Referenced in: none

Automatically associated channels: Nav1.1 , Nav1.2 , Nav1.5

Title: A disulfide tether stabilizes the block of sodium channels by the conotoxin μO§-GVIIJ.

Authors: Joanna Gajewiak, Layla Azam, Julita Imperial, Aleksandra Walewska, Brad R Green, Pradip K Bandyopadhyay, Shrinivasan Raghuraman, Beatrix Ueberheide, Marshall Bern, H Mimi Zhou, Natali A Minassian, Rebecca H Hagan, Mack Flinspach, Yi Liu, Grzegorz Bulaj, Alan D Wickenden, Baldomero M Olivera, Doju Yoshikami, Min-Min Zhang

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2014 Feb 18 , 111, 2758-63

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24497506

Abstract
A cone snail venom peptide, μO§-conotoxin GVIIJ from Conus geographus, has a unique posttranslational modification, S-cysteinylated cysteine, which makes possible formation of a covalent tether of peptide to its target Na channels at a distinct ligand-binding site. μO§-conotoxin GVIIJ is a 35-aa peptide, with 7 cysteine residues; six of the cysteines form 3 disulfide cross-links, and one (Cys24) is S-cysteinylated. Due to limited availability of native GVIIJ, we primarily used a synthetic analog whose Cys24 was S-glutathionylated (abbreviated GVIIJSSG). The peptide-channel complex is stabilized by a disulfide tether between Cys24 of the peptide and Cys910 of rat (r) NaV1.2. A mutant channel of rNaV1.2 lacking a cysteine near the pore loop of domain II (C910L), was >10(3)-fold less sensitive to GVIIJSSG than was wild-type rNaV1.2. In contrast, although rNaV1.5 was >10(4)-fold less sensitive to GVIIJSSG than NaV1.2, an rNaV1.5 mutant with a cysteine in the homologous location, rNaV1.5[L869C], was >10(3)-fold more sensitive than wild-type rNaV1.5. The susceptibility of rNaV1.2 to GVIIJSSG was significantly altered by treating the channels with thiol-oxidizing or disulfide-reducing agents. Furthermore, coexpression of rNaVβ2 or rNaVβ4, but not that of rNaVβ1 or rNaVβ3, protected rNaV1.1 to -1.7 (excluding NaV1.5) against block by GVIIJSSG. Thus, GVIIJ-related peptides may serve as probes for both the redox state of extracellular cysteines and for assessing which NaVβ- and NaVα-subunits are present in native neurons.