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Lightfoot JD, Adams EM, Kamath MM, Wells BL, Fuller KK. Aspergillus fumigatus Hypoxia Adaptation Is Critical for the Establishment of Fungal Keratitis. Invest Ophthalmol Vis Sci 2024; 65:31. [PMID: 38635243 PMCID: PMC11044834 DOI: 10.1167/iovs.65.4.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/15/2024] [Indexed: 04/19/2024] Open
Abstract
Purpose The poor visual outcomes associated with fungal keratitis (FK) underscore a need to identify fungal pathways that can serve as novel antifungal targets. In this report, we investigated whether hypoxia develops in the FK cornea and, by extension, if fungal hypoxia adaptation is essential for virulence in this setting. Methods C57BL/6J mice were inoculated with Aspergillus fumigatus and Fusarium solani var. petroliphilum via topical overlay or intrastromal injection. At various time points post-inoculation (p.i.), animals were injected with pimonidazole for the detection of tissue hypoxia through immunofluorescence imaging. The A. fumigatus srbA gene was deleted through Cas9-mediated homologous recombination and its virulence was assessed in the topical infection model using slit-lamp microscopy and optical coherence tomography (OCT). Results Topical inoculation with A. fumigatus resulted in diffuse pimonidazole staining across the epithelial and endothelial layers within 6 hours. Stromal hypoxia was evident by 48 hours p.i., which corresponded to leukocytic infiltration. Intrastromal inoculation with either A. fumigatus or F. solani similarly led to diffuse staining patterns across all corneal cell layers. The A. fumigatus srbA deletion mutant was unable to grow at oxygen levels below 3% in vitro, and corneas inoculated with the mutant failed to develop signs of corneal opacification, inflammation, or fungal burden. Conclusions These results suggest that fungal antigen rapidly drives the development of corneal hypoxia, thus rendering fungal SrbA or related pathways essential for the establishment of infection. Such pathways may therefore serve as targets for novel antifungal intervention.
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Affiliation(s)
- Jorge D. Lightfoot
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Emily M. Adams
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Manali M. Kamath
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Becca L. Wells
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Kevin K. Fuller
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Tang X, Zhang L, Ren S, Zhao Y, Liu K, Zhang Y. Stochastic Processes Derive Gut Fungi Community Assembly of Plateau Pikas ( Ochotona curzoniae) along Altitudinal Gradients across Warm and Cold Seasons. J Fungi (Basel) 2023; 9:1032. [PMID: 37888290 PMCID: PMC10607853 DOI: 10.3390/jof9101032] [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: 09/03/2023] [Revised: 10/05/2023] [Accepted: 10/18/2023] [Indexed: 10/28/2023] Open
Abstract
Although fungi occupy only a small proportion of the microbial community in the intestinal tract of mammals, they play important roles in host fat accumulation, nutrition metabolism, metabolic health, and immune development. Here, we investigated the dynamics and assembly of gut fungal communities in plateau pikas inhabiting six altitudinal gradients across warm and cold seasons. We found that the relative abundances of Podospora and Sporormiella significantly decreased with altitudinal gradients in the warm season, whereas the relative abundance of Sarocladium significantly increased. Alpha diversity significantly decreased with increasing altitudinal gradient in the warm and cold seasons. Distance-decay analysis showed that fungal community similarities were significantly and negatively correlated with elevation. The co-occurrence network complexity significantly decreased along the altitudinal gradients as the total number of nodes, number of edges, and degree of nodes significantly decreased. Both the null and neutral model analyses showed that stochastic or neutral processes dominated the gut fungal community assembly in both seasons and that ecological drift was the main ecological process explaining the variation in the gut fungal community across different plateau pikas. Homogeneous selection played a weak role in structuring gut fungal community assembly during the warm season. Collectively, these results expand our understanding of the distribution patterns of gut fungal communities and elucidate the mechanisms that maintain fungal diversity in the gut ecosystems of small mammals.
