TY - JOUR
T1 - N-acetylglucosamine affects cryptococcus neoformans cell-wall composition and melanin architecture
AU - Camacho, Emma
AU - Chrissian, Christine
AU - Cordero, Radames J.B.
AU - Lopes, Livia Liporagi
AU - Stark, Ruth E.
AU - Casadevall, Arturo
N1 - Funding Information:
This research was supported by a grant from the US National Institutes of Health (NIH R01-AI052733). The NMR facilities used in this work are operated by The City College and the CUNY Institute for Macromolecular Assemblies, with additional infrastructural support provided by NIH 8G12 MD007603 from the National Institute on Minority Health and Health Disparities of the National Institutes of Health. C. C. was the recipient of a fellowship award from the US Department of Education Graduate Assistance in Areas of National Need (GAANN) Program in Biochemistry, Biophysics, and Biodesign at The City College of New York (PA200A120211 and PA200A150068). L. L-L. was supported by a fellowship provided from ‘Conselho Nacional de Desen-volvimento Científico e Tecnológico (CNPq)’.
Funding Information:
This research was supported by a grant from the US National Institutes of Health (NIHR01-AI052733). The NMR facilities used in this work are operated by The City College and the CUNY Institute for Macromolecular Assemblies, with additional infrastructural support provided by NIH 8G12 MD007603 from the National Institute on Minority Health and Health Disparities of the National Institutes of Health. C. C. was the recipient of a fellowship award from the US Department of Education Graduate Assistance in Areas of National Need (GAANN) Program in Biochemistry, Biophysics, and Biodesign at The City College of New York (PA200A120211 and PA200A150068). L. L-L. was supported by a fellowship provided from ‘Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)’.
Publisher Copyright:
© 2017 The Authors.
PY - 2017/11
Y1 - 2017/11
N2 - Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother-daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In summary, GlcNAc supplementation had pleiotropic effects on cell-wall and melanin architectures, and thus established its capacity to perturb these structures, a property that could prove useful for metabolic tracking studies.
AB - Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother-daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In summary, GlcNAc supplementation had pleiotropic effects on cell-wall and melanin architectures, and thus established its capacity to perturb these structures, a property that could prove useful for metabolic tracking studies.
KW - Chitin
KW - Chitosan
KW - Fungal cell wall
KW - Melanin
KW - N-acetylglucosamine
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U2 - 10.1099/mic.0.000552
DO - 10.1099/mic.0.000552
M3 - Article
C2 - 29043954
AN - SCOPUS:85044376536
VL - 163
SP - 1540
EP - 1556
JO - Journal of General Microbiology
JF - Journal of General Microbiology
SN - 1350-0872
IS - 11
M1 - 000552
ER -