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Hong S, Sun Y, Chen H, Zhao P, Wang C. Fungus-insect interactions beyond bilateral regimes: the importance and strategy to outcompete host ectomicrobiomes by fungal parasites. Curr Opin Microbiol 2023; 74:102336. [PMID: 37320866 DOI: 10.1016/j.mib.2023.102336] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/07/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023]
Abstract
Fungus-insect interactions have long been investigated at the bilateral level to unveil the factors involved in mediating fungal entomopathogenicity and insect antifungal immunity. Emerging evidence has shown that insect cuticles are inhabited by different bacteria that can delay and deter fungal parasite infections. Entomopathogenic fungi (EPF), however, have evolved strategies to combat the colonization resistance mediated by insect ectomicrobiomes by producing antimicrobial peptides or antibiotic compounds. Deprivation of micronutrients may also be employed by EPF to counteract the ectomicrobiome antagonism. Further investigations of insect ectomicrobiome assemblage and fungal factors involved in outcompeting cuticular microbiomes may benefit the development of cost-effective mycoinsecticides while protecting ecologically and economically important insect species.
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Affiliation(s)
- Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanlei Sun
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haimin Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Pengfei Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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Senra MVX. In silico characterization of cysteine-stabilized αβ defensins from neglected unicellular microeukaryotes. BMC Microbiol 2023; 23:82. [PMID: 36966312 PMCID: PMC10040121 DOI: 10.1186/s12866-023-02817-w] [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: 10/14/2022] [Accepted: 03/09/2023] [Indexed: 03/27/2023] Open
Abstract
BACKGROUND The emergence of multi-resistant pathogens have increased dramatically in recent years, becoming a major public-health concern. Among other promising antimicrobial molecules with potential to assist in this worldwide struggle, cysteine-stabilized αβ (CS-αβ) defensins are attracting attention due their efficacy, stability, and broad spectrum against viruses, bacteria, fungi, and protists, including many known human pathogens. RESULTS Here, 23 genomes of ciliated protists were screened and two CS-αβ defensins with a likely antifungal activity were identified and characterized, using bioinformatics, from a culturable freshwater species, Laurentiella sp. (LsAMP-1 and LsAMP-2). Although any potential cellular ligand could be predicted for LsAMP-2; evidences from structural, molecular dynamics, and docking analyses suggest that LsAMP-1 may form stably associations with phosphatidylinositol 4,5-bisphosphates (PIP2), a phospholipid found on many eukaryotic cells, which could, in turn, represent an anchorage mechanism within plasma membrane of targeted cells. CONCLUSION These data stress that more biotechnology-oriented studies should be conducted on neglected protists, such ciliates, which could become valuable sources of novel bioactive molecules for therapeutic uses.
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Hong S, Sun Y, Chen H, Wang C. Suppression of the insect cuticular microbiomes by a fungal defensin to facilitate parasite infection. THE ISME JOURNAL 2023; 17:1-11. [PMID: 36127432 PMCID: PMC9751272 DOI: 10.1038/s41396-022-01323-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 12/24/2022]
Abstract
Insects can assemble defensive microbiomes on their body surfaces to defend against fungal parasitic infections. The strategies employed by fungal pathogens to combat host cuticular microbiotas remains unclear. Here, we report the identification and functional characterization of the defensin-like antimicrobial gene BbAMP1 encoded by the entomopathogenic fungus Beauveria bassiana. The mature peptide of BbAMP1 can coat fungal spores and can be secreted by the fungus to target and damage Gram-positive bacterial cells. Significant differences in insect survival were observed between the wild-type and BbAMP1 mutant strains during topical infection but not during injection assays that bypassed insect cuticles. Thus, BbAMP1 deletion considerably reduced fungal virulence while gene overexpression accelerated the fungal colonization of insects compared with the wild-type strain in natural infections. Topical infection of axenic Drosophila adults evidenced no difference in fly survivals between strains. However, the gnotobiotic infections with the addition of Gram-positive but not Gram-negative bacterial cells in fungal spore suspensions substantially increased the survival of the flies treated with ∆BbAMP1 compared to those infected by the wild-type and gene-overexpression strains. Bacterial colony counts and microbiome analysis confirmed that BbAMP1 could assist the fungus to manipulate insect surface bacterial loads. This study reveals that fungal defensin can suppress the host surface defensive microbiomes, which underscores the importance to extend the research scope of fungus-host interactions.
