Isolation and structural and pharmacological characterization of α-elapitoxin-Dpp2d, an amidated three finger toxin from black mamba venom

Wang, Ching-I Anderson, Reeks, Timothy, Vetter, Irina, Vergara, Irene, Kovtun, Oleksiy, Lewis, Richard J., Alewood, Paul F. and Durek, Thomas (2014) Isolation and structural and pharmacological characterization of α-elapitoxin-Dpp2d, an amidated three finger toxin from black mamba venom. Biochemistry, 53 23: 3758-3766. doi:10.1021/bi5004475


Author Wang, Ching-I Anderson
Reeks, Timothy
Vetter, Irina
Vergara, Irene
Kovtun, Oleksiy
Lewis, Richard J.
Alewood, Paul F.
Durek, Thomas
Title Isolation and structural and pharmacological characterization of α-elapitoxin-Dpp2d, an amidated three finger toxin from black mamba venom
Journal name Biochemistry   Check publisher's open access policy
ISSN 1520-4995
0006-2960
Publication date 2014-06-17
Sub-type Article (original research)
DOI 10.1021/bi5004475
Open Access Status
Volume 53
Issue 23
Start page 3758
End page 3766
Total pages 9
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2015
Language eng
Abstract We isolated a novel, atypical long-chain three-finger toxin (TFT), α-elapitoxin-Dpp2d (α-EPTX-Dpp2d), from black mamba (Dendroaspis polylepis polylepis) venom. Proteolytic digestion with trypsin and V8 protease, together with MS/MS de novo sequencing, indicated that the mature toxin has an amidated C-terminal arginine, a posttranslational modification rarely observed for snake TFTs. α-EPTX-Dpp2d was found to potently inhibit α7 neuronal nicotinic acetylcholine receptors (nAChR; IC50, 58 ± 24 nM) and muscle-type nAChR (IC50, 114 ± 37 nM) but did not affect α3β2 and α3β4 nAChR isoforms at 1 μM concentrations. Competitive radioligand binding assays demonstrated that α-EPTX-Dpp2d competes with epibatidine binding to the Lymnea stagnalis acetylcholine-binding protein (Ls-AChBP; IC50, 4.9 ± 2.3 nM). The activity profile and binding data are reminiscent of classical long-chain TFTs with a free carboxyl termini, suggesting that amidation does not significantly affect toxin selectivity. The crystal structure of α-EPTX-Dpp2d was determined at 1.7 Å resolution and displayed a dimeric toxin assembly with each monomer positioned in an antiparallel orientation. The dimeric structure is stabilized by extensive intermolecular hydrogen bonds and electrostatic interactions, which raised the possibility that the toxin may exist as a noncovalent homodimer in solution. However, chemical cross-linking and size-exclusion chromatography coupled with multiangle laser light scattering (MALLS) data indicated that the toxin is predominantly monomeric under physiological conditions. Because of its high potency and selectivity, we expect this toxin to be a valuable pharmacological tool for studying the structure and function of nAChRs.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
Institute for Molecular Bioscience - Publications
 
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