Events

Cantor Chemical Biology and Biophysics Seminar

Pushed to extremes: Probing protein and ligand conformations with biophysical perturbations

Presented by: Prof. Daniel Keedy

Abstract: Proteins do not adopt a single structure, but rather a fluctuating ensemble of conformations which collectively encode biological functions such as ligand binding, enzyme catalysis, and allosteric regulation.  However, it has been difficult to experimentally resolve alternative conformations of proteins and ligands at high resolution, limiting efforts to elucidate the fundamental connections between structural dynamics and function.  To help address this gap, my lab leverages a unique combination of avant-garde X-ray crystallography experiments and downstream computational modeling approaches to reveal distinct conformations of both proteins and bound small-molecule ligands.  Here, I will discuss two recent projects from our group in these areas.  First, we have used crystallography at room temperature (instead of the traditional cryogenic temperature) for a large number of small-molecule fragments with the archetypal protein tyrosine phosphatase, PTP1B, revealing alternative ligand binding poses, binding locations, and allosteric conformational responses seen only at RT.  Second, we have used crystallography at physiological temperature and at high pressure for an evolutionarily related but functionally distinct enzyme, STEP; we show that temperature vs. pressure capture distinct conformational states with respect to previous active-like structures, and induce substantially different patterns of ordered solvent.  Together with our lab’s related projects, this work illustrates the utility of perturbing protein conformational ensembles to gain new windows into their ligandability and function.