1
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Oberegger S, Misslinger M, Faserl K, Sarg B, Farhan H, Haas H. The cytosolic form of dual localized BolA family protein Bol3 is important for adaptation to iron starvation in Aspergillus fumigatus. Open Biol 2024; 14:240033. [PMID: 38919062 DOI: 10.1098/rsob.240033] [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: 02/08/2024] [Accepted: 04/23/2024] [Indexed: 06/27/2024] Open
Abstract
Aspergillus fumigatus is the predominant mould pathogen for humans. Adaption to host-imposed iron limitation has previously been demonstrated to be essential for its virulence. [2Fe-2S] clusters are crucial as cofactors of several metabolic pathways and mediate cytosolic/nuclear iron sensing in fungi including A. fumigatus. [2Fe-2S] cluster trafficking has been shown to involve BolA family proteins in both mitochondria and the cytosol/nucleus. Interestingly, both A. fumigatus homologues, termed Bol1 and Bol3, possess mitochondrial targeting sequences, suggesting the lack of cytosolic/nuclear versions. Here, we show by the combination of mutational, proteomic and fluorescence microscopic analyses that expression of the Bol3 encoding gene leads to dual localization of gene products to mitochondria and the cytosol/nucleus via alternative translation initiation downstream of the mitochondrial targeting sequence, which appears to be highly conserved in various Aspergillus species. Lack of either mitochondrial Bol1 or Bol3 was phenotypically inconspicuous while lack of cytosolic/nuclear Bol3 impaired growth during iron limitation but not iron sensing which indicates a particular importance of [2Fe-2S] cluster trafficking during iron limitation. Remarkably, cytosolic/nuclear Bol3 differs from the mitochondrial version only by N-terminal acetylation, a finding that was only possible by mutational hypothesis testing.
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Affiliation(s)
- Simon Oberegger
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Klaus Faserl
- Institute of Medical Biochemistry, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Bettina Sarg
- Institute of Medical Biochemistry, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Hesso Farhan
- Institute of Pathophysiology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
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2
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Braymer JJ, Stehling O, Stümpfig M, Rösser R, Spantgar F, Blinn CM, Mühlenhoff U, Pierik AJ, Lill R. Requirements for the biogenesis of [2Fe-2S] proteins in the human and yeast cytosol. Proc Natl Acad Sci U S A 2024; 121:e2400740121. [PMID: 38743629 PMCID: PMC11126956 DOI: 10.1073/pnas.2400740121] [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: 01/14/2024] [Accepted: 04/16/2024] [Indexed: 05/16/2024] Open
Abstract
The biogenesis of iron-sulfur (Fe/S) proteins entails the synthesis and trafficking of Fe/S clusters, followed by their insertion into target apoproteins. In eukaryotes, the multiple steps of biogenesis are accomplished by complex protein machineries in both mitochondria and cytosol. The underlying biochemical pathways have been elucidated over the past decades, yet the mechanisms of cytosolic [2Fe-2S] protein assembly have remained ill-defined. Similarly, the precise site of glutathione (GSH) requirement in cytosolic and nuclear Fe/S protein biogenesis is unclear, as is the molecular role of the GSH-dependent cytosolic monothiol glutaredoxins (cGrxs). Here, we investigated these questions in human and yeast cells by various in vivo approaches. [2Fe-2S] cluster assembly of cytosolic target apoproteins required the mitochondrial ISC machinery, the mitochondrial transporter Atm1/ABCB7 and GSH, yet occurred independently of both the CIA system and cGrxs. This mechanism was strikingly different from the ISC-, Atm1/ABCB7-, GSH-, and CIA-dependent assembly of cytosolic-nuclear [4Fe-4S] proteins. One notable exception to this cytosolic [2Fe-2S] protein maturation pathway defined here was yeast Apd1 which used the CIA system via binding to the CIA targeting complex through its C-terminal tryptophan. cGrxs, although attributed as [2Fe-2S] cluster chaperones or trafficking proteins, were not essential in vivo for delivering [2Fe-2S] clusters to either CIA components or target apoproteins. Finally, the most critical GSH requirement was assigned to Atm1-dependent export, i.e. a step before GSH-dependent cGrxs function. Our findings extend the general model of eukaryotic Fe/S protein biogenesis by adding the molecular requirements for cytosolic [2Fe-2S] protein maturation.
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Affiliation(s)
- Joseph J. Braymer
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Oliver Stehling
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Martin Stümpfig
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Ralf Rösser
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Farah Spantgar
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Catharina M. Blinn
- Department of Chemistry, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern67663, Germany
| | - Ulrich Mühlenhoff
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Antonio J. Pierik
- Department of Chemistry, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern67663, Germany
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
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3
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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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4
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Caballero P, Yap A, Bromley MJ, Haas H. The Transcription Factors AcuK and AcuM Influence Siderophore Biosynthesis of Aspergillus fumigatus. J Fungi (Basel) 2024; 10:327. [PMID: 38786682 PMCID: PMC11121910 DOI: 10.3390/jof10050327] [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: 03/18/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024] Open
Abstract
The mold Aspergillus fumigatus employs two high-affinity uptake systems, reductive iron assimilation (RIA) and siderophore-mediated iron acquisition (SIA), for the acquisition of the essential trace element iron. SIA has previously been shown to be crucial for virulence in mammalian hosts. Here, we show that a lack of AcuK or AcuM, transcription factors required for the activation of gluconeogenesis, decreases the production of both extra- and intracellular siderophores in A. fumigatus. The lack of AcuM or AcuK did not affect the expression of genes involved in RIA and SIA, suggesting that these regulators do not directly regulate iron homeostasis genes, but indirectly affect siderophore production through their influence on metabolism. Consistent with this, acetate supplementation reversed the intracellular siderophore production defect of ΔacuM and ΔacuK. Moreover, ΔacuM and ΔacuK displayed a similar growth defect under iron limitation and iron sufficiency, which suggests they have a general role in carbon metabolism apart from gluconeogenesis. In agreement with a potential role of the glyoxylate cycle in adaptation to iron starvation, transcript levels of the malate synthase-encoding acuE were found to be upregulated by iron limitation that is partially dependent on AcuK and AcuM. Together, these data demonstrate the influence of iron availability on carbon metabolism.
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Affiliation(s)
- Patricia Caballero
- Institute of Molecular Biology, Medical University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria; (P.C.); (A.Y.)
| | - Annie Yap
- Institute of Molecular Biology, Medical University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria; (P.C.); (A.Y.)
| | - Michael J. Bromley
- Manchester Fungal Infection Group, Division of Infection, Immunity, and Respiratory Medicine, The University of Manchester, Manchester M13 9PL, UK;
| | - Hubertus Haas
- Institute of Molecular Biology, Medical University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria; (P.C.); (A.Y.)