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Affiliation(s)
- Xianjiang Tang
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Xining 810008, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liangzhi Zhang
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Xining 810008, China
| | - Shien Ren
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Xining 810008, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yaqi Zhao
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Xining 810008, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kai Liu
- Qinghai Provincial Grassland Station, Xining 810008, China
| | - Yanming Zhang
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
- Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Xining 810008, China
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Betinova V, Toth Hervay N, Elias D, Horvathova A, Gbelska Y. The UPC2 gene in Kluyveromyces lactis stress adaptation. Folia Microbiol (Praha) 2022; 67:641-647. [PMID: 35352326 DOI: 10.1007/s12223-022-00968-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/10/2022] [Indexed: 11/25/2022]
Abstract
KlUpc2p, a transcription factor belonging to the fungal binuclear cluster family, is an important regulator of ergosterol biosynthesis and azole drug resistance in Kluyveromyces lactis. In this work, we show that the absence of KlUpc2p generates Rag- phenotype and modulates the K. lactis susceptibility to oxidants and calcofuor white. The KlUPC2 deletion leads to increased expression of KlMGA2 gene, encoding an important regulator of hypoxic and lipid biosynthetic genes in K. lactis and also KlHOG1 gene. The absence of KlUpc2p does not lead to statistically significant changes in glycerol, corroborating the expression of KlGPD1 gene, encoding NAD+-dependent glycerol-3-phosphate dehydrogenase, that is similar in both the deletion mutant and the parental wild-type strain. Increased sensitivity of Klupc2 mutant cells to brefeldin A accompanied with significant increase in KlARF2 gene expression point to the involvement of KlUpc2p in intracellular signaling. Our observations highlight the connections between ergosterol and fatty acid metabolism to modulate membrane properties and point to the possible involvement of KlUpc2p in K. lactis oxidative stress response.
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Affiliation(s)
- Veronika Betinova
- Faculty of Natural Sciences, Department of Microbiology and Virology, Comenius University in Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovak Republic
| | - Nora Toth Hervay
- Faculty of Natural Sciences, Department of Microbiology and Virology, Comenius University in Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovak Republic
| | - Daniel Elias
- Faculty of Natural Sciences, Department of Microbiology and Virology, Comenius University in Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovak Republic
| | - Agnes Horvathova
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38, Bratislava, Slovak Republic
| | - Yvetta Gbelska
- Faculty of Natural Sciences, Department of Microbiology and Virology, Comenius University in Bratislava, Ilkovicova 6, 842 15, Bratislava, Slovak Republic.
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Misslinger M, Hortschansky P, Brakhage AA, Haas H. Fungal iron homeostasis with a focus on Aspergillus fumigatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118885. [PMID: 33045305 DOI: 10.1016/j.bbamcr.2020.118885] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/15/2020] [Accepted: 10/01/2020] [Indexed: 02/08/2023]
Abstract
To maintain iron homeostasis, fungi have to balance iron acquisition, storage, and utilization to ensure sufficient supply and to avoid toxic excess of this essential trace element. As pathogens usually encounter iron limitation in the host niche, this metal plays a particular role during virulence. Siderophores are iron-chelators synthesized by most, but not all fungal species to sequester iron extra- and intracellularly. In recent years, the facultative human pathogen Aspergillus fumigatus has become a model for fungal iron homeostasis of siderophore-producing fungal species. This article summarizes the knowledge on fungal iron homeostasis and its links to virulence with a focus on A. fumigatus. It covers mechanisms for iron acquisition, storage, and detoxification, as well as the modes of transcriptional iron regulation and iron sensing in A. fumigatus in comparison to other fungal species. Moreover, potential translational applications of the peculiarities of fungal iron metabolism for treatment and diagnosis of fungal infections is addressed.
