Saleh, Aliabbas A. and Jones, Gary W. and Tinley, Frances C. and Delaney, Stephen F. and Alabaddi, Sahar H. and Fenlon, Keith and Doyle, Sean and Owens, Rebecca A. (2018) Systems impact of zinc chelation by the epipolythiodioxopiperazine dithiol gliotoxin in Aspergillus fumigatus: a new direction in natural product functionality. Metallomics, 10. pp. 854-866. ISSN 1756-591X

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Abstract

The non-ribosomal peptide gliotoxin, which autoinduces its own biosynthesis, has potent anti-fungal activity, especially in the combined absence of the gliotoxin oxidoreductase GliT and bis-thiomethyltransferase GtmA. Dithiol gliotoxin (DTG) is a substrate for both of these enzymes. Herein we demonstrate that DTG chelates Zn2+ (m/z 424.94), rapidly chelates Zn2+ from Zn(4-(2-pyridylazo)-resorcinol) (Zn(PAR)2) and also inhibits a Zn2+-dependent alkaline phosphatase (AP). Zn2+ addition rescues AP function following DTG-associated inhibition, and pre-incubation of DTG with Zn2+ completely protects AP activity. Zn2+ (1–50 μM) also significantly relieves the potent gliotoxin-mediated inhibition of Aspergillus fumigatus ΔgliT::ΔgtmA (p < 0.05), which infers in vivo dithiol gliotoxin-mediated sequestration of free Zn2+ or chelation from intracellular metalloenzymes as inhibitory mechanisms. Quantitative proteomic analysis revealed that excess Zn2+ alters the effect of gliotoxin on A. fumigatus ΔgliT, with differential abundance of secondary metabolism-associated proteins in the combinatorial condition. GtmA abundance increased 18.8 fold upon co-addition of gliotoxin and Zn2+ compared to gliotoxin alone, possibly to compensate for disruption to GtmA activity, as seen in in vitro assays. Furthermore, DTG effected significant in vitro aggregation of a number of protein classes, including Zn2+-dependent enzymes, while proteins were protected from aggregation by pre-incubating DTG with Zn2+. We conclude that DTG can act in vivo as a Zn2+ chelator, which can significantly impede A. fumigatus growth in the absence of GliT and GtmA.

Item Type:	Article
Additional Information:	This article is licensed under a Creative Commons Attribution Non-Commercial 3.0 Unported License: https://creativecommons.org/licenses/by-nc/3.0/
Keywords:	zinc chelation; epipolythiodioxopiperazine dithiol gliotoxin; Aspergillus fumigatus; natural product functionality;
Academic Unit:	Faculty of Science and Engineering > Biology
Item ID:	11151
Identification Number:	https://doi.org/10.1039/C8MT00052B
Depositing User:	Dr. Sean Doyle
Date Deposited:	08 Oct 2019 13:50
Journal or Publication Title:	Metallomics
Publisher:	Royal Society of Chemistry
Refereed:	Yes
URI:	https://pubs.rsc.org
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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