Role of CysI-CysIII Disulfide Bond on the Structure and Activity of ?-Conotoxins at Human Neuronal Nicotinic Acetylcholine Receptors.

ABSTRACT: ?-Conotoxins preferentially antagonize muscle and neuronal nicotinic acetylcholine receptors (nAChRs). Native ?-conotoxins have two disulfide links, CI-CIII and CII-CIV, and owing to the inherent properties of disulfide bonds, ?-conotoxins have been systematically engineered to improve their chemical and biological properties. In this study, we explored the possibility of simplifying the disulfide framework of ?-conotoxins Vc1.1, BuIA, ImI, and AuIB, by introducing [C2H,C8F] modification to the CI-CIII bond. We therefore explored the possibility of using hydrophobic packing of standard amino acid side chains to replace disulfide bonds as an alternative strategy to nonnatural amino acid cross-links. The impact of CI-CIII disulfide bond replacement on the conformation of the ?-conotoxins was investigated using molecular dynamics (MD) simulations and nuclear magnetic resonance chemical shift index study. Two-electrode voltage clamp techniques and MD simulations were used to study the impact of disulfide bond deletion on the activities of the peptides at human neuronal nAChRs. All disulfide-deleted variants except ImI[C2H,C8F] had reduced potency for inhibiting nAChRs. Our results suggest that the CI-CIII disulfide bond is important to stabilize the secondary structure of ?-conotoxins as well as their interaction with neuronal nAChR targets. Results from this study enrich our understanding of the function of the CI-CIII disulfide bond and are useful in guiding future structural engineering of the ?-conotoxins.

SUBMITTER: Tabassum N 

PROVIDER: S-EPMC6044955 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature