scholarly journals Divalent Metal Cations Potentiate the Predatory Capacity of Amoeba forCryptococcus neoformans

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Man Shun Fu ◽  
Arturo Casadevall
Keyword(s):  
Contaminated Soils ◽  
Divalent Cations ◽  
Pathogenic Fungus ◽  
Acanthamoeba Castellanii ◽  
Pathogenic Fungi ◽  
Important Variable ◽  
Yeast Cells ◽  
Experimental Conditions ◽  
Content Type ◽  
Practical Applications

ABSTRACTAmong the best-studied interactions between soil phagocytic predators and a human-pathogenic fungus is that ofAcanthamoeba castellaniiandCryptococcus neoformans. The experimental conditions used in amoeba-fungus confrontation assays can have major effects on whether the fungus or the protozoan is ascendant in the interaction. In the presence of Mg2+and Ca2+in phosphate-buffered saline (PBS),C. neoformanswas consistently killed when incubated withA. castellanii.A. castellaniisurvived better in the presence of Mg2+and Ca2+, even when incubated withC. neoformans. In the absence of Mg2+and Ca2+,C. neoformanssurvived when incubated withA. castellanii, and the percentage of dead amoebae was higher than when incubated without yeast cells. These results show that the presence of Mg2+and Ca2+can make a decisive contribution toward tilting the outcome of the interaction in favor of the amoeba. Of the two metals, Mg2+had a stronger effect than Ca2+. The cations enhancedA. castellaniiactivity againstC. neoformansvia enhanced phagocytosis, which is the major mechanism by which amoebae kill fungal cells. We found no evidence that amoebae use extracellular killing mechanisms in their interactions withC. neoformans. In summary, the presence of Mg2+and Ca2+enhanced the cell adhesion on the surfaces and the motility of the amoeba, thus increasing the chance for contact withC. neoformansand the frequency of phagocytosis. Our findings imply that the divalent cation concentration in soils could be an important variable for whether amoebae can controlC. neoformansin the environment.IMPORTANCEThe grazing of soil organisms by phagocytic predators such as amoebae is thought to select for traits that enable some of them to acquire the capacity for virulence in animals. Consequently, knowledge about the interactions between amoebae and soil microbes, such as pathogenic fungi, is important for understanding how virulence can emerge. We show that the interaction between an amoeba and the pathogenic fungusC. neoformansis influenced by the presence in the assay of magnesium and calcium, which potentiate amoebae. The results may also have practical applications, since enriching soils with divalent cations may reduceC. neoformansnumbers in contaminated soils.

scholarly journals Divalent metal cations potentiate the predatory capacity of amoeba forCryptococcus neoformans

2017 ◽  
Author(s):  
Man Shun Fu ◽  
Arturo Casadevall
Keyword(s):  
Contaminated Soils ◽  
Divalent Cations ◽  
Pathogenic Fungus ◽  
Acanthamoeba Castellanii ◽  
Pathogenic Fungi ◽  
Important Variable ◽  
Yeast Cells ◽  
Experimental Conditions ◽  
Practical Applications ◽  
Major Mechanism

