Quantitative proteomics reveals the mechanism and consequence of gliotoxin-mediated dysregulation of the methionine cycle in Aspergillus niger

Manzanares-Miralles, Lara; Sarikaya-Bayram, Özlem; Smith, Elizabeth B.; Dolan, Stephen K.; Bayram, Özgür; Jones, Gary W.; Doyle, Seán

doi:10.1016/j.jprot.2015.10.024

Cited by 23 publications

(29 citation statements)

References 61 publications

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“…This implies that GliT activity effectively compensates for the absence of GtmA in A. fumigatus Δ gtmA and that GtmA may have been an ancestral protective strategy against gliotoxin and/or other ETPs prior to the acquisition of the gliotoxin cluster by this organism. The presence of MT-II in non-ETP producing A. niger supports this hypothesis as MT-II has been shown to be involved in protection against gliotoxin and possibly other ETPs [15]. Subsequent redundancy of this superseded protection mechanism in A. fumigatus may have resulted in the neofunctionalization of GtmA and its interlinked association with the gliotoxin biosynthetic gene cluster.…”

Section: Discussionmentioning

confidence: 83%

“…Recently, it was shown that disruption of the uncharacterized methyltransferase MT-II in A. niger resulted in increased sensitivity to exogenous gliotoxin. Like GtmA, recombinantly expressed MT-II was shown to sequentially bis -thiomethylate dithiol gliotoxin, forming monomethylgliotoxin (MmGT) and then BmGT [15]. MT-II is an orthologue of GtmA (53% sequence identity), despite the fact that this organism does not produce gliotoxin.…”

Section: Introductionmentioning

confidence: 99%

“…MT-II is an orthologue of GtmA (53% sequence identity), despite the fact that this organism does not produce gliotoxin. This suggested that bis -thiomethylation may have an ancestral role in protecting organisms against dithiol-containing toxins in selected filamentous fungi, such as A. niger and A. nidulans [13,15]. However, it appears that ETP self-protection in producer organisms is dominated by reversible enzyme-catalysed epidisulfide formation, whereas the permanent, metabolically expensive mechanism of ETP S -methylation has become specialized to regulate ETP production in filamentous fungi [12].…”

Section: Introductionmentioning

confidence: 99%

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Structural, mechanistic and functional insight into gliotoxin bis -thiomethylation in Aspergillus fumigatus

et al. 2017

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Gliotoxin is an epipolythiodioxopiperazine (ETP) class toxin, contains a disulfide bridge that mediates its toxic effects via redox cycling and is produced by the opportunistic fungal pathogen Aspergillus fumigatus. Self-resistance against gliotoxin is effected by the gliotoxin oxidase GliT, and attenuation of gliotoxin biosynthesis is catalysed by gliotoxin S-methyltransferase GtmA. Here we describe the X-ray crystal structures of GtmA-apo (1.66 Å), GtmA complexed to S-adenosylhomocysteine (1.33 Å) and GtmA complexed to S-adenosylmethionine (2.28 Å), providing mechanistic insights into this important biotransformation. We further reveal that simultaneous elimination of the ability of A. fumigatus to dissipate highly reactive dithiol gliotoxin, via deletion of GliT and GtmA, results in the most significant hypersensitivity to exogenous gliotoxin observed to date. Indeed, quantitative proteomic analysis of ΔgliT::ΔgtmA reveals an uncontrolled over-activation of the gli-cluster upon gliotoxin exposure. The data presented herein reveal, for the first time, the extreme risk associated with intracellular dithiol gliotoxin biosynthesis—in the absence of an efficient dismutation capacity. Significantly, a previously concealed protective role for GtmA and functionality of ETP bis-thiomethylation as an ancestral protection strategy against dithiol compounds is now evident.

