Drug discovery campaigns directly targeting the
voltage-gated sodium channel NaV1.7, a highly prized target in
chronic pain, have not yet been clinically successful. In a differentiated approach, we demonstrated allosteric control of trafficking and activity of NaV1.7 by prevention of SUMOylation of
collapsin response mediator
protein 2 (CRMP2). Spinal administration of a SUMOylation incompetent CRMP2 (CRMP2 K374A) significantly attenuated
pain behavior in the spared nerve injury (SNI) model of
neuropathic pain, underscoring the importance of SUMOylation of CRMP2 as a pathologic event in
chronic pain. Using a rational design strategy, we identified a heptamer
peptide harboring CRMP2's SUMO motif that disrupted the CRMP2-Ubc9 interaction, inhibited CRMP2 SUMOylation, inhibited NaV1.7 membrane trafficking, and specifically inhibited NaV1.7
sodium influx in sensory neurons. Importantly, this
peptide reversed nerve injury-induced thermal and mechanical
hypersensitivity in the SNI model, supporting the practicality of discovering
pain drugs by indirectly targeting NaV1.7 via prevention of CRMP2 SUMOylation. Here, our goal was to map the unique interface between CRMP2 and Ubc9, the E2 SUMO conjugating
enzyme. Using computational and biophysical approaches, we demonstrate the
enzyme/substrate nature of Ubc9/CRMP2 binding and identify hot spots on CRMP2 that may form the basis of future drug discovery campaigns disrupting the CRMP2-Ubc9 interaction to recapitulate allosteric regulation of NaV1.7 for
pain relief.