Domain versatility in plant AB-toxins: Evidence for a local, pH-dependent rearrangement in the 2γ lectin site of the mistletoe lectin by applying ligand derivatives and modelling

Mistletoe lectin is a potent biohazard. Lectin activity in the toxic dimer primarily originates from the 2γ-subdomain (Tyr-site) of the B-subunit. Crystallographic information on lectin–sugar complexes is available only at acidic pH, where lectin activity is low. Thus, we mapped ligand-binding properties including comparison to ricin’s Tyr-site at neutral pH. Using these results and molecular dynamics simulations, a local conformational change was rendered likely. The obtained structural information is valuable for the design of potent inhibitors.