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    RNA-seq reveals the pan-transcriptomic impact of attenuating the gliotoxin self-protection mechanism in Aspergillus fumigatus


    O’Keeffe, Grainne and Hammel, Stephen and Owens, Rebecca A. and Keane, Thomas M. and Fitzpatrick, David A. and Jones, Gary W. and Doyle, Sean (2014) RNA-seq reveals the pan-transcriptomic impact of attenuating the gliotoxin self-protection mechanism in Aspergillus fumigatus. BMC Genomics, 15 (894). pp. 1-26. ISSN 1471-2164

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    Abstract

    Background: Aspergillus fumigatus produces a number of secondary metabolites, one of which, gliotoxin, has been shown to exhibit anti-fungal activity. Thus, A. fumigatus must be able to protect itself against gliotoxin. Indeed one of the genes in the gliotoxin biosynthetic gene cluster in A. fumigatus, gliT, is required for self-protection against the toxin- however the global self-protection mechanism deployed is unclear. RNA-seq was employed to identify genes differentially regulated upon exposure to gliotoxin in A. fumigatus wild-type and A. fumigatus ΔgliT, a strain that is hypersensitive to gliotoxin. Results: Deletion of A. fumigatus gliT resulted in altered expression of 208 genes (log2 fold change of 1.5) when compared to A. fumigatus wild-type, of which 175 genes were up-regulated and 33 genes were down-regulated. Expression of 164 genes was differentially regulated (log2 fold change of 1.5) in A. fumigatus wild-type when exposed to gliotoxin, consisting of 101 genes with up-regulated expression and 63 genes with down-regulated expression. Interestingly, a much larger number of genes, 1700, were found to be differentially regulated (log2 fold change of 1.5) in A. fumigatus ΔgliT when challenged with gliotoxin. These consisted of 508 genes with up-regulated expression, and 1192 genes with down-regulated expression. Functional Catalogue (FunCat) classification of differentially regulated genes revealed an enrichment of genes involved in both primary metabolic functions and secondary metabolism. Specifically, genes involved in gliotoxin biosynthesis, helvolic acid biosynthesis, siderophore-iron transport genes and also nitrogen metabolism genes and ribosome biogenesis genes underwent altered expression. It was confirmed that gliotoxin biosynthesis is induced upon exposure to exogenous gliotoxin, production of unrelated secondary metabolites is attenuated in A. fumigatus ΔgliT, while quantitative proteomic analysis confirmed disrupted translation in A. fumigatus ΔgliT challenged with exogenous gliotoxin. Conclusions: This study presents the first global investigation of the transcriptional response to exogenous gliotoxin in A. fumigatus wild-type and the hyper-sensitive strain, ΔgliT. Our data highlight the global and extensive affects of exogenous gliotoxin on a sensitive strain devoid of a self-protection mechanism and infer that GliT functionality is required for the optimal biosynthesis of selected secondary metabolites in A. fumigatus.

    Item Type: Article
    Additional Information: © 2014 O’Keeffe et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
    Keywords: Gliotoxin; RNA-seq; Transcriptome; Secondary metabolism; Fungal proteomics;
    Academic Unit: Faculty of Science and Engineering > Biology
    Item ID: 5742
    Depositing User: Dr. Sean Doyle
    Date Deposited: 28 Jan 2015 17:14
    Journal or Publication Title: BMC Genomics
    Publisher: BioMed Central
    Refereed: Yes
    URI:

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