1
|
Moraes D, Tristão GB, Rappleye CA, Ray SC, Ribeiro-Dias F, Gomes RS, Assunção LDP, Paccez JD, Zancopé-Oliveira RM, Silva-Bailão MG, Soares CMDA, Bailão AM. The influence of a copper efflux pump in Histoplasma capsulatum virulence. FEBS J 2024; 291:744-760. [PMID: 37950580 DOI: 10.1111/febs.16999] [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: 05/26/2022] [Revised: 10/01/2023] [Accepted: 10/09/2023] [Indexed: 11/12/2023]
Abstract
During the infectious process, pathogenic microorganisms must obtain nutrients from the host in order to survive and proliferate. These nutritional sources include the metallic nutrient copper. Despite its essentiality, copper in large amounts is toxic. Host defense mechanisms use high copper poisoning as a fungicidal strategy to control infection. Transcriptional analyses showed that yeast cultured in the presence of copper or inside macrophages (24 h) had elevated expression of CRP1, a copper efflux pump, suggesting that Histoplasma capsulatum could be exposed to a high copper environment in macrophages during the innate immune stage of infection. Accordingly, macrophages cultured in high copper are more efficient in controlling H. capsulatum growth. Also, silencing of ATP7a, a copper pump that promotes the copper influx in phagosomes, increases fungal survival in macrophages. The rich copper environment faced by the fungus is not dependent on IFN-γ, since fungal CRP1 expression is induced in untreated macrophages. Appropriately, CRP1 knockdown fungal strains are more susceptible to macrophage control than wild-type yeasts. Additionally, CRP1 silencing decreases fungal burden in mice during the phase of innate immune response (4-day postinfection) and CRP1 is required for full virulence in a macrophage cell lines (J774 A.1 and RAW 264.7), as well as primary cells (BMDM). Thus, induction of fungal copper detoxifying genes during innate immunity and the attenuated virulence of CRP1-knockdown yeasts suggest that H. capsulatum is exposed to a copper-rich environment at early infection, but circumvents this condition to establish infection.
Collapse
Affiliation(s)
- Dayane Moraes
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Gabriel Brum Tristão
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Chad A Rappleye
- Department of Microbiology, Ohio State University, Columbus, OH, USA
| | - Stephanie C Ray
- Department of Microbiology, Ohio State University, Columbus, OH, USA
| | - Fátima Ribeiro-Dias
- Laboratório de Imunidade Natural (LIN), Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Brazil
| | - Rodrigo Saar Gomes
- Laboratório de Imunidade Natural (LIN), Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Brazil
| | - Leandro do Prado Assunção
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Juliano Domiraci Paccez
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Rosely Maria Zancopé-Oliveira
- Laboratório de Micologia, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Mirelle Garcia Silva-Bailão
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Célia Maria de Almeida Soares
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Alexandre Melo Bailão
- Laboratório de Biologia Molecular (LBM), Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| |
Collapse
|
2
|
Moraes D, Rodrigues JGC, Silva MG, Soares LW, Soares CMDA, Bailão AM, Silva-Bailão MG. Copper acquisition and detoxification machineries are conserved in dimorphic fungi. FUNGAL BIOL REV 2023. [DOI: 10.1016/j.fbr.2022.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
3
|
A novel Zn 2-Cys 6 transcription factor clcA contributes to copper homeostasis in Aspergillus fumigatus. Curr Genet 2022; 68:605-617. [PMID: 35972528 DOI: 10.1007/s00294-022-01250-2] [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: 04/12/2022] [Revised: 07/29/2022] [Accepted: 07/30/2022] [Indexed: 11/03/2022]
Abstract
The filamentous fungus Aspergillus fumigatus is the most important pathogenic fungus among Aspergillus species associated with aspergillosis. A. fumigatus is exposed to diverse environmental stresses in the hosts during infection such as an excess of essential metal copper. To gain further insights into copper homeostasis, we generated an A. fumigatus laboratory evolved strain with increased fitness in copper stress, and identified the mutation in a Zn2-Cys6 type transcription factor clcA. We examined the role of clcA using the evolved and ∆clcA strains. The ∆clcA strain exhibited defective growth on minimal medium, PDA and copper-repleted medium, and defective conidiogenesis and conidial pigmentation. We found that clcA was required for the expressions of genes involved in conidiogenesis, conidial pigmentation, and transporters cdr1B and mfsB related to azole resistance. clcA was dispensable for the virulence in silkworm infection model. We report here that clcA plays an important role in hyphal growth, conidiogenesis, and copper adaptation.
Collapse
|
4
|
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.
Collapse
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,
| |
Collapse
|
5
|
Robinson JR, Isikhuemhen OS, Anike FN. Fungal-Metal Interactions: A Review of Toxicity and Homeostasis. J Fungi (Basel) 2021; 7:225. [PMID: 33803838 PMCID: PMC8003315 DOI: 10.3390/jof7030225] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/18/2022] Open
Abstract
Metal nanoparticles used as antifungals have increased the occurrence of fungal-metal interactions. However, there is a lack of knowledge about how these interactions cause genomic and physiological changes, which can produce fungal superbugs. Despite interest in these interactions, there is limited understanding of resistance mechanisms in most fungi studied until now. We highlight the current knowledge of fungal homeostasis of zinc, copper, iron, manganese, and silver to comprehensively examine associated mechanisms of resistance. Such mechanisms have been widely studied in Saccharomyces cerevisiae, but limited reports exist in filamentous fungi, though they are frequently the subject of nanoparticle biosynthesis and targets of antifungal metals. In most cases, microarray analyses uncovered resistance mechanisms as a response to metal exposure. In yeast, metal resistance is mainly due to the down-regulation of metal ion importers, utilization of metallothionein and metallothionein-like structures, and ion sequestration to the vacuole. In contrast, metal resistance in filamentous fungi heavily relies upon cellular ion export. However, there are instances of resistance that utilized vacuole sequestration, ion metallothionein, and chelator binding, deleting a metal ion importer, and ion storage in hyphal cell walls. In general, resistance to zinc, copper, iron, and manganese is extensively reported in yeast and partially known in filamentous fungi; and silver resistance lacks comprehensive understanding in both.
Collapse
Affiliation(s)
| | - Omoanghe S. Isikhuemhen
- Department of Natural Resources and Environmental Design, North Carolina Agricultural and Technical State University, 1601 East Market Street, Greensboro, NC 27411, USA; (J.R.R.); (F.N.A.)
| | | |
Collapse
|
6
|
Culbertson EM, Culotta VC. Copper in infectious disease: Using both sides of the penny. Semin Cell Dev Biol 2021; 115:19-26. [PMID: 33423931 DOI: 10.1016/j.semcdb.2020.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/28/2020] [Accepted: 12/08/2020] [Indexed: 12/17/2022]
Abstract
The transition metal Cu is an essential micronutrient that serves as a co-factor for numerous enzymes involved in redox and oxygen chemistry. However, Cu is also a potentially toxic metal, especially to unicellular microbes that are in direct contact with their environment. Since 400 BCE, Cu toxicity has been leveraged for its antimicrobial properties and even today, Cu based materials are being explored as effective antimicrobials against human pathogens spanning bacteria, fungi, and viruses, including the SARS-CoV-2 agent of the 2019-2020 pandemic. Given that Cu has the double-edged property of being both highly toxic and an essential micronutrient, it plays an active and complicated role at the host-pathogen interface. Humans have evolved methods of incorporating Cu into innate and adaptive immune processes and both sides of the penny (Cu toxicity and Cu as a nutrient) are employed. Here we review the evolution of Cu in biology and its multi-faceted roles in infectious disease, from the viewpoints of the microbial pathogens as well as the animal hosts they infect.
Collapse
Affiliation(s)
- Edward M Culbertson
- The Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Valeria C Culotta
- The Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA.
