Biology subjects

Kelly, J. E.

Publications and source records attributed to Kelly, J. E..

3 recordsLinked to original sources

bioRxiv2022

Lyophilization induces alterations in cryptococcal exopolysaccharide resulting in reduced antibody binding

The structural, antigenic, and immunological characterization of microbial polysaccharides requires purification that often involves detergent precipitation and lyophilization. Here we examine physicochemical changes induced by lyophilization on exopolysaccharide (EPS) of the pathogenic fungus Cryptococcus neoformans. Solution 1H NMR reveals significant anomeric signal attenuation following lyophilization of native EPS while 1H ssNMR shows few changes, suggesting diminished molecular motion and consequent broadening of 1H NMR polysaccharide resonances. 13C ssNMR, dynamic light scattering, and transmission electron microscopy show that, while native EPS has rigid molecular characteristics and contains small, loosely packed polysaccharide assemblies, lyophilized and resuspended EPS is disordered and contains larger dense rosette-like aggregates, suggesting that structural water molecules in the interior of the polysaccharide assemblies are removed during extensive lyophilization. Importantly, mAbs to C. neoformans polysaccharide binds the native EPS more strongly than lyophilized EPS. Together, these observations argue for caution when interpreting the biological and immunological attributes of polysaccharides that have been lyophilized to dryness.

microbiology↗

bioRxiv2021

CarboGrove: a resource of glycan-binding specificities through analyzed glycan-array datasets from all platforms

The volume and value of glycan-array data are increasing, but no common method and resource exists to analyze, integrate, and use the available data. To meet this need, we developed a resource of analyzed glycan-array data called CarboGrove. Building on the ability to process and interpret data from any type of glycan array, we populated the database with the results from 35 types of glycan arrays, 13 glycan families, 5 experimental methods, and 19 laboratories or companies. In meta-analyses of glycan-binding proteins, we observed glycan-binding specificities that were not uncovered from single sources. In addition, we confirmed the ability to efficiently optimize selections of glycan-binding proteins to be used in experiments for discriminating between closely related motifs. CarboGrove yields unprecedented access to the wealth of glycan-array data being produced and powerful capabilities for both experimentalists and bioinformaticians. TeaserWe introduce a resource that allows researchers to find, compare, study, and integrate analyses from all types of glycan-array data.

bioinformatics↗

bioRxiv2020

Solid-state NMR spectroscopy identifies three classes of lipids in C. neoformans melanized cell walls and whole fungal cells

A primary virulence-associated trait of the opportunistic fungal pathogen Cryptococcus neoformans is the production of melanin pigments that are deposited into the cell wall and interfere with the host immune response. Previously, our solid-state NMR studies of isolated melanized cell walls (melanin ghosts) revealed that the pigments are strongly associated with lipids, but their identities, origins, and potential roles were undetermined. Herein, we exploited spectral editing techniques to identify and quantify the lipid molecules associated with pigments in melanin ghosts. The lipid profiles were remarkably similar in whole C. neoformans cells, grown under either melanizing or non-melanizing conditions; triglycerides (TGs), sterol esters (SEs) and polyisoprenoids (PPs) were the major constituents. Although no quantitative differences were found between melanized and non-melanized cells, melanin ghosts were relatively enriched in SEs and PPs. In contrast to lipid structures reported during early stages of fungal growth in nutrient-rich media, variants found herein could be linked to nutrient stress, cell aging, and subsequent production of substances that promote chronic fungal infections. The fact that TGs and SEs are the typical cargo of lipid droplets suggests that these organelles could be connected to C. neoformans melanin synthesis. Moreover, the discovery of PPs is intriguing because dolichol is a well-established constituent of human neuromelanin. The presence of these lipid species even in non-melanized cells suggests that they could be produced constitutively under stress conditions in anticipation of melanin synthesis. These findings demonstrate that C. neoformans lipids are more varied compositionally and functionally than previously recognized.

biophysics↗