Vesicle-associated melanization in Cryptococcus neoformans.
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TLDR
A model for C. neoformans melanization is proposed that provides a mechanism for the assembly of melanin into relatively uniform spherical particles stacked in an orderly arrangement in the cell wall.Abstract:
Recently, several pathogenic fungi were shown to produce extracellular vesicles that contain various components associated with virulence. In the human pathogenic fungus Cryptococcus neoformans, these components included laccase, an enzyme that catalyses melanin synthesis. Spherical melanin granules have been observed in the cell wall of C. neoformans. Given that melanin granules have dimensions that are comparable to those of extracellular vesicles, and that metazoan organisms produce melanin in vesicular structures known as melanosomes, we investigated the role of vesicles in cryptococcal melanization. Extracellular vesicles melanized when incubated with the melanin precursor l-3,4-dihydroxyphenylalanine (l-DOPA). The kinetics of substrate incorporation into cells and vesicles was analysed using radiolabelled l-DOPA. The results indicated that substrate incorporation was different for cells and isolated vesicles. Acid-generated melanin ghosts stained with lipophilic dyes, implying the presence of associated lipid. A model for C. neoformans melanization is proposed that accounts for these observations and provides a mechanism for the assembly of melanin into relatively uniform spherical particles stacked in an orderly arrangement in the cell wall.read more
Citations
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Through the wall: extracellular vesicles in Gram-positive bacteria, mycobacteria and fungi
TL;DR: The current status of vesiculogenesis research in thick-walled microorganisms is described and the cargo and functions associated with EVs in these species are discussed.
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Synthesis and assembly of fungal melanin
TL;DR: Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall and take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances.
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Exosomes and other extracellular vesicles in host–pathogen interactions
TL;DR: This review highlights the composition and function of exosomes and other extracellular vesicle produced during viral, parasitic, fungal and bacterial infections and describes how these vesicles could function to either promote or inhibit host immunity.
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Cryptococcus neoformans and Cryptococcus gattii, the Etiologic Agents of Cryptococcosis
Kyung J. Kwon-Chung,James A. Fraser,Tamara L. Doering,Zhuo Wang,Guilhem Janbon,Alexander Idnurm,Yong Sun Bahn +6 more
TL;DR: Topics focused on in this article include species description, pathogenesis, life cycle, capsule, and stress response, which serve to highlight the specializations in virulence that have occurred in this unique encapsulated melanin-forming yeast that causes global deaths estimated at more than 600,000 annually.
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Bacillus anthracis produces membrane-derived vesicles containing biologically active toxins
Johanna Rivera,Radames J. B. Cordero,Antonio Nakouzi,Susana Frases,André Moraes Nicola,André Moraes Nicola,Arturo Casadevall +6 more
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References
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Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS.
Benjamin J. Park,Kathleen Wannemuehler,Barbara J. Marston,Nelesh P. Govender,Peter G. Pappas,Tom Chiller +5 more
TL;DR: The first attempt to estimate the global burden of cryptococcal meningitis finds the number of cases and deaths to be very high, with most occurring in sub-Saharan Africa.
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Determination of catecholamines in rat brain parts by reverse-phase ion-pair liquid chromatography
TL;DR: An improved method for the measurement of catecholamines in brain parts has been developed, based on reverse‐phase ion‐pair chromatography, which offers the advantages of high efficiency microparticulate liquid chromatography packings and the flexibility of ion‐ Pair chromatography.
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Extracellular Vesicles Produced by Cryptococcus neoformans Contain Protein Components Associated with Virulence
Marcio L. Rodrigues,Ernesto S. Nakayasu,Débora L. Oliveira,Leonardo Nimrichter,Joshua D. Nosanchuk,Igor C. Almeida,Arturo Casadevall +6 more
TL;DR: An efficient and general mechanism of secretion of pathogenesis-related molecules in C. neoformans is revealed, suggesting that extracellular vesicles function as “virulence bags” that deliver a concentrated payload of fungal products to host effector cells and tissues.
Journal ArticleDOI
Vesicular Polysaccharide Export in Cryptococcus neoformans Is a Eukaryotic Solution to the Problem of Fungal Trans-Cell Wall Transport
Marcio L. Rodrigues,Leonardo Nimrichter,Débora L. Oliveira,Susana Frases,Kildare Miranda,Oscar Zaragoza,Mauricio A. Álvarez,Antonio Nakouzi,Marta Feldmesser,Arturo Casadevall +9 more
TL;DR: It is demonstrated that C. neoformans produces extracellular vesicles during in vitro growth and animal infection and implies a novel mechanism for the release of the major virulence factor of C. Neoformans whereby polysaccharide packaged in lipid vesicle crosses the cell wall and the capsule network to reach the Extracellular environment.
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Serologic evidence for Cryptococcus neoformans infection in early childhood.
David L. Goldman,Hnin Khine,Jacob Abadi,Dania J. Lindenberg,Liise Anne Pirofski,Ramata Niang,Arturo Casadevall +6 more
TL;DR: The results suggest that the low incidence of symptomatic cryptococcal disease in children with AIDS is not a result of lack of exposure to C neoformans, and provide both indirect and direct evidence of C neo formans infection in immunocompetent children.