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García-Carnero LC, Martínez-Álvarez JA, Salazar-García LM, Lozoya-Pérez NE, González-Hernández SE, Tamez-Castrellón AK. Recognition of Fungal Components by the Host Immune System. Curr Protein Pept Sci 2021; 21:245-264. [PMID: 31889486 DOI: 10.2174/1389203721666191231105546] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 08/08/2019] [Accepted: 10/15/2019] [Indexed: 11/22/2022]
Abstract
By being the first point of contact of the fungus with the host, the cell wall plays an important role in the pathogenesis, having many molecules that participate as antigens that are recognized by immune cells, and also that help the fungus to establish infection. The main molecules reported to trigger an immune response are chitin, glucans, oligosaccharides, proteins, melanin, phospholipids, and others, being present in the principal pathogenic fungi with clinical importance worldwide, such as Histoplasma capsulatum, Paracoccidioides brasiliensis, Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Blastomyces dermatitidis, and Sporothrix schenckii. Knowledge and understanding of how the immune system recognizes and responds to fungal antigens are relevant for the future research and development of new diagnostic tools and treatments for the control of mycosis caused by these fungi.
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Affiliation(s)
- Laura C García-Carnero
- Department of Biology, Exact and Natural Sciences Division, Universidad de Guanajuato, Guanajuato, Mexico
| | - José A Martínez-Álvarez
- Department of Biology, Exact and Natural Sciences Division, Universidad de Guanajuato, Guanajuato, Mexico
| | - Luis M Salazar-García
- Department of Biology, Exact and Natural Sciences Division, Universidad de Guanajuato, Guanajuato, Mexico
| | - Nancy E Lozoya-Pérez
- Department of Biology, Exact and Natural Sciences Division, Universidad de Guanajuato, Guanajuato, Mexico
| | | | - Alma K Tamez-Castrellón
- Department of Biology, Exact and Natural Sciences Division, Universidad de Guanajuato, Guanajuato, Mexico
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Lenaers M, Reyns W, Czech J, Carleer R, Basak I, Deferme W, Krupinska P, Yildiz T, Saro S, Remans T, Vangronsveld J, De Laender F, Rineau F. Links Between Heathland Fungal Biomass Mineralization, Melanization, and Hydrophobicity. MICROBIAL ECOLOGY 2018; 76:762-770. [PMID: 29492595 DOI: 10.1007/s00248-018-1167-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
Comprehending the decomposition process is crucial for our understanding of the mechanisms of carbon (C) sequestration in soils. The decomposition of plant biomass has been extensively studied. It revealed that extrinsic biomass properties that restrict its access to decomposers influence decomposition more than intrinsic ones that are only related to its chemical structure. Fungal biomass has been much less investigated, even though it contributes to a large extent to soil organic matter, and is characterized by specific biochemical properties. In this study, we investigated the extent to which decomposition of heathland fungal biomass was affected by its hydrophobicity (extrinsic property) and melanin content (intrinsic property). We hypothesized that, as for plant biomass, hydrophobicity would have a greater impact on decomposition than melanin content. Mineralization was determined as the mineralization of soil organic carbon (SOC) into CO2 by headspace GC/MS after inoculation by a heathland soil microbial community. Results show that decomposition was not affected by hydrophobicity, but was negatively correlated with melanin content. We argue that it may indicate that either melanin content is both an intrinsic and extrinsic property, or that some soil decomposers evolved the ability to use surfactants to access to hydrophobic biomass. In the latter case, biomass hydrophobicity should not be considered as a crucial extrinsic factor. We also explored the ecology of decomposition, melanin content, and hydrophobicity, among heathland soil fungal guilds. Ascomycete black yeasts had the highest melanin content, and hyaline Basidiomycete yeasts the lowest. Hydrophobicity was an all-or-nothing trait, with most isolates being hydrophobic.
