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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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Luciano-Rosario D, Barda O, Tannous J, Frawley D, Bayram Ö, Prusky D, Sionov E, Keller NP. The histone demethylase KdmB is part of a trimeric protein complex and mediates virulence and mycotoxin production in Penicillium expansum. Fungal Genet Biol 2023; 169:103837. [PMID: 37722619 PMCID: PMC10755807 DOI: 10.1016/j.fgb.2023.103837] [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: 06/26/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/20/2023]
Abstract
Epigenetic modification of chromosome structure has increasingly been associated with alterations in secondary metabolism and sporulation defects in filamentous fungal pathogens. Recently, the epigenetic reader protein SntB was shown to govern virulence, spore production and mycotoxin synthesis in the fruit pathogen Penicillium expansum. Through immunoprecipitation-coupled mass spectrometry, we found that SntB is a member of a protein complex with KdmB, a histone demethylase and the essential protein RpdA, a histone deacetylase. Deletion of kdmB phenocopied some but not all characteristics of the ΔsntB mutant. KdmB deletion strains exhibited reduced lesion development on Golden Delicious apples and this was accompanied by decreased production of patulin and citrinin in host tissue. In addition, ΔkdmB mutants were sensitive to several cell wall stressors which possibly contributed to the decreased virulence observed on apples. Slight differences in spore production and germination rates of ΔkdmB mutants in vitro did not impact overall diameter growth in culture.
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Affiliation(s)
| | - Omer Barda
- Institute of Postharvest and Food Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
| | - Joanna Tannous
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Dean Frawley
- Faculty of Science and Engineering, National University of Ireland Maynooth, Kildare, Ireland
| | - Özgür Bayram
- Faculty of Science and Engineering, National University of Ireland Maynooth, Kildare, Ireland
| | - Dov Prusky
- Institute of Postharvest and Food Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
| | - Edward Sionov
- Institute of Postharvest and Food Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
| | - Nancy P Keller
- Department of Plant Pathology, University of Wisconsin, Madison, WI, USA; Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA.
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3
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Sasse C, Bastakis E, Bakti F, Höfer AM, Zangl I, Schüller C, Köhler AM, Gerke J, Krappmann S, Finkernagel F, Harting R, Strauss J, Heimel K, Braus GH. Induction of Aspergillus fumigatus zinc cluster transcription factor OdrA/Mdu2 provides combined cellular responses for oxidative stress protection and multiple antifungal drug resistance. mBio 2023; 14:e0262823. [PMID: 37982619 PMCID: PMC10746196 DOI: 10.1128/mbio.02628-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 10/06/2023] [Indexed: 11/21/2023] Open
Abstract
IMPORTANCE An overexpression screen of 228 zinc cluster transcription factor encoding genes of A. fumigatus revealed 11 genes conferring increased tolerance to antifungal drugs. Out of these, four oxidative stress and drug tolerance transcription factor encoding odr genes increased tolerance to oxidative stress and antifungal drugs when overexpressed. This supports a correlation between oxidative stress response and antifungal drug tolerance in A. fumigatus. OdrA/Mdu2 is required for the cross-tolerance between azoles, polyenes, and oxidative stress and activates genes for detoxification. Under oxidative stress conditions or when overexpressed, OdrA/Mdu2 accumulates in the nucleus and activates detoxifying genes by direct binding at their promoters, as we describe with the mdr1 gene encoding an itraconazole specific efflux pump. Finally, this work gives new insights about drug and stress resistance in the opportunistic pathogenic fungus A. fumigatus.
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Affiliation(s)
- Christoph Sasse
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Emmanouil Bastakis
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Fruzsina Bakti
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Annalena M. Höfer
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Isabella Zangl
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Campus, Tulln, Austria
- Core Facility Bioactive Molecules–Screening and Analysis, University of Natural Resources and Life Sciences, Vienna (BOKU), Austria
| | - Christoph Schüller
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Campus, Tulln, Austria
- Core Facility Bioactive Molecules–Screening and Analysis, University of Natural Resources and Life Sciences, Vienna (BOKU), Austria
| | - Anna M. Köhler
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Jennifer Gerke
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Sven Krappmann
- Institute of Microbiology–Clinical Microbiology, Immunology and Hygiene, University Hospital Erlangen and Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
- Center for Infection Research (ECI) and Medical Immunology Campus Erlangen (MICE), Erlangen, Germany
| | - Florian Finkernagel
- Center for Tumor Biology and Immunology, Core Facility Bioinformatics, Philipps University, Marburg, Germany
| | - Rebekka Harting
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Joseph Strauss
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Campus, Tulln, Austria
| | - Kai Heimel
- Department of Microbial Cell Biology, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
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Klugherz I, Basch M, Ng N, Zhu Z, Wagener N, Wagener J. Only One of Three Bcs1 Homologs in Aspergillus fumigatus Confers Respiratory Growth. J Fungi (Basel) 2023; 9:1074. [PMID: 37998879 PMCID: PMC10672213 DOI: 10.3390/jof9111074] [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: 10/04/2023] [Revised: 10/23/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023] Open
Abstract
The mitochondrial translocase Bcs1 is required for the correct assembly of complex III of the mitochondrial respiratory chain. Because of its importance, Bcs1 was recently proposed as a target for antifungal agents. The function of this AAA (ATPase Associated with diverse cellular Activities) protein has been extensively characterized in Saccharomyces cerevisiae. This yeast as well as previously studied mammals each encode only one homolog. In contrast, the pathogenic mold Aspergillus fumigatus encodes three putative Bcs1 homologs, none of which have been characterized to date. To study the role of these three homologs in A. fumigatus, conditional and deletion mutants of the respective genes AFUA_3G13000 (bcs1A), AFUA_4G01260 (bcs1B), and AFUA_2G14760 (bcs1C) were generated. A deletion or downregulation of bcs1A resulted in drastically reduced growth and sporulation rates and in a significantly altered susceptibility to azole antifungals. In contrast, mutants lacking Bcs1B or Bcs1C did not show any phenotypes differing from the wild type. Salicylhydroxamic acid-an inhibitor of the alternative oxidase that allows the respiratory chain to bypass complex III in some species-caused a complete growth arrest of the bcs1A deletion mutant. In a Galleria mellonella infection model, the deletion of bcs1A resulted in significantly decreased virulence. Only Bcs1A was able to partially complement a deletion of BCS1 in S. cerevisiae. The subcellular localization of Bcs1B and Bcs1C outside of mitochondria suggests that these Bcs1 homologs exert cellular functions different from that of Bcs1. Our data demonstrate that Bcs1A is the sole Bcs1 ortholog in A. fumigatus.
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Affiliation(s)
- Isabel Klugherz
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Marion Basch
- Zell- und Entwicklungsbiologie, Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152 Munich, Germany
| | - Natanya Ng
- Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, The University of Dublin, St James’s Hospital Campus, D08 RX0X Dublin, Ireland
| | - Zhaojun Zhu
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
| | - Nikola Wagener
- Zell- und Entwicklungsbiologie, Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152 Munich, Germany
| | - Johannes Wagener
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
- Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, The University of Dublin, St James’s Hospital Campus, D08 RX0X Dublin, Ireland
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Bakti F, Stupperich H, Schmitt K, Valerius O, Köhler AM, Meister C, Strohdiek A, Harting R, Sasse C, Heimel K, Neumann P, Ficner R, Braus GH. Fungal COP9 signalosome assembly requires connection of two trimeric intermediates for integration of intrinsic deneddylase. Proc Natl Acad Sci U S A 2023; 120:e2305049120. [PMID: 37603767 PMCID: PMC10477865 DOI: 10.1073/pnas.2305049120] [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: 03/29/2023] [Accepted: 08/01/2023] [Indexed: 08/23/2023] Open
Abstract
The conserved eight-subunit COP9 signalosome (CSN) is required for multicellular fungal development. The CSN deneddylase cooperates with the Cand1 exchange factor to control replacements of E3 ubiquitin cullin RING ligase receptors, providing specificity to eukaryotic protein degradation. Aspergillus nidulans CSN assembles through a heptameric pre-CSN, which is activated by integration of the catalytic CsnE deneddylase. Combined genetic and biochemical approaches provided the assembly choreography within a eukaryotic cell for native fungal CSN. Interactomes of functional GFP-Csn subunit fusions in pre-CSN deficient fungal strains were compared by affinity purifications and mass spectrometry. Two distinct heterotrimeric CSN subcomplexes were identified as pre-CSN assembly intermediates. CsnA-C-H and CsnD-F-G form independently of CsnB, which connects the heterotrimers to a heptamer and enables subsequent integration of CsnE to form the enzymatically active CSN complex. Surveillance mechanisms control accurate Csn subunit amounts and correct cellular localization for sequential assembly since deprivation of Csn subunits changes the abundance and location of remaining Csn subunits.
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Affiliation(s)
- Fruzsina Bakti
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Helena Stupperich
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Anna M. Köhler
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Cindy Meister
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Anja Strohdiek
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Rebekka Harting
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Christoph Sasse
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Kai Heimel
- Department of Microbial Cell Biology, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Piotr Neumann
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Goettingen Center for Molecular Biosciences, University of Goettingen, 37077Goettingen, Germany
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Chen Z, Zhang C, Pei L, Qian Q, Lu L. Production of L-Malic Acid by Metabolically Engineered Aspergillus nidulans Based on Efficient CRISPR-Cas9 and Cre- loxP Systems. J Fungi (Basel) 2023; 9:719. [PMID: 37504708 PMCID: PMC10381526 DOI: 10.3390/jof9070719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023] Open
Abstract
Aspergillus nidulans has been more extensively characterized than other Aspergillus species considering its morphology, physiology, metabolic pathways, and genetic regulation. As it has a rapid growth rate accompanied by simple nutritional requirements and a high tolerance to extreme cultural conditions, A. nidulans is a promising microbial cell factory to biosynthesize various products in industry. However, it remains unclear for whether it is also a suitable host for synthesizing abundant L-malic acid. In this study, we developed a convenient and efficient double-gene-editing system in A. nidulans strain TN02A7 based on the CRISPR-Cas9 and Cre-loxP systems. Using this gene-editing system, we made a L-malic acid-producing strain, ZQ07, derived from TN02A7, by deleting or overexpressing five genes (encoding Pyc, pyruvate carboxylase; OahA, oxaloacetate acetylhydrolase; MdhC, malate dehydrogenase; DctA, C4-dicarboxylic acid transporter; and CexA, citric acid transporter). The L-malic acid yield in ZQ07 increased to approximately 9.6 times higher (up to 30.7 g/L titer) than that of the original unedited strain TN02A7, in which the production of L-malic acid was originally very low. The findings in this study not only demonstrate that A. nidulans could be used as a potential host for biosynthesizing organic acids, but also provide a highly efficient gene-editing strategy in filamentous fungi.
