Probing backbone hydrogen bonding in PDZ/ligand interactions by protein amide-to-ester mutations

摘要: PDZ domains are scaffolding modules in protein-protein interactions that mediate numerous physiological functions by interacting canonically with the C-terminus or non-canonically an internal motif of protein ligands. A conserved carboxylate-binding site domain facilitates binding via backbone hydrogen bonds; however, little is known about role these bonds due to experimental challenges mutations. Here we address this interaction generating semisynthetic containing amide-to-ester mutations and evaluating importance individual for ligand binding. We observe substantial differential effects upon mutation PDZ2 postsynaptic density 95 other domains, suggesting bonding at contributes both affinity selectivity. In particular, hydrogen-bonding pattern surprisingly different between non-canonical canonical interaction. Our data provide a detailed understanding interactions.