TY - JOUR
T1 - The structural unit of melanin in the cell wall of the fungal pathogen Cryptococcus neoformans
AU - Camacho, Emma
AU - Vij, Raghav
AU - Chrissian, Christine
AU - Prados-Rosales, Rafael
AU - Gil, David
AU - O'Meally, Robert N.
AU - Cordero, Radames J.B.
AU - Cole, Robert N.
AU - McCaffery, J. Michael
AU - Stark, Ruth E.
AU - Casadevall, Arturo
N1 - Funding Information:
4Supported in part by National Institutes of Health Grant AI115091 from NIAID, Spanish Ministry of Economy and Competitiveness Grant SAF2016-77433-R, CICbioGUNE through the Severo Ochoa Excellence Accreditation SEV-2016-0644, and is a “Ramon y Cajal” fellow from the Spanish Ministry of Economy and Competitiveness.
Funding Information:
Acknowledgments—We thank Alexander Idnurm for kindly providing us with C. neoformans strain ST211A, Subhasish Chatterjee for useful discussions during the preliminary stages of this work, Carolina Coelho for critical reading of the manuscript, and Andre Nicola and Alexander Alanio for valuable discussion of experimental designs. We also gratefully acknowledge expertise and technical support from Barbara Smith (Microscopy Facility, School of Medicine, Johns Hopkins University) with transmission EM, SEM, and negative staining. We thank Joel Tang for technical support for data acquisition in connection with EPR analyses. City College of New York is supported by National Institutes of Health Grants PA200A120211 and PA200A150068. The NMR facilities used in this work are operated by City College and the CUNY Institute for Macromolecular Assemblies, with additional infrastructural support provided by Grant 8G12 MD007603 from the National Institute on Minority Health and Health Disparities of the National Institutes of Health.
Funding Information:
5 Supported by Hopkins Integrated Imaging Center and National Institutes of Health Grant 1S10OD012342 from NCRR for the acquisition of the Talos TEM.
Funding Information:
This work was supported by National Institutes of Health Grant R01-AI052733. The authors declare that they have no conflicts of interest with the con-tents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Insti-tutes of Health.
Publisher Copyright:
© 2019 Camacho et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2019/7/5
Y1 - 2019/7/5
N2 - Melanins are synthesized macromolecules that are found in all biological kingdoms. These pigments have a myriad of roles that range from microbial virulence to key components of the innate immune response in invertebrates. Melanins also exhibit unique properties with potential applications in physics and material sciences, ranging from electrical batteries to novel therapeutics. In the fungi, melanins, such as eumelanins, are components of the cell wall that provide protection against biotic and abiotic elements. Elucidation of the smallest fungal cell wall-associated melanin unit that serves as a building block is critical to understand the architecture of these polymers, its interaction with surrounding components, and their functional versatility. In this study, we used isopycnic gradient sedimentation, NMR,EPR, high-resolution microscopy, and proteomics to analyze the melanin in the cell wall of the human pathogenic fungus Cryptococcus neoformans. We observed that melanin is assembled into the cryptococcal cell wall in spherical structures ∼200 nm in diameter, termed melanin granules, which are in turn composed of nanospheres ∼30 nm in diameter, termed fungal melanosomes. We noted that melanin granules are closely associated with proteins that may play critical roles in the fungal melanogenesis and the supramolecular structure of this polymer. Using this structural information, we propose a model for C. neoformans' melanization that is similar to the process used in animal melanization and is consistent with the phylogenetic relatedness of the fungal and animal kingdoms.
AB - Melanins are synthesized macromolecules that are found in all biological kingdoms. These pigments have a myriad of roles that range from microbial virulence to key components of the innate immune response in invertebrates. Melanins also exhibit unique properties with potential applications in physics and material sciences, ranging from electrical batteries to novel therapeutics. In the fungi, melanins, such as eumelanins, are components of the cell wall that provide protection against biotic and abiotic elements. Elucidation of the smallest fungal cell wall-associated melanin unit that serves as a building block is critical to understand the architecture of these polymers, its interaction with surrounding components, and their functional versatility. In this study, we used isopycnic gradient sedimentation, NMR,EPR, high-resolution microscopy, and proteomics to analyze the melanin in the cell wall of the human pathogenic fungus Cryptococcus neoformans. We observed that melanin is assembled into the cryptococcal cell wall in spherical structures ∼200 nm in diameter, termed melanin granules, which are in turn composed of nanospheres ∼30 nm in diameter, termed fungal melanosomes. We noted that melanin granules are closely associated with proteins that may play critical roles in the fungal melanogenesis and the supramolecular structure of this polymer. Using this structural information, we propose a model for C. neoformans' melanization that is similar to the process used in animal melanization and is consistent with the phylogenetic relatedness of the fungal and animal kingdoms.
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U2 - 10.1074/jbc.RA119.008684
DO - 10.1074/jbc.RA119.008684
M3 - Article
C2 - 31118223
AN - SCOPUS:85069051473
SN - 0021-9258
VL - 294
SP - 10471
EP - 10489
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 27
ER -