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FRIL is a hyacinth bean lectin that has broad-spectrum antiviral activity by binding to complex type N-glycans on viruses. Recently, Dr. Che Ma’s group at Academia Sinica Genomics Research Center has demonstrated that FRIL’s recognition of complex type N-glycans and ConA’s recognition of oligomannose N-glycans is mediated by an extended binding site on loop B.

Dr. Che Ma’s team first found that inactive legume prolectins can be activated through deglycosylation with PNGase F. Key residues on FRIL’s extended binding site were then identified through X-ray crystallography and cryo-electron microscopy. Using site-directed mutagenesis, these residues were altered to shift FRIL’s glycan recognition towards oligomannose N-glycans. After three residue swaps and two insertions, researchers were able to create a FRIL mutant that binds specifically to oligomannose instead of its original ligand.

The results of this study promote a deeper understanding of FRIL’s extended binding site, and provide a comprehensive methodology for the activation of recombinant legume pro-lectins.

Funding for this research was provided by Academia Sinica and the Taiwan National Science and Technology Council. The study was published on March 5, 2026, in Nature Communications, with first authorship shared by postdoctoral researchers Yo-min Liu and Hong Thuy Vy Nguyen.