Determine the Crystal Structure of Complexes of Rv3671c (MarP) with Inhibitors

Crystallization conditions that yield a new crystal form of the protein when it was co-crystallized with its inhibitory compounds were found, but the crystal morphology (multiple plates) needs improvement. The crystal structure of this new crystal form was determined; it contains 12 monomers of Rv3671c per asymmetric unit. As intended, the active site of the protease in these crystals is solvent-accessible and displays partial difference electron density that likely corresponds to bound inhibitors. Partial electron density indicates partial occupancy or mobility of the inhibitor in the binding site of the protease. Dr. Tsodikov will perform optimization of these crystallization conditions, conditions for additional soaking of the sparingly water-soluble inhibitors into these crystals (to maximize the inhibitor occupancy) and crystal cryoprotection. Xray diffraction data will be collected on single crystals of the protease-inhibitor complexes at the Advanced Proton Source at the Argonne National Laboratories (Argonne, IL). As the protease structure of this crystal form has already been determined, only iterative cycles of refinement and building in the inhibitory compounds and solvent molecules for the 12 independent protease monomers will be needed to complete the structure determination. The structure will yield insight into the mechanism of action of the inhibitors as well as guide optimization of their chemical structure to improve their potency and other pharmacological properties.