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5
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Yao R, Li R, Wu X, Jin T, Luo Y, Li R, Huang Y. E3 ubiquitin ligase Hul6 modulates iron-dependent metabolism by regulating Php4 stability. J Biol Chem 2024; 300:105670. [PMID: 38272226 PMCID: PMC10882131 DOI: 10.1016/j.jbc.2024.105670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/28/2023] [Accepted: 01/12/2024] [Indexed: 01/27/2024] Open
Abstract
Schizosaccharomyces pombe Php4 is the regulatory subunit of the CCAAT-binding complexes and plays an important role in the regulation of iron homeostasis and iron-dependent metabolism. Here, we show that Php4 undergoes ubiquitin-dependent degradation in the late logarithmic and stationary phases. The degradation and ubiquitination of Php4 could be attenuated by deletion of hul6, a gene encoding a putative HECT-type E3 ubiquitin ligase. The expression levels of Hul6 and Php4 are oppositely regulated during cell growth. Hul6 interacts with the C-terminal region of Php4. Two lysine residues (K217 and K274) located in the C-terminal region of Php4 are required for its polyubiquitination. Increasing the levels of Php4 by deletion of hul6 or overexpression of php4 decreased expression of Php4 target proteins involved in iron-dependent metabolic pathways such as the tricarboxylic cycle and mitochondrial oxidative phosphorylation, thus causing increased sensitivity to high-iron and reductions in succinate dehydrogenase and mitochondrial complex II activities. Hul6 is located primarily in the mitochondrial outer membrane and most likely targets cytosolic Php4 for ubiquitination and degradation. Taken together, our data suggest that Hul6 regulates iron-dependent metabolism through degradation of Php4 under normal growth conditions. Our results also suggest that Hul6 promotes iron-dependent metabolism to help the cell to adapt to a nutrient-starved growth phase.
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Affiliation(s)
- Rui Yao
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Rongrong Li
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xiaoyu Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ting Jin
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ying Luo
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Rong Li
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, Nanjing, China.
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6
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McCotter SW, Kretschmer M, Lee CWJ, Heimel K, Kronstad JW. The Monothiol Glutaredoxin Grx4 Influences Iron Homeostasis and Virulence in Ustilago maydis. J Fungi (Basel) 2023; 9:1112. [PMID: 37998917 PMCID: PMC10672361 DOI: 10.3390/jof9111112] [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: 10/20/2023] [Revised: 11/12/2023] [Accepted: 11/13/2023] [Indexed: 11/25/2023] Open
Abstract
The corn smut fungus, Ustilago maydis, is an excellent model for studying biotrophic plant-pathogen interactions, including nutritional adaptation to the host environment. Iron acquisition during host colonization is a key aspect of microbial pathogenesis yet less is known about this process for fungal pathogens of plants. Monothiol glutaredoxins are central regulators of key cellular functions in fungi, including iron homeostasis, cell wall integrity, and redox status via interactions with transcription factors, iron-sulfur clusters, and glutathione. In this study, the roles of the monothiol glutaredoxin Grx4 in the biology of U. maydis were investigated by constructing strains expressing a conditional allele of grx4 under the control of the arabinose-inducible, glucose-repressible promoter Pcrg1. The use of conditional expression was necessary because Grx4 appeared to be essential for U. maydis. Transcriptome and genetic analyses with strains depleted in Grx4 revealed that the protein participates in the regulation of iron acquisition functions and is necessary for the ability of U. maydis to cause disease on maize seedlings. Taken together, this study supports the growing appreciation of monothiol glutaredoxins as key regulators of virulence-related phenotypes in pathogenic fungi.
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Affiliation(s)
- Sean W. McCotter
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, 301-2185 East Mall, Vancouver, BC V6T 1Z4, Canada; (S.W.M.); (M.K.); (C.W.J.L.)
| | - Matthias Kretschmer
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, 301-2185 East Mall, Vancouver, BC V6T 1Z4, Canada; (S.W.M.); (M.K.); (C.W.J.L.)
| | - Christopher W. J. Lee
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, 301-2185 East Mall, Vancouver, BC V6T 1Z4, Canada; (S.W.M.); (M.K.); (C.W.J.L.)
| | - Kai Heimel
- Institute of Microbiology and Genetics, Department of Microbial Cell Biology, Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany
| | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, 301-2185 East Mall, Vancouver, BC V6T 1Z4, Canada; (S.W.M.); (M.K.); (C.W.J.L.)
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7
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Pijuan J, Moreno DF, Yahya G, Moisa M, Ul Haq I, Krukiewicz K, Mosbah R, Metwally K, Cavalu S. Regulatory and pathogenic mechanisms in response to iron deficiency and excess in fungi. Microb Biotechnol 2023; 16:2053-2071. [PMID: 37804207 PMCID: PMC10616654 DOI: 10.1111/1751-7915.14346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 10/09/2023] Open
Abstract
Iron is an essential element for all eukaryote organisms because of its redox properties, which are important for many biological processes such as DNA synthesis, mitochondrial respiration, oxygen transport, lipid, and carbon metabolism. For this reason, living organisms have developed different strategies and mechanisms to optimally regulate iron acquisition, transport, storage, and uptake in different environmental responses. Moreover, iron plays an essential role during microbial infections. Saccharomyces cerevisiae has been of key importance for decrypting iron homeostasis and regulation mechanisms in eukaryotes. Specifically, the transcription factors Aft1/Aft2 and Yap5 regulate the expression of genes to control iron metabolism in response to its deficiency or excess, adapting to the cell's iron requirements and its availability in the environment. We also review which iron-related virulence factors have the most common fungal human pathogens (Aspergillus fumigatus, Cryptococcus neoformans, and Candida albicans). These factors are essential for adaptation in different host niches during pathogenesis, including different fungal-specific iron-uptake mechanisms. While being necessary for virulence, they provide hope for developing novel antifungal treatments, which are currently scarce and usually toxic for patients. In this review, we provide a compilation of the current knowledge about the metabolic response to iron deficiency and excess in fungi.
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Affiliation(s)
- Jordi Pijuan
- Laboratory of Neurogenetics and Molecular MedicineInstitut de Recerca Sant Joan de DéuBarcelonaSpain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIIIMadridSpain
| | - David F. Moreno
- Department of Molecular Cellular and Developmental BiologyYale UniversityNew HavenConnecticutUSA
- Systems Biology InstituteYale UniversityWest HavenConnecticutUSA
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
| | - Galal Yahya
- Department of Microbiology and Immunology, Faculty of PharmacyZagazig UniversityAl SharqiaEgypt
| | - Mihaela Moisa
- Faculty of Medicine and PharmacyUniversity of OradeaOradeaRomania
| | - Ihtisham Ul Haq
- Department of Physical Chemistry and Polymers TechnologySilesian University of TechnologyGliwicePoland
- Programa de Pós‐graduação em Inovação TecnológicaUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Katarzyna Krukiewicz
- Department of Physical Chemistry and Polymers TechnologySilesian University of TechnologyGliwicePoland
- Centre for Organic and Nanohybrid ElectronicsSilesian University of TechnologyGliwicePoland
| | - Rasha Mosbah
- Infection Control UnitHospitals of Zagazig UniversityZagazigEgypt
| | - Kamel Metwally
- Department of Medicinal Chemistry, Faculty of PharmacyUniversity of TabukTabukSaudi Arabia
- Department of Pharmaceutical Medicinal Chemistry, Faculty of PharmacyZagazig UniversityZagazigEgypt
| | - Simona Cavalu
- Faculty of Medicine and PharmacyUniversity of OradeaOradeaRomania
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Sun K, Li Y, Gai Y, Wang J, Jian Y, Liu X, Wu L, Shim WB, Lee YW, Ma Z, Haas H, Yin Y. HapX-mediated H2B deub1 and SreA-mediated H2A.Z deposition coordinate in fungal iron resistance. Nucleic Acids Res 2023; 51:10238-10260. [PMID: 37650633 PMCID: PMC10602907 DOI: 10.1093/nar/gkad708] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 07/26/2023] [Accepted: 08/15/2023] [Indexed: 09/01/2023] Open
Abstract
Plant pathogens are challenged by host-derived iron starvation or excess during infection, but the mechanism through which pathogens counteract iron stress is unclear. Here, we found that Fusarium graminearum encounters iron excess during the colonization of wheat heads. Deletion of heme activator protein X (FgHapX), siderophore transcription factor A (FgSreA) or both attenuated virulence. Further, we found that FgHapX activates iron storage under iron excess by promoting histone H2B deubiquitination (H2B deub1) at the promoter of the responsible gene. Meanwhile, FgSreA is shown to inhibit genes mediating iron acquisition during iron excess by facilitating the deposition of histone variant H2A.Z and histone 3 lysine 27 trimethylation (H3K27 me3) at the first nucleosome after the transcription start site. In addition, the monothiol glutaredoxin FgGrx4 is responsible for iron sensing and control of the transcriptional activity of FgHapX and FgSreA via modulation of their enrichment at target genes and recruitment of epigenetic regulators, respectively. Taken together, our findings elucidated the molecular mechanisms for adaptation to iron excess mediated by FgHapX and FgSreA during infection in F. graminearum and provide novel insights into regulation of iron homeostasis at the chromatin level in eukaryotes.
