Peptide Inhibitors of the alpha-Cobratoxin-Nicotinic Acetylcholine Receptor Interaction

Abstract

Venomous snakebites cause >100 000 deaths every year, in many cases via potent depression of human neuromuscular signaling by snake alpha-neurotoxins. Emergency therapy still relies on antibody-based antivenom, hampered by poor access, frequent adverse reactions, and cumbersome production/purification. Combining high-throughput discovery and subsequent structure-function characterization, we present simple peptides that bind alpha-cobratoxin (alpha-Cbtx) and prevent its inhibition of nicotinic acetylcholine receptors (nAChRs) as a lead for the development of alternative antivenoms. Candidate peptides were identified by phage display and deep sequencing, and hits were characterized by electrophysiological recordings, leading to an 8-mer peptide that prevented alpha-Cbtx inhibition of nAChRs. We also solved the peptide: alpha-Cbtx cocrystal structure, revealing that the peptide, although of unique primary sequence, binds to alpha-Cbtx by mimicking structural features of the nAChR binding pocket. This demonstrates the potential of small peptides to neutralize lethal snake toxins in vitro, establishing a potential route to simple, synthetic, low-cost antivenoms.