title: Two potent alpha3/5 conotoxins from piscivorous Conus achatinus.
abstract: Every cone snail produces a mixture of different conotoxins and secretes them to immobilize their prey and predators. alpha3/5 Conotoxins, isolated from fish-hunting cone snails, target muscle nicotinic acetylcholine receptors. The structure and function of alpha3/5 conotoxin from the piscivorous Conus achatinus have not been studied. We synthesized two pentadecamer peptides, Ac1.1a and Ac1.1b, with appropriate disulfide bonding, based on cDNA sequences of alpha3/5 conotoxins from C. achatinus. Ac1.1a and Ac1.1b differ by only one amino acid residue. They have similar potency on blocking recombinant mouse muscle acetylcholine receptor expressed in Xenopus laevis oocytes, with IC50 values of 36 nM and 26 nM, respectively. For Ac1.1b, deletion of the first three N-terminal amino acids did not change its activity, indicating that the N-terminus is not involved in the interaction with its receptor. Furthermore, our experiments indicate that both toxins strongly prefer the alpha1-delta subunit interface instead of the alpha1-gamma binding site on the mouse muscle nicotinic acetylcholine receptor. These peptides provide additional tools for the study of the structure and function of nicotinic receptor.
authors.affiliation: Institute of Protein Research, Tongji University, Shanghai 200092, China.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Chew
authors.forename: Edward
authors.initials: E
authors.lastname: Hawrot
authors.forename: Chengwu
authors.initials: C
authors.lastname: Chi
authors.forename: Chunguang
authors.initials: C
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D020916:Conotoxins / Q000138:chemical synthesis* / Q000302:isolation & purification / Q000494:pharmacology*; D017124:Conserved Sequence; D052078:Conus Snail / Q000737:chemistry* / Q000502:physiology; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D018733:Nicotinic Antagonists / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011235:Predatory Behavior / Q000502:physiology; D051381:Rats; D011978:Receptors, Nicotinic / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014981:Xenopus
chemical_list: C522308:Ac1.1a conotoxin, Conus achatinus; C522309:Ac1.1b conotoxin, Conus achatinus; D020916:Conotoxins; D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic