A Kinetic Origin of Vps34-IN-3 Selectivity for VPS34 over PI3Kα Revealed by Supervised Molecular Dynamics and Potential of Mean Force Analysis.
Abstract
The rational design of selective kinase inhibitors is hampered by the conserved ATP-binding pockets. Vps34-IN-3, a potent VPS34 inhibitor developed by Genentech, Inc., showed ∼95-fold selectivity over the closely related PI3Kα, yet the atomic-level mechanism underlying this selectivity remains unclear. Here, we combined supervised molecular dynamics (SuMD) and potential of mean force (PMF) analysis to reconstruct the complete binding and unbinding pathways of Vps34-IN-3 to both targets. Our calculations revealed that selectivity arose primarily from a dramatically higher dissociation barrier for VPS34, leading to a prolonged residence time on the intended target. In VPS34, a persistent hydrogen bond with Ile685 and a hydrophobic socket beneath the P-loop acted as a structural latch, raising the unbinding barrier to 6.37 kcal/mol. In contrast, the more open PI3Kα pocket presented a lower barrier of 3.71 kcal/mol. The computed residence-time ratio (∼80-fold) was strongly consistent with the experimentally measured selectivity (∼95-fold based on IC50 values), suggesting that the selectivity of Vps34-IN-3 is primarily kinetic in origin. Our integrated SuMD/PMF framework thus established a kinetic basis for inhibitor selectivity and provided a quantitative, transferable approach for predicting residence time in drug discovery.