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Affiliation(s)
- Ziqing Chen
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Chi Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Lingling Pei
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Qi Qian
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Centre for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
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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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Almaliki HS, Niu M, Keller NP, Yin G, Bennett JW. Mutational Analysis of Aspergillus fumigatus Volatile Oxylipins in a Drosophila Eclosion Assay. J Fungi (Basel) 2023; 9:jof9040402. [PMID: 37108857 PMCID: PMC10143813 DOI: 10.3390/jof9040402] [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: 02/02/2023] [Revised: 03/19/2023] [Accepted: 03/21/2023] [Indexed: 04/29/2023] Open
Abstract
Aspergillus fumigatus is a ubiquitous opportunistic pathogen. We have previously reported that volatile organic compounds (VOCs) produced by A. fumigatus cause delays in metamorphosis, morphological abnormalities, and death in a Drosophila melanogaster eclosion model. Here, we developed A. fumigatus deletion mutants with blocked oxylipin biosynthesis pathways (∆ppoABC) and then exposed the third instar larvae of D. melanogaster to a shared atmosphere with either A. fumigatus wild-type or oxylipin mutant cultures for 15 days. Fly larvae exposed to VOCs from wild-type A. fumigatus strains exhibited delays in metamorphosis and toxicity, while larvae exposed to VOCs from the ∆ppoABC mutant displayed fewer morphogenic delays and higher eclosion rates than the controls. In general, when fungi were pre-grown at 37 °C, the effects of the VOCs they produced were more pronounced than when they were pre-grown at 25 °C. GC-MS analysis revealed that the wild-type A. fumigatus Af293 produced more abundant VOCs at higher concentrations than the oxylipin-deficient strain Af293∆ppoABC did. The major VOCs detected from wild-type Af293 and its triple mutant included isopentyl alcohol, isobutyl alcohol, 2-methylbutanal, acetoin, and 1-octen-3-ol. Unexpectedly, compared to wild-type flies, the eclosion tests yielded far fewer differences in metamorphosis or viability when flies with immune-deficient genotypes were exposed to VOCs from either wild-type or ∆ppoABC oxylipin mutants. In particular, the toxigenic effects of Aspergillus VOCs were not observed in mutant flies deficient in the Toll (spz6) pathway. These data indicate that the innate immune system of Drosophila mediates the toxicity of fungal volatiles, especially via the Toll pathway.
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Affiliation(s)
- Hadeel S Almaliki
- Technical Institute of Samawa, Al-Furat Al-Awsat Technical University, Samawa 66001, Iraq
| | - Mengyao Niu
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Guohua Yin
- Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agricultural Sciences in Weifang, Weifang 261325, China
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Joan W Bennett
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
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9
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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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10
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Online Biomass Monitoring Enables Characterization of the Growth Pattern of Aspergillus fumigatus in Liquid Shake Conditions. J Fungi (Basel) 2022; 8:jof8101013. [PMID: 36294578 PMCID: PMC9605507 DOI: 10.3390/jof8101013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 12/02/2022] Open
Abstract
Numerous filamentous fungal species are extensively studied due to their role as model organisms, workhorses in biotechnology, or as pathogens for plants, animals, and humans. Growth studies are mainly carried out on solid media. However, studies concerning gene expression, biochemistry, or metabolism are carried out usually in liquid shake conditions, which do not correspond to the growth pattern on solid media. The reason for this practice is the problem of on-line growth monitoring of filamentous fungal species, which usually form pellets in liquid shake cultures. Here, we compared the time-consuming and tedious process of dry-weight determination of the mold Aspergillus fumigatus with online monitoring of biomass in liquid shake culture by the parallelizable CGQ (“cell growth quantifier”), which implements dynamic biomass determination by backscattered light measurement. The results revealed a strong correlation of CGQ-mediated growth monitoring and classical biomass measurement of A. fumigatus grown over a time course. Moreover, CGQ-mediated growth monitoring displayed the difference in growth of A. fumigatus in response to the limitation of iron or nitrogen as well as the growth defects of previously reported mutant strains (ΔhapX, ΔsrbA). Furthermore, the frequently used wild-type strain Af293 showed largely decreased and delayed growth in liquid shake cultures compared to other strains (AfS77, A1160p+, AfS35). Taken together, the CGQ allows for robust, automated biomass monitoring of A. fumigatus during liquid shake conditions, which largely facilitates the characterization of the growth pattern of filamentous fungal species.
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11
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Won TH, Bok JW, Nadig N, Venkatesh N, Nickles G, Greco C, Lim FY, González JB, Turgeon BG, Keller NP, Schroeder FC. Copper starvation induces antimicrobial isocyanide integrated into two distinct biosynthetic pathways in fungi. Nat Commun 2022; 13:4828. [PMID: 35973982 PMCID: PMC9381783 DOI: 10.1038/s41467-022-32394-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/29/2022] [Indexed: 01/26/2023] Open
Abstract
The genomes of many filamentous fungi, such as Aspergillus spp., include diverse biosynthetic gene clusters of unknown function. We previously showed that low copper levels upregulate a gene cluster that includes crmA, encoding a putative isocyanide synthase. Here we show, using untargeted comparative metabolomics, that CrmA generates a valine-derived isocyanide that contributes to two distinct biosynthetic pathways under copper-limiting conditions. Reaction of the isocyanide with an ergot alkaloid precursor results in carbon-carbon bond formation analogous to Strecker amino-acid synthesis, producing a group of alkaloids we term fumivalines. In addition, valine isocyanide contributes to biosynthesis of a family of acylated sugar alcohols, the fumicicolins, which are related to brassicicolin A, a known isocyanide from Alternaria brassicicola. CrmA homologs are found in a wide range of pathogenic and non-pathogenic fungi, some of which produce fumicicolin and fumivaline. Extracts from A. fumigatus wild type (but not crmA-deleted strains), grown under copper starvation, inhibit growth of diverse bacteria and fungi, and synthetic valine isocyanide shows antibacterial activity. CrmA thus contributes to two biosynthetic pathways downstream of trace-metal sensing.
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Affiliation(s)
- Tae Hyung Won
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Jin Woo Bok
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nischala Nadig
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nandhitha Venkatesh
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Grant Nickles
- Department of Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Claudio Greco
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Molecular Microbiology, John Innes Centre, Norwich, NR4 7UH, United Kingdom
| | - Fang Yun Lim
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Jennifer B González
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, USA
- 104 Peckham Hall, Nazareth College, 4245 East Avenue, Rochester, NY, USA
| | - B Gillian Turgeon
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
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Strong PJ, Self R, Allikian K, Szewczyk E, Speight R, O'Hara I, Harrison MD. Filamentous fungi for future functional food and feed. Curr Opin Biotechnol 2022; 76:102729. [PMID: 35525176 DOI: 10.1016/j.copbio.2022.102729] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/16/2022] [Accepted: 03/29/2022] [Indexed: 11/19/2022]
Abstract
In this review, we offer our opinion of current and expected trends regarding the use of mushrooms and mycelia in food and feed. Mushrooms have provided food for millennia and production methods and species diversity have recently expanded. Beyond mushrooms, cultured fungal mycelia are now harvested as a primary product for food. Mushrooms and mycelia provide dietary protein, lipids and fatty acids, vitamins, fibre, and flavour, and can improve the organoleptic properties of processed foods (including meat analogues). Further, they are often key ingredients in nutritional or therapeutic supplements because of diverse specialised metabolites. Mycelia can also improve feed conversion efficiency, gut health, and wellbeing in livestock. New molecular tools, coupled with quality genetic data, are improving production technologies, enabling the synthesis of specialised metabolites, and creating new processing and valorisation opportunities. Production systems for submerged culture are capital intensive, but investment is required considering the scale of the protein market.
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Affiliation(s)
- Peter James Strong
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; School of Biology and Environmental Sciences, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; ARC Centre of Excellence in Synthetic Biology, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
| | - Rachel Self
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; School of Biology and Environmental Sciences, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia
| | - Kathrine Allikian
- Nourish Ingredients, Unit 2, 6 Pelle Street, Mitchell, Canberra, Australian Capital Territory 2911, Australia
| | - Edyta Szewczyk
- Bolt Threads, 5858 Horton St, Suite 400, Emeryville, CA 94608, United States
| | - Robert Speight
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; School of Biology and Environmental Sciences, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; ARC Centre of Excellence in Synthetic Biology, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Ian O'Hara
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; ARC Centre of Excellence in Synthetic Biology, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia
| | - Mark D Harrison
- Centre for Agriculture and the Bioeconomy, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia; School of Biology and Environmental Sciences, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia
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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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14
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Leisen T, Werner J, Pattar P, Safari N, Ymeri E, Sommer F, Schroda M, Suárez I, Collado IG, Scheuring D, Hahn M. Multiple knockout mutants reveal a high redundancy of phytotoxic compounds contributing to necrotrophic pathogenesis of Botrytis cinerea. PLoS Pathog 2022; 18:e1010367. [PMID: 35239739 PMCID: PMC8923502 DOI: 10.1371/journal.ppat.1010367] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 03/15/2022] [Accepted: 02/12/2022] [Indexed: 11/19/2022] Open
Abstract
Botrytis cinerea is a major plant pathogen infecting more than 1400 plant species. During invasion, the fungus rapidly kills host cells, which is believed to be supported by induction of programmed plant cell death. To comprehensively evaluate the contributions of most of the currently known plant cell death inducing proteins (CDIPs) and metabolites for necrotrophic infection, an optimized CRISPR/Cas9 protocol was established which allowed to perform serial marker-free mutagenesis to generate multiple deletion mutants lacking up to 12 CDIPs. Whole genome sequencing of a 6x and 12x deletion mutant revealed a low number of off-target mutations which were unrelated to Cas9-mediated cleavage. Secretome analyses confirmed the loss of secreted proteins encoded by the deleted genes. Infection tests with the mutants revealed a successive decrease in virulence with increasing numbers of mutated genes, and varying effects of the knockouts on different host plants. Comparative analysis of mutants confirmed significant roles of two polygalacturonases (PG1, PG2) and the phytotoxic metabolites botrydial and botcinins for infection, but revealed no or only weak effects of deletion of the other CDIPs. Nicotiana benthamiana plants with mutated or silenced coreceptors of pattern recognition receptors, SOBIR1 and BAK1, showed similar susceptibility as control plants to infection by B. cinerea wild type and a 12x deletion mutant. These results raise doubts about a major role of manipulation of these plant defence regulators for B. cinerea infection. Despite the loss of most of the known phytotoxic compounds, the on planta secretomes of the multiple mutants retained substantial phytotoxic activity, proving that further, as yet unknown CDIPs contribute to necrosis and virulence. Our study has addressed for the first time systematically the functional redundancy of fungal virulence factors, and demonstrates that B. cinerea releases a highly redundant cocktail of proteins to achieve necrotrophic infection of a wide variety of host plants.
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Affiliation(s)
- Thomas Leisen
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Janina Werner
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Patrick Pattar
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Nassim Safari
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Edita Ymeri
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Frederik Sommer
- Department of Biology, Molecular Biotechnology & Systems Biology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Michael Schroda
- Department of Biology, Molecular Biotechnology & Systems Biology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Ivonne Suárez
- Departamento de Biomedicina, Biotecnología y Salud Pública, Laboratorio de Microbiología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Puerto Real, Cádiz, Spain
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real, Cádiz, Spain
| | - Isidro G. Collado
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real, Cádiz, Spain
| | - David Scheuring
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Matthias Hahn
- Department of Biology, Phytopathology group, Technische Universität Kaiserslautern, Kaiserslautern, Germany
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15
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Thrikawala S, Niu M, Keller NP, Rosowski EE. Cyclooxygenase production of PGE2 promotes phagocyte control of A. fumigatus hyphal growth in larval zebrafish. PLoS Pathog 2022; 18:e1010040. [PMID: 35333905 PMCID: PMC8986117 DOI: 10.1371/journal.ppat.1010040] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/06/2022] [Accepted: 03/03/2022] [Indexed: 11/30/2022] Open
Abstract
Invasive aspergillosis is a common opportunistic infection, causing >50% mortality in infected immunocompromised patients. The specific molecular mechanisms of the innate immune system that prevent pathogenesis of invasive aspergillosis in immunocompetent individuals are not fully understood. Here, we used a zebrafish larva-Aspergillus infection model to identify cyclooxygenase (COX) enzyme signaling as one mechanism that promotes host survival. Larvae exposed to the pan-COX inhibitor indomethacin succumb to infection at a significantly higher rate than control larvae. COX signaling is both macrophage- and neutrophil-mediated. However, indomethacin treatment has no effect on phagocyte recruitment. Instead, COX signaling promotes phagocyte-mediated inhibition of germination and invasive hyphal growth. Increased germination and invasive hyphal growth is also observed in infected F0 crispant larvae with mutations in genes encoding for COX enzymes (ptgs2a/b). Protective COX-mediated signaling requires the receptor EP2 and exogenous prostaglandin E2 (PGE2) rescues indomethacin-induced decreased immune control of fungal growth. Collectively, we find that COX signaling activates the PGE2-EP2 pathway to increase control A. fumigatus hyphal growth by phagocytes in zebrafish larvae.
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Affiliation(s)
- Savini Thrikawala
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Mengyao Niu
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nancy P. Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Emily E. Rosowski
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
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16
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Gerke J, Köhler AM, Wennrich JP, Große V, Shao L, Heinrich AK, Bode HB, Chen W, Surup F, Braus GH. Biosynthesis of Antibacterial Iron-Chelating Tropolones in Aspergillus nidulans as Response to Glycopeptide-Producing Streptomycetes. FRONTIERS IN FUNGAL BIOLOGY 2022; 2:777474. [PMID: 37744088 PMCID: PMC10512232 DOI: 10.3389/ffunb.2021.777474] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/06/2021] [Indexed: 09/26/2023]
Abstract
The soil microbiome comprises numerous filamentous fungi and bacteria that mutually react and challenge each other by the production of bioactive secondary metabolites. Herein, we show in liquid co-cultures that the presence of filamentous Streptomycetes producing antifungal glycopeptide antibiotics induces the production of the antibacterial and iron-chelating tropolones anhydrosepedonin (1) and antibiotic C (2) in the mold Aspergillus nidulans. Additionally, the biosynthesis of the related polyketide tripyrnidone (5) was induced, whose novel tricyclic scaffold we elucidated by NMR and HRESIMS data. The corresponding biosynthetic polyketide synthase-encoding gene cluster responsible for the production of these compounds was identified. The tropolones as well as tripyrnidone (5) are produced by genes that belong to the broad reservoir of the fungal genome for the synthesis of different secondary metabolites, which are usually silenced under standard laboratory conditions. These molecules might be part of the bacterium-fungus competition in the complex soil environment, with the bacterial glycopeptide antibiotic as specific environmental trigger for fungal induction of this cluster.
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Affiliation(s)
- Jennifer Gerke
- Department of Moleuclar Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-Universität Göttingen, Göttingen, Germany
| | - Anna M. Köhler
- Department of Moleuclar Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-Universität Göttingen, Göttingen, Germany
| | - Jan-Peer Wennrich
- Microbial Drugs Department, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, Germany
| | - Verena Große
- Department of Moleuclar Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-Universität Göttingen, Göttingen, Germany
| | - Lulu Shao
- Microbial Drugs Department, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, Germany
| | - Antje K. Heinrich
- Molecular Biotechnology, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Helge B. Bode
- Molecular Biotechnology, Goethe University Frankfurt, Frankfurt am Main, Germany
- Department of Natural Products in Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Wanping Chen
- Department of Moleuclar Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-Universität Göttingen, Göttingen, Germany
| | - Frank Surup
- Microbial Drugs Department, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, Germany
| | - Gerhard H. Braus
- Department of Moleuclar Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-Universität Göttingen, Göttingen, Germany
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17
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Nickles G, Ludwikoski I, Bok JW, Keller NP. Comprehensive Guide to Extracting and Expressing Fungal Secondary Metabolites with Aspergillus fumigatus as a Case Study. Curr Protoc 2021; 1:e321. [PMID: 34958718 DOI: 10.1002/cpz1.321] [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: 11/06/2022]
Abstract
Fungal secondary metabolites (SMs) have captured the interest of natural products researchers in academia and industry for decades. In recent years, the high rediscovery rate of previously characterized metabolites is making it increasingly difficult to uncover novel compounds. Additionally, the vast majority of fungal SMs reside in genetically intractable fungi or are silent under normal laboratory conditions in genetically tractable fungi. The fungal natural products community has broadly overcome these barriers by altering the physical growth conditions of the fungus and heterologous/homologous expression of biosynthetic gene cluster regulators or proteins. The protocols described here summarize vital methodologies needed when researching SM production in fungi. We also summarize the growth conditions, genetic backgrounds, and extraction protocols for every published SM in Aspergillus fumigatus, enabling readers to easily replicate the production of previously characterized SMs. Readers will also be equipped with the tools for developing their own strategy for expressing and extracting SMs from their given fungus or a suitable heterologous model system. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Making glycerol stocks from spore suspensions Alternate Protocol 1: Creating glycerol stocks from non-sporulating filamentous fungi Basic Protocol 2: Activating spore-suspension glycerol stocks Basic Protocol 3: Extracting secondary metabolites from Aspergillus spp grown on solid medium Alternate Protocol 2: Extracting secondary metabolites from Aspergillus spp using ethyl acetate Alternate Protocol 3: High-volume metabolite extraction using ethyl acetate Alternate Protocol 4: Extracting secondary metabolites from Aspergillus spp in liquid medium Support Protocol: Creating an overlay culture Basic Protocol 4: Extracting DNA from filamentous fungi Basic Protocol 5: Creating a DNA construct with double-joint PCR Alternate Protocol 5: Creating a DNA construct with yeast recombineering Basic Protocol 6: Transformation of Aspergillus spp Basic Protocol 7: Co-culturing fungi and bacteria for extraction of secondary metabolites.
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Affiliation(s)
- Grant Nickles
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Isabelle Ludwikoski
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jin Woo Bok
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin
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Pleiotropic Effects of the P5-Type ATPase SpfA on Stress Response Networks Contribute to Virulence in the Pathogenic Mold Aspergillus fumigatus. mBio 2021; 12:e0273521. [PMID: 34663092 PMCID: PMC8524344 DOI: 10.1128/mbio.02735-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus is a human-pathogenic mold that extracts nutrients from the environment or from host tissues by secreting hydrolytic enzymes. The ability of A. fumigatus to adjust secretion levels in proportion to demand relies on the assistance of the unfolded protein response (UPR), an adaptive stress response pathway that regulates the unique protein-folding environment of the endoplasmic reticulum (ER). The P5-type ATPase Spf1 has recently been implicated in a novel mechanism of ER homeostasis that involves correcting errors in ER-membrane protein targeting. However, the contribution of this protein to the biology of A. fumigatus is unknown. Here, we employed a gene knockout and RNA sequencing strategy to determine the functional role of the A. fumigatus gene coding for the orthologous P5 ATPase SpfA. The data reveal that the spfA gene is induced by ER stress in a UPR-dependent manner. In the absence of spfA, the A. fumigatus transcriptome shifts toward a profile of altered redox and lipid balance, in addition to a signature of ER stress that includes srcA, encoding a second P-type ATPase in the ER. A ΔspfA deletion mutant showed increased sensitivity to ER stress, oxidative stress, and antifungal drugs that target the cell wall or plasma membrane. The combined loss of spfA and srcA exacerbated these phenotypes and attenuated virulence in two animal infection models. These findings demonstrate that the ER-resident ATPases SpfA and SrcA act jointly to support diverse adaptive functions of the ER that are necessary for fitness in the host environment. IMPORTANCE The fungal UPR is an adaptive signaling pathway in the ER that buffers fluctuations in ER stress but also serves as a virulence regulatory hub in species of pathogenic fungi that rely on secretory pathway homeostasis for pathogenicity. This study demonstrates that the gene encoding the ER-localized P5-type ATPase SpfA is a downstream target of the UPR in the pathogenic mold A. fumigatus and that it works together with a second ER-localized P-type ATPase, SrcA, to support ER homeostasis, oxidative stress resistance, susceptibility to antifungal drugs, and virulence of A. fumigatus.
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Liu L, Sasse C, Dirnberger B, Valerius O, Fekete-Szücs E, Harting R, Nordzieke DE, Pöggeler S, Karlovsky P, Gerke J, Braus GH. Secondary metabolites of Hülle cells mediate protection of fungal reproductive and overwintering structures against fungivorous animals. eLife 2021; 10:68058. [PMID: 34635205 PMCID: PMC8510581 DOI: 10.7554/elife.68058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 09/04/2021] [Indexed: 12/14/2022] Open
Abstract
Fungal Hülle cells with nuclear storage and developmental backup functions are reminiscent of multipotent stem cells. In the soil, Hülle cells nurse the overwintering fruiting bodies of Aspergillus nidulans. The genome of A. nidulans harbors genes for the biosynthesis of xanthones. We show that enzymes and metabolites of this biosynthetic pathway accumulate in Hülle cells under the control of the regulatory velvet complex, which coordinates development and secondary metabolism. Deletion strains blocked in the conversion of anthraquinones to xanthones accumulate emodins and are delayed in maturation and growth of fruiting bodies. Emodin represses fruiting body and resting structure formation in other fungi. Xanthones are not required for sexual development but exert antifeedant effects on fungivorous animals such as springtails and woodlice. Our findings reveal a novel role of Hülle cells in establishing secure niches for A. nidulans by accumulating metabolites with antifeedant activity that protect reproductive structures from animal predators.
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Affiliation(s)
- Li Liu
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Christoph Sasse
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Benedict Dirnberger
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Oliver Valerius
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Enikő Fekete-Szücs
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Rebekka Harting
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Daniela E Nordzieke
- University of Göttingen, Genetics of Eukaryotic Microorganisms and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Stefanie Pöggeler
- University of Göttingen, Genetics of Eukaryotic Microorganisms and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Petr Karlovsky
- University of Göttingen, Molecular Phytopathology and Mycotoxin Research, Göttingen, Germany
| | - Jennifer Gerke
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
| | - Gerhard H Braus
- University of Göttingen, Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Göttingen, Germany
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20
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Aguiar M, Orasch T, Misslinger M, Dietl AM, Gsaller F, Haas H. The Siderophore Transporters Sit1 and Sit2 Are Essential for Utilization of Ferrichrome-, Ferrioxamine- and Coprogen-Type Siderophores in Aspergillus fumigatus. J Fungi (Basel) 2021; 7:768. [PMID: 34575806 PMCID: PMC8470733 DOI: 10.3390/jof7090768] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/18/2022] Open
Abstract
Siderophore-mediated acquisition of iron has been shown to be indispensable for the virulence of several fungal pathogens, the siderophore transporter Sit1 was found to mediate uptake of the novel antifungal drug VL-2397, and siderophores were shown to be useful as biomarkers as well as for imaging of fungal infections. However, siderophore uptake in filamentous fungi is poorly characterized. The opportunistic human pathogen Aspergillus fumigatus possesses five putative siderophore transporters. Here, we demonstrate that the siderophore transporters Sit1 and Sit2 have overlapping, as well as unique, substrate specificities. With respect to ferrichrome-type siderophores, the utilization of ferrirhodin and ferrirubin depended exclusively on Sit2, use of ferrichrome A depended mainly on Sit1, and utilization of ferrichrome, ferricrocin, and ferrichrysin was mediated by both transporters. Moreover, both Sit1 and Sit2 mediated use of the coprogen-type siderophores coprogen and coprogen B, while only Sit1 transported the bacterial ferrioxamine-type xenosiderophores ferrioxamines B, G, and E. Neither Sit1 nor Sit2 were important for the utilization of the endogenous siderophores fusarinine C and triacetylfusarinine C. Furthermore, A. fumigatus was found to lack utilization of the xenosiderophores schizokinen, basidiochrome, rhizoferrin, ornibactin, rhodotorulic acid, and enterobactin. Taken together, this study characterized siderophore use by A. fumigatus and substrate characteristics of Sit1 and Sit2.
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Affiliation(s)
| | | | | | | | | | - Hubertus Haas
- Institute of Molecular Biology/Biocenter, Medical University of Innsbruck, A-6020 Innsbruck, Austria; (M.A.); (T.O.); (M.M.); (A.-M.D.); (F.G.)
