Differentiated extracts from freshwater and terrestrial mollusks inhibit virulence factor production in Cryptococcus neoformans

Abstract

The human fungal pathogen, Cryptococcus neoformans, is responsible for deadly infections among immunocompromised individuals with the evolution of antifungal resistance driving the need for discovery of new compounds that inhibit fungal virulence factors, rather than kill the pathogen. Recently, exploration into natural sources (e.g., plants, invertebrates, microbes) of antifungal agents has garnered attention by integrating a One Health approach for new compound discovery. Here, we explore extracts from three mollusk species (freshwater and terrestrial) and evaluate effects against the growth and virulence factor production (i.e., thermotolerance, melanin, capsule, and biofilm) in C. neoformans. We demonstrate that clarified extracts of Planorbella pilsbryi have a fungicidal effect on cryptococcal cells in a comparable way to fluconazole. Similarly, all extracts of Cipangopaludina chinensis not only affect cryptococcal thermotolerance but also impair biofilm and capsule production with clarified extracts of Cepaea nemoralis also conveying the latter effect. Next, inhibitory activity of extracts against peptidases related to these virulence factors combined with quantitative proteomics defined distinct proteome signatures and proposed proteins driving the observed anti-virulence properties. Overall, this work highlights the potential of compounds derived from natural sources to inhibit virulence factor production in a clinically important fungal pathogen.

Integrating the analysis of human biopsies using post‐translational modifications proteomics

“…Using N‐terminomics approaches such as TAILS (Anowai et al, 2022; Das et al, 2023; Gordon et al, 2019; Kleifeld et al, 2010), Subtiligase enrichment (Julien et al, 2016; Mahrus et al, 2008), COFRADIC/ChaFRADIC (Gevaert et al, 2003; Venne et al, 2015), HYTANE (Chen et al, 2016), HUNTER (Weng et al, 2019), or CHOPS (Griswold et al, 2019), cells and tissue‐wide profiling of proteolysis, from targeted processing of substrates to degradation, can now be done routinely. Importantly, proteolysis is a key PTM used by bacteria (Eckhard et al, 2017; Lentz et al, 2018; Marshall et al, 2020), viruses (Chen et al, 2023; Jagdeo et al, 2015, 2018; Pablos et al, 2021), fungi (Ball et al, 2019; Gutierrez‐Gongora et al, 2023; Gutierrez‐Gongora & Geddes‐McAlister, 2022; Pettersen, Dufour, & Arrieta, 2022), and parasites (Coffey et al, 2018; Li et al, 2016), and N‐terminomic approaches can also be used to study these interactions. Using primary human cells, TAILS was used to identify substrates of mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) in B cells (Klein et al, 2015).…”