NMR analysis reveals 17β-estradiol induced conformational change in ERβ ligand binding domain expressed in E. coli.

Nuclear magnetic resonance (NMR) spectroscopy is a useful biophysical technique to study the ligand-protein interaction. In this report, we have used bacterially produced ERβ and its domains for studying the functional analysis of ligand-protein interaction. Briefly, ERβ and its transactivation domain (TAD) and ligand binding domain (LBD) were subcloned and overexpressed using a prokaryotic expression system. The recombinant proteins were purified using Ni(+2)-IDA affinity chromatography and analyzed by NMR. Purified ERβ and TAD show similar conformation in the absence or presence of 17β-estradiol. However, LBD shows altered conformation in the presence of 17β-estradiol. These findings suggest that ERβ produced in bacteria exhibits a conformation such that its LBD remains masked and consequently it binds less to 17β-estradiol. Such study may help to develop the therapeutic approaches for controlling the estradiol-mediated gene expression in hormone dependent diseases.