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Affiliation(s)
- Song Hong
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanlei Sun
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haimin Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Chengshu Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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Snelders NC, Rovenich H, Thomma BPHJ. Microbiota manipulation through the secretion of effector proteins is fundamental to the wealth of lifestyles in the fungal kingdom. FEMS Microbiol Rev 2022; 46:6590816. [PMID: 35604874 PMCID: PMC9438471 DOI: 10.1093/femsre/fuac022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
Fungi are well-known decomposers of organic matter that thrive in virtually any environment on earth where they encounter wealths of other microbes. Some fungi evolved symbiotic lifestyles, including pathogens and mutualists, that have mostly been studied in binary interactions with their hosts. However, we now appreciate that such interactions are greatly influenced by the ecological context in which they take place. While establishing their symbioses, fungi not only interact with their hosts, but also with the host-associated microbiota. Thus, they target the host and its associated microbiota as a single holobiont. Recent studies have shown that fungal pathogens manipulate the host microbiota by means of secreted effector proteins with selective antimicrobial activity to stimulate disease development. In this review we discuss the ecological contexts in which such effector-mediated microbiota manipulation is relevant for the fungal lifestyle and argue that this is not only relevant for pathogens of plants and animals, but beneficial in virtually any niche where fungi occur. Moreover, we reason that effector-mediated microbiota manipulation likely evolved already in fungal ancestors that encountered microbial competition long before symbiosis with land plants and mammalian animals evolved. Thus, we claim that effector-mediated microbiota manipulation is fundamental to fungal biology.
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Affiliation(s)
- Nick C Snelders
- Institute for Plant Sciences, University of Cologne, Cologne, Germany.,Theoretical Biology & Bioinformatics Group, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Hanna Rovenich
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Bart P H J Thomma
- Institute for Plant Sciences, University of Cologne, Cologne, Germany.,Cluster of Excellence on Plant Sciences, Institute for Plant Sciences, University of Cologne, CologneGermany
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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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Kollakalnaduvil Raghavan RM, Ali Pannippara M, Kesav S, Mathew A, G Bhat S, Hatha Aa M, Kk E. MFAP9: Characterization of an extracellular thermostable antibacterial peptide from marine fungus with biofilm eradication potential. J Pharm Biomed Anal 2020; 194:113808. [PMID: 33303270 DOI: 10.1016/j.jpba.2020.113808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/24/2020] [Accepted: 11/25/2020] [Indexed: 11/17/2022]
Abstract
An extracellular thermostable antibacterial peptide designated as MFAP9 was purified from marine Aspergillus fumigatus BTMF9 by ammonium sulfate precipitation followed by ion exchange chromatography on a DEAE-sepharose column. The molecular weight of MFAP9 was found to be∼3 kDa in SDS-PAGE gel corresponding a single intensity peak in MALDI-TOF. The distinct peak with a retention time of 32.5 min appeared in high performance liquid chromatography (HPLC), further confirming the purity. Isoelectric focusing, two-dimensional gel electrophoresis and peptide mass fingerprinting were performed for the characterization of MFAP9. Functional analysis of purified MFAP9 exhibited strong antibacterial activity against Bacillus circulans (NCIM 2107) with MIC and MBC values of 0.525 μg/mL and 4.2 μg/mL, respectively. The in vitro antibiofilm effect of MFAP9 was analyzed against bacteria which have strong biofilm forming potential. The antibiofilm effect of MFAP9 treatment on Bacillus pumilus was examined using scanning electron microscopy. MFAP9 was found to be active at high temperatures and a wide range of pH (28). In addition, it showed varied sensitivity towards proteolytic enzymes. The peptide was nontoxic to human RBCs at higher concentrations. These results indicate that MFAP9 is an antibacterial peptide, suitable for the development of novel anti-infective agent with strong antibiofilm potential.