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Affiliation(s)
- Kewei Sun
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yiqing Li
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yunpeng Gai
- School of Grassland Science, Beijing Forestry University, Beijing, China
| | - Jingrui Wang
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yunqing Jian
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xin Liu
- Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Liang Wu
- Institute of Crop Science, Zhejiang University, Hangzhou, China
| | - Won-Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, USA
| | - Yin-Won Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Hubertus Haas
- Instiute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck A-6020, Austria
| | - Yanni Yin
- State Key Laboratory of Rice Biology, the Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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9
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Happacher I, Aguiar M, Yap A, Decristoforo C, Haas H. Fungal siderophore metabolism with a focus on Aspergillus fumigatus: impact on biotic interactions and potential translational applications. Essays Biochem 2023; 67:829-842. [PMID: 37313590 PMCID: PMC10500206 DOI: 10.1042/ebc20220252] [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: 04/03/2023] [Revised: 05/22/2023] [Accepted: 05/26/2023] [Indexed: 06/15/2023]
Abstract
Iron is an essential trace element that is limiting in most habitats including hosts for fungal pathogens. Siderophores are iron-chelators synthesized by most fungal species for high-affinity uptake and intracellular handling of iron. Moreover, virtually all fungal species including those lacking siderophore biosynthesis appear to be able to utilize siderophores produced by other species. Siderophore biosynthesis has been shown to be crucial for virulence of several fungal pathogens infecting animals and plants revealing induction of this iron acquisition system during virulence, which offers translational potential of this fungal-specific system. The present article summarizes the current knowledge on the fungal siderophore system with a focus on Aspergillus fumigatus and its potential translational application including noninvasive diagnosis of fungal infections via urine samples, imaging of fungal infections via labeling of siderophores with radionuclides such as Gallium-68 for detection with positron emission tomography, conjugation of siderophores with fluorescent probes, and development of novel antifungal strategies.
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Affiliation(s)
- Isidor Happacher
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Mario Aguiar
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Annie Yap
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
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10
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Yap A, Volz R, Paul S, Moye-Rowley WS, Haas H. Regulation of High-Affinity Iron Acquisition, Including Acquisition Mediated by the Iron Permease FtrA, Is Coordinated by AtrR, SrbA, and SreA in Aspergillus fumigatus. mBio 2023; 14:e0075723. [PMID: 37093084 PMCID: PMC10294635 DOI: 10.1128/mbio.00757-23] [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: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/25/2023] Open
Abstract
Iron acquisition is crucial for virulence of the human pathogen Aspergillus fumigatus. Previous studies indicated that this mold regulates iron uptake via both siderophores and reductive iron assimilation by the GATA factor SreA and the SREBP regulator SrbA. Here, characterization of loss of function as well as hyperactive alleles revealed that transcriptional activation of iron uptake depends additionally on the Zn2Cys6 regulator AtrR, most likely via cooperation with SrbA. Mutational analysis of the promoter of the iron permease-encoding ftrA gene identified a 210-bp sequence, which is both essential and sufficient to impart iron regulation. Further studies located functional sequences, densely packed within 75 bp, that largely resemble binding motifs for SrbA, SreA, and AtrR. The latter, confirmed by chromatin immunoprecipitation (ChIP) analysis, is the first one not fully matching the 5'-CGGN12CCG-3' consensus sequence. The results presented here emphasize for the first time the direct involvement of SrbA, AtrR, and SreA in iron regulation. The essential role of both AtrR and SrbA in activation of iron acquisition underlines the coordination of iron homeostasis with biosynthesis of ergosterol and heme as well as adaptation to hypoxia. The rationale is most likely the iron dependence of these pathways along with the enzymatic link of biosynthesis of ergosterol and siderophores. IMPORTANCE Aspergillus fumigatus is the most common filamentous fungal pathogen infecting humans. Iron acquisition via siderophores has previously been shown to be essential for virulence of this mold species. Here, we demonstrate that AtrR, a transcription factor previously shown to control ergosterol biosynthesis, azole resistance, and adaptation to hypoxia, is essential for activation of iron acquisition, including siderophore biosynthesis and uptake. Dissection of an iron-regulated promoter identified binding motifs for AtrR and the two previously identified regulators of iron acquisition, SrbA and SreA. Altogether, this study identified a new regulator required for maintenance of iron homeostasis, revealed insights into promoter architecture for iron regulation, and emphasized the coordinated regulation of iron homeostasis ergosterol biosynthesis and adaptation to hypoxia.
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Affiliation(s)
- Annie Yap
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Ricarda Volz
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Sanjoy Paul
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - W. Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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11
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Happacher I, Aguiar M, Alilou M, Abt B, Baltussen TJH, Decristoforo C, Melchers WJG, Haas H. The Siderophore Ferricrocin Mediates Iron Acquisition in Aspergillus fumigatus. Microbiol Spectr 2023; 11:e0049623. [PMID: 37199664 PMCID: PMC10269809 DOI: 10.1128/spectrum.00496-23] [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: 02/02/2023] [Accepted: 04/28/2023] [Indexed: 05/19/2023] Open
Abstract
The opportunistic fungal pathogen Aspergillus fumigatus utilizes two high-affinity iron uptake mechanisms, termed reductive iron assimilation (RIA) and siderophore-mediated iron acquisition (SIA). The latter has been shown to be crucial for virulence of this fungus and is a target for development of novel strategies for diagnosis and treatment of fungal infections. So far, research on SIA in this mold focused mainly on the hyphal stage, revealing the importance of extracellular fusarinine-type siderophores in iron acquisition as well as of the siderophore ferricrocin in intracellular iron handling. The current study aimed to characterize iron acquisition during germination. High expression of genes involved in biosynthesis and uptake of ferricrocin in conidia and during germination, independent of iron availability, suggested a role of ferricrocin in iron acquisition during germination. In agreement, (i) bioassays indicated secretion of ferricrocin during growth on solid media during both iron sufficiency and limitation, (ii) ferricrocin was identified in the supernatant of conidia germinating in liquid media during both iron sufficiency and limitation, (iii) in contrast to mutants lacking all siderophores, mutants synthesizing ferricrocin but lacking fusarinine-type siderophores were able to grow under iron limitation in the absence of RIA, and (iv) genetic inactivation of the ferricrocin transporter Sit1 decreased germination in the absence of RIA. Taken together, this study revealed that ferricrocin has not only an intracellular role but also functions as an extracellular siderophore to support iron acquisition. The iron availability-independent ferricrocin secretion and uptake during early germination indicate developmental, rather than iron regulation. IMPORTANCE Aspergillus fumigatus is one of the most common airborne fungal pathogens for humans. Low-molecular-mass iron chelators, termed siderophores, have been shown to play a central role in iron homeostasis and, consequently, virulence of this mold. Previous studies demonstrated the crucial role of secreted fusarinine-type siderophores, such as triacetylfusarinine C, in iron acquisition, as well as of the ferrichrome-type siderophore ferricrocin in intracellular iron storage and transport. Here, we demonstrate that ferricrocin is also secreted to mediate iron acquisition during germination together with reductive iron assimilation. During early germination, ferricrocin secretion and uptake were not repressed by iron availability, indicating developmental regulation of this iron acquisition system in this growth phase.
