Binding modes and interaction mechanism of bisphenol A and its analogs in constitutive androstane receptor

Environmental pollutants, such as bisphenol A (BPA) and its analogs, are key molecules in the production of commercial products that are used in daily life, posing a threat to human health. BPA and its analogs modify the functional activity of nuclear receptors (NRs), acting as endocrine disruptors. The constitutive androstane receptor (CAR) is a nuclear hormone receptor that plays a critical role in xenobiotic metabolism, and bisphenols antagonize CAR activity. Although the binding mechanisms of BPA and its analogs to other NRs have been reported, the binding modes of bisphenols in CAR remain unclear. Therefore, in this study, we performed molecular docking to understand the binding modes and interaction patterns of BPA and its analogs with the CAR ligand-binding domain using an inverse agonist-bound structural conformation because bisphenols antagonize CAR functional activity. The complexes of the top-binding bisphenols were subjected to molecular dynamics simulations. BPA and its analogs showed strong binding affinities for CAR. However, the binding energy of BPA (−86.4 kJ/mol) was lower than that of its analogs (−94.13 to 141.2 kJ/mol). Hydrophobic and polar residues (Phe161, Asn165, Leu206, Phe217, Tyr224, Thr225, L246, I334, I337) in the binding pocket largely contribute to the binding energy. This study provides crucial information on the key residues of the CAR responsible for bisphenol binding, which may help design better therapeutics for CAR and bisphenol-associated diseases.