| |
Collapse
|
7
|
Kang S, Seo H, Moon HS, Kwon JH, Park YS, Yun CW. The Role of Zinc in Copper Homeostasis of Aspergillus fumigatus. Int J Mol Sci 2020; 21:ijms21207665. [PMID: 33081273 PMCID: PMC7593903 DOI: 10.3390/ijms21207665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
Copper is an essential metal ion that performs many physiological functions in living organisms. Deletion of Afmac1, which is a copper-responsive transcriptional activator in A. fumigatus, results in a growth defect on aspergillus minimal medium (AMM). Interestingly, we found that zinc starvation suppressed the growth defect of the Δafmac1 strain on AMM. In addition, the growth defect of the Δafmac1 strain was recovered by copper supplementation or introduction of the CtrC gene into the Δafmac1 strain. However, chelation of copper by addition of BCS to AMM failed to recover the growth defect of the Δafmac1 strain. Through Northern blot analysis, we found that zinc starvation upregulated CtrC and CtrA2, which encode membrane copper transporters. Interestingly, we found that the conserved ZafA binding motif 5'-CAA(G)GGT-3' was present in the upstream region of CtrC and CtrA2 and that mutation of the binding motif led to failure of ZafA binding to the upstream region of CtrC and upregulation of CtrC expression under zinc starvation. Furthermore, the binding activity of ZafA to the upstream region of CtrC was inversely proportional to the zinc concentration, and copper inhibited the binding of ZafA to the upstream region of CtrC under a low zinc concentration. Taken together, these results suggest that ZafA upregulates copper metabolism by binding to the ZafA binding motif in the CtrC promoter region under low zinc concentration, thus regulating copper homeostasis. Furthermore, we found that copper and zinc interact in cells to maintain metal homeostasis.
Collapse
Affiliation(s)
| | | | | | | | | | - Cheol-Won Yun
- Correspondence: ; Tel.: +82-2-3290-3456; Fax: +82-2-927-9028
| |
Collapse
|
8
|
Culbertson EM, Bruno VM, Cormack BP, Culotta VC. Expanded role of the Cu-sensing transcription factor Mac1p in Candida albicans. Mol Microbiol 2020; 114:1006-1018. [PMID: 32808698 DOI: 10.1111/mmi.14591] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 12/11/2022]
Abstract
As part of the innate immune response, the host withholds metal micronutrients such as Cu from invading pathogens, and microbes respond through metal starvation stress responses. With the opportunistic fungal pathogen Candida albicans, the Cu-sensing transcription factor Mac1p governs the cellular response to Cu starvation by controlling Cu import. Mac1p additionally controls reactive oxygen species (ROS) homeostasis by repressing a Cu-containing superoxide dismutase (SOD1) and inducing Mn-containing SOD3 as a non-Cu alternative. We show here that C. albicans Mac1p is essential for virulence in a mouse model for disseminated candidiasis and that the cellular functions of Mac1p extend beyond Cu uptake and ROS homeostasis. Specifically, mac1∆/∆ mutants are profoundly deficient in mitochondrial respiration and Fe accumulation, both Cu-dependent processes. Surprisingly, these deficiencies are not simply the product of impaired Cu uptake; rather mac1∆/∆ mutants appear defective in Cu allocation. The respiratory defect of mac1∆/∆ mutants was greatly improved by a sod1∆/∆ mutation, demonstrating a role for SOD1 repression by Mac1p in preserving respiration. Mac1p downregulates the major Cu consumer SOD1 to spare Cu for respiration that is essential for virulence of this fungal pathogen. The implications for such Cu homeostasis control in other pathogenic fungi are discussed.
Collapse
Affiliation(s)
- Edward M Culbertson
- The Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Vincent M Bruno
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Brendan P Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Valeria C Culotta
- The Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| |
Collapse
|
9
|
Absent regulation of iron acquisition by the copper regulator Mac1 in A. fumigatus. Biochem J 2020; 477:2967-2970. [PMID: 32812643 DOI: 10.1042/bcj20200286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/29/2020] [Accepted: 07/27/2020] [Indexed: 02/06/2023]
Abstract
Aspergillus fumigatus is the most common cause of invasive aspergillosis, a life-threatening infection mainly affecting immunocompromised patients. The essential metals copper and iron play crucial roles in virulence of this mold. Recently, the copper-regulatory transcription factor Mac1 was reported to additionally be involved in the control of iron acquisition. However, in the current study, neither growth assays on solid and in liquid media, analysis of siderophore production nor expression analysis of genes involved in iron acquisition indicated the involvement of Mac1 in the regulation of iron uptake in A. fumigatus.
Collapse
|
10
|
Response to the letter 'Absent regulation of iron acquisition by the copper regulator Mac1 in A. fumigatus'. Biochem J 2020; 477:3055-3058. [PMID: 32845274 DOI: 10.1042/bcj20200341] [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: 05/04/2020] [Revised: 07/02/2020] [Accepted: 07/27/2020] [Indexed: 11/17/2022]
Abstract
The answer to the letter 'Absent regulation of iron acquisition by the copper regulator Mac1 in A. fumigatus' has been prepared. We explained our data and showed supplementary information to answer the questions. And we respect the results of other groups first and explain the differences from our results.
Collapse
|
11
|
Antsotegi-Uskola M, Markina-Iñarrairaegui A, Ugalde U. New insights into copper homeostasis in filamentous fungi. Int Microbiol 2019; 23:65-73. [PMID: 31093811 PMCID: PMC6981102 DOI: 10.1007/s10123-019-00081-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/15/2019] [Accepted: 04/23/2019] [Indexed: 01/06/2023]
Abstract
Copper is a metal ion that is required as a micronutrient for growth and proliferation. However, copper accumulation generates toxicity by multiple mechanisms, potentially leading to cell death. Due to its toxic nature at high concentrations, different chemical variants of copper have been extensively used as antifungal agents in agriculture and medicine. Most studies on copper homeostasis have been carried out in bacteria, yeast, and mammalian organisms. However, knowledge on filamentous fungi is less well documented. This review summarizes the knowledge gathered in the last few years about copper homeostasis in the filamentous fungi Aspergillus fumigatus and Aspergillus nidulans: The mechanism of action of copper, the uptake and detoxification systems, their regulation at the transcriptional level, and the role of copper homeostasis in fungal pathogenicity are presented.
Collapse
Affiliation(s)
- Martzel Antsotegi-Uskola
- Microbial Biochemistry Laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, San Sebastian, Spain
| | - Ane Markina-Iñarrairaegui
- Microbial Biochemistry Laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, San Sebastian, Spain
| | - Unai Ugalde
- Microbial Biochemistry Laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, San Sebastian, Spain.
| |
Collapse
|
12
|
Song J, Li R, Jiang J. Copper Homeostasis in Aspergillus fumigatus: Opportunities for Therapeutic Development. Front Microbiol 2019; 10:774. [PMID: 31031736 PMCID: PMC6473158 DOI: 10.3389/fmicb.2019.00774] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/26/2019] [Indexed: 11/13/2022] Open
Abstract
Aspergillus fumigatus can cause severe invasive aspergillosis in immunocompromised individuals. Copper, an essential but potentially toxic trace element for A. fumigatus, plays a critical role at the host-pathogen axis during infection. Accumulating evidence demonstrates that the host utilizes copper compartmentalization within macrophages to combat A. fumigatus infection. To survive under host-imposed copper toxicity, A. fumigatus has evolved sophisticated machinery to regulate copper homeostasis. Thus, targeting molecular pathways critical for copper homeostasis regulation provides an opportunity to improve therapeutic options for aspergillosis caused by A. fumigatus. In this review, we describe the copper homeostatic mechanisms by which A. fumigatus acquires and controls copper levels and explores the responses of the pathogen to alter copper levels in the host. Finally, we discuss the regulatory mechanisms of copper homeostasis that could be targeted for antifungal drug development.
Collapse
Affiliation(s)
- Jinxing Song
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province and School of Life Science, Jiangsu Normal University, Xuzhou, China
| | - Rongpeng Li
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province and School of Life Science, Jiangsu Normal University, Xuzhou, China
| | - Jihong Jiang
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province and School of Life Science, Jiangsu Normal University, Xuzhou, China
| |
Collapse
|
13
|
Copper Utilization, Regulation, and Acquisition by Aspergillus fumigatus. Int J Mol Sci 2019; 20:ijms20081980. [PMID: 31018527 PMCID: PMC6514546 DOI: 10.3390/ijms20081980] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 01/01/2023] Open
Abstract
Copper is an essential micronutrient for the opportunistic human pathogen, Aspergillus fumigatus. Maintaining copper homeostasis is critical for survival and pathogenesis. Copper-responsive transcription factors, AceA and MacA, coordinate a complex network responsible for responding to copper in the environment and determining which response is necessary to maintain homeostasis. For example, A. fumigatus uses copper exporters to mitigate the toxic effects of copper while simultaneously encoding copper importers and small molecules to ensure proper supply of the metal for copper-dependent processes such a nitrogen acquisition and respiration. Small molecules called isocyanides recently found to be produced by A. fumigatus may bind copper and partake in copper homeostasis similarly to isocyanide copper chelators in bacteria. Considering that the host uses copper as a microbial toxin and copper availability fluctuates in various environmental niches, understanding how A. fumigatus maintains copper homeostasis will give insights into mechanisms that facilitate the development of invasive aspergillosis and its survival in nature.
Collapse
|