Isolation and characterisation of conomap-Vt, a D-amino acid containing excitatory peptide from the venom of a vermivorous cone snail.
Cone snail venom is a rich source of bioactives, in particular small disulfide rich peptides that disrupt synaptic transmission. Here, we report the discovery of conomap-Vt (Conp-Vt), an unusual linear tetradecapeptide isolated from Conus vitulinus venom. The sequence displays no homology to known conopeptides, but displays significant homology to peptides of the MATP (myoactive tetradecapeptide) family, which are important endogenous neuromodulators in molluscs, annelids and insects. Conp-Vt showed potent excitatory activity in several snail isolated tissue preparations. Similar to ACh, repeated doses of Conp-Vt were tachyphylactic. Since nicotinic and muscarinic antagonists failed to block its effect and Conp-Vt desensitised tissue remained responsive to ACh, it appears that Conp-Vt contractions were non-cholinergic in origin. Finally, biochemical studies revealed that Conp-Vt is the first member of the MATP family with a d-amino acid. Interestingly, the isomerization of L-Phe to D-Phe enhanced biological activity, suggesting that this post-translational modified conopeptide may have evolved for prey capture.
Dutertre
Sébastien
S
Institute for Molecular Bioscience, The University of Queensland, Brisbane, 4072 Qld, Australia.
Lumsden
Natalie G
NG
Alewood
Paul F
PF
Lewis
Richard J
RJ
D000109:Acetylcholine / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D020916:Conotoxins / Q000737:chemistry*; D052078:Conus Snail / Q000737:chemistry*; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification*; D010649:Phenylalanine / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D011950:Receptors, Cholinergic / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013618:Tachyphylaxis; D014357:Trypsin / Q000378:metabolism
D020916:Conotoxins; D010455:Peptides; D011950:Receptors, Cholinergic; D010649:Phenylalanine; D014357:Trypsin; D000109:Acetylcholine