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Affiliation(s)
- Matthias Misslinger
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany; Department Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Hubertus Haas
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
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Hapala I, Griac P, Holic R. Metabolism of Storage Lipids and the Role of Lipid Droplets in the Yeast Schizosaccharomyces pombe. Lipids 2020; 55:513-535. [PMID: 32930427 DOI: 10.1002/lipd.12275] [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: 06/16/2020] [Revised: 07/14/2020] [Accepted: 07/29/2020] [Indexed: 12/12/2022]
Abstract
Storage lipids, triacylglycerols (TAG), and steryl esters (SE), are predominant constituents of lipid droplets (LD) in fungi. In several yeast species, metabolism of TAG and SE is linked to various cellular processes, including cell division, sporulation, apoptosis, response to stress, and lipotoxicity. In addition, TAG are an important source for the generation of value-added lipids for industrial and biomedical applications. The fission yeast Schizosaccharomyces pombe is a widely used unicellular eukaryotic model organism. It is a powerful tractable system used to study various aspects of eukaryotic cellular and molecular biology. However, the knowledge of S. pombe neutral lipids metabolism is quite limited. In this review, we summarize and discuss the current knowledge of the homeostasis of storage lipids and of the role of LD in the fission yeast S. pombe with the aim to stimulate research of lipid metabolism and its connection with other essential cellular processes. We also discuss the advantages and disadvantages of fission yeast in lipid biotechnology and recent achievements in the use of S. pombe in the biotechnological production of valuable lipid compounds.
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Affiliation(s)
- Ivan Hapala
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Peter Griac
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Roman Holic
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
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Chung H, Lee YH. Hypoxia: A Double-Edged Sword During Fungal Pathogenesis? Front Microbiol 2020; 11:1920. [PMID: 32903454 PMCID: PMC7434965 DOI: 10.3389/fmicb.2020.01920] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/21/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular oxygen functions as an electron acceptor for aerobic respiration and a substrate for key metabolisms and cellular processes. Most eukaryotes develop direct or indirect oxygen sensors and reprogram transcriptional and translational metabolisms to adapt to altered oxygen availability under varying oxygen concentrations. Human fungal pathogens manipulate transcriptional levels of genes related to virulence as well as oxygen-dependent metabolisms such as ergosterol homeostasis when they are confronted with oxygen limitation (hypoxia) during infection. Oxygen states in plant tissues also vary depending on site, species, and external environment, potentially providing hypoxia to plant pathogens during infection. In this review, knowledge on the regulation of oxygen sensing and adaptive mechanisms in eukaryotes and nascent understanding of hypoxic responses in plant pathogens are summarized and discussed.
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Affiliation(s)
- Hyunjung Chung
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea.,Center for Fungal Genetic Resources, Plant Immunity Research Center, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
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Chung H, Kim S, Kim KT, Hwang BG, Kim HJ, Lee SJ, Lee YH. A novel approach to investigate hypoxic microenvironment during rice colonization by Magnaporthe oryzae. Environ Microbiol 2020; 21:1151-1169. [PMID: 30773773 DOI: 10.1111/1462-2920.14563] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 02/13/2019] [Indexed: 01/22/2023]
Abstract
Because molecular oxygen functions as the final acceptor of electrons during aerobic respiration and a substrate for diverse enzymatic reactions, eukaryotes employ various mechanisms to maintain cellular homeostasis under varying oxygen concentration. Human fungal pathogens change the expression of genes involved in virulence and oxygen-required metabolisms such as ergosterol (ERG) synthesis when they encounter oxygen limitation (hypoxia) during infection. The oxygen level in plant tissues also fluctuates, potentially creating hypoxic stress to pathogens during infection. However, little is known about how in planta oxygen dynamics impact pathogenesis. In this study, we investigated oxygen dynamics in rice during infection by Magnaporthe oryzae via two approaches. First, rice leaves infected by M. oryzae were noninvasively probed using a microscopic oxygen sensor. Second, an immunofluorescence assay based on a chemical probe, pimonidazole, was used. Both methods showed that oxygen concentration in rice decreased after fungal penetration. We also functionally characterized five hypoxia-responsive genes participating in ERG biosynthesis for their role in pathogenesis. Resulting insights and tools will help study the nature of in planta oxygen dynamics in other pathosystems.
