Azemiopsin from Azemiops feae Viper Venom, a Novel Polypeptide Ligand of Nicotinic Acetylcholine Receptor

Autor: Vladislav G. Starkov, Sarah C. R. Lummis, Ngoc Anh Hoang, Daniel Bertrand, Andrew J. Thompson, Werner Sieghart, Igor E. Kasheverov, T. V. Andreeva, Maxim N. Zhmak, Joachim Ramerstorfer, Yuri N. Utkin, Elena V. Kryukova, Victor I. Tsetlin, Christoph Weise
Rok vydání: 2012
Předmět:
Neurotransmitter Transport
Male
Nicotinic Acetylcholine Receptors
Molecular Sequence Data
Radioreceptor Assays
Venom
Peptide
Viper Venoms
Receptors
Nicotinic
Ligands
complex mixtures
Biochemistry
Mice
03 medical and health sciences
chemistry.chemical_compound
Peptide synthesis
Toxins
Animals
Amino Acid Sequence
Molecular Biology
Peptide sequence
Chromatography
High Pressure Liquid
030304 developmental biology
Cys-loop Receptors
chemistry.chemical_classification
Mice
Inbred BALB C
0303 health sciences
Sequence Homology
Amino Acid
Edman degradation
Circular Dichroism
Snake Venom
030302 biochemistry & molecular biology
Cell Biology
3. Good health
Nicotinic acetylcholine receptor
chemistry
Snake venom
Spectrometry
Mass
Matrix-Assisted Laser Desorption-Ionization
Protein Structure and Folding
Azemiops feae
Neurotoxin
Peptides
Cys-loop receptors
Zdroj: Journal of Biological Chemistry; Vol 287
The Journal of Biological Chemistry
ISSN: 0021-9258
Popis: Background: Venoms from rare snake species may contain toxins of new structural or/and pharmacological types. Results: Amino acid sequence of the new polypeptide azemiopsin isolated from Azemiops feae viper venom was established, and its biological activity was determined. Conclusion: Azemiopsin is the first natural toxin that blocks nicotinic acetylcholine receptors and does not contain disulfide bridges. Significance: Azemiopsin is the first member of a new toxin group.
Azemiopsin, a novel polypeptide, was isolated from the Azemiops feae viper venom by combination of gel filtration and reverse-phase HPLC. Its amino acid sequence (DNWWPKPPHQGPRPPRPRPKP) was determined by means of Edman degradation and mass spectrometry. It consists of 21 residues and, unlike similar venom isolates, does not contain cysteine residues. According to circular dichroism measurements, this peptide adopts a β-structure. Peptide synthesis was used to verify the determined sequence and to prepare peptide in sufficient amounts to study its biological activity. Azemiopsin efficiently competed with α-bungarotoxin for binding to Torpedo nicotinic acetylcholine receptor (nAChR) (IC50 0.18 ± 0.03 μm) and with lower efficiency to human α7 nAChR (IC50 22 ± 2 μm). It dose-dependently blocked acetylcholine-induced currents in Xenopus oocytes heterologously expressing human muscle-type nAChR and was more potent against the adult form (α1β1ϵδ) than the fetal form (α1β1γδ), EC50 being 0.44 ± 0.1 μm and 1.56 ± 0.37 μm, respectively. The peptide had no effect on GABAA (α1β3γ2 or α2β3γ2) receptors at a concentration up to 100 μm or on 5-HT3 receptors at a concentration up to 10 μm. Ala scanning showed that amino acid residues at positions 3–6, 8–11, and 13–14 are essential for binding to Torpedo nAChR. In biological activity azemiopsin resembles waglerin, a disulfide-containing peptide from the Tropidechis wagleri venom, shares with it a homologous C-terminal hexapeptide, but is the first natural toxin that blocks nAChRs and does not possess disulfide bridges.
Databáze: OpenAIRE
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