bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.10.04.616735

Cross-species protection suggests Entamoeba histolytica trogocytosis enables complement resistance through the transfer of negative regulators of complement activation

Ruyechan, M.·Huang, W.·Ralston, K. S.
View original source ↗Export metadata ↓

Abstract

Entamoeba histolytica is a major cause of diarrheal disease. E. histolytica trophozoites ("amoebae") can invade the intestine and disseminate via the bloodstream, resisting complement lysis through unknown mechanisms. Amoebae kill human cells by performing trogocytosis. After performing trogocytosis, amoebae display human proteins on their own surface and are resistant to lysis by human serum. In this study we sought to further evaluate the mechanism by which amoebae resist complement. To test if complement is responsible for lysis of amoebae, C3-depleted serum was compared to replete serum, and C3 was required for lysis. Amoebae were allowed to perform trogocytosis of human cells and exposed to mouse serum. Although they had performed trogocytosis on a different species than the source of the serum, they were protected from lysis. To test if the protection from lysis by mouse serum was due to the functional interchangeability of human and mouse complement pathway proteins, human CD46 or CD55 (negative regulators of complement activation) were exogenously expressed. Amoebae that expressed human CD46 or CD55 were protected from lysis by mouse serum, indicating that display of human proteins was sufficient to inhibit mouse complement activation. Finally, amoebae were allowed to perform trogocytosis of a cell type in which the complement pathway is not conserved, and they did not become resistant to lysis. Overall, these findings are consistent with the model that trogocytosis enables amoebic acquisition and display of host proteins, including negative regulators of the complement pathway, that provide protection from complement lysis. Since other microbes can perform trogocytosis, this novel mechanism for complement resistance might apply to other infections.

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ruyechan, M., Huang, W., Ralston, K. S.. 2024-10-05. Cross-species protection suggests Entamoeba histolytica trogocytosis enables complement resistance through the transfer of negative regulators of complement activation. https://doi.org/10.1101/2024.10.04.616735

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Matrix-controlled emergence of biofilm architecture shapes antimicrobial survival

Biofilms are structured microbial communities whose extracellular matrix is widely regarded as a basis of their protection against antimicrobial compounds. Yet how matrix production by individual bacteria gives rise to collective architecture and antimicrobial protection remains poorly understood. Here, we systematically varied expression of the master biofilm regulator csgD in Salmonella enterica and found that increasing matrix production reorganizes biofilms from dense, isotropic packings into sparse, nematically aligned communities by altering cell-cell interactions. By combining experimentally measured biofilm architectures with reaction-diffusion modeling, we show that these structural changes produce distinct patterns of antimicrobial killing, ranging from preferential killing near the liquid-biofilm interface to more uniform killing throughout the community. Consequently, increasing matrix production unexpectedly reduces antimicrobial survival by shifting the biofilm into different transport regimes, while strain-specific physiological differences further modulate antimicrobial depletion. Rather than acting as a passive barrier, EPS therefore shapes antimicrobial susceptibility by reorganizing biofilm architecture and its transport properties. EPS thus provides a physical link between molecular regulation, collective architecture and antimicrobial survival, providing a quantitative framework for understanding how cellular matrix production generates emergent biofilm function.

microbiology↗
bioRxiv2026

Mapping virulence-associated protein interaction networks reveals regulators of thermotolerance in Cryptococcus neoformans

Protein-protein interactions (PPIs) influence critical biological processes in pathogenic microorganisms, such as the human fungal pathogen, Cryptococcus neoformans. Fungal thermotolerance and stress response pathways are key virulence determinants that directly impact pathogen adaptation and survival and the infection process. To establish a comprehensive baseline of PPIs in C. neoformans and explore these interactions to infer functional roles for uncharacterized proteins, we applied size exclusion chromatography coupled with mass spectrometry to the secreted and cellular proteomes of the fungi. As a result, 216 and 1699 unique proteins were identified across 24 secretome and proteome fractions, respectively. The predicted secretome networks included expected proteins associated with vesicles and virulence, indicating a role in extracellular defense. Whereas the cryptococcal proteome highlighted interactions among proteins with defined roles in fungal virulence for protein stability and thermotolerance, including two previously uncharacterized proteins, CNAG_00287 and CNAG_05199, putatively involved in complex formation with heat-shock proteins (HSP). Based on sequence and structure homology, we propose that CNAG_00287 is a tetratricopeptide repeat-containing co-chaperone that modulates Hsp 70 activity and CNAG_05199 functions as a Hsp70. We validated the thermotolerance role of CNAG_00287 in heat-related stress, as its absence significantly impaired fungal growth in nutrient-limited media at 37 {degrees}C. Together, this work resolves virulence-associated PPIs within C. neoformans and reveals new molecular regulators of thermotolerance that underpin fungal pathogenicity.

microbiology↗
bioRxiv2026

Environmental filtering and host identity collectively shape root-associated microbiomes of Ericaceae and ectomycorrhizal plants in fumarole fields

Background Symbiosis with microbes is a key strategy that has enabled plants to colonize extreme environments. Since the benefits conferred by root-associated microbes depend on both environmental conditions and host-microbe combinations, plant adaptation to harsh environments is closely linked to the assembly of root microbial communities. Understanding how environmental and host filtering jointly shape these communities is therefore fundamental to elucidating the mechanisms underlying plant adaptation to extreme environments. Results In this study, we investigated the differentiation of root-associated prokaryotic and fungal communities and individual operational taxonomic units (OTUs) across two contrasting habitats surrounding fumaroles, solfatara-field and forest-edge habitats, and six dominant Ericaceae and ectomycorrhizal plant taxa. Prokaryotic and fungal OTUs rarely exhibited strong preferences for both habitat and host identity. Instead, many of prokaryotic and fungal OTUs specialized to one of these niches, collectively generating root microbial communities differentiated by both factors. Nonetheless, striking specializations in habitat and host niches were observed in the fungal family Hyaloscyphaceae (Helotiales). To gain insight into the evolutionary basis of microbial specialization, we examined phylogenetic signals in preference phenotypes. The resulting weak phylogenetic signals in these preference phenotypes further suggest that this fungal clade has undergone substantial ecological divergence. Conclusion Overall, our findings indicate that root-associated microbial communities in extreme environments are assembled through the accumulation of microbial taxa specialized to either habitat or host, and that strong ecological specialization in fungi can arise with little phylogenetic constraint.

microbiology↗