Gliotoxin effects on fungal growth: Mechanisms and exploitation

• Published in: Fungal genetics and biology Vol. 49; no. 4; pp. 302 - 312
• Main Authors: Carberry, Stephen, Molloy, Emer, Hammel, Stephen, O’Keeffe, Grainne, Jones, Gary W., Kavanagh, Kevin, Doyle, Sean
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2012
• Subjects: Antifungal Agents - isolation & purification; Antifungal Agents - metabolism; Antifungal Agents - pharmacology; antifungal properties; Ascomycota - drug effects; aspartic proteinases; Aspergillosis - microbiology; Aspergillus; Aspergillus - drug effects; Aspergillus flavus; Aspergillus fumigatus; Aspergillus fumigatus - drug effects; Aspergillus fumigatus - genetics; Aspergillus fumigatus - growth & development; Aspergillus fumigatus - physiology; Aspergillus nidulellus; Aspergillus niger; Aspergillus oryzae; Aspergillus terreus; Biomarkers; catalase; Cochliobolus heterostrophus; Diamide - pharmacology; Down-Regulation; Fungal Proteins - metabolism; fungi; Fusarium - drug effects; Gene Expression Regulation, Fungal - drug effects; Gene Expression Regulation, Fungal - physiology; genes; Gibberella zeae; Gliotoxin - isolation & purification; Gliotoxin - metabolism; Gliotoxin - pharmacology; Glutathione - metabolism; growth retardation; loci; microbial growth; Natural products; Neurospora crassa; Neurospora crassa - drug effects; NRPS; Oxidation-Reduction; Oxidoreductases - genetics; Oxidoreductases - metabolism; proteins; Proteomics; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Sequence Deletion; superoxide dismutase; Superoxide Dismutase - metabolism; Up-Regulation; Yeast; Aspergillus; Yeast; NRPS; Aspergillus fumigatus; Natural products; Proteomics
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2012.02.003

► Gliotoxin exposure induces proteome remodelling in Aspergillus fumigatus. ► Intracellular glutathione facilitates gliotoxin sensitivity, via ROS formation. ► Gliotoxin exhibits potent antifungal effects. ► Gliotoxin resistance facilitates detection of targeted gene deletion. ► Gliotoxin may be part of the oxidant defense system in A. fumigatus. Although initially investigated for its antifungal properties, little is actually known about the effect of gliotoxin on Aspergillus fumigatus and other fungi. We have observed that exposure of A. fumigatus to exogenous gliotoxin (14μg/ml), under gliotoxin-limited growth conditions, results in significant alteration of the expression of 27 proteins (up- and down-regulated >1.9-fold; p<0.05) including de novo expression of Cu, Zn superoxide dismutase, up-regulated allergen Asp f3 expression and down-regulated catalase and a peroxiredoxin levels. Significantly elevated glutathione GSH levels (p<0.05), along with concomitant resistance to diamide, were evident in A. fumigatus ΔgliT, lacking gliotoxin oxidoreductase, a gliotoxin self-protection gene. Saccharomyces cerevisiae deletents (Δsod1 and Δyap1) were hypersensitive to exogenous gliotoxin, while Δgsh1 was resistant. Significant gliotoxin-mediated (5μg/ml) growth inhibition (p<0.001) of Aspergillus nidulans, Aspergillus terreus, Aspergillus niger, Cochliobolus heterostrophus and Neurospora crassa was also observed. Growth of Aspergillus flavus, Fusarium graminearum and Aspergillus oryzae was significantly inhibited (p<0.001) at gliotoxin (10μg/ml), indicating differential gliotoxin sensitivity amongst fungi. Re-introduction of gliT into A. fumigatus ΔgliT, at a different locus (ctsD; AFUA_4G07040, an aspartic protease), with selection on gliotoxin, facilitated deletion of ctsD without use of additional antibiotic selection markers. Absence of ctsD expression was accompanied by restoration of gliT expression, and resistance to gliotoxin. Thus, we propose gliT/gliotoxin as a useful selection marker system for fungal transformation. Finally, we suggest incorporation of gliotoxin sensitivity assays into all future fungal functional genomic studies.