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Affiliation(s)
- Mathias Lenaers
- Centre for Environmental Sciences, Research Group Environmental Biology, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Wouter Reyns
- Centre for Environmental Sciences, Research Group Environmental Biology, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur, Belgium
| | - Jan Czech
- Centre for Environmental Sciences, Research Group of Applied and Analytical Chemistry, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Robert Carleer
- Centre for Environmental Sciences, Research Group of Applied and Analytical Chemistry, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Indranil Basak
- Institute for Materials Research IMO-IMOMEC, Hasselt University, Diepenbeek, Belgium
| | - Wim Deferme
- Institute for Materials Research IMO-IMOMEC, Hasselt University, Diepenbeek, Belgium
| | | | - Talha Yildiz
- PXL, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Sherilyn Saro
- PXL, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Tony Remans
- PXL, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Jaco Vangronsveld
- Centre for Environmental Sciences, Research Group Environmental Biology, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium
| | - Frederik De Laender
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur, Belgium
| | - Francois Rineau
- Centre for Environmental Sciences, Research Group Environmental Biology, Hasselt University, Agoralaan Building D, B-3590, Diepenbeek, Belgium.
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Abstract
Melanins represent virulence factors for several pathogenic fungi; the number of examples is growing. Thus, albino mutants of several genera (in one case, mutated precisely in the melanizing enzyme) exhibit decreased virulence in mice. We consider the phenomenon in relation to known chemical properties of melanin, beginning with biosynthesis from ortho-hydroquinone precursors which, when oxidized enzymatically to quinones, polymerize spontaneously to melanin. It follows that melanizing intermediates are cross-linking reagents; melanization stabilizes the external cell wall against hydrolysis and is thought to determine semipermeability in the osmotic ram (the appressorium) of certain plant pathogens. Polymeric melanins undergo reversible oxidation-reduction reactions between cell wall-penetrating quinone and hydroquinone oxidation states and thus represent polymeric redox buffers; using strong oxidants, it is possible to titrate the melanin on living cells and thereby demonstrate protection conferred by melanin in several species. The amount of buffering per cell approximately neutralizes the amount of oxidant generated by a single macrophage. Moreover, the intermediate oxidation state, the semiquinone, is a very stable free radical and is thought to trap unpaired electrons. We have suggested that the oxidation state of external melanin may be regulated by external Fe(II). An independent hypothesis holds that in Cryptococcus neoformans, an important function of the melanizing enzyme (apart from melanization) is the oxidation of Fe(II) to Fe(III), thereby forestalling generation of the harmful hydroxyl radical from H(2)O(2). Thus, problems in fungal pathogenesis have led to evolving hypotheses regarding melanin functioning.
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Abstract
Melanins represent virulence factors for several pathogenic fungi; the number of examples is growing. Thus, albino mutants of several genera (in one case, mutated precisely in the melanizing enzyme) exhibit decreased virulence in mice. We consider the phenomenon in relation to known chemical properties of melanin, beginning with biosynthesis from ortho-hydroquinone precursors which, when oxidized enzymatically to quinones, polymerize spontaneously to melanin. It follows that melanizing intermediates are cross-linking reagents; melanization stabilizes the external cell wall against hydrolysis and is thought to determine semipermeability in the osmotic ram (the appressorium) of certain plant pathogens. Polymeric melanins undergo reversible oxidation-reduction reactions between cell wall-penetrating quinone and hydroquinone oxidation states and thus represent polymeric redox buffers; using strong oxidants, it is possible to titrate the melanin on living cells and thereby demonstrate protection conferred by melanin in several species. The amount of buffering per cell approximately neutralizes the amount of oxidant generated by a single macrophage. Moreover, the intermediate oxidation state, the semiquinone, is a very stable free radical and is thought to trap unpaired electrons. We have suggested that the oxidation state of external melanin may be regulated by external Fe(II). An independent hypothesis holds that in Cryptococcus neoformans, an important function of the melanizing enzyme (apart from melanization) is the oxidation of Fe(II) to Fe(III), thereby forestalling generation of the harmful hydroxyl radical from H(2)O(2). Thus, problems in fungal pathogenesis have led to evolving hypotheses regarding melanin functioning.
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Affiliation(s)
- E S Jacobson
- McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249, USA.
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Rolz C, Cabrera SD, Valdez MJ, De Arriola MDC, Valladares J. Biodegradation of pretreated ex-fermented sugar cane chips by fungal enzymes and mixtures of anaerobic bacteria. Biotechnol Prog 1986; 2:120-30. [PMID: 20568204 DOI: 10.1002/btpr.5420020306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- C Rolz
- Central American Research Institute for Industry (ICAITI), P.O. Box 1552, Guatemala City, Guatemala
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