AbstractAmong the best studied interaction between soil phagocytic predators and a human pathogenic fungus is that ofAcanthamoeba castellaniiandCryptococcus neoformans. The experimental conditions used in amoeba-fungal confrontation assays can have major effects on whether the fungus or the protozoan is ascendant in the interaction. In the presence of Mg2+and Ca2+in PBS,C. neoformanswas consistently killed when incubated withA. castellanii.A. castellaniisurvived better in the presence of Mg2+and Ca2+, even when incubated withC. neoformans. In the absence of Mg2+and Ca2+,C. neoformanssurvived when incubated withA. castellanii, and the percentage of dead amoeba was higher than when incubated without yeast cells. These results show that the presence of Mg2+and Ca2+can make a decisive contribution toward tilting the outcome of the interaction in favor of amoeba. Of the two metals Mg2+had a stronger effect than Ca2+. Cations enhancedA. castellaniiactivity againstC. neoformansthrough enhanced phagocytosis, which is the major mechanism for amoeba to kill fungal cells. We found no evidence that amoeba uses extracellular killing mechanisms in their interactions withC. neoformans. In summary, the presence of Mg2+and Ca2+enhanced cell adhesion on surface and motility of amoeba, thus increasing the chance for contact ofC. neoformansand the frequency of phagocytosis. Our findings imply that divalent cation concentration in soils could be an important variable for whether amoeba can controlC. neoformansin the environment.ImportanceGrazing of soil organisms by phagocytic predators such as amoeba is thought to select for traits that allow some of them to acquire the capacity for virulence in animals. Consequently, knowledge about the interactions between amoeba and soil microbes, such as pathogenic fungi, is important for understanding how virulence can emerge. We show that the interaction between amoeba and the pathogenic fungusC. neoformansis influenced by the presence of magnesium and calcium in the assay, which potentiate amoeba. The results may also have practical applications since enriching soils with divalent cations may reduceC. neoformansnumbers in contaminated soils.

scholarly journals Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle

2013 ◽  
Vol 80 (5) ◽  
pp. 1553-1560 ◽  
Author(s):  
Scott W. Behie ◽  
Michael J. Bidochka
Keyword(s):  
Panicum Virgatum ◽  
Pathogenic Fungus ◽  
Insect Herbivory ◽  
Pathogenic Fungi ◽  
Nitrogen Transfer ◽  
Metarhizium Robertsii ◽  
Content Type ◽  
Lecanicillium Lecanii ◽  
Worldwide Distribution ◽  
Insect Pathogenic Fungi

ABSTRACTThe study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungusMetarhizium robertsii. That is, the endophytic capability and insect pathogenicity ofM. robertsiiare coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in fiveMetarhiziumspecies representing those with broad (M. robertsii,M. brunneum, andM. guizhouense) and narrower insect host ranges (M. acridumandM. flavoviride), as well as the insect-pathogenic fungiBeauveria bassianaandLecanicillium lecanii. Insects were injected with15N-labeled nitrogen, and we tracked the incorporation of15N into two dicots, haricot bean (Phaseolus vulgaris) and soybean (Glycine max), and two monocots, switchgrass (Panicum virgatum) and wheat (Triticum aestivum), in the presence of these fungi in soil microcosms. AllMetarhiziumspecies andB. bassianabut notL. lecaniishowed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high,M. robertsiiwas able to transfer insect-derived nitrogen to plants.Metarhiziumspp. andB. bassianahave a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities.

scholarly journals The Pathogenic Fungus Paracoccidioides brasiliensis Exports Extracellular Vesicles Containing Highly Immunogenic α-Galactosyl Epitopes

2011 ◽  
Vol 10 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Milene C. Vallejo ◽  
Alisson L. Matsuo ◽  
Luciane Ganiko ◽  
Lia C. Soares Medeiros ◽  
Kildare Miranda ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Fungal Pathogens ◽  
Histoplasma Capsulatum ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Yeast Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dimorphic Fungus ◽  
Content Type

