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Liu F, Zeng M, Zhou X, Huang F, Song Z. Aspergillus fumigatus escape mechanisms from its harsh survival environments. Appl Microbiol Biotechnol 2024; 108:53. [PMID: 38175242 DOI: 10.1007/s00253-023-12952-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/09/2023] [Accepted: 10/19/2023] [Indexed: 01/05/2024]
Abstract
Aspergillus fumigatus is a ubiquitous pathogenic mold and causes several diseases, including mycotoxicosis, allergic reactions, and systemic diseases (invasive aspergillosis), with high mortality rates. In its ecological niche, the fungus has evolved and mastered many reply strategies to resist and survive against negative threats, including harsh environmental stress and deficiency of essential nutrients from natural environments, immunity responses and drug treatments in host, and competition from symbiotic microorganisms. Hence, treating A. fumigatus infection is a growing challenge. In this review, we summarized A. fumigatus reply strategies and escape mechanisms and clarified the main competitive or symbiotic relationships between A. fumigatus, viruses, bacteria, or fungi in host microecology. Additionally, we discussed the contemporary drug repertoire used to treat A. fumigatus and the latest evidence of potential resistance mechanisms. This review provides valuable knowledge which will stimulate further investigations and clinical applications for treating and preventing A. fumigatus infections. KEY POINTS: • Harsh living environment was a great challenge for A. fumigatus survival. • A. fumigatus has evolved multiple strategies to escape host immune responses. • A. fumigatus withstands antifungal drugs via intrinsic escape mechanisms.
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Affiliation(s)
- Fangyan Liu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, 646000, People's Republic of China
| | - Meng Zeng
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, 646000, People's Republic of China
- Department of Clinical Laboratory, Yongchuan Hospital of Chongqing Medical University, Chongqing, 402160, People's Republic of China
| | - Xue Zhou
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, 646000, People's Republic of China
| | - Fujiao Huang
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, 646000, People's Republic of China
| | - Zhangyong Song
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, 646000, People's Republic of China.
- Molecular Biotechnology Platform, Public Center of Experimental Technology, Southwest Medical University, Luzhou, 646000, People's Republic of China.
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2
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Rossetto D, Sebastianelli L, Oberegger S, Todorovic S, Haas H, Mansy SS. Peptide Mimics of the Cysteine-Rich Regions of HapX and SreA Bind a [2Fe-2S] Cluster In Vitro. Adv Biol (Weinh) 2024; 8:e2300545. [PMID: 38574244 DOI: 10.1002/adbi.202300545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 02/07/2024] [Indexed: 04/06/2024]
Abstract
HapX and SreA are transcription factors that regulate the response of the fungus Aspergillus fumigatus to the availability of iron. During iron starvation, HapX represses genes involved in iron consuming pathways and upon a shift to iron excess, HapX activates these same genes. SreA blocks the expression of genes needed for iron uptake during periods of iron availability. Both proteins possess cysteine-rich regions (CRR) that are hypothesized to be necessary for the sensing of iron levels. However, the contribution of each of these domains to the function of the protein has remained unclear. Here, the ability of peptide analogs of each CRR is determined to bind an iron-sulfur cluster in vitro. UV-vis and resonance Raman (RR) spectroscopies reveal that each CRR is capable of coordinating a [2Fe-2S] cluster with comparable affinities. The iron-sulfur cluster coordinated to the CRR-B domain of HapX displays particularly high stability. The data are consistent with HapX and SreA mediating responses to cellular iron levels through the direct coordination of [2Fe-2S] clusters. The high stability of the CRR-B peptide may also find use as a starting point for the development of new green catalysts.