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21
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Misslinger M, Petrik M, Pfister J, Hubmann I, Bendova K, Decristoforo C, Haas H. Desferrioxamine B-Mediated Pre-Clinical In Vivo Imaging of Infection by the Mold Fungus Aspergillus fumigatus. J Fungi (Basel) 2021; 7:734. [PMID: 34575772 PMCID: PMC8472378 DOI: 10.3390/jof7090734] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/26/2021] [Accepted: 09/04/2021] [Indexed: 12/16/2022] Open
Abstract
Fungal infections are a serious threat, especially for immunocompromised patients. Early and reliable diagnosis is crucial to treat such infections. The bacterially produced siderophore desferrioxamine B (DFO-B) is utilized by a variety of microorganisms for iron acquisition, while mammalian cells lack the uptake of DFO-B chelates. DFO-B is clinically approved for a variety of long-term chelation therapies. Recently, DFO-B-complexed gallium-68 ([68Ga]Ga-DFO-B) was shown to enable molecular imaging of bacterial infections by positron emission tomography (PET). Here, we demonstrate that [68Ga]Ga-DFO-B can also be used for the preclinical molecular imaging of pulmonary infection caused by the fungal pathogen Aspergillus fumigatus in a rat aspergillosis model. Moreover, by combining in vitro uptake studies and the chemical modification of DFO-B, we show that the cellular transport efficacy of ferrioxamine-type siderophores is impacted by the charge of the molecule and, consequently, the environmental pH. The chemical derivatization has potential implications for its diagnostic use and characterizes transport features of ferrioxamine-type siderophores.
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Affiliation(s)
- Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria;
| | - Milos Petrik
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77900 Olomouc, Czech Republic; (M.P.); (K.B.)
| | - Joachim Pfister
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (J.P.); (I.H.)
| | - Isabella Hubmann
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (J.P.); (I.H.)
| | - Katerina Bendova
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77900 Olomouc, Czech Republic; (M.P.); (K.B.)
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (J.P.); (I.H.)
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria;
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22
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Arastehfar A, Carvalho A, Houbraken J, Lombardi L, Garcia-Rubio R, Jenks J, Rivero-Menendez O, Aljohani R, Jacobsen I, Berman J, Osherov N, Hedayati M, Ilkit M, Armstrong-James D, Gabaldón T, Meletiadis J, Kostrzewa M, Pan W, Lass-Flörl C, Perlin D, Hoenigl M. Aspergillus fumigatus and aspergillosis: From basics to clinics. Stud Mycol 2021; 100:100115. [PMID: 34035866 PMCID: PMC8131930 DOI: 10.1016/j.simyco.2021.100115] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The airborne fungus Aspergillus fumigatus poses a serious health threat to humans by causing numerous invasive infections and a notable mortality in humans, especially in immunocompromised patients. Mould-active azoles are the frontline therapeutics employed to treat aspergillosis. The global emergence of azole-resistant A. fumigatus isolates in clinic and environment, however, notoriously limits the therapeutic options of mould-active antifungals and potentially can be attributed to a mortality rate reaching up to 100 %. Although specific mutations in CYP 51A are the main cause of azole resistance, there is a new wave of azole-resistant isolates with wild-type CYP 51A genotype challenging the efficacy of the current diagnostic tools. Therefore, applications of whole-genome sequencing are increasingly gaining popularity to overcome such challenges. Prominent echinocandin tolerance, as well as liver and kidney toxicity posed by amphotericin B, necessitate a continuous quest for novel antifungal drugs to combat emerging azole-resistant A. fumigatus isolates. Animal models and the tools used for genetic engineering require further refinement to facilitate a better understanding about the resistance mechanisms, virulence, and immune reactions orchestrated against A. fumigatus. This review paper comprehensively discusses the current clinical challenges caused by A. fumigatus and provides insights on how to address them.
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Affiliation(s)
- A. Arastehfar
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - A. Carvalho
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B's - PT Government Associate Laboratory, Guimarães/Braga, Portugal
| | - J. Houbraken
- Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands
| | - L. Lombardi
- UCD Conway Institute and School of Medicine, University College Dublin, Dublin 4, Ireland
| | - R. Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - J.D. Jenks
- Department of Medicine, University of California San Diego, San Diego, CA, 92103, USA
- Clinical and Translational Fungal-Working Group, University of California San Diego, La Jolla, CA, 92093, USA
| | - O. Rivero-Menendez
- Medical Mycology Reference Laboratory, National Center for Microbiology, Instituto de Salud Carlos III, Madrid, 28222, Spain
| | - R. Aljohani
- Department of Infectious Diseases, Imperial College London, London, UK
| | - I.D. Jacobsen
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology—Hans Knöll Institute, Jena, Germany
- Institute for Microbiology, Friedrich Schiller University, Jena, Germany
| | - J. Berman
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology—Hans Knöll Institute, Jena, Germany
| | - N. Osherov
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine Ramat-Aviv, Tel-Aviv, 69978, Israel
| | - M.T. Hedayati
- Invasive Fungi Research Center/Department of Medical Mycology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - M. Ilkit
- Division of Mycology, Department of Microbiology, Faculty of Medicine, Çukurova University, 01330, Adana, Turkey
| | | | - T. Gabaldón
- Life Sciences Programme, Supercomputing Center (BSC-CNS), Jordi Girona, Barcelona, 08034, Spain
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB), Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010, Barcelona, Spain
| | - J. Meletiadis
- Clinical Microbiology Laboratory, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | | | - W. Pan
- Medical Mycology, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - C. Lass-Flörl
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - D.S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - M. Hoenigl
- Department of Medicine, University of California San Diego, San Diego, CA, 92103, USA
- Section of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Medical University of Graz, 8036, Graz, Austria
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, San Diego, CA 92093, USA
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23
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Peroxiredoxin Asp f3 Is Essential for Aspergillus fumigatus To Overcome Iron Limitation during Infection. mBio 2021; 12:e0097621. [PMID: 34399627 PMCID: PMC8406167 DOI: 10.1128/mbio.00976-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus is an important fungal pathogen that causes allergic reactions but also life-threatening infections. One of the most abundant A. fumigatus proteins is Asp f3. This peroxiredoxin is a major fungal allergen and known for its role as a virulence factor, vaccine candidate, and scavenger of reactive oxygen species. Based on the hypothesis that Asp f3 protects A. fumigatus against killing by immune cells, we investigated the susceptibility of a conditional aspf3 mutant by employing a novel assay. Surprisingly, Asp f3-depleted hyphae were killed as efficiently as the wild type by human granulocytes. However, we identified an unexpected growth defect of mutants that lack Asp f3 under low-iron conditions, which explains the avirulence of the Δaspf3 deletion mutant in a murine infection model. A. fumigatus encodes two Asp f3 homologues which we named Af3l (Asp f3-like) 1 and Af3l2. Inactivation of Af3l1, but not of Af3l2, exacerbated the growth defect of the conditional aspf3 mutant under iron limitation, which ultimately led to death of the double mutant. Inactivation of the iron acquisition repressor SreA partially compensated for loss of Asp f3 and Af3l1. However, Asp f3 was not required for maintaining iron homeostasis or siderophore biosynthesis. Instead, we show that it compensates for a loss of iron-dependent antioxidant enzymes. Iron supplementation restored the virulence of the Δaspf3 deletion mutant in a murine infection model. Our results unveil the crucial importance of Asp f3 to overcome nutritional immunity and reveal a new biological role of peroxiredoxins in adaptation to iron limitation.
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24
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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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25
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Abstract
The fungal kingdom has provided advances in our ability to identify biosynthetic gene clusters (BGCs) and to examine how gene composition of BGCs evolves across species and genera. However, little is known about the evolution of specific BGC regulators that mediate how BGCs produce secondary metabolites (SMs). A bioinformatics search for conservation of the Aspergillus fumigatus xanthocillin BGC revealed an evolutionary trail of xan-like BGCs across Eurotiales species. Although the critical regulatory and enzymatic genes were conserved in Penicillium expansum, overexpression (OE) of the conserved xan BGC transcription factor (TF) gene, PexanC, failed to activate the putative xan BGC transcription or xanthocillin production in P. expansum, in contrast to the role of AfXanC in A. fumigatus. Surprisingly, OE::PexanC was instead found to promote citrinin synthesis in P. expansum via trans induction of the cit pathway-specific TF, ctnA, as determined by cit BGC expression and chemical profiling of ctnA deletion and OE::PexanC single and double mutants. OE::AfxanC results in significant increases of xan gene expression and metabolite synthesis in A. fumigatus but had no effect on either xanthocillin or citrinin production in P. expansum. Bioinformatics and promoter mutation analysis led to the identification of an AfXanC binding site, 5'-AGTCAGCA-3', in promoter regions of the A. fumigatus xan BGC genes. This motif was not in the ctnA promoter, suggesting a different binding site of PeXanC. A compilation of a bioinformatics examination of XanC orthologs and the presence/absence of the 5'-AGTCAGCA-3' binding motif in xan BGCs in multiple Aspergillus and Penicillium spp. supports an evolutionary divergence of XanC regulatory targets that we speculate reflects an exaptation event in the Eurotiales. IMPORTANCE Fungal secondary metabolites (SMs) are an important source of pharmaceuticals on one hand and toxins on the other. Efforts to identify the biosynthetic gene clusters (BGCs) that synthesize SMs have yielded significant insights into how variation in the genes that compose BGCs may impact subsequent metabolite production within and between species. However, the role of regulatory genes in BGC activation is less well understood. Our finding that the bZIP transcription factor XanC, located in the xanthocillin BGC of both Aspergillus fumigatus and Penicillium expansum, has functionally diverged to regulate different BGCs in these two species emphasizes that the diversification of BGC regulatory elements may sometimes occur through exaptation, which is the co-option of a gene that evolved for one function to a novel function. Furthermore, this work suggests that the loss/gain of transcription factor binding site targets may be an important mediator in the evolution of secondary-metabolism regulatory elements.
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26
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Baldin C, Kühbacher A, Merschak P, Sastré-Velásquez LE, Abt B, Dietl AM, Haas H, Gsaller F. Inducible Selectable Marker Genes to Improve Aspergillus fumigatus Genetic Manipulation. J Fungi (Basel) 2021; 7:506. [PMID: 34202756 PMCID: PMC8305790 DOI: 10.3390/jof7070506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 01/01/2023] Open
Abstract
The hygromycin B phosphotransferase gene from Escherichia coli and the pyrithiamine resistance gene from Aspergillus oryzae are two dominant selectable marker genes widely used to genetically manipulate several fungal species. Despite the recent development of CRISPR/Cas9 and marker-free systems, in vitro molecular tools to study Aspergillus fumigatus, which is a saprophytic fungus causing life-threatening diseases in immunocompromised hosts, still rely extensively on the use of dominant selectable markers. The limited number of drug selectable markers is already a critical aspect, but the possibility that their introduction into a microorganism could induce enhanced virulence or undesired effects on metabolic behavior constitutes another problem. In this context, here, we demonstrate that the use of ptrA in A. fumigatus leads to the secretion of a compound that allows the recovery of thiamine auxotrophy. In this study, we developed a simple modification of the two commonly used dominant markers in which the development of resistance can be controlled by the xylose-inducible promoter PxylP from Penicillium chrysogenum. This strategy provides an easy solution to avoid undesired side effects, since the marker expression can be readily silenced when not required.
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Affiliation(s)
| | | | | | | | | | | | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (C.B.); (A.K.); (P.M.); (L.E.S.-V.); (B.A.); (A.-M.D.)
| | - Fabio Gsaller
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (C.B.); (A.K.); (P.M.); (L.E.S.-V.); (B.A.); (A.-M.D.)