ABSTRACTExosome-like vesicles containing virulence factors, enzymes, and antigens have recently been characterized in fungal pathogens, such asCryptococcus neoformansandHistoplasma capsulatum. Here, we describe extracellular vesicles carrying highly immunogenic α-linked galactopyranosyl (α-Gal) epitopes inParacoccidioides brasiliensis. P. brasiliensisis a dimorphic fungus that causes human paracoccidioidomycosis (PCM). For vesicle preparations, cell-free supernatant fluids from yeast cells cultivated in Ham's defined medium-glucose were concentrated in an Amicon ultrafiltration system and ultracentrifuged at 100,000 ×g. P. brasiliensisantigens were present in preparations from phylogenetically distinct isolates Pb18 and Pb3, as observed in immunoblots revealed with sera from PCM patients. In an enzyme-linked immunosorbent assay (ELISA), vesicle components containing α-Gal epitopes reacted strongly with anti-α-Gal antibodies isolated from both Chagas' disease and PCM patients, withMarasmius oreadesagglutinin (MOA) (a lectin that recognizes terminal α-Gal), but only faintly with natural anti-α-Gal. Reactivity was inhibited after treatment with α-galactosidase. Vesicle preparations analyzed by electron microscopy showed vesicular structures of 20 to 200 nm that were labeled both on the surface and in the lumen with MOA. InP. brasiliensiscells, components carrying α-Gal epitopes were found distributed on the cell wall, following a punctuated confocal pattern, and inside large intracellular vacuoles. Lipid-free vesicle fractions reacted with anti-α-Gal in ELISA only when not digested with α-galactosidase, while reactivity with glycoproteins was reduced after β-elimination, which is indicative of partial O-linked chain localization. Our findings open new areas to explore in terms of host-parasite relationships in PCM and the role playedin vivoby vesicle components and α-galactosyl epitopes.

scholarly journals Morphogenetic Circuitry Regulating Growth and Development in the Dimorphic Pathogen Penicillium marneffei

2012 ◽  
Vol 12 (2) ◽  
pp. 154-160 ◽  
Author(s):  
Kylie J. Boyce ◽  
Alex Andrianopoulos
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungus ◽  
Hyphal Growth ◽  
Penicillium Marneffei ◽  
Yeast Cells ◽  
Asexual Development ◽  
Infectious Agents ◽  
Temperature Dependent ◽  
Content Type ◽  
Human Pathogenic Fungus

ABSTRACTPenicillium marneffeiis an emerging human-pathogenic fungus endemic to Southeast Asia. Like a number of other fungal pathogens,P. marneffeiexhibits temperature-dependent dimorphic growth and grows in two distinct cellular morphologies, hyphae at 25°C and yeast cells at 37°C. Hyphae can differentiate to produce the infectious agents, asexual spores (conidia), which are inhaled into the host lung, where they are phagocytosed by pulmonary alveolar macrophages. Within macrophages, conidia germinate into unicellular yeast cells, which divide by fission. This minireview focuses on the current understanding of the genes required for the morphogenetic control of conidial germination, hyphal growth, asexual development, and yeast morphogenesis inP. marneffei.

scholarly journals Iron Metabolism, Pseudohypha Production, and Biofilm Formation through a Multicopper Oxidase in the Human-Pathogenic Fungus Candida parapsilosis

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Tanmoy Chakraborty ◽  
Zsófia Tóth ◽  
Renáta Tóth ◽  
Csaba Vágvölgyi ◽  
Attila Gácser
Keyword(s):  
Iron Metabolism ◽  
Biofilm Formation ◽  
Iron Uptake ◽  
Candida Parapsilosis ◽  
Iron Acquisition ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Multicopper Oxidase ◽  
Immunocompromised Patients ◽  
Content Type

ABSTRACT Among all the essential micronutrients, iron plays an important role in mammalian biology. It is also essential for pathogens infecting mammalian hosts, including bacteria, fungi, and protozoans. As the availability of accessible iron is limited within the mammalian host, several human-pathogenic fungal pathogens, such as Candida albicans, Cryptococcus neoformans, Candida glabrata, and Aspergillus fumigatus, have developed various iron uptake mechanisms. Although Candida parapsilosis is the second or third most common non-albicans Candida species associated with systemic and superficial Candida infections in immunocompromised patients, the mechanisms of iron uptake and homoeostasis remain unknown in this fungus. In the current report, we show that a homologue of the multicopper oxidase gene FET3 is present in the genome of C. parapsilosis (CPAR2_603600) and plays a significant role in iron acquisition. We found that homozygous deletion mutants of CPAR2_603600 showed defects under low-iron conditions and were also sensitive to various stressors. Our results also revealed that the levels of pseudohypha formation and biofilm formation were reduced in the null mutants compared to the wild type. This phenotypic defect could be partially rescued by supplementation with excess iron in the growth medium. The expression levels of the orthologues of various iron metabolism-related genes were also altered in the mutants compared to the parental strain. In conclusion, our report describes the role of CPAR2_603600 in iron homoeostasis maintenance as well as morphology and biofilm formation regulation in this pathogenic fungus. IMPORTANCE C. parapsilosis is the second or third most common opportunistic human-pathogenic Candida species, being responsible for severe fungal infections among immunocompromised patients, especially low-birth-weight infants (0 to 2 years of age). Among the major virulence factors that pathogenic fungi possess is the ability to compete with the host for essential micronutrients, including iron. Accessible iron is required for the maintenance of several metabolic processes. In order to obtain accessible iron from the host, pathogenic fungi have developed several iron acquisition and metabolic mechanisms. Although C. parapsilosis is a frequent cause of invasive candidiasis, little is known about what iron metabolic processes this fungus possesses that could contribute to the species’ virulent behavior. In this study, we identified the multicopper oxidase FET3 gene that regulates iron homeostasis maintenance and also plays important roles in the morphology of the fungus as well as in biofilm formation, two additional factors in fungal virulence.

scholarly journals The PbMDJ1 Gene Belongs to a Conserved MDJ1/LON Locus in Thermodimorphic Pathogenic Fungi and Encodes a Heat Shock Protein That Localizes to both the Mitochondria and Cell Wall of Paracoccidioides brasiliensis

2006 ◽  
Vol 5 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Wagner L. Batista ◽  
Alisson L. Matsuo ◽  
Luciane Ganiko ◽  
Tânia F. Barros ◽  
Thiago R. Veiga ◽  
...  
Keyword(s):  
Cell Wall ◽  
Heat Shock ◽  
Cell Surface ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Yeast Cells ◽  
Shock Proteins

ABSTRACT J-domain (DnaJ) proteins, of the Hsp40 family, are essential cofactors of their cognate Hsp70 chaperones, besides acting as independent chaperones. In the present study, we have demonstrated the presence of Mdj1, a mitochondrial DnaJ member, not only in the mitochondria, where it is apparently sorted, but also in the cell wall of Paracoccidioides brasiliensis, a thermodimorphic pathogenic fungus. The molecule (PbMdj1) was localized to fungal yeast cells using both confocal and electron microscopy and also flow cytometry. The anti-recombinant PbMdj1 antibodies used in the reactions specifically recognized a single 55-kDa mitochondrial and cell wall (alkaline β-mercaptoethanol extract) component, compatible with the predicted size of the protein devoid of its matrix peptide-targeting signal. Labeling was abundant throughout the cell wall and especially in the budding regions; however, anti-PbMdj1 did not affect fungal growth in the concentrations tested in vitro, possibly due to the poor access of the antibodies to their target in growing cells. Labeled mitochondria stood preferentially close to the plasma membrane, and gold particles were detected in the thin space between them, toward the cell surface. We show that Mdj1 and the mitochondrial proteinase Lon homologues are heat shock proteins in P. brasiliensis and that their gene organizations are conserved among thermodimorphic fungi and Aspergillus, where the genes are adjacent and have a common 5′ region. This is the first time a DnaJ member has been observed on the cell surface, where its function is speculative.

scholarly journals MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

2015 ◽  
Vol 14 (4) ◽  
pp. 396-405 ◽  
Author(s):  
Yanfang Shang ◽  
Peilin Chen ◽  
Yixiong Chen ◽  
Yuzhen Lu ◽  
Chengshu Wang
Keyword(s):  
Cell Wall ◽  
Target Genes ◽  
Response Regulator ◽  
Pathogenic Fungus ◽  
Functional Divergence ◽  
Pathogenic Fungi ◽  
Wild Type ◽  
Metarhizium Robertsii ◽  
Content Type ◽  
Cell Autolysis

