Revealing Griffithsin recognition of diverse virus-associated N-glycans using atomistic simulations: glycan...

Lectins have emerged as important natural carbohydrate-recognition molecules with growing relevance in healthcare applications. Among them, griffithsin is an algae-derived lectin with broad antiviral activity against enveloped viruses. Existing literature has largely linked this activity to its ability to bind oligomannose glycans. However, viral envelope glycoproteins exhibit considerable heterogeneity in glycan types and content. Accordingly, the role of these diverse glycans in griffithsin recognition remains elusive. Addressing this gap, here, we studied the interactions of griffithsin with 16 commonly found viral-associated glycans, encompassing all major types: high-mannose, hybrid, and complex glycans, using all-atom molecular dynamics simulations. Our results show that griffithsin preferentially binds to all high-mannose glycans, irrespective of their branch length. Apart from high-mannose, it stably binds to hybrid glycans through the mannose-containing arm and to asialylated complex glycans via N-acetylglucosamine moieties, but it repels sialylated complex glycans. Our study reveals a distinct interaction pattern. The conserved Asp and Tyr residues of the carbohydrate-binding domain anchor mannose/N-acetylglucosamine residues through cooperative hydrogen bonding, electrostatic and CH-π interactions. Interestingly, these key interacting sugar residues in the majority of glycans are directly connected to the N-glycan core. For glycans with extended mannose branching, both terminal and core-linked glycans are involved, forming a stronger bidentate complex. The results suggest that adequate conformational flexibility and glycan residue accessibility, along with favorable molecular interactions, are essential for stable complex formation. Our study provides the first comprehensive understanding of the molecular basis of how glycan compositions and branching patterns determine binding interactions with griffithsin. It also offers unprecedented insights into the complex binding interfaces that can guide the rational design of glycan-targeted antiviral strategies.