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27
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The response regulator Skn7 of Aspergillus fumigatus is essential for the antifungal effect of fludioxonil. Sci Rep 2021; 11:5317. [PMID: 33674651 PMCID: PMC7935864 DOI: 10.1038/s41598-021-84740-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/18/2021] [Indexed: 01/01/2023] Open
Abstract
Aspergillus fumigatus is an important fungal pathogen that represents a major threat for severely immunocompromised patients. Cases of invasive aspergillosis are associated with a high mortality rate, which reflects the limited treatment options that are currently available. The development of novel therapeutic approaches is therefore an urgent task. An interesting compound is fludioxonil, a derivative of the bacterial secondary metabolite pyrrolnitrin. Both agents possess potent antimicrobial activity against A. fumigatus and trigger a lethal activation of the group III hybrid histidine kinase TcsC, the major sensor kinase of the High Osmolarity Glycerol (HOG) pathway in A. fumigatus. In the current study, we have characterized proteins that operate downstream of TcsC and analyzed their roles in the antifungal activity of fludioxonil and in other stress situations. We found that the SskA-SakA axis of the HOG pathway and Skn7 can independently induce an increase of the internal glycerol concentration, but each of these individual responses amounts for only half of the level found in the wild type. The lethal fludioxonil-induced ballooning occurs in the sskA and the sakA mutant, but not in the skn7-deficient strain, although all three strains show comparable glycerol responses. This indicates that an elevated osmotic pressure is necessary, but not sufficient and that a second, decisive and Skn7-dependent mechanism mediates the antifungal activity. We assume that fludioxonil triggers a reorganization in the fungal cell wall that reduces its rigidity, which in combination with the elevated osmotic pressure executes the lethal expansion of the fungal cells. Two findings link Skn7 to the cell wall of A. fumigatus: (1) the fludioxonil-induced massive increase in the chitin content depends on Skn7 and (2) the skn7 mutant is more resistant to the cell wall stressor Calcofluor white. In conclusion, our data suggest that the antifungal activity of fludioxonil in A. fumigatus relies on two distinct and synergistic processes: A high internal osmotic pressure and a weakened cell wall. The involvement of Skn7 in both processes most likely accounts for its particular importance in the antifungal activity of fludioxonil.
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28
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Dümig M, Binder J, Gaculenko A, Daul F, Winandy L, Hasenberg M, Gunzer M, Fischer R, Künzler M, Krappmann S. The infectious propagules of Aspergillus fumigatus are coated with antimicrobial peptides. Cell Microbiol 2021; 23:e13301. [PMID: 33331054 DOI: 10.1111/cmi.13301] [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: 09/21/2020] [Revised: 12/11/2020] [Accepted: 12/13/2020] [Indexed: 11/29/2022]
Abstract
Fungal spores are unique cells that mediate dispersal and survival in the environment. For pathogenic fungi encountering a susceptible host, these specialised structures may serve as infectious particles. The main causative agent of the opportunistic disease aspergillosis, Aspergillus fumigatus, produces asexual spores, the conidia, that become dissipated by air flows or water currents but also serve as propagules to infect a susceptible host. We demonstrate that the defX gene of this mould encodes putative antimicrobial peptides resembling cysteine-stabilised (CS)αβ defensins that are expressed in a specific spatial and temporal manner in the course of asexual spore formation. Localisation studies on strains expressing a fluorescent proxy or tagged defX alleles expose that these antimicrobial peptides are secreted to coat the conidial surface. Deletion mutants reveal that the spore-associated defX gene products delay the growth of Gram-positive Staphylococcus aureus and demonstrate that the defX gene and presumably its encoded spore-associated defensins confer a growth advantage to the fungal opponent over bacterial competitors. These findings have implications with respect to the ecological niche of A. fumigatus that serves as a 'virulence school' for this human pathogenic mould; further relevance is given for the infectious process resulting in aspergillosis, considering competition with the host microbiome or co-infecting microorganisms to break colonisation resistance at host surfaces.
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Affiliation(s)
- Michaela Dümig
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jasmin Binder
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anastasia Gaculenko
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Franziska Daul
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Lex Winandy
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Mike Hasenberg
- Imaging Centre Essen (IMCES) - Electron Microscopy Unit, University Hospital and University Duisburg-Essen, Essen, Germany.,Institute for Experimental Immunology and Imaging, University Hospital and University Duisburg-Essen, Essen, Germany
| | - Matthias Gunzer
- Institute for Experimental Immunology and Imaging, University Hospital and University Duisburg-Essen, Essen, Germany
| | - Reinhard Fischer
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Markus Künzler
- Department of Biology, Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | - Sven Krappmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Erlangen, Germany
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Bertuzzi M, van Rhijn N, Krappmann S, Bowyer P, Bromley MJ, Bignell EM. On the lineage of Aspergillus fumigatus isolates in common laboratory use. Med Mycol 2021; 59:7-13. [PMID: 32944768 PMCID: PMC7779236 DOI: 10.1093/mmy/myaa075] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/03/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
The origin of isolates routinely used by the community of Aspergillus fumigatus researchers is periodically a matter of intense discussion at our centre, as the construction of recombinant isolates have sometimes followed convoluted routes, the documentation describing their lineages is fragmented, and the nomenclature is confusing. As an aide memoir, not least for our own benefit, we submit the following account and tabulated list of strains (Table 1) in an effort to collate all of the relevant information in a single, easily accessible document. To maximise the accuracy of this record we have consulted widely amongst the community of Medical Mycologists using these strains. All the strains described are currently available from one of these organisations, namely the Fungal Genetics Stock Centre (FGSC), FungiDB, Ensembl Fungi and The National Collection of Pathogenic Fungi (NCPF) at Public Health England. Display items from this manuscript are also featured on FungiDB. LAY ABSTRACT We present a concise overview on the definition, origin and unique genetic makeup of the Aspergillus fumigatus isolates routinely in use by the fungal research community, to aid researchers to describe past and new strains and the experimental differences observed more accurately.
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Affiliation(s)
- Margherita Bertuzzi
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Manchester, UK
- Lydia Becker Institute of Immunology and Inflammation, Biology, Medicine and Health. The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Norman van Rhijn
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Manchester, UK
- Lydia Becker Institute of Immunology and Inflammation, Biology, Medicine and Health. The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Sven Krappmann
- Institute of Clinical Microbiology, Immunology and Hygiene, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Paul Bowyer
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Manchester, UK
- Lydia Becker Institute of Immunology and Inflammation, Biology, Medicine and Health. The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Michael J Bromley
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Manchester, UK
- Lydia Becker Institute of Immunology and Inflammation, Biology, Medicine and Health. The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Elaine M Bignell
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Manchester, UK
- Lydia Becker Institute of Immunology and Inflammation, Biology, Medicine and Health. The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
- MRC Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
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Galactosaminogalactan activates the inflammasome to provide host protection. Nature 2020; 588:688-692. [PMID: 33268895 PMCID: PMC8086055 DOI: 10.1038/s41586-020-2996-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 09/23/2020] [Indexed: 01/18/2023]
Abstract
Inflammasomes are important sentinels of innate immune defense activated in response to diverse stimuli, including pathogen-associated molecular patterns (PAMPs)1. Activation of the inflammasome provides host defense against aspergillosis2,3, a major health concern for immunocompromised patients; however, the Aspergillus fumigatus PAMPs responsible for inflammasome activation are not known. Here we discovered that A. fumigatus galactosaminogalactan (GAG) is a novel PAMP that activates the NLRP3 inflammasome. Binding of GAG to ribosomal proteins inhibited cellular translation machinery, thereby activating the NLRP3 inflammasome. The galactosamine moiety bound to ribosomal proteins and blocked cellular translation, triggering NLRP3 inflammasome activation. In mice, a GAG-deficient Aspergillus mutant Δgt4c failed to elicit protective inflammasome activation and exhibited enhanced virulence. Moreover, administration of GAG protected mice from DSS-induced colitis in an inflammasome-dependent manner. Thus, ribosomes connect sensing of this fungal PAMP to activation of an innate immune response.
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Böhmer I, Spadinger A, Ebel F. Functional comparison of the group III hybrid histidine kinases TcsC of Aspergillus fumigatus and NikA of Aspergillus nidulans. Med Mycol 2020; 58:362-371. [PMID: 31254343 DOI: 10.1093/mmy/myz069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/14/2019] [Accepted: 06/04/2019] [Indexed: 11/13/2022] Open
Abstract
In filamentous fungi, group III hybrid histidine kinases (HHKs) are major and nonredundant sensing proteins of the high osmolarity glycerol pathway. In this study, we have compared the biological functions of the two homologous group III HHKs TcsC of Aspergillus fumigatus and NikA of A. nidulans. As expected from previous studies, the corresponding mutants are severely impaired in their ability to adapt to hyperosmotic stress and are both resistant to the antifungal agent fludioxonil. However, our data also reveal novel phenotypes and differences between these mutants. Both TcsC and NikA are required for wild-type-like growth on Czapek-Dox medium and a normal resistance to certain oxidative stressors, whereas an increased resistance to the cell wall disturbing agents Congo red and Calcofluor white was found for the ΔtcsC but not for the ΔnikA mutant. With respect to the cell wall reorganizations that are triggered by fludioxonil in a TcsC/NikA-dependent manner, we observed similarities but also striking differences. Strains from seven Aspergillus species, including A. fumigatus and A. nidulans incorporated more chitin into their cell walls in response to fludioxonil. In contrast, fludioxonil treatment resulted in a shedding of surface accessible galactomannan and β-1,3-glucan in all Aspergillus strains tested except A. nidulans. Hence, the fludioxonil-induced activation of NikA results in a distinct and apparently A. nidulans-specific pattern of cell wall reorganizations that is not due to NikA itself, but its integration into the A. nidulans signaling network.
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Affiliation(s)
- Isabella Böhmer
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany
| | - Anja Spadinger
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany
| | - Frank Ebel
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany
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Lin CJ, Hou YH, Chen YL. The histone acetyltransferase GcnE regulates conidiation and biofilm formation in Aspergillus fumigatus. Med Mycol 2020; 58:248-259. [PMID: 31100153 DOI: 10.1093/mmy/myz043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 03/22/2019] [Accepted: 04/11/2019] [Indexed: 01/03/2023] Open
Abstract
Histone modifications play a crucial role in eukaryotic gene regulation. The Spt-Ada-Gcn5-acetyltransferase (SAGA) complex controls histone acetylation, with Gcn5 (GcnE) acting as the acetyltransferase. In the Aspergillus species, GcnE has been shown to regulate asexual development and secondary metabolism. Apart from this, GcnE is required for pathogenicity in plant fungal pathogen A. flavus; however, the role of GcnE in the pathogenicity of human pathogenic fungus A. fumigatus is unknown. In this study, we uncovered the key roles of GcnE in A. fumigatus conidiation, stress responses, and biofilm formation. We observed that deletion of gcnE resulted in aberrant conidiation in which conidiophores displayed abnormal phialide formation. In addition, the ΔgcnE mutant grew slightly faster under limited nitrogen sources (1 mM of ammonium or nitrate) compared to the wild type. The ΔgcnE mutant exhibited increased susceptibility to cell wall-perturbing agents, H2O2 and menadione but enhanced tolerance to LiCl. Furthermore, we showed that GcnE is involved in biofilm formation, and overexpression of adherence-related genes such as somA or uge3 partially rescued biofilm formation defects in the ΔgcnE mutant background. Interestingly, GcnE was not required for virulence in a neutropenic murine model of invasive aspergillosis. These results suggest that GcnE is critical for conidiation and biofilm formation but not virulence in A. fumigatus.
