The Aspergillus giganteus antifungal protein AFPNN5353activates the cell wall integrity pathway and perturbs calcium homeostasis

BMC Microbiology

Research Article

Andrea Eigentler¹  Florentine Marx¹  Ulrike Binder²  Vera Meyer³  Mojca Bencina⁴ 

[1]Biocenter, Division of Molecular Biology, Innsbruck Medical University, Fritz-Pregl Strasse 3, A-6020, Innsbruck, Austria

[2]Biocenter, Division of Molecular Biology, Innsbruck Medical University, Fritz-Pregl Strasse 3, A-6020, Innsbruck, Austria

[3]Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Fritz-Pregl Strasse 3, A-6020, Innsbruck, Austria

[4]Department of Applied and Molecular Microbiology, Institute of Biotechnology, Berlin University of Technology, Gustav-Meyer-Allee 25, D-13355, Berlin, Germany

[5]Department of Biotechnology, National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia

[6]Excellent NMR, Future Innovation for Sustainable Technologies Centre of Excellence, Hajdrihova 19, SI-1000, Ljubljana, Slovenia

关键词: Caspofungin;    BAPTA;    Antifungal Protein;    Mechanical Perturbation;    Sensitive Fungus;   

DOI  :  10.1186/1471-2180-11-209

 received in 2011-05-25, accepted in 2011-09-23,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe antifungal protein AFPNN5353 is a defensin-like protein of Aspergillus giganteus. It belongs to a group of secretory proteins with low molecular mass, cationic character and a high content of cysteine residues. The protein inhibits the germination and growth of filamentous ascomycetes, including important human and plant pathogens and the model organsims Aspergillus nidulans and Aspergillus niger.ResultsWe determined an AFPNN5353 hypersensitive phenotype of non-functional A. nidulans mutants in the protein kinase C (Pkc)/mitogen-activated protein kinase (Mpk) signalling pathway and the induction of the α-glucan synthase A (agsA) promoter in a transgenic A. niger strain which point at the activation of the cell wall integrity pathway (CWIP) and the remodelling of the cell wall in response to AFPNN5353. The activation of the CWIP by AFPNN5353, however, operates independently from RhoA which is the central regulator of CWIP signal transduction in fungi.Furthermore, we provide evidence that calcium (Ca2+) signalling plays an important role in the mechanistic function of this antifungal protein. AFPNN5353 increased about 2-fold the cytosolic free Ca2+ ([Ca2+]c) of a transgenic A. niger strain expressing codon optimized aequorin. Supplementation of the growth medium with CaCl2 counteracted AFPNN5353 toxicity, ameliorated the perturbation of the [Ca2+]c resting level and prevented protein uptake into Aspergillus sp. cells.ConclusionsThe present study contributes new insights into the molecular mechanisms of action of the A. giganteus antifungal protein AFPNN5353. We identified its antifungal activity, initiated the investigation of pathways that determine protein toxicity, namely the CWIP and the Ca2+ signalling cascade, and studied in detail the cellular uptake mechanism in sensitive target fungi. This knowledge contributes to define new potential targets for the development of novel antifungal strategies to prevent and combat infections of filamentous fungi which have severe negative impact in medicine and agriculture.

【 授权许可】

Unknown   
© Binder et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.