Although the proteins in all the current major classes considered to be druggable are folded in their native states, intrinsically disordered proteins (IDPs) are becoming attractive candidates for therapeutic intervention by small drug-like molecules. IDPs are challenging targets because they exist as ensembles of structures, thereby making them unsuitable for standard rational drug design approaches, which require the knowledge of the three-dimensional structure of the proteins to be drugged. As we review in this chapter, several different small molecule strategies are currently under investigation to target IDPs, including: (i) to stabilise IDPs in their natively disordered states, (ii) to inhibit interactions with ordered or disordered protein partners, and (iii) to induce allosteric inhibition. In this context, biophysical techniques, including in particular nuclear magnetic resonance (NMR) spectroscopy and small-angle X-ray scattering (SAXS) coupled with molecular dynamics simulations and chemoinformatics approaches, are increasingly used to characterize the structural ensembles of IDPs and the specific interactions that they make with their binding partners. By analysing the results of recent studies, we describe the main structural features that may render IDPs druggable, and describe techniques that can be used for drug discovery programs focused on IDPs.
Keywords: Drug design; Drug discovery; Intrinsically disordered proteins; Nuclear magnetic resonance spectroscopy; Small molecule library.