Abstract
Background: Individuals are exposed daily to environmental pollutants which may act as endocrine-disrupting chemicals (EDCs) causing a range of developmental, reproductive, metabolic or neoplastic diseases. With their mostly hydrophobic pocket that serves as a docking site for endogenous and exogenous ligands, nuclear receptors (NRs) can be primary targets of small molecule environmental contaminants. However, most of these compounds are chemically unrelated to natural hormones so their binding modes and associated hormonal activities are hardly predictable.Objectives: We conducted a correlative analysis of structural and functional data to gain insight into the mechanisms by which twelve members of representative families of pollutants bind to and activate the estrogen receptors ERα and ERβ. Methods: We have used a battery of biochemical, structural, biophysical and cell-based approaches to characterize the interaction between ERs and their environmental ligands. Results: Our study reveals that the chemically diverse compounds bind to ERs via varied sets of protein ligand interactions reflecting their differential activities, binding affinities and specificities. We show that xenoestrogens bind to both ERs with affinities ranging from sub nanomolar to micromolar values and act in a subtype-dependent fashion as full agonists or partial agonists/antagonists by using different combinations of the activation functions 1 and 2 of ERα and ERβ. Conclusions: The precise characterization of the interactions between major environmental pollutants and two of their primary biological targets provides rational guidelines for the design of safer chemicals and will increase the accuracy and usefulness of structure-based computational methods, allowing for activity prediction of chemicals in risk assessment.