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Section: Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural, mechanistic and functional insight into gliotoxin bis -thiomethylation in Aspergillus fumigatus

et al. 2017

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“…Gliotoxin exposure induces elevated GtmA abundance in A. fumigatus DgliT, 9 and Manzanares-Miralles et al reported that gliotoxin induces significantly increased abundance of the GtmA ortholog in Aspergillus niger, in which the gli cluster is absent. 37 Interestingly, while Zn 2+ exposure alone had no significant effect on the abundance of GtmA in A. fumigatus, combinatorial exposure with gliotoxin resulted in significantly elevated GtmA abundance (18.8-fold and p o 0.01) compared to that in the presence of gliotoxin only (Table 2). Allied to GtmA activity data (Fig.…”

Section: +mentioning

confidence: 94%

Systems impact of zinc chelation by the epipolythiodioxopiperazine dithiol gliotoxin inAspergillus fumigatus: a new direction in natural product functionality

et al. 2018

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Significance to metallomicsDithiol gliotoxin is a near-terminal biosynthetic intermediate from the gliotoxin biosynthetic pathway in the human pathogen Aspergillus fumigatus. Chemically reduced gliotoxin, dithiol gliotoxin (DTG), is revealed as a biological zinc chelator, and conversely, zinc can relieve the hitherto cryptic fungal autotoxicity of DTG. There is a systems-wide impact of zinc chelation by DTG on the fungal proteome, and we suggest it is DTG, as opposed to gliotoxin, which chelates zinc from metalloproteins. Since gliotoxin can be sequestered by both fungi and bacteria, our findings infer a new avenue to interfere with, and exploit, cellular zinc homeostasis in microorganisms. IntroductionGliotoxin and holomycin are microbial natural products, which are produced by fungal and bacterial spp., respectively (Fig. 1). [1][2][3] Both are low molecular mass metabolites, and each contains a disulphide bridge formed by the action of oxidoreductases, namely GliT and HlmI, on the respective dithiol precursor (Fig. 1). [4][5][6] Disulphide bridge formation is essential for microbial self-protection against these reactive dithiol intermediates, and is a pre-requisite for the Major Facilitator Superfamily transporter GliA-mediated secretion of gliotoxin by Aspergillus fumigatus. 5-8Both metabolites are also present as bis-thiomethylated forms, and gliotoxin bis-thiomethyltransferase GtmA converts dithiol gliotoxin (DTG) to bis-dethiobis(methylthio)gliotoxin (BmGT) in A. fumigatus, whereas the origin of the cognate activity against dithiol holomycin in Streptomyces clavuligeris is unknown (Fig. 1). 9,10Bernardo et al. have shown that upon uptake by eukaryotic cells,

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“…All media used were as previously described by 20. Cultures were grown at 30°C with shaking at 200 rpm.…”

Section: Methodsmentioning

confidence: 99%

Towards understanding the gliotoxin detoxification mechanism: in vivo thiomethylation protects yeast from gliotoxin cytotoxicity

Smith¹,

Dolan²,

Fitzpatrick³

et al. 2016

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Gliotoxin (GT) is a mycotoxin produced by some species of ascomycete fungi including the opportunistic human pathogen Aspergillus fumigatus. In order to produce GT the host organism needs to have evolved a self-protection mechanism. GT contains a redox-cycling disulfide bridge that is important in mediating toxicity. Recently is has been demonstrated that A. fumigatus possesses a novel thiomethyltransferase protein called GtmA that has the ability to thiomethylate GT in vivo, which aids the organism in regulating GT biosynthesis. It has been suggested that thiomethylation of GT and similar sulfur-containing toxins may play a role in providing self-protection in host organisms. In this work we have engineered Saccharomyces cerevisiae, a GT-naïve organism, to express A. fumigatus GtmA. We demonstrate that GtmA can readily thiomethylate GT in yeast, which results in protection of the organism from exogenous GT. Our work has implications for understanding the evolution of GT self-protection mechanisms in organisms that are GT producers and non-producers.

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Quantitative proteomics reveals the mechanism and consequence of gliotoxin-mediated dysregulation of the methionine cycle in Aspergillus niger

Cited by 23 publications

References 61 publications

Structural, mechanistic and functional insight into gliotoxin bis -thiomethylation in Aspergillus fumigatus

Structural, mechanistic and functional insight into gliotoxin bis -thiomethylation in Aspergillus fumigatus

Systems impact of zinc chelation by the epipolythiodioxopiperazine dithiol gliotoxin inAspergillus fumigatus: a new direction in natural product functionality

Towards understanding the gliotoxin detoxification mechanism: in vivo thiomethylation protects yeast from gliotoxin cytotoxicity

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