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Affiliation(s)
- Daniele Rossetto
- D-CIBIO, University of Trento, via Sommarive 9, Trento, 38123, Italy
| | - Lorenzo Sebastianelli
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, T6G 2G2, Canada
| | - Simon Oberegger
- Institute of Molecular Biology, Medical University of Innsbruck, Innrain 80, Innsbruck, 6020, Austria
| | - Smilja Todorovic
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av da República, Oeiras, 2780-157, Portugal
| | - Hubertus Haas
- Institute of Molecular Biology, Medical University of Innsbruck, Innrain 80, Innsbruck, 6020, Austria
| | - Sheref S Mansy
- D-CIBIO, University of Trento, via Sommarive 9, Trento, 38123, Italy
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, T6G 2G2, Canada
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3
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Vig I, Benkő Z, Gila BC, Palczert Z, Jakab Á, Nagy F, Miskei M, Lee MK, Yu JH, Pócsi I, Emri T. Functional characterization of genes encoding cadmium pumping P 1B-type ATPases in Aspergillus fumigatus and Aspergillus nidulans. Microbiol Spectr 2023; 11:e0028323. [PMID: 37676031 PMCID: PMC10581124 DOI: 10.1128/spectrum.00283-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 06/12/2023] [Indexed: 09/08/2023] Open
Abstract
Several P1B-type ATPases are important Cd2+/Cu2+ pumps in Aspergillus species, and they are tightly associated with the heavy metal stress tolerance of these ascomycetous fungi. To better understand the roles of the two P1B-type ATPases, Aspergillus nidulans CrpA Cd2+/Cu2+ pump (orthologue of the Candida albicans Crp1 Cd2+/Cu2+ pump) and Aspergillus fumigatus PcaA Cd2+ pump (orthologue of the Saccharomyces cerevisiae Pca1 Cd2+ pump), we have generated individual mutants and characterized their heavy metal susceptibilities. The deletion of CrpA in A. nidulans has led to the increased sensitivity of the fungus to stresses induced by Zn2+, Fe2+, or the combination of oxidative-stress-inducing menadione sodium bisulfite and Fe3+. Heterologous expression of A. fumigatus PcaA in the S. cerevisiae pca1 deletion mutant has resulted in enhanced tolerance of the yeast to stresses elicited by Cd2+or Zn2+ but not by Fe2+/Fe3+ or Cu2+. Mammalian host immune defense can attack microbes by secreting Zn2+ or Cu2+, and the oxidative stress induced by host immune systems can also disturb metal (Cu2+, Fe2+, and Zn2+) homeostasis in microbes. In summary, PcaA and CrpA can protect fungal cells from these complex stresses that contribute to the virulence of the pathogenic Aspergillus species. Moreover, due to their presence on the fungal cell surface, these P1B-type ATPases may serve as a novel drug target in the future. IMPORTANCE Mammalian host immune defense disrupts heavy metal homeostasis of fungal pathogens. P1B-type ATPase of Aspergillus fumigatus and Aspergillus nidulans may help to cope with this stress and serve as virulence traits. In our experiments, both A. nidulans Cd2+/Cu2+ pump CrpA and A. fumigatus Cd2+ pump PcaA protected fungal cells from toxic Zn2+, and CrpA also decreased Fe2+ susceptibility most likely indirectly. In addition, CrpA protected cells against the combined stress induced by the oxidative stressor menadione and Fe3+. Since P1B-type ATPases are present on the fungal cell surface, these proteins may serve as a novel drug target in the future.
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Affiliation(s)
- Ildikó Vig
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
- ELRN-UD Fungal Stress Biology Research Group, Debrecen, Hungary
| | - Zsigmond Benkő
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
| | - Barnabás Cs. Gila
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
| | - Zoltán Palczert
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
| | - Ágnes Jakab
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Fruzsina Nagy
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Márton Miskei
- ELRN-UD Fungal Stress Biology Research Group, Debrecen, Hungary
| | - Mi-Kyung Lee
- Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup-si, South Korea
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
- ELRN-UD Fungal Stress Biology Research Group, Debrecen, Hungary
| | - Tamás Emri
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, Debrecen, Hungary
- ELRN-UD Fungal Stress Biology Research Group, Debrecen, Hungary
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Traynor AM, Sarikaya-Bayram Ö, Bayram Ö, Antonio Calera J, Doyle S. Proteomic dissection of the role of GliZ in gliotoxin biosynthesis in Aspergillus fumigatus. Fungal Genet Biol 2023; 166:103795. [PMID: 37023941 DOI: 10.1016/j.fgb.2023.103795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/08/2023]
Abstract
