Ligand discrimination between active and inactive activation loop conformations of Aurora-A kinase is unmodified by phosphorylation. Issue 14 (12th March 2019)

• Record Type: Journal Article
• Authors: Gilburt, James A. H.; Girvan, Paul; Blagg, Julian; Ying, Liming; Dodson, Charlotte A.
• Is Part Of: Chemical science. Volume 10:Issue 14(2019)
• Page Start: 4069
• Page End: 4076
• Publication Date: 2019-03-12
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8sc03669a
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Activation loop phosphorylation changes the position of equilibrium between DFG-in-like and DFG-out-like conformations but not the conformational preference of inhibitors. Abstract : Structure-based drug design is commonly used to guide the development of potent and specific enzyme inhibitors. Many enzymes – such as protein kinases – adopt multiple conformations, and conformational interconversion is expected to impact on the design of small molecule inhibitors. We measured the dynamic equilibrium between DFG-in-like active and DFG-out-like inactive conformations of the activation loop of unphosphorylated Aurora-A alone, in the presence of the activator TPX2, and in the presence of kinase inhibitors. The unphosphorylated kinase had a shorter residence time of the activation loop in the active conformation and a shift in the position of equilibrium towards the inactive conformation compared with phosphorylated kinase for all conditions measured. Ligand binding was associated with a change in the position of conformational equilibrium which was specific to each ligand and independent of the kinase phosphorylation state. As a consequence of this, the ability of a ligand to discriminate between active and inactive activation loop conformations was also independent of phosphorylation. Importantly, we discovered that the presence of multiple enzyme conformations can lead to a plateau in the overall ligand K d, despite increasing affinity for the chosen target conformation, and modelled the conformational discrimination necessary for a conformation-promoting ligand.