, The Netherlands.
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The antifungal protein PAF interferes with PKC/MPK and cAMP/PKA signalling of Aspergillus nidulans
Article first published online: 2 NOV 2009
DOI: 10.1111/j.1365-2958.2009.06936.x
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
Additional Information
How to Cite
Binder, U., Oberparleiter, C., Meyer, V. and Marx, F. (2010), The antifungal protein PAF interferes with PKC/MPK and cAMP/PKA signalling of Aspergillus nidulans. Molecular Microbiology, 75: 294–307. doi: 10.1111/j.1365-2958.2009.06936.x
Publication History
- Issue published online: 13 JAN 2010
- Article first published online: 2 NOV 2009
- Accepted 18 October, 2009.
Summary
The Penicillium chrysogenum antifungal protein PAF inhibits polar growth and induces apoptosis in Aspergillus nidulans. We report here that two signalling cascades are implicated in its antifungal activity. PAF activates the cAMP/protein kinase A (Pka) signalling cascade. A pkaA deletion mutant exhibited reduced sensitivity towards PAF. This was substantiated by the use of pharmacological modulators: PAF aggravated the effect of the activator 8-Br-cAMP and partially relieved the repressive activity of caffeine. Furthermore, the Pkc/mitogen-activated protein kinase (Mpk) signalling cascade mediated basal resistance to PAF, which was independent of the small GTPase RhoA. Non-functional mutations of both genes resulted in hypersensitivity towards PAF. PAF did not increase MpkA phosphorylation or induce enzymes involved in the remodelling of the cell wall, which normally occurs in response to activators of the cell wall integrity pathway. Notably, PAF exposure resulted in actin gene repression and a deregulation of the chitin deposition at hyphal tips of A. nidulans, which offers an explanation for the morphological effects evoked by PAF and which could be attributed to the interconnection of the two signalling pathways. Thus, PAF represents an excellent tool to study signalling pathways in this model organism and to define potential fungal targets to develop new antifungals.