Gliotoxin (GT) biosynthesis in fungi is encoded by the gli biosynthetic gene cluster. While GT addition autoinduces biosynthesis, Zn2+ has been shown to attenuate cluster activity, and it was speculated that identification of Zn2Cys6 binuclear transcription factor GliZ binding partners might provide insight into this observation. Using the Tet-ON induction system, doxycycline (DOX) presence induced GliZ fusion protein expression in, and recovery of GT biosynthesis by, A. fumigatus ΔgliZ::HA-gliZ and ΔgliZ::TAP-gliZ strains, respectively. Quantitative RT-PCR confirmed that DOX induces gli cluster gene expression (n = 5) in both A. fumigatus HA-GliZ and TAP-GliZ strains. GT biosynthesis was evident in Czapek-Dox and in Sabouraud media, however tagged GliZ protein expression was more readily detected in Sabouraud media. Unexpectedly, Zn2+ was essential for GliZ fusion protein expression in vivo, following 3 h DOX induction. Moreover, HA-GliZ abundance was significantly higher in either DOX/GT or DOX/Zn2+, compared to DOX-only. This suggests that while GT induction is still intact, Zn2+ inhibition of HA-GliZ production in vivo is lost. Co-immunoprecipitation revealed that GT oxidoreductase GliT associates with GliZ in the presence of GT, suggesting a potential protective role. Additional putative HA-GliZ interacting proteins included cystathionine gamma lyase, ribosomal protein L15 and serine hydroxymethyltransferase (SHMT). Total mycelial quantitative proteomic data revealed that GliT and GtmA, as well as several other gli cluster proteins, are increased in abundance or uniquely expressed with GT addition. Proteins involved in sulphur metabolism are also differentially expressed with GT or Zn2+ presence. Overall, we disclose that under DOX induction GliZ functionality is unexpectedly evident in zinc-replete media, subject to GT induction and that GliT appears to associate with GliZ, potentially to prevent DTG-mediated GliZ inactivation by zinc ejection.
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Affiliation(s)
- Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | | | - Özgür Bayram
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - José Antonio Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain, Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland.
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Ye J, Wang Y, Li X, Wan Q, Zhang Y, Lu L. Synergistic Antifungal Effect of a Combination of Iron Deficiency and Calcium Supplementation. Microbiol Spectr 2022; 10:e0112122. [PMID: 35674440 PMCID: PMC9241635 DOI: 10.1128/spectrum.01121-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/19/2022] [Indexed: 01/10/2023] Open
Abstract
Fungal diseases have become a major public health issue worldwide. Increasing drug resistance and the limited number of available antifungals result in high morbidity and mortality. Metal-based drugs have been reported to be therapeutic agents against major protozoan diseases, but knowledge of their ability to function as antifungals is limited. In this study, we found that calcium supplementation combined with iron deficiency causes dramatic growth inhibition of the human fungal pathogens Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans. Calcium induces the downregulation of iron uptake-related genes and, in particular, causes a decrease in the expression of the transcription factor HapX, which tends to transcriptionally activate siderophore-mediated iron acquisition under iron-deficient conditions. Iron deficiency causes calcium overload and the overproduction of intracellular reactive oxygen species (ROS), and perturbed ion homeostasis suppresses fungal growth. These phenomena are consistently identified in azole-resistant A. fumigatus isolates. The findings here imply that low iron availability lets cells mistakenly absorb calcium as a substitute, causing calcium abnormalities. Thus, there is a mutual effect between iron and calcium in fungal pathogens, and the combination of calcium with an iron chelator could serve to improve antifungal therapy. IMPORTANCE Millions of immunocompromised people are at a higher risk of developing different types of severe fungal diseases. The limited number of antifungals and the emergence of antimicrobial resistance highlight an urgent need for new strategies against invasive fungal infections. Here, we report that calcium can interfere with iron absorption of fungal pathogens, especially in iron-limited environments. Thus, a combination of calcium supplementation with an iron chelator inhibits the growth of human fungal pathogens, including Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans. Moreover, we demonstrate that iron deficiency induces a nonspecific calcium uptake response, which results in toxic levels of metal. Findings in this study suggest that a microenvironment with excess calcium and limited iron is an efficient strategy to curb the growth of fungal pathogens, especially for drug-resistant isolates.
