DAL, lectin from Dioclea altissima: Three-dimensional structure resolution by X-ray diffraction and in silico prospection for targeting Mpro from SARS-CoV-2.

Plant lectins are carbohydrate-binding proteins with diverse biological functions and growing biomedical relevance due to their ability to recognize specific glycan structures. Here, we report the high-resolution crystallographic structure of a lectin from D. altissima seeds (DAL), resolved by X-ray diffraction at 2.21 Å (PDB ID: 7LJG). The structure reveals a homodimeric fold consistent with other lectins from the Dioclea genus, reinforcing its conserved molecular architecture. Other lectins reported within the Dioclea genus share the conserved β-sandwich fold typical of this group, while DAL exhibits unique amino acid substitutions at the carbohydrate-binding site that may influence its flexibility and interaction with other proteins. To explore DAL's potential antiviral activity against SARS-CoV-2, we performed molecular docking and molecular dynamics simulations targeting the main viral protease (Mpro). The results indicated that DAL forms a stable complex with Mpro, engaging key residues within the active site and exhibiting stronger predicted binding affinity than Nirmatrelvir, the currently approved COVID-19 therapeutic. Together, these findings highlight DAL as a promising scaffold for antiviral drug development, bridging structural insights and computational analysis to guide future experimental exploration.