A novel 4/6-type alpha-conotoxin VilA selectively inhibits nAchR α3β2 subtype

Conotoxins （CTxs） are typically small peptides composed of 12-50 amino acid residues with 2-5 disulfide bridges. Most of them potently and selectively target a wide variety of ion channels and membrane receptors. They are highly valued as neuropharmacological probes and in pharmaceut- ical development. In this work, a novel α4/6-CTx named VilA （RDCCSNPPCAHNNPDC-NH2） was identified from a cDNA library of the venom ducts of Conus virgo （C. virgo）. VilA was then synthe- sized chemically and its disulfide connectivity was identified as ＇C1-C3, C2-C4＇. Its molecular targets were further assessed using two-electrode voltage clamping. The results indicated that VilA select- ively inhibited nicotinic acetylcholine receptor （nAChR）α3β2 subtype with an ICso of 845.5 nM, but did not target dorsal root ganglion sodium （Na＋）-, potassium （K＋）- or calcium （Ca2＋）-ion channels. Further structure-activity relationship analysis demonstrated that Arg1 and His11 but not Asp2 were the functional residues. To the best of our knowledge, VilA is the first 4/6 α-CTx that selectively inhibits nAChR α3β2 subtype. This finding expands the knowledge of targets of α4/6-family CTxs.