The anisin1 gene encodes a defensin-like protein and supports the fitness of Aspergillus nidulans
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ORIGINAL PAPER
The anisin1 gene encodes a defensin-like protein and supports the fitness of Aspergillus nidulans Andrea Eigentler • Istva´n Po´csi • Florentine Marx
Received: 18 August 2011 / Revised: 17 October 2011 / Accepted: 24 October 2011 / Published online: 24 November 2011 Ó The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract In the genome of Aspergillus nidulans, a defensin-like protein, Anisin1, was annotated with high homology to the mosquito defensin AaDefA1. So far, no studies exist on defensins from filamentous ascomycetes. Therefore, we characterized the anisin1 gene in A. nidulans and generated a deletion mutant, which suffered from a defect in mitospore development and produced less conidia at 42°C compared to the reference strain. In surface cultures of A. nidulans wild type, the anisin1 expression correlated with that of the central regulator for asexual development, brlA, and with the major scavanger of H2O2 stress, catB, which is indicative for cell differentiation in developing fungi. Interestingly, brlA and anisin1 expressions were deregulated in a DsrrA strain that covers a central role in the histidine-to-aspartate (His-Asp) phosphorelay signaling pathway and shows impaired asexual development and H2O2 detoxification. In submers cultures of A. nidulans wild type and other mutants of the His-Asp phosphorelay signaling pathway, anisin1 was repressed, but derepressed in a DsrrA background, and anisin1 transcription was further increased in this mutant by H2O2
Communicated by Axel Brakhage.
Electronic supplementary material The online version of this article (doi:10.1007/s00203-011-0773-y) contains supplementary material, which is available to authorized users. A. Eigentler F. Marx (&) Biocenter, Division of Molecular Biology, Innsbruck Medical University, Fritz-Pregl Strasse 3, 6020 Innsbruck, Austria e-mail: [email protected] I. Po´csi Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, P.O. Box 63, 4032 Debrecen, Hungary
addition. We therefore conclude that the secreted protein Anisin1 contributes to the optimal development of A. nidulans and we further propose that it has a sensing/ signaling function for elevated H2O2 levels. Keywords Defensin Asexual development Oxidative stress Aspergillus nidulans
Introduction Antimicrobial peptides (AMPs), such as defensins, are widely distributed in nature as they can be found in organisms ranging from bacteria, plants, insects to humans where they are the product of gene transcription and translation of a single gene (Raj and Dentino 2002; Aerts et al. 2008). In higher eukaryotes, the synthesis of AMPs occurs constitutively or after infection or injury and forms a first line of defense against invading pathogens. Importantly, AMPs represent inducible effector molecules that act as modulators of the innate immune system beside their antimicrobial toxicity (Gallo et al. 2002; Hancock and Patrzykat 2002; Raj and Dentino 2002; Tok
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