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Affiliation(s)
- Jing Ye
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yamei Wang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xinyu Li
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Qinyi Wan
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yuanwei Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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6
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Yap A, Talasz H, Lindner H, Würzner R, Haas H. Ambient Availability of Amino Acids, Proteins, and Iron Impacts Copper Resistance of Aspergillus fumigatus. Front Cell Infect Microbiol 2022; 12:847846. [PMID: 35531339 PMCID: PMC9072627 DOI: 10.3389/fcimb.2022.847846] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/23/2022] [Indexed: 12/02/2022] Open
Abstract
The transition metals iron and copper are required by virtually all organisms but are toxic in excess. Acquisition of both metals and resistance to copper excess have previously been shown to be important for virulence of the most common airborne human mold pathogen, Aspergillus fumigatus. Here we demonstrate that the ambient availability of amino acids and proteins increases the copper resistance of A. fumigatus wild type and particularly of the ΔcrpA mutant that lacks export-mediated copper detoxification. The highest-protecting activity was found for L-histidine followed by L-asparagine, L-aspartate, L-serine, L-threonine, and L-tyrosine. Other amino acids and proteins also displayed significant but lower protection. The protecting activity of non-proteinogenic D-histidine, L-histidine-mediated growth inhibition in the absence of high-affinity copper uptake, determination of cellular metal contents, and expression analysis of copper-regulated genes suggested that histidine inhibits low-affinity but not high-affinity copper acquisition by extracellular copper complexation. An increase in the cellular copper content was found to be accompanied by an increase in the iron content, and, in agreement, iron starvation increased copper susceptibility, which underlines the importance of cellular metal balancing. Due to the role of iron and copper in nutritional immunity, these findings are likely to play an important role in the host niche.
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Affiliation(s)
- Annie Yap
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Heribert Talasz
- Protein Micro-Analysis Facility, Institute of Medical Biochemistry, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Herbert Lindner
- Protein Micro-Analysis Facility, Institute of Medical Biochemistry, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Reinhard Würzner
- Institute of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology, and Public Health, Medical University of Innsbruck, Innsbruck, Austria
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
- *Correspondence: Hubertus Haas,
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Traynor AM, Owens RA, Coughlin CM, Holton MC, Jones GW, Calera JA, Doyle S. At the metal-metabolite interface in Aspergillus fumigatus: towards untangling the intersecting roles of zinc and gliotoxin. MICROBIOLOGY (READING, ENGLAND) 2021; 167. [PMID: 34738889 PMCID: PMC8743625 DOI: 10.1099/mic.0.001106] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cryptic links between apparently unrelated metabolic systems represent potential new drug targets in fungi. Evidence of such a link between zinc and gliotoxin (GT) biosynthesis in Aspergillus fumigatus is emerging. Expression of some genes of the GT biosynthetic gene cluster gli is influenced by the zinc-dependent transcription activator ZafA, zinc may relieve GT-mediated fungal growth inhibition and, surprisingly, GT biosynthesis is influenced by zinc availability. In A. fumigatus, dithiol gliotoxin (DTG), which has zinc-chelating properties, is converted to either GT or bis-dethiobis(methylthio)gliotoxin (BmGT) by oxidoreductase GliT and methyltransferase GtmA, respectively. A double deletion mutant lacking both GliT and GtmA was previously observed to be hypersensitive to exogenous GT exposure. Here we show that compared to wild-type exposure, exogenous GT and the zinc chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN) inhibit A. fumigatus ΔgliTΔgtmA growth, specifically under zinc-limiting conditions, which can be reversed by zinc addition. While GT biosynthesis is evident in zinc-depleted medium, addition of zinc (1 µM) suppressed GT and activated BmGT production. In addition, secretion of the unferrated siderophore, triacetylfusarinine C (TAFC), was evident by A. fumigatus wild-type (at >5 µM zinc) and ΔgtmA (at >1 µM zinc) in a low-iron medium. TAFC secretion suggests that differential zinc-sensing between both strains may influence fungal Fe3+ requirement. Label-free quantitative proteomic analysis of both strains under equivalent differential zinc conditions revealed protein abundance alterations in accordance with altered metabolomic observations, in addition to increased GliT abundance in ΔgtmA at 5 µM zinc, compared to wild-type, supporting a zinc-sensing deficiency in the mutant strain. The relative abundance of a range of oxidoreductase- and secondary metabolism-related enzymes was also evident in a zinc- and strain-dependent manner. Overall, we elaborate new linkages between zinc availability, natural product biosynthesis and oxidative stress homeostasis in A. fumigatus.
