Crystal structures of Ryanodine Receptor reveal dantrolene and azumolene interactions guiding inhibitor development.

Summary

High-resolution structures of the RyR Repeat12 domain reveal cooperative binding of dantrolene/azumolene with nucleotides, identify key tryptophan contacts, and show a clamshell-like domain closure. ITC and structural comparisons support allosteric effects on RyR gating, and structure-based screening yielded a new binder at the same pocket, guiding next-generation RyR inhibitor development.

Key Findings

• Resolved high-resolution crystal structures of RyR Repeat12 bound to dantrolene/azumolene and nucleotides, showing cooperative binding in a pseudosymmetric cleft.
• Identified key interactions (Trp880, Trp994) and a clamshell-like closure upon ligand binding.
• ITC demonstrated nucleotide-enhanced affinity and lower affinity for RyR2 due to nearby substitutions.
• Structure-based screening discovered a potent compound binding the same site with a distinct mode.

Clinical Implications

Structure-guided optimization may yield RyR inhibitors with improved safety and pharmacokinetics over dantrolene, potentially transforming prevention and treatment of malignant hyperthermia and other RyR-driven crises in anesthesia.

Limitations

• Structures are domain-level and may not fully capture full-channel conformational dynamics.
• Functional validation in whole-channel electrophysiology and in vivo models remains to be established.

Future Directions

Perform full-channel functional assays and medicinal chemistry optimization guided by the R12 pocket, assessing efficacy and safety in malignant hyperthermia models.