Closed-state inactivation and pore-blocker modulation mechanisms of human CaV2.2.

N-type voltage-gated calcium (Ca V) channels mediate Ca²⁺ influx at presynaptic terminals in response to action potentials and play vital roles in synaptogenesis, release of neurotransmitters, and nociceptive transmission. Here, we elucidate a cryo-electron microscopy (cryo-EM) structure of the human Ca V 2.2 complex in apo, ziconotide-bound, and two Ca V 2.2-specific pore blockers-bound states. The second voltage-sensing domain (VSD) is captured in a resting-state conformation, trapped by a phosphatidylinositol 4,5-bisphosphate (PIP 2) molecule, which is distinct from the other three VSDs of Ca V 2.2, as well as activated VSDs observed in previous structures of Ca V channels. This structure reveals the molecular basis for the unique inactivation process of Ca V 2.2 channels, in which the intracellular gate formed by S6 helices is closed and a W-helix from the domain II–III linker stabilizes closed-state inactivation. The structures of this inactivated, drug-bound complex lay a solid foundation for developing new state-dependent blockers for treatment of chronic pain. [Display omitted] • W768 on W-helix is a structural determinant for CSI of Ca V 2.2 channel • Voltage-sensing domain II was trapped in the resting state by a PIP 2 molecule • Ziconotide is located on the top of the selectivity filter blocking ion influx • Small molecules, PD173212 and Ca V 2.2 blocker 1, occupy the D III –D IV fenestration site Dong et al. report the cryo-EM structures of Ca V 2.2 complexes in apo state and ligand-bound states. A six-turn helix (W-helix) is determined underneath the pore domain, which contributes to the closed-state inactivation mechanism of Ca V 2.2 channel. The pore-blocking mechanisms of ziconotide, PD173212 and Ca V 2.2 blocker-1, are unraveled. [ABSTRACT FROM AUTHOR]