Identification and Utilization of a Chemical Probe to Interrogate the Roles of PIKfyve in the Lifecycle of β‑Coronaviruses

From a designed library of indolyl pyrimidinamines, we
identified
a highly potent and cell-active chemical probe (17) that
inhibits phosphatidylinositol-3-phosphate 5-kinase (PIKfyve). Comprehensive
evaluation of inhibitor selectivity confirmed that this PIKfyve probe
demonstrates excellent kinome-wide selectivity. A structurally related
indolyl pyrimidinamine (30) was characterized as a negative
control that lacks PIKfyve inhibitory activity and exhibits exquisite
selectivity when profiled broadly. Chemical probe 17 disrupts
multiple phases of the lifecycle of β-coronaviruses: viral replication
and viral entry. The diverse antiviral roles of PIKfyve have not been
previously probed comprehensively in a single study or using the same
compound set. Our scaffold is a distinct chemotype that lacks the
canonical morpholine hinge-binder of classical lipid kinase inhibitors
and has a non-overlapping kinase off-target profile with known PIKfyve
inhibitors. Our chemical probe set can be used by the community to
further characterize the role of PIKfyve in virology.