Gabaergic insecticides exploration: characterization of one GABAA receptor binding site

GASTALDI, MARÍA SALOMÉ; FELSZTYNA, IVÁN; SÁNCHEZ-BORZONE, MARIELA EUGENIA; GARCÍA, DANIEL ASMED; MIGUEL, VIRGINIA

Ottawa

Congreso; International Union of Pure and Applied Biophysics Focused Meeting; 2022

IUPAB - University of Ottawa

The insect GABAA receptor (RDL) is an important protein target for natural and artificial insecticides that act by blocking the channel and inhibiting the ions flux through it. We aim to characterize the fluralaner binding site, to develop tools that allow us to obtain new insecticidal compounds that share this same blocking site. This site is targeted by isoxazolines, a new generation of Non-Competitive Antagonists (NCA) insecticides compounds, being fluralaner a canonical representative of this chemical class. Different 3D models of the Aedes aegypti homopentamer RDL were developed in our group by homology modeling, due to the fact that there is no available crystallographic structure of the receptor. Distinct templates corresponding to different conformational states of the channel were used. We have evaluated the performance of the models by protein-ligand Molecular Docking assays, in order to determine which of them is capable of replicating the fluralaner binding pose. The model obtained from the 3RHW template (PDB ID 3RHW), which has an open channel conformation, was the one that best replicated both the hydrogen bond interaction reported by pharmacological assays: between an glutamine residue in TM1 of the receptor and the fluralaner. As well as the spatial orientation of the fluralaner molecule at the receptor blocking site: between TM1 of one subunit and TM3 of the adjacent subunit. These Molecular Docking assays of the fluralaner at its binding site, allowed us to select a model of the Aedes aegypti GABAA receptor that reproduces that reported by previous works. We performed ALL ATOM detail Molecular Dynamics simulations to characterize the protein-ligand interactions, which allowed us to validate the selected model since the interactions were as expected.