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Affiliation(s)
- Hyunjung Chung
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea
| | - Seongbeom Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea
| | - Ki-Tae Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea
| | - Bae-Geun Hwang
- Department of Mechanical Engineering, Center for Biofluid and Biomimic Research, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Hye-Jeong Kim
- Department of Mechanical Engineering, Center for Biofluid and Biomimic Research, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Sang-Joon Lee
- Department of Mechanical Engineering, Center for Biofluid and Biomimic Research, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea.,Center for Fungal Genetic Resources, Plant Immunity Research Center, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea
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Mattila HK, Mäkinen M, Lundell T. Hypoxia is regulating enzymatic wood decomposition and intracellular carbohydrate metabolism in filamentous white rot fungus. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:26. [PMID: 32123543 PMCID: PMC7038570 DOI: 10.1186/s13068-020-01677-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 02/05/2020] [Indexed: 05/20/2023]
Abstract
BACKGROUND Fungal decomposition of wood is considered as a strictly aerobic process. However, recent findings on wood-decaying fungi to produce ethanol from various lignocelluloses under oxygen-depleted conditions lead us to question this. We designed gene expression study of the white rot fungus Phlebia radiata (isolate FBCC0043) by adopting comparative transcriptomics and functional genomics on solid lignocellulose substrates under varying cultivation atmospheric conditions. RESULTS Switch to fermentative conditions was a major regulator for intracellular metabolism and extracellular enzymatic degradation of wood polysaccharides. Changes in the expression profiles of CAZy (carbohydrate-active enzyme) encoding genes upon oxygen depletion, lead into an alternative wood decomposition strategy. Surprisingly, we noticed higher cellulolytic activity under fermentative conditions in comparison to aerobic cultivation. In addition, our results manifest how oxygen depletion affects over 200 genes of fungal primary metabolism including several transcription factors. We present new functions for acetate generating phosphoketolase pathway and its potential regulator, Adr1 transcription factor, in carbon catabolism under oxygen depletion. CONCLUSIONS Physiologically resilient wood-decomposing Basidiomycota species P. radiata is capable of thriving under respirative and fermentative conditions utilizing only untreated lignocellulose as carbon source. Hypoxia-response mechanism in the fungus is, however, divergent from the regulation described for Ascomycota fermenting yeasts or animal-pathogenic species of Basidiomycota.
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Affiliation(s)
- Hans Kristian Mattila
- Department of Microbiology, Faculty of Agriculture and Forestry, Viikki Campus, University of Helsinki, 00014 Helsinki, Finland
| | - Mari Mäkinen
- Department of Microbiology, Faculty of Agriculture and Forestry, Viikki Campus, University of Helsinki, 00014 Helsinki, Finland
- Present Address: VTT Technical Research Centre of Finland Ltd, 02044 VTT Espoo, Finland
| | - Taina Lundell
- Department of Microbiology, Faculty of Agriculture and Forestry, Viikki Campus, University of Helsinki, 00014 Helsinki, Finland
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Outline of the biosynthesis and regulation of ergosterol in yeast. World J Microbiol Biotechnol 2019; 35:98. [PMID: 31222401 DOI: 10.1007/s11274-019-2673-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 06/09/2019] [Indexed: 10/26/2022]
Abstract
Sterols are crucial functional components for eukaryotic cell membrane. Due to versatile activities, sterols show wide applications in food and pharmaceutical industries. Ergosterol not only reflects cell growth but also serves as the precursor for manufacturing steroid drugs. To date, the ergosterol biosynthetic pathway in yeast has been reported, and the industrial production of ergosterol is achieved by yeast fermentation or extraction from fungal mycelia. Here, we summarize its biosynthesis, regulation, transportation, and subcellular location of enzymes in yeast. In particular, we review the regulation of ergosterol biosynthesis at transcriptional, translational and post-translational levels. Furthermore, we advocate metabolic engineering and fermentation strategies for high-level production of ergosterol. This study may provide evaluable insights into metabolic engineering of yeast for scaled-up fermentation production of ergosterol or beyond.
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