Chemical synthesis and 1H-NMR 3D structure determination of AgTx2-MTX chimera, a new potential blocker for Kv1.2 channel, derived from MTX and AgTx2 scorpion toxins.
Agitoxin 2 (AgTx2) is a 38-residue scorpion toxin, cross-linked by three disulfide bridges, which acts on voltage-gated K(+) (Kv) channels. Maurotoxin (MTX) is a 34-residue scorpion toxin with an uncommon four-disulfide bridge reticulation, acting on both Ca(2+)-activated and Kv channels. A 39-mer chimeric peptide, named AgTx2-MTX, was designed from the sequence of the two toxins and chemically synthesized. It encompasses residues 1-5 of AgTx2, followed by the complete sequence of MTX. As established by enzyme cleavage, the new AgTx2-MTX molecule displays half-cystine pairings of the type C1-C5, C2-C6, C3-C7, and C4-C8, which is different from that of MTX. The 3D structure of AgTx2-MTX solved by (1)H-NMR, revealed both alpha-helical and beta-sheet structures, consistent with a common alpha/beta scaffold of scorpion toxins. Pharmacological assays of AgTx2-MTX revealed that this new molecule is more potent than both original toxins in blocking rat Kv1.2 channel. Docking simulations, performed with the 3D structure of AgTx2-MTX, confirmed this result and demonstrated the participation of the N-terminal domain of AgTx2 in its increased affinity for Kv1.2 through additional molecular contacts. Altogether, the data indicated that replacement of the N-terminal domain of MTX by the one of AgTx2 in the AgTx2-MTX chimera results in a reorganization of the disulfide bridge arrangement and an increase of affinity to the Kv1.2 channel.
Pimentel
Cyril
C
Architecture et fonction des Macromolecules Biologiques, Centre National de la Recherche Scientifique, 13288 Marseille Cedex 09, France.
M'Barek
Sarrah
S
Visan
Violetta
V
Grissmer
Stephan
S
Sampieri
François
F
Sabatier
Jean-Marc
JM
Darbon
Hervé
H
Fajloun
Ziad
Z
D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D003435:Crotalid Venoms / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D051663:Kv1.2 Potassium Channel / Q000037:antagonists & inhibitors*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D012604:Scorpion Venoms / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D014162:Transfection
D003435:Crotalid Venoms; D051663:Kv1.2 Potassium Channel; D011994:Recombinant Proteins; D012604:Scorpion Venoms; C104498:maurotoxin; C070121:beta-agkistrodotoxin