Stapled Voltage-Gated Calcium Channel (Ca V) α-Interaction Domain (AID) Peptides Act As Selective Protein-Protein Interaction Inhibitors of Ca V Function

ACS Chem Neurosci. 2017 Jun 21;8(6):1313-1326. doi: 10.1021/acschemneuro.6b00454. Epub 2017 Mar 17.

Abstract

For many voltage-gated ion channels (VGICs), creation of a properly functioning ion channel requires the formation of specific protein-protein interactions between the transmembrane pore-forming subunits and cystoplasmic accessory subunits. Despite the importance of such protein-protein interactions in VGIC function and assembly, their potential as sites for VGIC modulator development has been largely overlooked. Here, we develop meta-xylyl (m-xylyl) stapled peptides that target a prototypic VGIC high affinity protein-protein interaction, the interaction between the voltage-gated calcium channel (CaV) pore-forming subunit α-interaction domain (AID) and cytoplasmic β-subunit (CaVβ). We show using circular dichroism spectroscopy, X-ray crystallography, and isothermal titration calorimetry that the m-xylyl staples enhance AID helix formation are structurally compatible with native-like AID:CaVβ interactions and reduce the entropic penalty associated with AID binding to CaVβ. Importantly, electrophysiological studies reveal that stapled AID peptides act as effective inhibitors of the CaVα1:CaVβ interaction that modulate CaV function in an CaVβ isoform-selective manner. Together, our studies provide a proof-of-concept demonstration of the use of protein-protein interaction inhibitors to control VGIC function and point to strategies for improved AID-based CaV modulator design.

Keywords: AID:CaVβ interaction; Voltage-gated calcium channel (CaV); X-ray crystallography; electrophysiology; protein−protein interaction antagonist; stapled peptide.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Calcium Channels / drug effects*
  • Calcium Channels / metabolism*
  • Humans
  • Peptides / metabolism
  • Peptides / pharmacology*
  • Protein Interaction Domains and Motifs / drug effects*
  • Protein Subunits / metabolism*

Substances

  • Calcium Channels
  • Peptides
  • Protein Subunits