ABSTRACT Two-component signaling pathways generally include sensor histidine kinases and response regulators. We identified an ortholog of the response regulator protein Skn7 in the insect-pathogenic fungus Metarhizium robertsii , which we named MrSkn7. Gene deletion assays and functional characterizations indicated that MrSkn7 functions as a transcription factor. The MrSkn7 null mutant of M. robertsii lost the ability to sporulate and had defects in cell wall biosynthesis but was not sensitive to oxidative and osmotic stresses compared to the wild type. However, the mutant was able to produce spores under salt stress. Insect bioassays using these spores showed that the virulence of the mutant was significantly impaired compared to that of the wild type due to the failures to form the infection structure appressorium and evade host immunity. In particular, deletion of MrSkn7 triggered cell autolysis with typical features such as cell vacuolization, downregulation of repressor genes, and upregulation of autolysis-related genes such as extracellular chitinases and proteases. Promoter binding assays confirmed that MrSkn7 could directly or indirectly control different putative target genes. Taken together, the results of this study help us understand the functional divergence of Skn7 orthologs as well as the mechanisms underlying the development and control of virulence in insect-pathogenic fungi.

scholarly journals The Intermediates in Branched-Chain Amino Acid Biosynthesis Are Indispensable for Conidial Germination of the Insect-Pathogenic Fungus Metarhizium robertsii

2020 ◽  
Vol 86 (20) ◽  
Author(s):  
Feifei Luo ◽  
Hongxia Zhou ◽  
Xue Zhou ◽  
Xiangyun Xie ◽  
You Li ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Conidial Germination ◽  
Keto Acid ◽  
Metarhizium Robertsii ◽  
Content Type ◽  
Branched Chain Amino Acid ◽  
Key Enzyme ◽  
Branched Chain

ABSTRACT Metarhizium spp. are well-known biocontrol agents used worldwide to control different insect pests. Keto-acid reductoisomerase (ILVC) is a key enzyme for branched-chain amino acid (BCAA) biosynthesis, and it regulates many physiological activities. However, its functions in insect-pathogenic fungi are poorly understood. In this work, we identified MrilvC in M. robertsii and dissected its roles in fungal growth, conidiation, germination, destruxin biosynthesis, environmental stress response, and insecticidal virulence. BCAA metabolism affects conidial yields and germination. However, BCAAs cannot recover the conidial germination of an MrilvC-deficient strain. Further feeding assays with intermediates showed that some conidia of the ΔMrilvC mutant start to germinate. Therefore, it is the germination defect that causes the complete failures of conidial penetration and pathogenicity in the ΔMrilvC mutant. In conclusion, we found intermediates in BCAA biosynthesis are indispensable for Metarhizium robertsii conidial germination. This study will advance our understanding of the fungal germination mechanism. IMPORTANCE Branched-chain amino acid (BCAA) metabolism plays a significant role in many biological activities beyond protein synthesis. Spore germination initiates the first stage of vegetative growth, which is critical for the virulence of pathogenic fungi. In this study, we demonstrated that the keto-acid reductoisomerase MrILVC, a key enzyme for BCAA biosynthesis, from the insect-pathogenic fungus Metarhizium robertsii is associated with conidial germination and fungal pathogenicity. Surprisingly, the germination of the ΔMrilvC mutant was restored when supplemented with the intermediates of BCAA metabolism rather than three BCAAs. The result was significantly different from that of plant-pathogenic fungi. Therefore, this report highlights that the intermediates in BCAA biosynthesis are indispensable for conidial germination of M. robertsii.

scholarly journals A hidden battle in the dirt: soil amoebae interactions withParacoccidioidesspp

