CgNa, a type I toxin from the giant Caribbean sea anemone Condylactis gigantea shows structural similarities to both type I and II toxins, as well as distinctive structural and functional properties(1).
CgNa (Condylactis gigantea neurotoxin) is a 47-amino-acid- residue toxin from the giant Caribbean sea anemone Condylactis gigantea. The structure of CgNa, which was solved by 1H-NMR spectroscopy, is somewhat atypical and displays significant homology with both type I and II anemone toxins. CgNa also displays a considerable number of exceptions to the canonical structural elements that are thought to be essential for the activity of this group of toxins. Furthermore, unique residues in CgNa define a characteristic structure with strong negatively charged surface patches. These patches disrupt a surface-exposed cluster of hydrophobic residues present in all anemone-derived toxins described to date. A thorough characterization by patch-clamp analysis using rat DRG (dorsal root ganglion) neurons indicated that CgNa preferentially binds to TTX-S (tetrodotoxin-sensitive) voltage-gated sodium channels in the resting state. This association increased the inactivation time constant and the rate of recovery from inactivation, inducing a significant shift in the steady state of inactivation curve to the left. The specific structural features of CgNa may explain its weaker inhibitory capacity when compared with the other type I and II anemone toxins.
Salceda
Emilio
E
Instituto de Fisiología, Universidad Autónoma de Puebla, 14 Sur 6301, 72570 Puebla, México.
Pérez-Castells
Javier
J
López-Méndez
Blanca
B
Garateix
Anoland
A
Salazar
Hector
H
López
Omar
O
Aneiros
Abel
A
Ständker
Ludger
L
Béress
Lászlo
L
Forssmann
Wolf-Georg
WG
Soto
Enrique
E
Jiménez-Barbero
Jesús
J
Giménez-Gallego
Guillermo
G
D000595:Amino Acid Sequence; D000818:Animals; D017691:Caribbean Region; D003064:Cnidarian Venoms / Q000737:chemistry* / Q000145:classification / Q000378:metabolism* / Q000494:pharmacology; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000187:drug effects; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar; D012615:Sea Anemones / Q000737:chemistry*; D012996:Solutions; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D003064:Cnidarian Venoms; D007473:Ion Channels; D010455:Peptides; D012996:Solutions; D013779:Tetrodotoxin