Povolotsky, T. L. | Search bioRxiv

bioRxiv2024

Structural Determinants of Mucins in Influenza Virus Inhibition: The Synergistic Role of Sialylated Glycans and Molecular Size

Mucins are heavily glycosylated proteins that play a crucial role in protecting mucosal surfaces against pathogens, including influenza viruses. This study investigates the antiviral properties of bovine submaxillary mucins (BSM) as a model for oral mucins against the influenza virus (A/H3N2 subtype), focusing on glycan composition and mucin size. BSM was purified, and characterized by proteomic and glycomic analysis and its antiviral efficacy was assessed after selective removal of sialic acids, N-glycans, or all glycans via enzymatic and chemical treatments. We employed virus binding and inhibition assays, including microscale thermophoresis (MST) and hemagglutination inhibition (HAI), to characterize processed mucins for structure activity correlations. Removal of sialic acids reduced BSMs antiviral activity by over 10-fold, while complete glycan removal abolished it entirely, highlighting sialylated O-glycans as critical for viral inhibition. N-glycan removal had minimal impact on antiviral efficacy. A size-dependent antiviral effect was observed: smaller mucin fragments ([~]50 and 330 kDa), which retained comparable O-glycosylation patterns, showed significantly reduced inhibition and viral binding affinity compared to intact BSM. These findings underscore the importance of mucin size and sialylated O-glycans in antiviral defense mechanisms against influenza. SignificanceThis study sheds light on the intrinsic antiviral properties of mucin from the bovine submaxillary gland, revealing the roles of glycans and mucins size in binding and inhibiting influenza virus. Our findings suggest a clear correlation between sialylated O-glycans and mucin size with the antiviral efficacy. Ultimately, we show that mucin-derived fragments retaining virus-binding capacity, with defined size and O-glycosylation patterns, can be isolated from mucin and could serve as versatile building blocks for designing next-generation antiviral biomaterials.

biochemistry↗

bioRxiv2021

Imaging Flow Cytometry reveals a dual role for exopolysaccharides in biofilms: To promote self-adhesion while repelling non-self-community members

In nature, bacteria are establishing differentiated communities referred to as biofilms. These multicellular communities are held together by self-produced polymers that allow the community members to adhere to the surface as well as to neighbor bacteria. Here, we report that exopolysaccharides prevent Bacillus subtilis from co-aggregating with a distantly related bacterium Bacillus mycoides, while maintaining their role in promoting self-adhesion and co-adhesion with phylogenetically related bacterium, Bacillus atrophaeus. The defensive role of the exopolysaccharides is due to the specific regulation of bacillaene. Single cell analysis of biofilm and free-living bacterial cells using imaging flow cytometry confirmed a specific role for the exopolysaccharides in microbial competition repelling B. mycoides. Unlike exopolysaccharides, the matrix protein TasA induced bacillaene but inhibited the expression of the biosynthetic clusters for surfactin, and therefore its overall effect on microbial competition during floating biofilm formation was neutral. Thus, the exopolysaccharides provide a dual fitness advantage for biofilm-forming cells, as it acts to promote co-aggregation of related species, as well as, a secreted cue for chemical interference with non-compatible partners. These results experimentally demonstrate a general assembly principle of complex communities and provides an appealing explanation for how closely related species are favored during community assembly. Furthermore, the differential regulation of surfactin and bacillaene by the extracellular matrix may explain the spatio-temporal gradients of antibiotic production within biofilms.

microbiology↗