title: Conotoxin TVIIA, a novel peptide from the venom of Conus tulipa 2. Three-dimensional solution structure.
abstract: The three-dimensional solution structure of conotoxin TVIIA, a 30-residue polypeptide from the venom of the piscivorous cone snail Conus tulipa, has been determined using 2D 1H NMR spectroscopy. TVIIA contains six cysteine residues which form a 'four-loop' structural framework common to many peptides from Conus venoms including the omega-, delta-, kappa-, and muO-conotoxins. However, TVIIA does not belong to these well-characterized pharmacological classes of conotoxins, but displays high sequence identity with conotoxin GS, a muscle sodium channel blocker from Conus geographus. Structure calculations were based on 562 interproton distance restraints inferred from NOE data, together with 18 backbone and nine side-chain torsion angle restraints derived from spin-spin coupling constants. The final family of 20 structures had mean pairwise rms differences over residues 2-27 of 0.18+/-0.05 A for the backbone atoms and 1.39+/-0.33 A for all heavy atoms. The structure consists of a triple-stranded, antiparallel beta sheet with +2x, -1 topology (residues 7-9, 16-20 and 23-27) and several beta turns. The core of the molecule is formed by three disulfide bonds which form a cystine knot motif common to many toxic and inhibitory polypeptides. The global fold, molecular shape and distribution of amino-acid sidechains in TVIIA is similar to that previously reported for conotoxin GS, and comparison with other four-loop conotoxin structures provides further indication that TVIIA and GS represent a new and distinct subgroup of this structural family. The structure of TVIIA determined in this study provides the basis for determining a structure-activity relationship for these molecules and their interaction with target receptors.
authors.affiliation: Centre for Drug Design and Development, The Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: J M
authors.initials: JM
authors.lastname: Hill
authors.forename: P F
authors.initials: PF
authors.lastname: Alewood
authors.forename: D J
authors.initials: DJ
authors.lastname: Craik
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002853:Chromatography, Liquid; D020916:Conotoxins / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008978:Mollusk Venoms / Q000737:chemistry*; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D012908:Snails / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; D020916:Conotoxins; D004220:Disulfides; D008978:Mollusk Venoms; D010455:Peptides; C413603:conotoxin TVIIA; C058597:conotoxin GS; D003545:Cysteine