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Affiliation(s)
| | - Manzur Ali Pannippara
- Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India; Department of Biotechnology, MES College Marampally, Aluva, 683 107, Kerala, India.
| | - Sapna Kesav
- Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India; Department of Marine Biology, Microbiology and Biochemistry, Cochin University of Science and Technology, Cochin, 682 016, Kerala, India
| | - Abraham Mathew
- Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India; P.G. and Research Department of Botany, St. Peter's College, Kolenchery, 682311, Kerala, India
| | - Sarita G Bhat
- Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682 022, Kerala, India
| | - Mohamed Hatha Aa
- Department of Marine Biology, Microbiology and Biochemistry, Cochin University of Science and Technology, Cochin, 682 016, Kerala, India
| | - Elyas Kk
- Department of Biotechnology, Calicut University, Malappuram, 673 635, Kerala, India
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A Novel Secreted Cysteine-Rich Anionic (Sca) Protein from the Citrus Postharvest Pathogen Penicillium digitatum Enhances Virulence and Modulates the Activity of the Antifungal Protein B (AfpB). J Fungi (Basel) 2020; 6:jof6040203. [PMID: 33023232 PMCID: PMC7711571 DOI: 10.3390/jof6040203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 12/16/2022] Open
Abstract
Antifungal proteins (AFPs) from ascomycete fungi could help the development of antimycotics. However, little is known about their biological role or functional interactions with other fungal biomolecules. We previously reported that AfpB from the postharvest pathogen Penicillium digitatum cannot be detected in the parental fungus yet is abundantly produced biotechnologically. While aiming to detect AfpB, we identified a conserved and novel small Secreted Cysteine-rich Anionic (Sca) protein, encoded by the gene PDIG_23520 from P. digitatum CECT 20796. The sca gene is expressed during culture and early during citrus fruit infection. Both null mutant (Δsca) and Sca overproducer (Scaop) strains show no phenotypic differences from the wild type. Sca is not antimicrobial but potentiates P. digitatum growth when added in high amounts and enhances the in vitro antifungal activity of AfpB. The Scaop strain shows increased incidence of infection in citrus fruit, similar to the addition of purified Sca to the wild-type inoculum. Sca compensates and overcomes the protective effect of AfpB and the antifungal protein PeAfpA from the apple pathogen Penicillium expansum in fruit inoculations. Our study shows that Sca is a novel protein that enhances the growth and virulence of its parental fungus and modulates the activity of AFPs.
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Contreras G, Wang N, Schäfer H, Wink M. Oxidative stress and the presence of bacteria increase gene expression of the antimicrobial peptide aclasin, a fungal CSαβ defensin in Aspergillus clavatus. PeerJ 2019; 7:e6290. [PMID: 30828484 PMCID: PMC6394349 DOI: 10.7717/peerj.6290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/15/2018] [Indexed: 12/17/2022] Open
Abstract
Background Antimicrobial peptides (AMPs) represent a broad class of naturally occurring antimicrobial compounds. Plants, invertebrates and fungi produce various AMPs as, for example, defensins. Most of these defensins are characterised by the presence of a cysteine-stabilised α-helical and β-sheet (CSαβ) motif. The changes in gene expression of a fungal CSαβ defensin by stress conditions were investigated in Aspergillus clavatus. A. clavatus produces the CSαβ defensin Aclasin, which is encoded by the aclasin gene. Methods Aclasin expression was evaluated in submerged mycelium cultures under heat shock, osmotic stress, oxidative stress and the presence of bacteria by quantitative real-time PCR. Results Aclasin expression increased two fold under oxidative stress conditions and in the presence of viable and heat-killed Bacillus megaterium. Under heat shock and osmotic stress, aclasin expression decreased. Discussion The results suggest that oxidative stress and the presence of bacteria might regulate fungal defensin expression. Moreover, fungi might recognise microorganisms as plants and animals do.
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Affiliation(s)
- Gabriela Contreras
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Nessa Wang
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Holger Schäfer
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
| | - Michael Wink
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Baden-Württemberg, Germany
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