Neutron Scattering Analysis of Cryptococcus neoformans Polysaccharide Reveals Solution Rigidity and Repeating Fractal-like Structural Patterns
Date
2024-02-12
Journal Title
Journal ISSN
Volume Title
Publisher
Biomacromolecules
Abstract
Cryptococcus neoformans is a fungal pathogen that can cause life-threatening brain infections in immunocompromised individuals. Unlike other fungal pathogens, it possesses a protective polysaccharide capsule that is crucial for its virulence. During infections, Cryptococcus cells release copious amounts of extracellular polysaccharides (exo-PS) that interfere with host immune responses. Both exo-PS and capsular-PS play pivotal roles in Cryptococcus infections and serve as essential targets for disease diagnosis and vaccine development strategies. However, understanding their structure is complicated by their polydispersity, complexity, sensitivity to sample isolation and processing, and scarcity of methods capable of isolating and analyzing them while preserving their native structure. In this study, we employ small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS) for the first time to investigate both fungal cell suspensions and extracellular polysaccharides in solution. Our data suggests that exo-PS in solution exhibits collapsed chain-like behavior and demonstrates mass fractal properties that indicate a relatively condensed pore structure in aqueous environments. This observation is also supported by scanning electron microscopy (SEM). The local structure of the polysaccharide is characterized as a rigid rod, with a length scale corresponding to 3–4 repeating units. This research not only unveils insights into exo-PS and capsular-PS structures but also demonstrates the potential of USANS for studying changes in cell dimensions and the promise of contrast variation in future neutron scattering studies.
Graphical abstract available at: https://doi.org/10.1021/acs.biomac.3c00911
Description
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Biomacromolecules, copyright © 2023 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.biomac.3c00911. This article will be embargoed until 2/12/2025.
Keywords
carbohydrates, chemical structure, irradiation, neutron scattering, scattering
Citation
Wang, Ziwei, Susana C. M. Teixeira, Camilla Strother, Anthony Bowen, Arturo Casadevall, and Radamés J. B. Cordero. “Neutron Scattering Analysis of Cryptococcus Neoformans Polysaccharide Reveals Solution Rigidity and Repeating Fractal-like Structural Patterns.” Biomacromolecules 25, no. 2 (February 12, 2024): 690–99. https://doi.org/10.1021/acs.biomac.3c00911.