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Affiliation(s)
- Chi-Jan Lin
- Department of Plant Pathology and Microbiology, National Taiwan University, 10617 Taipei, Taiwan
| | - Yi-Hsuan Hou
- Department of Plant Pathology and Microbiology, National Taiwan University, 10617 Taipei, Taiwan
| | - Ying-Lien Chen
- Department of Plant Pathology and Microbiology, National Taiwan University, 10617 Taipei, Taiwan
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Leisen T, Bietz F, Werner J, Wegner A, Schaffrath U, Scheuring D, Willmund F, Mosbach A, Scalliet G, Hahn M. CRISPR/Cas with ribonucleoprotein complexes and transiently selected telomere vectors allows highly efficient marker-free and multiple genome editing in Botrytis cinerea. PLoS Pathog 2020; 16:e1008326. [PMID: 32804988 PMCID: PMC7451986 DOI: 10.1371/journal.ppat.1008326] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 08/27/2020] [Accepted: 07/10/2020] [Indexed: 01/09/2023] Open
Abstract
CRISPR/Cas has become the state-of-the-art technology for genetic manipulation in diverse organisms, enabling targeted genetic changes to be performed with unprecedented efficiency. Here we report on the first establishment of robust CRISPR/Cas editing in the important necrotrophic plant pathogen Botrytis cinerea based on the introduction of optimized Cas9-sgRNA ribonucleoprotein complexes (RNPs) into protoplasts. Editing yields were further improved by development of a novel strategy that combines RNP delivery with cotransformation of transiently stable vectors containing telomeres, which allowed temporary selection and convenient screening for marker-free editing events. We demonstrate that this approach provides superior editing rates compared to existing CRISPR/Cas-based methods in filamentous fungi, including the model plant pathogen Magnaporthe oryzae. Genome sequencing of edited strains revealed very few additional mutations and no evidence for RNP-mediated off-targeting. The high performance of telomere vector-mediated editing was demonstrated by random mutagenesis of codon 272 of the sdhB gene, a major determinant of resistance to succinate dehydrogenase inhibitor (SDHI) fungicides by in bulk replacement of the codon 272 with codons encoding all 20 amino acids. All exchanges were found at similar frequencies in the absence of selection but SDHI selection allowed the identification of novel amino acid substitutions which conferred differential resistance levels towards different SDHI fungicides. The increased efficiency and easy handling of RNP-based cotransformation is expected to accelerate molecular research in B. cinerea and other fungi. In this study, we describe the establishment of the CRISPR/Cas technology for genome editing in the gray mold fungus Botrytis cinerea, one of the economically most important plant pathogens worldwide. We report the development of a strategy which combines the introduction of an optimized nuclear-targeted Cas9-single guide RNA ribonucleoprotein complex (RNP) and a repair template together with unstable telomere vectors for transient selection into fungal protoplasts. A high proportion of the transformants contains the desired genetic changes, and the telomere vector is lost subsequently when selection is stopped. This system allowed introduction of changes into the genome without the requirement of selection markers. It shows superior editing efficiencies compared to existing CRISPR/Cas protocols for filamentous fungi, and leads to a very low number of additional off-target mutations. To demonstrate the performance of our protocol, we conducted for the first time a site-directed, random mutagenesis in a gene encoding an important fungicide target. This approach allows new applications such as in vivo structure-function analysis of proteins and rational fungicide resistance studies. As demonstrated with the rice blast pathogen Magnaporthe oryzae, the RNP-based CRISPR/Cas toolset with telomere vectors can be transferred to other fungi and is expected to boost their genetic manipulation.
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Affiliation(s)
- Thomas Leisen
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
| | - Fabian Bietz
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
| | - Janina Werner
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
| | - Alex Wegner
- RWTH Aachen University, Department of Plant Physiology, Aachen, Germany
| | - Ulrich Schaffrath
- RWTH Aachen University, Department of Plant Physiology, Aachen, Germany
| | - David Scheuring
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
| | - Felix Willmund
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
| | | | | | - Matthias Hahn
- University of Kaiserslautern, Department of Biology, Kaiserslautern, Germany
- * E-mail:
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Functional Coupling between the Unfolded Protein Response and Endoplasmic Reticulum/Golgi Ca 2+-ATPases Promotes Stress Tolerance, Cell Wall Biosynthesis, and Virulence of Aspergillus fumigatus. mBio 2020; 11:mBio.01060-20. [PMID: 32487759 PMCID: PMC7267887 DOI: 10.1128/mbio.01060-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Many species of pathogenic fungi deploy the unfolded protein response (UPR) to expand the folding capacity of the endoplasmic reticulum (ER) in proportion to the demand for virulence-related proteins that traffic through the secretory pathway. Although Ca2+ plays a pivotal role in ER function, the mechanism by which transcriptional upregulation of the protein folding machinery is coordinated with Ca2+ homeostasis is incompletely understood. In this study, we investigated the link between the UPR and genes encoding P-type Ca2+-ATPases in the human-pathogenic mold Aspergillus fumigatus We demonstrate that acute ER stress increases transcription of the srcA gene, encoding a member of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) family, as well as that of pmrA, encoding a secretory pathway Ca2+-ATPase (SPCA) in the Golgi membrane. Loss of the UPR transcription factor HacA prevented the induction of srcA and pmrA transcription during ER stress, defining these ER/Golgi Ca2+ pumps as novel downstream targets of this pathway. While deletion of srcA alone caused no major deficiencies, a ΔsrcA/ΔpmrA mutant displayed a severe polarity defect, was hypersensitive to ER stress, and showed attenuated virulence. In addition, cell wall analyses revealed a striking reduction in mannose levels in the absence of both Ca2+ pumps. The ΔhacA mutant was hypersensitive to agents that block calcineurin-dependent signaling, consistent with a functional coupling between the UPR and Ca2+ homeostasis. Together, these findings demonstrate that the UPR integrates the need for increased levels of chaperone and folding enzymes with an influx of Ca2+ into the secretory pathway to support fungal growth, stress adaptation, and pathogenicity.IMPORTANCE The UPR is an intracellular signal transduction pathway that maintains homeostasis of the ER. The pathway is also tightly linked to the expression of virulence-related traits in diverse species of human-pathogenic and plant-pathogenic fungal species, including the predominant mold pathogen infecting humans, Aspergillus fumigatus Despite advances in the understanding of UPR signaling, the linkages and networks that are governed by this pathway are not well defined. In this study, we revealed that the UPR is a major driving force for stimulating Ca2+ influx at the ER and Golgi membranes and that the coupling between the UPR and Ca2+ import is important for virulence, cell wall biosynthesis, and resistance to antifungal compounds that inhibit Ca2+ signaling.
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35
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Liu J, Li J, Gao N, Zhang X, Zhao G, Song X. Identification and characterization of a protein Bro1 essential for sophorolipids synthesis in Starmerella bombicola. J Ind Microbiol Biotechnol 2020; 47:437-448. [PMID: 32377991 DOI: 10.1007/s10295-020-02272-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 03/23/2020] [Indexed: 01/27/2023]
Abstract
Sophorolipids (SLs) are surface-active molecules produced by the non-pathogenic yeast Starmerella bombicola CGMCC 1576. Several genes involved in the synthesis of SLs have been identified. However, the regulation mechanism of the synthesis pathway for SLs has not been investigated. We recently discovered a protein in S. bombicola, which is structurally related to Yarrowia lipolytica YlBro1. To identify the function of the protein SbBro1 in S. bombicola, the deletion, overexpression, and complementary mutant strains were constructed. We found that the deletion mutant no longer produced SLs. Transcriptome analysis indicated that the expression levels of the key enzyme genes of SLs biosynthetic pathway were significantly down-regulated in the Δbro1, especially the expression level of cyp52m1 encoding the first rate-limiting enzyme in SL synthesis pathway was down-regulated 13-folds and the expression of fatty acid β-oxidation-related enzymes was also down-regulated. This study can give insight into the regulation of SL synthesis.
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Affiliation(s)
- Jun Liu
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China
| | - Jiashan Li
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China
| | - Na Gao
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China
| | - Xinyu Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China
| | - Guoqin Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China
| | - Xin Song
- State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China. .,National Glycoengineering Research Center, Shandong University, Binhai Road 72, Qingdao, 266237, Shandong, People's Republic of China.
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Tannous J, Barda O, Luciano-Rosario D, Prusky DB, Sionov E, Keller NP. New Insight Into Pathogenicity and Secondary Metabolism of the Plant Pathogen Penicillium expansum Through Deletion of the Epigenetic Reader SntB. Front Microbiol 2020; 11:610. [PMID: 32328048 PMCID: PMC7160234 DOI: 10.3389/fmicb.2020.00610] [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] [Received: 01/21/2020] [Accepted: 03/19/2020] [Indexed: 12/23/2022] Open
Abstract
Penicillium expansum is one of the most harmful post-harvest pathogens of pomaceous fruits and the causal agent of blue rot disease. During infection, P. expansum produces the toxic secondary metabolites patulin and citrinin that can impact virulence and, further, render the fruit inedible. Several studies have shown that epigenetic machinery controls synthesis of secondary metabolites in fungi. In this regard, the epigenetic reader, SntB, has been reported to govern the production of multiple toxins in Aspergillus species, and impact virulence of plant pathogenic fungi. Here we show that deletion of sntB in P. expansum results in several phenotypic changes in the fungus including stunted vegetative growth, reduced conidiation, but enhanced germination rates as well as decreased virulence on Golden Delicious apples. In addition, a decrease in both patulin and citrinin biosynthesis in vitro and patulin in apples, was observed. SntB positively regulates expression of three global regulators of virulence and secondary metabolism (LaeA, CreA, and PacC) which may explain in part some of the phenotypic and virulence defects of the PeΔsntB strain. Lastly, results from this study revealed that the controlled environmental factors (low temperatures and high CO2 levels) to which P. expansum is commonly exposed during fruit storage, resulted in a significant reduction of sntB expression and consequent patulin and citrinin reduction. These data identify the epigenetic reader SntB as critical factor regulated in post-harvest pathogens under storage conditions and a potential target to control fungal colonization and decaying of stored fruit.
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Affiliation(s)
- Joanna Tannous
- Department of Medical Microbiology and Immunology, University of Wisconsin - Madison, Madison, WI, United States
| | - Omer Barda
- Institute of Postharvest and Food Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
| | | | - Dov B Prusky
- Institute of Postharvest and Food Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel.,College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China
| | - Edward Sionov
- Institute of Postharvest and Food Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin - Madison, Madison, WI, United States.,Food Research Institute, University of Wisconsin - Madison, Madison, WI, United States.,Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, United States
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37
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Mouyna I, Dellière S, Beauvais A, Gravelat F, Snarr B, Lehoux M, Zacharias C, Sun Y, de Jesus Carrion S, Pearlman E, Sheppard DC, Latgé JP. What Are the Functions of Chitin Deacetylases in Aspergillus fumigatus? Front Cell Infect Microbiol 2020; 10:28. [PMID: 32117802 PMCID: PMC7016196 DOI: 10.3389/fcimb.2020.00028] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/15/2020] [Indexed: 11/13/2022] Open
Abstract
Deacetylation of chitin by chitin deacetylases (Cda) results in the formation of chitosan. Chitosan, a polymer of β1,4 linked glucosamine, plays multiple roles in the function of the fungal cell wall, including virulence and evasion of host immune responses. In this study, the roles of chitosan and putative CDAs in cell wall structure and virulence of Aspergillus fumigatus were investigated. Low levels of chitosan were found in the conidial and cell wall of A. fumigatus. Seven putative CDA genes were identified, disrupted and the phenotype of the single mutants and the septuple mutants were investigated. No alterations in fungal cell wall chitosan levels, changes in fungal growth or alterations in virulence were detected in the single or septuple Δcda1-7 mutant strains. Collectively, these results suggest that chitosan is a minority component of the A. fumigatus cell wall, and that the seven candidate Cda proteins do not play major roles in fungal cell wall synthesis or virulence. However, Cda2 is involved in conidiation, suggesting that this enzyme may play a role in N-acetyl-glucosamine metabolism.
