Ivermectin affects Arabidopsis thaliana microtubules through predicted binding site of β-tubulin

The ivermectin is a potent nematocide and insecticide, which has low toxicity for humans and domestic animals, but due to low biotransformation, it can be dangerous for non-target organisms. The recent determination of ivermectin absorption and accumulation in tissues of higher plants and multiple shreds of evidence of its negative impact on plant physiology provide a basis for the search for ivermectin's molecular targets and mechanisms of action in plant cells. In this research, for the first time, the ivermectin effect on microtubules of Arabidopsis thaliana cells was studied. It was revealed that ivermectin (250 μg mL^-1) disrupts the microtubule network, induces the loss of microtubule orientation, leads to microtubule curvature and shrinkage, and their longitudinal and cross-linked bundling in various cells of A. thaliana primary roots. Further, the previously proposed binding of ivermectin to the β1-tubulin taxane site was developed and confirmed using molecular dynamics simulations of ivermectin complexes with Haemonchus contortus and A. thaliana β1-tubulins. It was predicted that similar to other microtubule stabilizing agents ivermectin binding causes M-loop stabilization in both H. contortus and A. thaliana β-tubulin, which leads to the enhancement of lateral contacts between subunits of adjacent protofilaments preventing microtubule depolymerization.