2019 ◽  
Author(s):  
Patrícia Albuquerque ◽  
André Moraes Nicola ◽  
Diogo Almeida Gomes Magnabosco ◽  
Lorena da Silveira Derengowski ◽  
Luana Soares Crisóstomo ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Acanthamoeba Castellanii ◽  
Pathogenic Fungi ◽  
Yeast Cells ◽  
Its Sequencing ◽  
Fungal Virulence ◽  
Evolution Of Virulence ◽  
Natural Predator ◽  
Molecular Patterns

AbstractParacoccidioidesspp. are thermodimorphic pathogenic fungi endemic to Latin America. Predation is believed to drive the evolution of virulence for soil saprophytes. We evaluated the presence of environmental amoeboid predators in soil from armadillo burrows whereParacoccidioideshad been previously detected and tested if interaction ofParacoccidioideswith amoebae increased fungal virulence. Nematodes, ciliates and amoebae – all potential predators of fungi – grew in cultures from soil samples. Microscopical observation and ITS sequencing identified the amoebae asAcanthamoebaspp,Allovahlkampfia spelaeaandVermamoeba vermiformis. These three amoebae efficiently ingested, killed and digestedParacoccidioidesspp. yeast cells, as did laboratory-adapted axenicAcanthamoeba castellanii. Sequential co-cultivation ofParacoccidioideswithA. castellaniiselected for phenotypical traits related to survival of the fungus within a natural predator as well as in murine macrophages and in vivo (Galleria mellonellaand mice). This increase in virulence is linked to the accumulation of cell wall alpha-glucans, polysaccharides that masks recognition of fungal molecular patterns by host pattern recognition receptors. Altogether, our results indicate thatParacoccidioidesinhabits a complex environment with multiple amoeboid predators that can exert selective pressure to guide the evolution of virulence traits.

scholarly journals Protein Phosphatase Pph3 and Its Regulatory Subunit Psy2 Regulate Rad53 Dephosphorylation and Cell Morphogenesis during Recovery from DNA Damage in Candida albicans

2011 ◽  
Vol 10 (11) ◽  
pp. 1565-1573 ◽  
Author(s):  
Ling Ling Sun ◽  
Wan Jie Li ◽  
Hai Tao Wang ◽  
Jie Chen ◽  
Ping Deng ◽  
...  
Keyword(s):  
Dna Damage ◽  
Candida Albicans ◽  
Uv Light ◽  
Pathogenic Fungus ◽  
Genotoxic Stress ◽  
Filamentous Growth ◽  
Yeast Cells ◽  
Regulatory Subunit ◽  
Content Type ◽  
Dna Damaging Agents

ABSTRACT The ability of the pathogenic fungus Candida albicans to switch cellular morphologies is important for infection and virulence. Recent studies have revealed that C. albicans yeast cells can switch to filamentous growth under genotoxic stress in a manner dependent on the DNA replication/damage checkpoint. Here, we have investigated the functions of Pph3 (orf19.4378) and Psy2 (orf19.3685), whose orthologues in Saccharomyces cerevisiae mediate the dephosphorylation of the DNA damage checkpoint kinase Rad53 and the histone variant H2AX during recovery from DNA damage. Deleting PPH3 or PSY2 causes hypersensitivity to DNA-damaging agents, including cisplatin, methylmethane sulfonate (MMS), and UV light. In addition, pph3 Δ and psy2 Δ cells exhibit strong filamentous growth under genotoxic stress. Flow cytometry analysis shows that the mutant cells have lost the ability to adapt to genotoxic stress and remain arrested even after the stress is withdrawn. Furthermore, we show that Pph3 and Psy2 are required for the dephosphorylation of Rad53, but not H2AX, during DNA damage recovery. Taken together, these results show that C. albicans Pph3 and Psy2 have important roles in mediating genotoxin-induced filamentous growth and regulating Rad53 dephosphorylation.

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