Structural Biology of the Human Androgen Receptor for next generation drug design

The aim of this PhD project is to elucidate the mechanism of action of a novel class of human androgen receptor antagonists (MEL6), which were recently discovered in the KU Leuven Molecular Endocrinology Laboratory. Fragments of the human androgen receptor will be expressed in and purified to high purity from E. coli and utilized for crystallization experiments. While the structures of agonist complexes are already available, all efforts have failed to crystallize a complex of the hAR ligand binding domain (AR-LBD) bound to an antagonist. Therefore, we will follow a novel approach. First of all, the novel confirmed class of antagonists is significantly different in shape from the classical antagonists. Molecular modeling of AR-LBD:MEL6 complexes has suggested a binding mode that may stabilize the antagonistic conformation. Therefore, a classical co-crystallization approach will be followed. Secondly, we aim to crystallize the hAR-LBD in the presence of additional facilitator molecules, which can induce different crystal packings that may allow for soaking of antagonists or stabilization of the antagonistic conformation. These molecules are the so-called Poly-Oxometalates (POMs), which are being developed at the KU Leuven, Department of Chemistry, where also the MEL6 derivatives are being produced. Apart from the new MEL6 ligands, I will also attempt to soak the currently used drug molecules with the POM-protein crystal complexes, as structural information of them is still absent as well. In parallel with the two tracks of structural biology work, I will perform biophysical screening experiments to identify more potent ligand derivatives. As more insights are being gathered about the interactions of the N-terminus of the androgen receptor with cellular cofactors, in the final stage of this project, I will also focus on solving the structure of fragments of the androgen receptor N-terminal domain with (fragments of) its cellular cofactors.