Structural Basis of Wee Kinases Functionality and Inactivation by Diverse Small Molecule Inhibitors

Members
of the Wee family of kinases negatively regulate the cell
cycle via phosphorylation of CDK1 and are considered potential drug
targets. Herein, we investigated the structure–function relationship
of human Wee1, Wee2, and Myt1 (PKMYT1). Purified recombinant full-length
proteins and kinase domain constructs differed substantially in phosphorylation
states and catalytic competency, suggesting complex mechanisms of
activation. A series of crystal structures reveal unique features
that distinguish Wee1 and Wee2 from Myt1 and establish the structural
basis of differential inhibition by the widely used Wee1 inhibitor
MK-1775. Kinome profiling and cellular studies demonstrate that, in
addition to Wee1 and Wee2, MK-1775 is an equally potent inhibitor
of the polo-like kinase PLK1. Several previously unrecognized inhibitors
of Wee kinases were discovered and characterized. Combined, the data
provide a comprehensive view on the catalytic and structural properties
of Wee kinases and a framework for the rational design of novel inhibitors
thereof.