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 ...
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.
Related Citations:
Conotoxin TVIIA, a novel peptide from the venom of Conus tulipa 1. Isolation, characterisation and chemical synthesis Hill, J.M., Atkins, A.R., Loughnan, M.L., Jones, A., Adams, D.A., Martin, R., Lewis, R.J., Craik, D.J., Alewood, P.F. (2000) Eur J Biochem 267: 4642
Solution structure of the sodium channel antagonist conotoxin GS: a new molecular caliper for probing sodium channel geometry Hill, J.M., Alewood, P.F., Craik, D.J. (1997) Structure 5: 571
Organizational Affiliation:
Centre for Drug Design and Development, The Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
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