Molecular evolution of GM3-binding peptides using a phage display method

Influenza virus binds to sialylgalactose (Neu5Ac-Gal) structure on host cells at the first step of infection. The peptide drugs are able to block the virus-sugar interaction. In our previous study, the ganglioside GM3 (Neu5Acα2-3Galβ1-4Glcβ1-1'ceramide)-binding pentadecapeptide has been obtained from a random phage-displayed peptide library. However, since the phage library employed in our previous study did not have enough diversity, we attempted the directed evolution to improve the binding affinity of the GM3-binding peptide (c01). We constructed the randomized sublibrary of c01 with its diversity of about two million recombinants. Four round of the affinity selection against GM3 monolayer was performed and the binding affinities of the isolated phage clones to glycolipids were analyzed by ELISA. Two phage clones (4-11 and 4-16) showed high affinity for GM3 rather than that of the original c01 peptide, moreover the binding specificity of the 4-11 clone improved.