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Affiliation(s)
| | - Sarah Dellière
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
| | | | - Fabrice Gravelat
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
- Departments of Microbiology and Immunology, Medicine, McGill University, Montréal, QC, Canada
| | - Brendan Snarr
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
- Departments of Microbiology and Immunology, Medicine, McGill University, Montréal, QC, Canada
| | - Mélanie Lehoux
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
| | - Caitlin Zacharias
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
- Departments of Microbiology and Immunology, Medicine, McGill University, Montréal, QC, Canada
| | - Yan Sun
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, United States
| | - Steven de Jesus Carrion
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, United States
| | - Eric Pearlman
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, United States
| | - Donald C. Sheppard
- Infectious Diseases in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, QC, Canada
- Departments of Microbiology and Immunology, Medicine, McGill University, Montréal, QC, Canada
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Abstract
Aspergillus fumigatus is a saprotrophic fungus; its primary habitat is the soil. In its ecological niche, the fungus has learned how to adapt and proliferate in hostile environments. This capacity has helped the fungus to resist and survive against human host defenses and, further, to be responsible for one of the most devastating lung infections in terms of morbidity and mortality. In this review, we will provide (i) a description of the biological cycle of A. fumigatus; (ii) a historical perspective of the spectrum of aspergillus disease and the current epidemiological status of these infections; (iii) an analysis of the modes of immune response against Aspergillus in immunocompetent and immunocompromised patients; (iv) an understanding of the pathways responsible for fungal virulence and their host molecular targets, with a specific focus on the cell wall; (v) the current status of the diagnosis of different clinical syndromes; and (vi) an overview of the available antifungal armamentarium and the therapeutic strategies in the clinical context. In addition, the emergence of new concepts, such as nutritional immunity and the integration and rewiring of multiple fungal metabolic activities occurring during lung invasion, has helped us to redefine the opportunistic pathogenesis of A. fumigatus.
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Affiliation(s)
- Jean-Paul Latgé
- School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Georgios Chamilos
- School of Medicine, University of Crete, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
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Traynor AM, Sheridan KJ, Jones GW, Calera JA, Doyle S. Involvement of Sulfur in the Biosynthesis of Essential Metabolites in Pathogenic Fungi of Animals, Particularly Aspergillus spp.: Molecular and Therapeutic Implications. Front Microbiol 2019; 10:2859. [PMID: 31921039 PMCID: PMC6923255 DOI: 10.3389/fmicb.2019.02859] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
Fungal sulfur uptake is required for incorporation into the sidechains of the amino acids cysteine and methionine, and is also essential for the biosynthesis of the antioxidant glutathione (GSH), S-adenosylmethionine (SAM), the key source of methyl groups in cellular transmethylation reactions, and S-adenosylhomocysteine (SAH). Biosynthesis of redox-active gliotoxin in the opportunistic fungal pathogen Aspergillus fumigatus has been elucidated over the past 10 years. Some fungi which produce gliotoxin-like molecular species have undergone unexpected molecular rewiring to accommodate this high-risk biosynthetic process. Specific disruption of gliotoxin biosynthesis, via deletion of gliK, which encodes a γ-glutamyl cyclotransferase, leads to elevated intracellular antioxidant, ergothioneine (EGT), levels, and confirms crosstalk between the biosynthesis of both sulfur-containing moieties. Gliotoxin is ultimately formed by gliotoxin oxidoreductase GliT-mediated oxidation of dithiol gliotoxin (DTG). In fact, DTG is a substrate for both GliT and a bis-thiomethyltransferase, GtmA. GtmA converts DTG to bisdethiobis(methylthio)gliotoxin (BmGT), using 2 mol SAM and resultant SAH must be re-converted to SAM via the action of the Methyl/Met cycle. In the absence of GliT, DTG fluxes via GtmA to BmGT, which results in both SAM depletion and SAH overproduction. Thus, the negative regulation of gliotoxin biosynthesis via GtmA must be counter-balanced by GliT activity to avoid Methyl/Met cycle dysregulation, SAM depletion and trans consequences on global cellular biochemistry in A. fumigatus. DTG also possesses potent Zn2+ chelation properties which positions this sulfur-containing metabolite as a putative component of the Zn2+ homeostasis system within fungi. EGT plays an essential role in high-level redox homeostasis and its presence requires significant consideration in future oxidative stress studies in pathogenic filamentous fungi. In certain filamentous fungi, sulfur is additionally indirectly required for the formation of EGT and the disulfide-bridge containing non-ribosomal peptide, gliotoxin, and related epipolythiodioxopiperazines. Ultimately, interference with emerging sulfur metabolite functionality may represent a new strategy for antifungal drug development.
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Affiliation(s)
- Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Ireland
| | | | - Gary W Jones
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, United Kingdom
| | - José A Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Ireland
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40
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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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41
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Dietl AM, Misslinger M, Aguiar MM, Ivashov V, Teis D, Pfister J, Decristoforo C, Hermann M, Sullivan SM, Smith LR, Haas H. The Siderophore Transporter Sit1 Determines Susceptibility to the Antifungal VL-2397. Antimicrob Agents Chemother 2019; 63:e00807-19. [PMID: 31405865 PMCID: PMC6761561 DOI: 10.1128/aac.00807-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/18/2019] [Indexed: 01/07/2023] Open
Abstract
VL-2397 (previously termed ASP2397) is an antifungal, aluminum-chelating cyclic hexapeptide with a structure analogous to that of ferrichrome-type siderophores, whereby replacement of aluminum by iron was shown to decrease the antifungal activity of this compound. Here, we found that inactivation of an importer for ferrichrome-type siderophores, termed Sit1, renders Aspergillus fumigatus resistant to VL-2397. Moreover, expression of the endogenous sit1 gene under the control of a xylose-inducible promoter (to uncouple sit1 expression from iron repression) combined with C-terminal tagging with a fluorescent protein demonstrated localization of Sit1 in the plasma membrane and xylose-dependent VL-2397 susceptibility. This underlines that Sit1-mediated uptake is essential for VL-2397 susceptibility. Under xylose-induced sit1 expression, VL-2397 also retained antifungal activity after replacing aluminum with iron, which demonstrates that VL-2397 bears antifungal activity independent of cellular aluminum importation. Analysis of sit1 expression indicated that the reduced antifungal activity of the iron-chelated VL-2397 is caused by downregulation of sit1 expression by the imported iron. Furthermore, we demonstrate that defects in iron homeostatic mechanisms modulate the activity of VL-2397. In contrast to A. fumigatus and Candida glabrata, Saccharomyces cerevisiae displays intrinsic resistance to VL-2397 antifungal activity. However, expression of sit1 from A. fumigatus, or its homologue from C. glabrata, resulted in susceptibility to VL-2397, which suggests that the intrinsic resistance of S. cerevisiae is based on lack of uptake and that A. fumigatus, C. glabrata, and S. cerevisiae share an intracellular target for VL-2397.
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Affiliation(s)
- Anna-Maria Dietl
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Matthias Misslinger
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Mario M Aguiar
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Vasyl Ivashov
- Division Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - David Teis
- Division Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Joachim Pfister
- Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Hermann
- Department of Anesthesiology and Critical Care Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | | | | | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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Kjærbølling I, Mortensen UH, Vesth T, Andersen MR. Strategies to establish the link between biosynthetic gene clusters and secondary metabolites. Fungal Genet Biol 2019; 130:107-121. [DOI: 10.1016/j.fgb.2019.06.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 05/26/2019] [Accepted: 06/02/2019] [Indexed: 01/01/2023]
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43
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Millet N, Moya-Nilges M, Sachse M, Krijnse Locker J, Latgé JP, Mouyna I. Aspergillus fumigatus exoβ(1-3)glucanases family GH55 are essential for conidial cell wall morphogenesis. Cell Microbiol 2019; 21:e13102. [PMID: 31424155 DOI: 10.1111/cmi.13102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/30/2019] [Accepted: 08/13/2019] [Indexed: 01/28/2023]
Abstract
The cell wall of Aspergillus fumigatus is predominantly composed of polysaccharides. The central fibrillar core of the cell wall is composed of a branched β(1-3)glucan, to which the chitin and the galactomannan are covalently bound. Softening of the cell wall is an essential event during fungal morphogenesis, wherein rigid cell wall structures are cleaved by glycosyl hydrolases. In this study, we characterised the role of the glycosyl hydrolase GH55 members in A. fumigatus fungal morphogenesis. We showed that deletion of the six genes of the GH55 family stopped conidial cell wall maturation at the beginning of the development process, leading to abrogation of conidial separation: the shape of conidia became ovoid, and germination was delayed. In conclusion, the reorganisation and structuring of the conidial cell wall mediated by members of the GH55 family is essential for their maturation, normal dissemination, and germination.
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Affiliation(s)
- Nicolas Millet
- Aspergillus Unit, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Maryse Moya-Nilges
- Unité Technologie et service Bioimagerie Ultrastructurale, Institut Pasteur, Paris, France
| | - Martin Sachse
- Unité Technologie et service Bioimagerie Ultrastructurale, Institut Pasteur, Paris, France
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44
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Muszkieta L, Fontaine T, Beau R, Mouyna I, Vogt MS, Trow J, Cormack BP, Essen LO, Jouvion G, Latgé JP. The Glycosylphosphatidylinositol-Anchored DFG Family Is Essential for the Insertion of Galactomannan into the β-(1,3)-Glucan-Chitin Core of the Cell Wall of Aspergillus fumigatus. mSphere 2019; 4:e00397-19. [PMID: 31366710 PMCID: PMC6669337 DOI: 10.1128/msphere.00397-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 06/25/2019] [Indexed: 11/20/2022] Open
Abstract
The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. At the cell wall level, enzyme activities are involved in postsynthesis polysaccharide modifications such as cleavage, elongation, branching, and cross-linking. Glycosylphosphatidylinositol (GPI)-anchored proteins have been shown to participate in cell wall biosynthesis and specifically in polysaccharide remodeling. Among these proteins, the DFG family plays an essential role in controlling polar growth in yeast. In the filamentous fungus and opportunistic human pathogen Aspergillus fumigatus, the DFG gene family contains seven orthologous DFG genes among which only six are expressed under in vitro growth conditions. Deletions of single DFG genes revealed that DFG3 plays the most important morphogenetic role in this gene family. A sextuple-deletion mutant resulting from the deletion of all in vitro expressed DFG genes did not contain galactomannan in the cell wall and has severe growth defects. This study has shown that DFG members are absolutely necessary for the insertion of galactomannan into the cell wall of A. fumigatus and that the proper cell wall localization of the galactomannan is essential for correct fungal morphogenesis in A. fumigatusIMPORTANCE The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. Enzymes involved in postsynthesis polysaccharide modifications, such as cleavage, elongation, branching, and cross-linking, are essential for fungal life. Here, we investigated in Aspergillus fumigatus the role of the members of the Dfg family, one of the 4 GPI-anchored protein families common to yeast and molds involved in cell wall remodeling. Molecular and biochemical approaches showed that DFG members are required for filamentous growth, conidiation, and cell wall organization and are essential for the life of this fungal pathogen.
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Affiliation(s)
| | | | - Rémi Beau
- Unité des Aspergillus, Institut Pasteur, Paris, France
| | | | | | - Jonathan Trow
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brendan P Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lars-Oliver Essen
- Faculty of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Gregory Jouvion
- Histopathologie humaine et modèles animaux, Institut Pasteur, Paris, France
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45
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Sass G, Ansari SR, Dietl AM, Déziel E, Haas H, Stevens DA. Intermicrobial interaction: Aspergillus fumigatus siderophores protect against competition by Pseudomonas aeruginosa. PLoS One 2019; 14:e0216085. [PMID: 31067259 PMCID: PMC6505954 DOI: 10.1371/journal.pone.0216085] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/12/2019] [Indexed: 12/27/2022] Open
Abstract
Pseudomonas aeruginosa and Aspergillus fumigatus are pathogens frequently co-inhabiting immunocompromised patient airways, particularly in people with cystic fibrosis. Both microbes depend on the availability of iron, and compete for iron in their microenvironment. We showed previously that the P. aeruginosa siderophore pyoverdine is the main instrument in battling A. fumigatus biofilms, by iron chelation and denial of iron to the fungus. Here we show that A. fumigatus siderophores defend against anti-fungal P. aeruginosa effects. P. aeruginosa supernatants produced in the presence of wildtype A. fumigatus planktonic supernatants (Afsup) showed less activity against A. fumigatus biofilms than P. aeruginosa supernatants without Afsup, despite higher production of pyoverdine by P. aeruginosa. Supernatants of A. fumigatus cultures lacking the sidA gene (AfΔsidA), unable to produce hydroxamate siderophores, were less capable of protecting A. fumigatus biofilms from P. aeruginosa supernatants and pyoverdine. AfΔsidA biofilm was more sensitive towards inhibitory effects of pyoverdine, the iron chelator deferiprone (DFP), or amphothericin B than wildtype A. fumigatus biofilm. Supplementation of sidA-deficient A. fumigatus biofilm with A. fumigatus siderophores restored resistance to pyoverdine. The A. fumigatus siderophore production inhibitor celastrol sensitized wildtype A. fumigatus biofilms towards the anti-fungal activity of DFP. In conclusion, A. fumigatus hydroxamate siderophores play a pivotal role in A. fumigatus competition for iron against P. aeruginosa.
