Cysteine-Rich α-Conotoxin SII Displays Novel Interactions at the Muscle Nicotinic Acetylcholine Receptor
Publication Name
ACS Chemical Neuroscience
Abstract
α-Conotoxins that target muscle nicotinic acetylcholine receptors (nAChRs) commonly fall into two structural classes, frameworks I and II containing two and three disulfide bonds, respectively. Conotoxin SII is the sole member of the cysteine-rich framework II with ill-defined interactions at the nAChRs. Following directed synthesis of α-SII, NMR analysis revealed a well-defined structure containing a 310-helix frequently employed by framework I α-conotoxins; α-SII acted at the muscle nAChR with half-maximal inhibitory concentrations (IC50) of 120 nM (adult) and 370 nM (fetal) though weakly at neuronal nAChRs. Truncation of α-SII to a two disulfide bond amidated peptide with framework I disulfide connectivity led to similar activity. Surprisingly, the more constrained α-SII was less stable under mild reducing conditions and displayed a unique docking mode at the nAChR.
Open Access Status
This publication is not available as open access
Volume
13
Issue
8
First Page
1245
Last Page
1250
Funding Number
APP1072113
Funding Sponsor
National Health and Medical Research Council