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Affiliation(s)
- Isidor Happacher
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Mario Aguiar
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Mostafa Alilou
- Institute of Pharmacy, Unit of Pharmacognosy, Center for Molecular Biosciences Innsbruck, Austria
| | - Beate Abt
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Tim J. H. Baltussen
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Willem J. G. Melchers
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
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12
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Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa. Appl Environ Microbiol 2023; 89:e0171422. [PMID: 36533942 PMCID: PMC9888271 DOI: 10.1128/aem.01714-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa ΔgrxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the ΔgrxD mutant under PQ toxicity. Constitutively high expression of iscR, nfuA, tpx, and fprB was observed in the ΔgrxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the ΔgrxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa. IMPORTANCE Glutaredoxins (Grxs) are ubiquitous disulfide reductase enzymes. Monothiol Grxs, containing a CXXS motif, play an essential role in iron homeostasis and maturation of [Fe-S] cluster proteins in various organisms. We now establish that the human pathogen Pseudomonas aeruginosa GrxD is crucial for bacterial virulence, maturation of [Fe-S] clusters and facilitation of Ohr enzyme activity. GrxD contains a conserved signature monothiol motif (C29GFS), in which C29 is essential for its function in an oxidative stress protection. Our findings reveal the physiological roles of GrxD in oxidative stress protection and virulence of P. aeruginosa.
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Yap A, Glarcher I, Misslinger M, Haas H. Characterization and engineering of the xylose-inducible xylP promoter for use in mold fungal species. Metab Eng Commun 2022; 15:e00214. [DOI: 10.1016/j.mec.2022.e00214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/04/2022] [Accepted: 11/14/2022] [Indexed: 11/21/2022] Open
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Kubisch C, Kövilein A, Aliyu H, Ochsenreither K. RNA-Seq Based Transcriptome Analysis of Aspergillus oryzae DSM 1863 Grown on Glucose, Acetate and an Aqueous Condensate from the Fast Pyrolysis of Wheat Straw. J Fungi (Basel) 2022; 8:jof8080765. [PMID: 35893132 PMCID: PMC9394295 DOI: 10.3390/jof8080765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 11/16/2022] Open
Abstract
Due to its acetate content, the pyrolytic aqueous condensate (PAC) formed during the fast pyrolysis of wheat straw could provide an inexpensive substrate for microbial fermentation. However, PAC also contains several inhibitors that make its detoxification inevitable. In our study, we examined the transcriptional response of Aspergillus oryzae to cultivation on 20% detoxified PAC, pure acetate and glucose using RNA-seq analysis. Functional enrichment analysis of 3463 significantly differentially expressed (log2FC >2 & FDR < 0.05) genes revealed similar metabolic tendencies for both acetate and PAC, as upregulated genes in these cultures were mainly associated with ribosomes and RNA processing, whereas transmembrane transport was downregulated. Unsurprisingly, metabolic pathway analysis revealed that glycolysis/gluconeogenesis and starch and sucrose metabolism were upregulated for glucose, whereas glyoxylate and the tricarboxylic acid (TCA) cycle were important carbon utilization pathways for acetate and PAC, respectively. Moreover, genes involved in the biosynthesis of various amino acids such as arginine, serine, cysteine and tryptophan showed higher expression in the acetate-containing cultures. Direct comparison of the transcriptome profiles of acetate and PAC revealed that pyruvate metabolism was the only significantly different metabolic pathway and was overexpressed in the PAC cultures. Upregulated genes included those for methylglyoxal degradation and alcohol dehydrogenases, which thus represent potential targets for the further improvement of fungal PAC tolerance.
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Huber EM, Hortschansky P, Scheven MT, Misslinger M, Haas H, Brakhage AA, Groll M. Structural insights into cooperative DNA recognition by the CCAAT-binding complex and its bZIP transcription factor HapX. Structure 2022; 30:934-946.e4. [PMID: 35472306 DOI: 10.1016/j.str.2022.04.001] [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: 03/08/2022] [Revised: 03/21/2022] [Accepted: 03/31/2022] [Indexed: 11/25/2022]
Abstract
The heterotrimeric CCAAT-binding complex (CBC) is a fundamental eukaryotic transcription factor recognizing the CCAAT box. In certain fungi, like Aspergilli, the CBC cooperates with the basic leucine zipper HapX to control iron metabolism. HapX functionally depends on the CBC, and the stable interaction of both requires DNA. To study this cooperative effect, X-ray structures of the CBC-HapX-DNA complex were determined. Downstream of the CCAAT box, occupied by the CBC, a HapX dimer binds to the major groove. The leash-like N terminus of the distal HapX subunit contacts the CBC, and via a flexible polyproline type II helix mediates minor groove interactions that stimulate sequence promiscuity. In vitro and in vivo mutagenesis suggest that the structural and functional plasticity of HapX results from local asymmetry and its ability to target major and minor grooves simultaneously. The latter feature may also apply to related transcription factors such as yeast Hap4 and distinct Yap family members.
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Affiliation(s)
- Eva M Huber
- Chair of Biochemistry, Center for Protein Assemblies, Technical University of Munich, Ernst-Otto-Fischer-Straße 8, 85748 Garching, Germany
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (Leibniz-HKI), Adolf-Reichwein-Straße 23, 07745 Jena, Germany
| | - Mareike T Scheven
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (Leibniz-HKI), Adolf-Reichwein-Straße 23, 07745 Jena, Germany
| | - Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (Leibniz-HKI), Adolf-Reichwein-Straße 23, 07745 Jena, Germany; Institute for Microbiology, Friedrich Schiller University Jena, Neugasse 25, 07743 Jena, Germany.
| | - Michael Groll
- Chair of Biochemistry, Center for Protein Assemblies, Technical University of Munich, Ernst-Otto-Fischer-Straße 8, 85748 Garching, Germany.
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16
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Amich J. Sulfur Metabolism as a Promising Source of New Antifungal Targets. J Fungi (Basel) 2022; 8:295. [PMID: 35330297 PMCID: PMC8951744 DOI: 10.3390/jof8030295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 02/23/2022] [Accepted: 03/11/2022] [Indexed: 12/31/2022] Open
Abstract
Fungal infections are a growing threat to human health. Despite their clinical relevance, there is a surprisingly limited availability of clinically approved antifungal agents, which is seriously aggravated by the recent appearance and fast spread of drug resistance. It is therefore clear that there is an urgent need for novel and efficient antifungals. In this context, metabolism is recognized as a promising source for new antifungal targets and, indeed, there are new drugs in development that target metabolic pathways. Fungal sulfur metabolism is particularly interesting, as many of its processes are essential for viability and/or pathogenicity and it shows substantial differences with human metabolism. This short-review will summarize our current knowledge of sulfur-related genes and routes that are important for Aspergillus fumigatus virulence, which consequently could be pursued for drug development.
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Affiliation(s)
- Jorge Amich
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Majadahonda, 28222 Madrid, Spain;
- Manchester Fungal Infection Group (MFIG), Division of Evolution, Infection, and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, UK
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17
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Hu G, Horianopoulos L, Sánchez-León E, Caza M, Jung W, Kronstad JW. The monothiol glutaredoxin Grx4 influences thermotolerance, cell wall integrity, and Mpk1 signaling in Cryptococcus neoformans. G3 (BETHESDA, MD.) 2021; 11:jkab322. [PMID: 34542604 PMCID: PMC8527476 DOI: 10.1093/g3journal/jkab322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/27/2021] [Indexed: 02/07/2023]
Abstract
Monothiol glutaredoxins are important regulators of iron homeostasis that play conserved roles in the sensing and trafficking of iron-sulfur clusters. We previously characterized the role of the monothiol glutaredoxin Grx4 in iron homeostasis, the interaction with the iron regulator Cir1, and virulence in Cryptococcus neoformans. This important fungal pathogen causes cryptococcal meningoencephalitis in immunocompromised individuals worldwide. Here, we demonstrate that Grx4 is required for proliferation at elevated temperatures (both 37°C and 39°C) and under stress conditions. In particular, the grx4Δ mutant was hypersensitive to SDS, calcofluor white (CFW), and caffeine, suggesting that Grx4 is required for membrane and cell wall integrity (CWI). In this context, we found that Grx4 regulated the phosphorylation of the Mpk1 mitogen-activated protein kinase (MAPK) of the CWI pathway in cells grown at elevated temperature or upon treatment with CFW, caffeine, or SDS. The grx4Δ mutant also displayed increased sensitivity to FK506 and cyclosporin A, two inhibitors of the calcineurin pathway, indicating that Grx4 may influence growth at higher temperatures in parallel with calcineurin signaling. Upon thermal stress or calcium treatment, loss of Grx4 also caused partial mis-localization of Crz1, the transcription factor that is a calcineurin substrate. The phenotypes of the grx4Δ, crz1Δ, and cna1Δ (calcineurin) mutants suggest shared contributions to the regulation of temperature, cell wall, and other stresses. In summary, we show that Grx4 is also a key regulator of the responses to a variety of stress conditions in addition to its roles in iron homeostasis in C. neoformans.
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Affiliation(s)
- Guanggan Hu
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Linda Horianopoulos
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Eddy Sánchez-León
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Mélissa Caza
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Wonhee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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18
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López-Berges MS, Scheven MT, Hortschansky P, Misslinger M, Baldin C, Gsaller F, Werner ER, Krüger T, Kniemeyer O, Weber J, Brakhage AA, Haas H. The bZIP Transcription Factor HapX Is Post-Translationally Regulated to Control Iron Homeostasis in Aspergillus fumigatus. Int J Mol Sci 2021; 22:ijms22147739. [PMID: 34299357 PMCID: PMC8307855 DOI: 10.3390/ijms22147739] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 07/15/2021] [Indexed: 11/21/2022] Open
Abstract
The airborne fungus Aspergillus fumigatus causes opportunistic infections in humans with high mortality rates in immunocompromised patients. Previous work established that the bZIP transcription factor HapX is essential for virulence via adaptation to iron limitation by repressing iron-consuming pathways and activating iron acquisition mechanisms. Moreover, HapX was shown to be essential for transcriptional activation of vacuolar iron storage and iron-dependent pathways in response to iron availability. Here, we demonstrate that HapX has a very short half-life during iron starvation, which is further decreased in response to iron, while siderophore biosynthetic enzymes are very stable. We identified Fbx22 and SumO as HapX interactors and, in agreement, HapX post-translational modifications including ubiquitination of lysine161, sumoylation of lysine242 and phosphorylation of threonine319. All three modifications were enriched in the immediate adaptation from iron-limiting to iron-replete conditions. Interfering with these post-translational modifications, either by point mutations or by inactivation, of Fbx22 or SumO, altered HapX degradation, heme biosynthesis and iron resistance to different extents. Consistent with the need to precisely regulate HapX protein levels, overexpression of hapX caused significant growth defects under iron sufficiency. Taken together, our results indicate that post-translational regulation of HapX is important to control iron homeostasis in A. fumigatus.
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Affiliation(s)
- Manuel Sánchez López-Berges
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
| | - Mareike Thea Scheven
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Clara Baldin
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Fabio Gsaller
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria;
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Jakob Weber
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
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19
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Jung WH, Sánchez-León E, Kronstad JW. Coordinated regulation of iron metabolism in Cryptococcus neoformans by GATA and CCAAT transcription factors: connections with virulence. Curr Genet 2021; 67:583-593. [PMID: 33760942 DOI: 10.1007/s00294-021-01172-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 10/21/2022]
Abstract
Iron acquisition is critical for pathogenic fungi to adapt to and survive within the host environment. However, to same extent, the fungi must also avoid the detrimental effects caused by excess iron. The importance of iron has been demonstrated for the physiology and virulence of major fungal pathogens of humans including Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans. In particular, numerous studies have revealed that aspects of iron acquisition, metabolism, and homeostasis in the fungal pathogens are tightly controlled by conserved transcriptional regulators including a GATA-type iron transcription factor and the CCAAT-binding complex (CBC)/HapX orthologous protein complex. However, the specific downstream regulatory networks are slightly different in each fungus. In addition, roles have been proposed or demonstrated for other factors including monothiol glutaredoxins, BolA-like proteins, and Fe-S cluster incorporation on the GATA-type iron transcription factor and the CBC/HapX orthologous protein complex, although limited information is available. Here we focus on recent work on C. neoformans in the context of an emerging framework for fungal regulation of iron acquisition, metabolism, and homeostasis. Our specific goal is to summarize recent findings on transcriptional networks governed by the iron regulators Cir1 and HapX in C. neoformans.
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Affiliation(s)
- Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, 17546, Korea.
| | - Eddy Sánchez-León
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
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Chatterji A, Sengupta R. Cellular S-denitrosylases: Potential role and interplay of Thioredoxin, TRP14, and Glutaredoxin systems in thiol-dependent protein denitrosylation. Int J Biochem Cell Biol 2021; 131:105904. [DOI: 10.1016/j.biocel.2020.105904] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 12/11/2022]
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21
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de Assis LJ, Silva LP, Bayram O, Dowling P, Kniemeyer O, Krüger T, Brakhage AA, Chen Y, Dong L, Tan K, Wong KH, Ries LNA, Goldman GH. Carbon Catabolite Repression in Filamentous Fungi Is Regulated by Phosphorylation of the Transcription Factor CreA. mBio 2021; 12:e03146-20. [PMID: 33402538 PMCID: PMC8545104 DOI: 10.1128/mbio.03146-20] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023] Open
Abstract
Filamentous fungi of the genus Aspergillus are of particular interest for biotechnological applications due to their natural capacity to secrete carbohydrate-active enzymes (CAZy) that target plant biomass. The presence of easily metabolizable sugars such as glucose, whose concentrations increase during plant biomass hydrolysis, results in the repression of CAZy-encoding genes in a process known as carbon catabolite repression (CCR), which is undesired for the purpose of large-scale enzyme production. To date, the C2H2 transcription factor CreA has been described as the major CC repressor in Aspergillus spp., although little is known about the role of posttranslational modifications in this process. In this work, phosphorylation sites were identified by mass spectrometry on Aspergillus nidulans CreA, and subsequently, the previously identified but uncharacterized site S262, the characterized site S319, and the newly identified sites S268 and T308 were chosen to be mutated to nonphosphorylatable residues before their effect on CCR was investigated. Sites S262, S268, and T308 are important for CreA protein accumulation and cellular localization, DNA binding, and repression of enzyme activities. In agreement with a previous study, site S319 was not important for several here-tested phenotypes but is key for CreA degradation and induction of enzyme activities. All sites were shown to be important for glycogen and trehalose metabolism. This study highlights the importance of CreA phosphorylation sites for the regulation of CCR. These sites are interesting targets for biotechnological strain engineering without the need to delete essential genes, which could result in undesired side effects.IMPORTANCE In filamentous fungi, the transcription factor CreA controls carbohydrate metabolism through the regulation of genes encoding enzymes required for the use of alternative carbon sources. In this work, phosphorylation sites were identified on Aspergillus nidulans CreA, and subsequently, the two newly identified sites S268 and T308, the previously identified but uncharacterized site S262, and the previously characterized site S319 were chosen to be mutated to nonphosphorylatable residues before their effect on CCR was characterized. Sites S262, S268, and T308 are important for CreA protein accumulation and cellular localization, DNA binding, and repression of enzyme activities. In agreement with a previous study, site S319 is not important for several here-tested phenotypes but is key for CreA degradation and induction of enzyme activities. This work characterized novel CreA phosphorylation sites under carbon catabolite-repressing conditions and showed that they are crucial for CreA protein turnover, control of carbohydrate utilization, and biotechnologically relevant enzyme production.
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Affiliation(s)
| | - Lilian Pereira Silva
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto, Brazil
- Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - Ozgur Bayram
- Biology Department, Maynooth University, Maynooth, Kildare, Ireland
| | - Paul Dowling
- Biology Department, Maynooth University, Maynooth, Kildare, Ireland
| | - Olaf Kniemeyer
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Thomas Krüger
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Axel A Brakhage
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Yingying Chen
- Faculty of Health Science, University of Macau, Macau, China
| | - Liguo Dong
- Faculty of Health Science, University of Macau, Macau, China
| | - Kaeling Tan
- Faculty of Health Science, University of Macau, Macau, China
| | - Koon Ho Wong
- Faculty of Health Science, University of Macau, Macau, China
| | - Laure N A Ries
- University of Exeter, MRC Centre for Medical Mycology, Exeter, United Kingdom
| | - Gustavo H Goldman
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto, Brazil
- Institute for Advanced Study, Technical University of Munich, Garching, Germany
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22
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Sinorhizobium meliloti YrbA binds divalent metal cations using two conserved histidines. Biosci Rep 2020; 40:226508. [PMID: 32970113 PMCID: PMC7538681 DOI: 10.1042/bsr20202956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 11/23/2022] Open
Abstract
Sinorhizobium meliloti is a nitrogen-fixing bacterium forming symbiotic nodules with the legume Medicago truncatula. S. meliloti possesses two BolA-like proteins (BolA and YrbA), the function of which is unknown. In organisms where BolA proteins and monothiol glutaredoxins (Grxs) are present, they contribute to the regulation of iron homeostasis by bridging a [2Fe–2S] cluster into heterodimers. A role in the maturation of iron–sulfur (Fe–S) proteins is also attributed to both proteins. In the present study, we have performed a structure–function analysis of SmYrbA showing that it coordinates diverse divalent metal ions (Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) using His32 and His67 residues, that are also used for Fe–S cluster binding in BolA–Grx heterodimers. It also possesses the capacity to form heterodimers with the sole monothiol glutaredoxin (SmGrx2) present in this species. Using cellular approaches analyzing the metal tolerance of S. meliloti mutant strains inactivated in the yrbA and/or bolA genes, we provide evidence for a connection of YrbA with the regulation of iron homeostasis. The mild defects in M. truncatula nodulation reported for the yrbA bolA mutant as compared with the stronger defects in nodule development previously observed for a grx2 mutant suggest functions independent of SmGrx2. These results help in clarifying the physiological role of BolA-type proteins in bacteria.
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23
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HapX, an Indispensable bZIP Transcription Factor for Iron Acquisition, Regulates Infection Initiation by Orchestrating Conidial Oleic Acid Homeostasis and Cytomembrane Functionality in Mycopathogen Beauveria bassiana. mSystems 2020; 5:5/5/e00695-20. [PMID: 33051379 PMCID: PMC7567583 DOI: 10.1128/msystems.00695-20] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Conidial maturation and germination are highly coupled physiological processes in filamentous fungi that are critical for the pathogenicity of mycopathogens. Compared to the mechanisms involved in conidial germination, those of conidial reserves during maturation are less understood. The insect-pathogenic fungus Beauveria bassiana, as a representative species of filamentous fungi, is important for applied and fundamental research. In addition to its conserved roles in fungal adaptation to iron status, the bZIP transcription factor HapX acts as a master regulator involved in conidial virulence and regulates fatty acid/lipid metabolism. Further investigation revealed that the Δ9-fatty acid desaturase gene (Ole1) is a direct downstream target of HapX. This study reveals the HapX-Ole1 pathway involved in the fatty acid/lipid accumulation associated with conidial maturation and provides new insights into the startup mechanism of infection caused by spores from pathogenic fungi. In pathogenic filamentous fungi, conidial germination not only is fundamental for propagation in the environment but is also a critical step of infection. In the insect mycopathogen Beauveria bassiana, we genetically characterized the role of the basic leucine zipper (bZIP) transcription factor HapX (BbHapX) in conidial nutrient reserves and pathogen-host interaction. Ablation of BbHapX resulted in an almost complete loss of virulence in the topical inoculation and intrahemocoel injection assays. Comparative transcriptomic analysis revealed that BbHapX is required for fatty acid (FA)/lipid metabolism, and biochemical analyses indicated that BbHapX loss caused a significant reduction in conidial FA contents. Exogenous oleic acid could partially or completely restore the impaired phenotypes of the ΔBbHapX mutant, including germination rate, membrane integrity, vegetative growth, and virulence. BbHapX mediates fungal iron acquisition which is not required for desaturation of stearic acid. Additionally, inactivation of the Δ9-fatty acid desaturase gene (BbOle1) generated defects similar to those of the ΔBbHapX mutant; oleic acid also had significant restorative effects on the defective phenotypes of the ΔBbOle1 mutant. A gel retarding assay revealed that BbHapX directly regulated the expression of BbOle1. Lipidomic analyses indicated that both BbHapX and BbOle1 contributed to the homeostasis of phospholipids with nonpolar tails derived from oleic acid; therefore, exogenous phospholipids could significantly restore membrane integrity. These data reveal that the HapX-Ole1 pathway contributes to conidial fatty acid/lipid reserves and that there are important links between the lipid biology and membrane functionality involved in the early stages of infection caused by B.bassiana. IMPORTANCE Conidial maturation and germination are highly coupled physiological processes in filamentous fungi that are critical for the pathogenicity of mycopathogens. Compared to the mechanisms involved in conidial germination, those of conidial reserves during maturation are less understood. The insect-pathogenic fungus Beauveria bassiana, as a representative species of filamentous fungi, is important for applied and fundamental research. In addition to its conserved roles in fungal adaptation to iron status, the bZIP transcription factor HapX acts as a master regulator involved in conidial virulence and regulates fatty acid/lipid metabolism. Further investigation revealed that the Δ9-fatty acid desaturase gene (Ole1) is a direct downstream target of HapX. This study reveals the HapX-Ole1 pathway involved in the fatty acid/lipid accumulation associated with conidial maturation and provides new insights into the startup mechanism of infection caused by spores from pathogenic fungi.