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Affiliation(s)
- Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Rebecca A Owens
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Claudia M Coughlin
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Maeve C Holton
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Gary W Jones
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, UK
| | - José A Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
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Abstract
Aspergillus fumigatus is a major opportunistic fungal pathogen of immunocompromised and immunocompetent hosts. To successfully establish an infection, A. fumigatus needs to use host carbon sources, such as acetate, present in the body fluids and peripheral tissues. However, utilization of acetate as a carbon source by fungi in the context of infection has not been investigated. This work shows that acetate is metabolized via different pathways in A. fumigatus and that acetate utilization is under the regulatory control of a transcription factor (TF), FacB. A. fumigatus acetate utilization is subject to carbon catabolite repression (CCR), although this is only partially dependent on the TF and main regulator of CCR CreA. The available extracellular carbon source, in this case glucose and acetate, significantly affected A. fumigatus virulence traits such as secondary metabolite secretion and cell wall composition, with the latter having consequences for resistance to oxidative stress, antifungal drugs, and human neutrophil-mediated killing. Furthermore, deletion of facB significantly impaired the in vivo virulence of A. fumigatus in both insect and mammalian models of invasive aspergillosis. This is the first report on acetate utilization in A. fumigatus, and this work further highlights the importance of available host-specific carbon sources in shaping fungal virulence traits and subsequent disease outcome, and a potential target for the development of antifungal strategies. IMPORTANCE Aspergillus fumigatus is an opportunistic fungal pathogen in humans. During infection, A. fumigatus is predicted to use host carbon sources, such as acetate, present in body fluids and peripheral tissues, to sustain growth and promote colonization and invasion. This work shows that A. fumigatus metabolizes acetate via different pathways, a process that is dependent on the transcription factor FacB. Furthermore, the type and concentration of the extracellular available carbon source were determined to shape A. fumigatus virulence determinants such as secondary metabolite secretion and cell wall composition. Subsequently, interactions with immune cells are altered in a carbon source-specific manner. FacB is required for A. fumigatus in vivo virulence in both insect and mammalian models of invasive aspergillosis. This is the first report that characterizes acetate utilization in A. fumigatus and highlights the importance of available host-specific carbon sources in shaping virulence traits and potentially subsequent disease outcome.
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Toledo H, Sánchez CI, Marín L, Amich J, Calera JA. Regulation of zinc homeostatic genes by environmental pH in the filamentous fungus Aspergillus fumigatus. Environ Microbiol 2021; 24:643-666. [PMID: 33687784 DOI: 10.1111/1462-2920.15452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 11/30/2022]
Abstract
Aspergillus fumigatus can grow over a broad range of pH values even though zinc availability is greatly conditioned by ambient pH. It has been previously shown that regulation of zinc homeostatic genes in this fungus relies on the transcription factor ZafA. In addition, their expression is further modulated by the transcription factor PacC depending on ambient pH, which allows this fungus to grow in diverse types of niches, including soils and the lungs of immunosuppressed hosts. In this work the regulation by PacC of genes zrfB and zrfC that are expressed, respectively, under acidic and alkaline zinc-limiting conditions have been analysed in detail. Thus, data that extend the current model for PacC function, including the role of the full-length PacC72 protein and the PacC processed forms (PacC53 and PacC27 ) on gene expression has been provided, and a new mechanism for the repression of acid-expressed genes in alkaline media based on interference with the start of transcription has been described. Moreover, it was proposed that the transcription of both acid-expressed and alkaline-expressed genes under zinc-limiting conditions might also rely on a third factor (putatively Pontin/Reptin), which may be required to integrate the action of PacC and ZafA into gene specific transcriptional responses.
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Affiliation(s)
- Héctor Toledo
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Servicio de Microbiología Clínica y Parasitología, Hospital Universitario Virgen del Rocío, Sevilla, Spain
| | - Clara Inés Sánchez
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Escuela de Microbiología, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Laura Marín
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain
| | - Jorge Amich
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Manchester Fungal Infection Group, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - José Antonio Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
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10
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Soares LW, Bailão AM, Soares CMDA, Bailão MGS. Zinc at the Host-Fungus Interface: How to Uptake the Metal? J Fungi (Basel) 2020; 6:jof6040305. [PMID: 33233335 PMCID: PMC7711662 DOI: 10.3390/jof6040305] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 12/31/2022] Open
Abstract
Zinc is an essential nutrient for all living organisms. However, firm regulation must be maintained since micronutrients also can be toxic in high concentrations. This notion is reinforced when we look at mechanisms deployed by our immune system, such as the use of chelators or membrane transporters that capture zinc, when threatened with pathogens, like fungi. Pathogenic fungi, on the other hand, also make use of a variety of transporters and specialized zinc captors to survive these changes. In this review, we sought to explain the mechanisms, grounded in experimental analysis and described to date, utilized by pathogenic fungi to maintain optimal zinc levels.
