Less is More: Design of a Highly Stable Disulfide-Deleted Mutant of Analgesic Cyclic α-Conotoxin Vc1.1

• Published in: Scientific reports Vol. 5; no. 1; p. 13264
• Main Authors: Yu, Rilei, Seymour, Victoria A. L., Berecki, Géza, Jia, Xinying, Akcan, Muharrem, Adams, David J., Kaas, Quentin, Craik, David J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20.08.2015; Nature Publishing Group
• Subjects: 631/154/309/2419; 639/638/309/606; Amides - chemistry; Amino Acid Sequence; Analgesics - metabolism; Animals; Calcium Channels - metabolism; Cell Line; Conotoxins - chemistry; Conotoxins - genetics; Disulfides - metabolism; Enzyme Stability; Humanities and Social Sciences; Inhibitory Concentration 50; Magnetic Resonance Spectroscopy; Molecular Sequence Data; multidisciplinary; Mutation - genetics; Oocytes - metabolism; Protein Conformation; Rats; Receptors, GABA - metabolism; Receptors, Nicotinic - metabolism; Recombinant Proteins - chemistry; Science; Solutions; Temperature; Xenopus - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep13264

Cyclic α-conotoxin Vc1.1 (cVc1.1) is an orally active peptide with analgesic activity in rat models of neuropathic pain. It has two disulfide bonds, which can have three different connectivities, one of which is the native and active form. In this study we used computational modeling and nuclear magnetic resonance to design a disulfide-deleted mutant of cVc1.1, [C2H,C8F]cVc1.1, which has a larger hydrophobic core than cVc1.1 and, potentially, additional surface salt bridge interactions. The new variant, hcVc1.1, has similar structure and serum stability to cVc1.1 and is highly stable at a wide range of pH and temperatures. Remarkably, hcVc1.1 also has similar selectivity to cVc1.1, as it inhibited recombinant human α9α10 nicotinic acetylcholine receptor-mediated currents with an IC 50 of 13 μM and rat N-type (Ca v 2.2) and recombinant human Ca v 2.3 calcium channels via GABA B receptor activation, with an IC 50 of ~900 pM. Compared to cVc1.1, the potency of hcVc1.1 is reduced three-fold at both analgesic targets, whereas previous attempts to replace Vc1.1 disulfide bonds by non-reducible dicarba linkages resulted in at least 30-fold decreased activity. Because it has only one disulfide bond, hcVc1.1 is not subject to disulfide bond shuffling and does not form multiple isomers during peptide synthesis.