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Affiliation(s)
- Gabriele Sass
- California Institute for Medical Research, San Jose, California, United States of America
- * E-mail:
| | - Shajia R. Ansari
- California Institute for Medical Research, San Jose, California, United States of America
| | - Anna-Maria Dietl
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Eric Déziel
- INRS-Institut Armand-Frappier, Laval, Quebec, Canada
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - David A. Stevens
- California Institute for Medical Research, San Jose, California, United States of America
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
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46
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Valsecchi I, Lai JI, Stephen-Victor E, Pillé A, Beaussart A, Lo V, Pham CLL, Aimanianda V, Kwan AH, Duchateau M, Gianetto QG, Matondo M, Lehoux M, Sheppard DC, Dufrene YF, Bayry J, Guijarro JI, Sunde M, Latgé JP. Assembly and disassembly of Aspergillus fumigatus conidial rodlets. ACTA ACUST UNITED AC 2019; 5:100023. [PMID: 32743139 PMCID: PMC7389560 DOI: 10.1016/j.tcsw.2019.100023] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 02/22/2019] [Accepted: 02/23/2019] [Indexed: 11/27/2022]
Abstract
The rodlet structure present on the Aspergillus fumigatus conidial surface hides conidia from immune recognition. In spite of the essential biological role of the rodlets, the molecular basis for their self-assembly and disaggregation is not known. Analysis of the soluble forms of conidia-extracted and recombinant RodA by NMR spectroscopy has indicated the importance of disulfide bonds and identified two dynamic regions as likely candidates for conformational change and intermolecular interactions during conversion of RodA into the amyloid rodlet structure. Point mutations introduced into the RODA sequence confirmed that (1) mutation of a single cysteine was sufficient to block rodlet formation on the conidial surface and (2) both presumed amyloidogenic regions were needed for proper rodlet assembly. Mutations in the two putative amyloidogenic regions retarded and disturbed, but did not completely inhibit, the formation of the rodlets in vitro and on the conidial surface. Even in a disturbed form, the presence of rodlets on the surface of the conidia was sufficient to immunosilence the conidium. However, in contrast to the parental conidia, long exposure of mutant conidia lacking disulfide bridges within RodA or expressing RodA carrying the double (I115S/I146G) mutation activated dendritic cells with the subsequent secretion of proinflammatory cytokines. The immune reactivity of the RodA mutant conidia was not due to a modification in the RodA structure, but to the exposure of different pathogen-associated molecular patterns on the surface as a result of the modification of the rodlet surface layer. The full degradation of the rodlet layer, which occurs during early germination, is due to a complex array of cell wall bound proteases. As reported earlier, this loss of the rodlet layer lead to a strong anti-fumigatus host immune response in mouse lungs.
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Affiliation(s)
- Isabel Valsecchi
- Unité des Aspergillus, Institut Pasteur, Paris, France.,Biological NMR Technological Platform, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Jennifer I Lai
- School of Medical Sciences and Sydney Nano, The University of Sydney, NSW 2006, Australia
| | - Emmanuel Stephen-Victor
- Institut National de la Santé et de la Recherche Médicale, Centre de Recherche des Cordeliers, Sorbonne Université, Paris, France
| | - Ariane Pillé
- Biological NMR Technological Platform, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Audrey Beaussart
- Institute of Life Sciences, Université Catholique de Louvain, Croix du Sud, 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium.,Walloon Excellence in Life Sciences and Biotechnology, Belgium
| | - Victor Lo
- School of Medical Sciences and Sydney Nano, The University of Sydney, NSW 2006, Australia
| | - Chi L L Pham
- School of Medical Sciences and Sydney Nano, The University of Sydney, NSW 2006, Australia
| | | | - Ann H Kwan
- School of Life and Environmental Sciences and Sydney Nano, The University of Sydney, NSW 2006, Australia
| | - Magalie Duchateau
- Pasteur Proteomics Platform, Mass Spectrometry for Biology Unit, Institut Pasteur, CNRS USR 2000, Paris, France
| | - Quentin Giai Gianetto
- Pasteur Proteomics Platform, Mass Spectrometry for Biology Unit, Institut Pasteur, CNRS USR 2000, Paris, France.,Bioinformatics and Biostatistics Hub, C3BI, CNRS USR 3756, Institut Pasteur, Paris, France
| | - Mariette Matondo
- Pasteur Proteomics Platform, Mass Spectrometry for Biology Unit, Institut Pasteur, CNRS USR 2000, Paris, France
| | - Melanie Lehoux
- Departments of Medicine, Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Donald C Sheppard
- Departments of Medicine, Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Yves F Dufrene
- Institute of Life Sciences, Université Catholique de Louvain, Croix du Sud, 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium.,Walloon Excellence in Life Sciences and Biotechnology, Belgium
| | - Jagadeesh Bayry
- Institut National de la Santé et de la Recherche Médicale, Centre de Recherche des Cordeliers, Sorbonne Université, Paris, France
| | - J Iñaki Guijarro
- Biological NMR Technological Platform, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Margaret Sunde
- School of Medical Sciences and Sydney Nano, The University of Sydney, NSW 2006, Australia
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Two KTR Mannosyltransferases Are Responsible for the Biosynthesis of Cell Wall Mannans and Control Polarized Growth in Aspergillus fumigatus. mBio 2019; 10:mBio.02647-18. [PMID: 30755510 PMCID: PMC6372797 DOI: 10.1128/mbio.02647-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It allows fungal pathogens to survive environmental challenge posed by nutrient stress and host defenses, and it also is central to polarized growth. The cell wall is mainly composed of polysaccharides organized in a three-dimensional network. Aspergillus fumigatus produces a cell wall galactomannan whose biosynthetic pathway and biological functions remain poorly defined. Here, we described two new mannosyltransferases essential to the synthesis of the cell wall galactomannan. Their absence leads to a growth defect with misregulation of polarization and altered conidiation, with conidia which are bigger and more permeable than the conidia of the parental strain. This study showed that in spite of its low concentration in the cell wall, this polysaccharide is absolutely required for cell wall stability, for apical growth, and for the full virulence of A. fumigatus. Fungal cell wall mannans are complex carbohydrate polysaccharides with different structures in yeasts and molds. In contrast to yeasts, their biosynthetic pathway has been poorly investigated in filamentous fungi. In Aspergillus fumigatus, the major mannan structure is a galactomannan that is cross-linked to the β-1,3-glucan-chitin cell wall core. This polymer is composed of a linear mannan with a repeating unit composed of four α1,6-linked and α1,2-linked mannoses with side chains of galactofuran. Despite its use as a biomarker to diagnose invasive aspergillosis, its biosynthesis and biological function were unknown. Here, we have investigated the function of three members of the Ktr (also named Kre2/Mnt1) family (Ktr1, Ktr4, and Ktr7) in A. fumigatus and show that two of them are required for the biosynthesis of galactomannan. In particular, we describe a newly discovered form of α-1,2-mannosyltransferase activity encoded by the KTR4 gene. Biochemical analyses showed that deletion of the KTR4 gene or the KTR7 gene leads to the absence of cell wall galactomannan. In comparison to parental strains, the Δktr4 and Δktr7 mutants showed a severe growth phenotype with defects in polarized growth and in conidiation, marked alteration of the conidial viability, and reduced virulence in a mouse model of invasive aspergillosis. In yeast, the KTR proteins are involved in protein 0- and N-glycosylation. This study provided another confirmation that orthologous genes can code for proteins that have very different biological functions in yeasts and filamentous fungi. Moreover, in A. fumigatus, cell wall mannans are as important structurally as β-glucans and chitin.
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Xia C, Li Z, Xu Y, Yang P, Gao L, Yan Q, Li S, Wang Y, Qu Y, Song X. Introduction of heterologous transcription factors and their target genes into Penicillium oxalicum leads to increased lignocellulolytic enzyme production. Appl Microbiol Biotechnol 2019; 103:2675-2687. [DOI: 10.1007/s00253-018-09612-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 12/18/2018] [Accepted: 12/28/2018] [Indexed: 12/16/2022]
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49
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Qiao YM, Yu RL, Zhu P. Advances in targeting and heterologous expression of genes involved in the synthesis of fungal secondary metabolites. RSC Adv 2019; 9:35124-35134. [PMID: 35530690 PMCID: PMC9074735 DOI: 10.1039/c9ra06908a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/18/2019] [Indexed: 01/11/2023] Open
Abstract
Gene targeting involves integration of foreign DNA into the fungal genome by several strategies including Agrobacterium tumefaciens-mediated transformation (ATMT).
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Affiliation(s)
- Yun-Ming Qiao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines
- NHC Key Laboratory of Biosynthesis of Natural Products
- CAMS Key Laboratory of Enzyme and Biocatalysis of Natural Drugs
- Institute of Materia Medica
- Chinese Academy of Medical Sciences
| | - Rui-Lin Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines
- NHC Key Laboratory of Biosynthesis of Natural Products
- CAMS Key Laboratory of Enzyme and Biocatalysis of Natural Drugs
- Institute of Materia Medica
- Chinese Academy of Medical Sciences
| | - Ping Zhu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines
- NHC Key Laboratory of Biosynthesis of Natural Products
- CAMS Key Laboratory of Enzyme and Biocatalysis of Natural Drugs
- Institute of Materia Medica
- Chinese Academy of Medical Sciences
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50
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Dietl AM, Binder U, Shadkchan Y, Osherov N, Haas H. Siroheme Is Essential for Assimilation of Nitrate and Sulfate as Well as Detoxification of Nitric Oxide but Dispensable for Murine Virulence of Aspergillus fumigatus. Front Microbiol 2018; 9:2615. [PMID: 30483221 PMCID: PMC6240589 DOI: 10.3389/fmicb.2018.02615] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/12/2018] [Indexed: 11/30/2022] Open
Abstract
The saprophytic mold Aspergillus fumigatus is the most common airborne fungal pathogen causing severe invasive fungal infections in immunocompromised patients. Siroheme is a heme-like prosthetic group used by plants and microorganisms for sulfate and nitrate assimilation but is absent in higher eukaryotes. Here, we investigated the role of siroheme in A. fumigatus by deletion of the gene encoding the bifunctional dehydrogenase/ferrochelatase enzyme Met8. Met8-deficiency resulted in the inability to utilize sulfate and nitrate as sulfur and nitrogen sources, respectively. These results match previous data demonstrating that siroheme is an essential cofactor for nitrite and sulfite reductases. Moreover, Met8-deficiency caused significantly decreased resistance against nitric oxide (NO) underlining the importance of nitrite reductase in NO detoxification. Met8-deficiency did not affect virulence in murine models for invasive aspergillosis indicating that neither NO-detoxification nor assimilation of sulfate and nitrate play major roles in virulence in this host. Interestingly, Met8-deficiency resulted in mild virulence attenuation in the Galleria mellonella infection model revealing differences in interaction of A. fumigatus with G. mellonella and mouse.
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Affiliation(s)
- Anna-Maria Dietl
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Ulrike Binder
- Division of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Yana Shadkchan
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Nir Osherov
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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