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11
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López‐Berges MS. ZafA-mediated regulation of zinc homeostasis is required for virulence in the plant pathogen Fusarium oxysporum. MOLECULAR PLANT PATHOLOGY 2020; 21:244-249. [PMID: 31750619 PMCID: PMC6988419 DOI: 10.1111/mpp.12891] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
During infection, soilborne fungal pathogens face limiting conditions of different metal ions, including zinc. The role of zinc homeostasis in fungal pathogenicity on plants remains poorly understood. Here it is shown that the transcription factor ZafA, orthologous to Saccharomyces cerevisiae Zap1, functions as a key regulator of zinc homeostasis and virulence in Fusarium oxysporum, a cross-kingdom pathogen that causes vascular wilt on more than 100 plant species and opportunistic infections in humans. Expression of zafA is induced under zinc-limiting conditions and repressed by zinc. Interestingly, zafA is markedly up-regulated during early stages of plant infection, suggesting that F. oxysporum must cope with limited availability of zinc. Deletion of zafA results in deactivation of high-affinity zinc transporters, leading to impaired growth under zinc deficiency. Fusarium oxysporum strains lacking ZafA are reduced in their capability to invade and kill tomato plants and the non-vertebrate animal model Galleria mellonella. Collectively, the results indicate that ZafA-mediated adaptation to zinc deficiency is required for full virulence of F. oxysporum on plant and animal hosts.
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Affiliation(s)
- Manuel S. López‐Berges
- Departamento de GenéticaCampus de Excelencia Internacional Agroalimentario (ceiA3)Universidad de Córdoba14071CórdobaSpain
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Traynor AM, Sheridan KJ, Jones GW, Calera JA, Doyle S. Involvement of Sulfur in the Biosynthesis of Essential Metabolites in Pathogenic Fungi of Animals, Particularly Aspergillus spp.: Molecular and Therapeutic Implications. Front Microbiol 2019; 10:2859. [PMID: 31921039 PMCID: PMC6923255 DOI: 10.3389/fmicb.2019.02859] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
Fungal sulfur uptake is required for incorporation into the sidechains of the amino acids cysteine and methionine, and is also essential for the biosynthesis of the antioxidant glutathione (GSH), S-adenosylmethionine (SAM), the key source of methyl groups in cellular transmethylation reactions, and S-adenosylhomocysteine (SAH). Biosynthesis of redox-active gliotoxin in the opportunistic fungal pathogen Aspergillus fumigatus has been elucidated over the past 10 years. Some fungi which produce gliotoxin-like molecular species have undergone unexpected molecular rewiring to accommodate this high-risk biosynthetic process. Specific disruption of gliotoxin biosynthesis, via deletion of gliK, which encodes a γ-glutamyl cyclotransferase, leads to elevated intracellular antioxidant, ergothioneine (EGT), levels, and confirms crosstalk between the biosynthesis of both sulfur-containing moieties. Gliotoxin is ultimately formed by gliotoxin oxidoreductase GliT-mediated oxidation of dithiol gliotoxin (DTG). In fact, DTG is a substrate for both GliT and a bis-thiomethyltransferase, GtmA. GtmA converts DTG to bisdethiobis(methylthio)gliotoxin (BmGT), using 2 mol SAM and resultant SAH must be re-converted to SAM via the action of the Methyl/Met cycle. In the absence of GliT, DTG fluxes via GtmA to BmGT, which results in both SAM depletion and SAH overproduction. Thus, the negative regulation of gliotoxin biosynthesis via GtmA must be counter-balanced by GliT activity to avoid Methyl/Met cycle dysregulation, SAM depletion and trans consequences on global cellular biochemistry in A. fumigatus. DTG also possesses potent Zn2+ chelation properties which positions this sulfur-containing metabolite as a putative component of the Zn2+ homeostasis system within fungi. EGT plays an essential role in high-level redox homeostasis and its presence requires significant consideration in future oxidative stress studies in pathogenic filamentous fungi. In certain filamentous fungi, sulfur is additionally indirectly required for the formation of EGT and the disulfide-bridge containing non-ribosomal peptide, gliotoxin, and related epipolythiodioxopiperazines. Ultimately, interference with emerging sulfur metabolite functionality may represent a new strategy for antifungal drug development.
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Affiliation(s)
- Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Ireland
| | | | - Gary W Jones
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, United Kingdom
| | - José A Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Ireland
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