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Misslinger M, Hortschansky P, Brakhage AA, Haas H. Fungal iron homeostasis with a focus on Aspergillus fumigatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118885. [PMID: 33045305 DOI: 10.1016/j.bbamcr.2020.118885] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/15/2020] [Accepted: 10/01/2020] [Indexed: 02/08/2023]
Abstract
To maintain iron homeostasis, fungi have to balance iron acquisition, storage, and utilization to ensure sufficient supply and to avoid toxic excess of this essential trace element. As pathogens usually encounter iron limitation in the host niche, this metal plays a particular role during virulence. Siderophores are iron-chelators synthesized by most, but not all fungal species to sequester iron extra- and intracellularly. In recent years, the facultative human pathogen Aspergillus fumigatus has become a model for fungal iron homeostasis of siderophore-producing fungal species. This article summarizes the knowledge on fungal iron homeostasis and its links to virulence with a focus on A. fumigatus. It covers mechanisms for iron acquisition, storage, and detoxification, as well as the modes of transcriptional iron regulation and iron sensing in A. fumigatus in comparison to other fungal species. Moreover, potential translational applications of the peculiarities of fungal iron metabolism for treatment and diagnosis of fungal infections is addressed.
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Affiliation(s)
- Matthias Misslinger
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany; Department Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Hubertus Haas
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
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25
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Berndt C, Christ L, Rouhier N, Mühlenhoff U. Glutaredoxins with iron-sulphur clusters in eukaryotes - Structure, function and impact on disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148317. [PMID: 32980338 DOI: 10.1016/j.bbabio.2020.148317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/07/2020] [Accepted: 09/18/2020] [Indexed: 12/12/2022]
Abstract
Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind iron-sulphur (Fe/S) clusters is one of the more recent and major developments concerning their functional properties. Glutaredoxins are present in most organisms. All members of the class II subfamily (including most monothiol glutaredoxins), but also some members of the class I (mostly dithiol glutaredoxins) and class III (land plant-specific monothiol or dithiol glutaredoxins) are Fe/S proteins. In glutaredoxins characterised so far, the [2Fe2S] cluster is coordinated by two active-site cysteine residues and two molecules of non-covalently bound glutathione in homo-dimeric complexes bridged by the cluster. In contrast to dithiol glutaredoxins, monothiol glutaredoxins possess no or very little oxidoreductase activity, but have emerged as important players in cellular iron metabolism. In this review we summarise the recent developments of the most prominent Fe/S glutaredoxins in eukaryotes, the mitochondrial single domain monothiol glutaredoxin 5, the chloroplastic single domain monothiol glutaredoxin S14 and S16, the nuclear/cytosolic multi-domain monothiol glutaredoxin 3, and the mitochondrial/cytosolic dithiol glutaredoxin 2.
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Affiliation(s)
- Carsten Berndt
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Merowingerplatz1a, 40225 Düsseldorf, Germany
| | - Loïck Christ
- Université de Lorraine, INRAE, IAM, F-54000 Nancy, France
| | | | - Ulrich Mühlenhoff
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch Str. 6, 35032 Marburg, Germany.
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26
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Talib EA, Outten CE. Iron-sulfur cluster biogenesis, trafficking, and signaling: Roles for CGFS glutaredoxins and BolA proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118847. [PMID: 32910989 DOI: 10.1016/j.bbamcr.2020.118847] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/24/2020] [Accepted: 09/01/2020] [Indexed: 01/08/2023]
Abstract
The synthesis and trafficking of iron-sulfur (Fe-S) clusters in both prokaryotes and eukaryotes requires coordination within an expanding network of proteins that function in the cytosol, nucleus, mitochondria, and chloroplasts in order to assemble and deliver these ancient and essential cofactors to a wide variety of Fe-S-dependent enzymes and proteins. This review focuses on the evolving roles of two ubiquitous classes of proteins that operate in this network: CGFS glutaredoxins and BolA proteins. Monothiol or CGFS glutaredoxins possess a Cys-Gly-Phe-Ser active site that coordinates an Fe-S cluster in a homodimeric complex. CGFS glutaredoxins also form [2Fe-2S]-bridged heterocomplexes with BolA proteins, which possess an invariant His and an additional His or Cys residue that serve as cluster ligands. Here we focus on recent discoveries in bacteria, fungi, humans, and plants that highlight the shared and distinct roles of CGFS glutaredoxins and BolA proteins in Fe-S cluster biogenesis, Fe-S cluster storage and trafficking, and Fe-S cluster signaling to transcriptional factors that control iron metabolism--.
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Affiliation(s)
- Evan A Talib
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA.
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27
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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.
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28
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Martínez-Pastor MT, Puig S. Adaptation to iron deficiency in human pathogenic fungi. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118797. [PMID: 32663505 DOI: 10.1016/j.bbamcr.2020.118797] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/13/2020] [Accepted: 07/05/2020] [Indexed: 02/08/2023]
Abstract
Iron is an essential micronutrient for virtually all eukaryotic organisms and plays a central role during microbial infections. Invasive fungal diseases are associated with strikingly high rates of mortality, but their impact on human health is usually underestimated. Upon a fungal infection, hosts restrict iron availability in order to limit the growth and virulence of the pathogen. Here, we use two model yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, to delve into the response to iron deficiency of human fungal pathogens, such as Candida glabrata, Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans. Fungi possess common and species-specific mechanisms to acquire iron and to control the response to iron limitation. Upon iron scarcity, fungi activate a wide range of elegant strategies to capture and import exogenous iron, mobilize iron from intracellular stores, and modulate their metabolism to economize and prioritize iron utilization. Hence, iron homeostasis genes represent remarkable virulence factors that can be used as targets for the development of novel antifungal treatments.
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Affiliation(s)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
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29
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Furukawa T, Scheven MT, Misslinger M, Zhao C, Hoefgen S, Gsaller F, Lau J, Jöchl C, Donaldson I, Valiante V, Brakhage AA, Bromley MJ, Haas H, Hortschansky P. The fungal CCAAT-binding complex and HapX display highly variable but evolutionary conserved synergetic promoter-specific DNA recognition. Nucleic Acids Res 2020; 48:3567-3590. [PMID: 32086516 PMCID: PMC7144946 DOI: 10.1093/nar/gkaa109] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 02/07/2020] [Accepted: 02/18/2020] [Indexed: 12/13/2022] Open
Abstract
To sustain iron homeostasis, microorganisms have evolved fine-tuned mechanisms for uptake, storage and detoxification of the essential metal iron. In the human pathogen Aspergillus fumigatus, the fungal-specific bZIP-type transcription factor HapX coordinates adaption to both iron starvation and iron excess and is thereby crucial for virulence. Previous studies indicated that a HapX homodimer interacts with the CCAAT-binding complex (CBC) to cooperatively bind bipartite DNA motifs; however, the mode of HapX-DNA recognition had not been resolved. Here, combination of in vivo (genetics and ChIP-seq), in vitro (surface plasmon resonance) and phylogenetic analyses identified an astonishing plasticity of CBC:HapX:DNA interaction. DNA motifs recognized by the CBC:HapX protein complex comprise a bipartite DNA binding site 5′-CSAATN12RWT-3′ and an additional 5′-TKAN-3′ motif positioned 11–23 bp downstream of the CCAAT motif, i.e. occasionally overlapping the 3′-end of the bipartite binding site. Phylogenetic comparison taking advantage of 20 resolved Aspergillus species genomes revealed that DNA recognition by the CBC:HapX complex shows promoter-specific cross-species conservation rather than regulon-specific conservation. Moreover, we show that CBC:HapX interaction is absolutely required for all known functions of HapX. The plasticity of the CBC:HapX:DNA interaction permits fine tuning of CBC:HapX binding specificities that could support adaptation of pathogens to their host niches.
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Affiliation(s)
- Takanori Furukawa
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Mareike Thea Scheven
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
| | - Matthias Misslinger
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Can Zhao
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Sandra Hoefgen
- Leibniz Research Group Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
| | - Fabio Gsaller
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Jeffrey Lau
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Christoph Jöchl
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Ian Donaldson
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Vito Valiante
- Leibniz Research Group Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany.,Friedrich Schiller University Jena, Jena D-07745, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany.,Friedrich Schiller University Jena, Jena D-07745, Germany
| | - Michael J Bromley
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
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30
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Gupta M, Outten CE. Iron-sulfur cluster signaling: The common thread in fungal iron regulation. Curr Opin Chem Biol 2020; 55:189-201. [PMID: 32234663 DOI: 10.1016/j.cbpa.2020.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/02/2020] [Accepted: 02/20/2020] [Indexed: 02/07/2023]
Abstract
Iron homeostasis in fungi involves balancing iron uptake and storage with iron utilization to achieve adequate, nontoxic levels of this essential nutrient. Extensive work in the nonpathogenic yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe has uncovered unique iron regulation networks for each organism that control iron metabolism via distinct molecular mechanisms. However, common themes have emerged from these studies. The activities of all fungal iron-sensing transcription factors characterized to date are regulated via iron-sulfur cluster signaling. Furthermore, glutaredoxins often play a key role in relaying the intracellular iron status to these DNA-binding proteins. Recent work with fungal pathogens, including Candida and Aspergillus species and Cryptococcus neoformans, has revealed novel iron regulation mechanisms, yet similar roles for iron-sulfur clusters and glutaredoxins in iron signaling have been confirmed. This review will focus on these recent discoveries regarding iron regulation pathways in both pathogenic and nonpathogenic fungi.
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Affiliation(s)
- Malini Gupta
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 29208
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 29208.
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31
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Xue K, Prezioso SM, Christendat D. QuiC2 represents a functionally distinct class of dehydroshikimate dehydratases identified in Listeria species including Listeria monocytogenes. Environ Microbiol 2020; 22:2680-2692. [PMID: 32190965 DOI: 10.1111/1462-2920.14987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 03/09/2020] [Accepted: 03/16/2020] [Indexed: 11/28/2022]
Abstract
Many Listeria species including L. monocytogenes contain the pathway for the biosynthesis of protocatechuate from shikimate and quinate. The qui1 and qui2 operons within these Listeria spp. encode enzymes for this pathway. The diversion of shikimate pathway intermediates in some Listeria species to produce protocatechuate suggests an important biological role for this compound to these organisms. A total of seven ORFs, including quiC2, were identified within qui1 and qui2, however only three proteins encoded by the operons have been functionally annotated. The final step in Listeria's protocatechuate biosynthesis involves the conversion of dehydroshikimate by a dehydroshikimate dehydratase (DSD). In this study, we demonstrate that QuiC2 functions as a DSD in Listeria spp. through biochemical and structural analyses. Moreover, we show that QuiC2 forms a phylogenetic cluster distinct from other functionally annotated DSDs. The individual phylogenetic clusters of DSD are represented by enzymes that produce protocatechuate for distinct biological processes. Similarly, QuiC2 is expected to produce protocatechuate for a novel biological process. We postulate that protocatechuate produced by DSDs found within the QuiC2 phylogenetic cluster provides an ecological niche for representative organisms.
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Affiliation(s)
- Kevin Xue
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
| | - Stephanie M Prezioso
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
| | - Dinesh Christendat
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
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32
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Bauer I, Misslinger M, Shadkchan Y, Dietl AM, Petzer V, Orasch T, Abt B, Graessle S, Osherov N, Haas H. The Lysine Deacetylase RpdA Is Essential for Virulence in Aspergillus fumigatus. Front Microbiol 2019; 10:2773. [PMID: 31866965 PMCID: PMC6905131 DOI: 10.3389/fmicb.2019.02773] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/13/2019] [Indexed: 12/15/2022] Open
Abstract
Current suboptimal treatment options of invasive fungal infections and emerging resistance of the corresponding pathogens urge the need for alternative therapy strategies and require the identification of novel antifungal targets. Aspergillus fumigatus is the most common airborne opportunistic mold pathogen causing invasive and often fatal disease. Establishing a novel in vivo conditional gene expression system, we demonstrate that downregulation of the class 1 lysine deacetylase (KDAC) RpdA leads to avirulence of A. fumigatus in a murine model for pulmonary aspergillosis. The xylP promoter used has previously been shown to allow xylose-induced gene expression in different molds. Here, we demonstrate for the first time that this promoter also allows in vivo tuning of A. fumigatus gene activity by supplying xylose in the drinking water of mice. In the absence of xylose, an A. fumigatus strain expressing rpdA under control of the xylP promoter, rpdAxylP, was avirulent and lung histology showed significantly less fungal growth. With xylose, however, rpdAxylP displayed full virulence demonstrating that xylose was taken up by the mouse, transported to the site of fungal infection and caused rpdA induction in vivo. These results demonstrate that (i) RpdA is a promising target for novel antifungal therapies and (ii) the xylP expression system is a powerful new tool for in vivo gene silencing in A. fumigatus.
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Affiliation(s)
- Ingo Bauer
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Yana Shadkchan
- Department of Clinical Microbiology and Immunology, Aspergillus and Antifungal Research Laboratory, Sackler School of Medicine, Tel Aviv University, Tel Aviv-Yafo, Israel
| | - Anna-Maria Dietl
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Verena Petzer
- Department of Internal Medicine II (Infectious Diseases, Immunology, Rheumatology and Pneumology), Medical University of Innsbruck, Innsbruck, Austria
| | - Thomas Orasch
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Beate Abt
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Stefan Graessle
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Nir Osherov
- Department of Clinical Microbiology and Immunology, Aspergillus and Antifungal Research Laboratory, Sackler School of Medicine, Tel Aviv University, Tel Aviv-Yafo, Israel
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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