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A beta-Hairpin Structure in a 13-mer Peptide that Binds a-Bungarotoxin with High Affinity and Neutralizes its Toxicity
Structural highlights
Function3L21A_BUNMU Binds with high affinity to muscular (tested on Torpedo marmorata, Kd=0.4 nM) and neuronal (tested on chimeric alpha-7/CHRNA7, Kd=0.95 nM) nicotinic acetylcholine receptor (nAChR) and inhibits acetylcholine from binding to the receptor, thereby impairing neuromuscular and neuronal transmission (PubMed:9305882). It also shows an activity on GABA(A) receptors (PubMed:16549768, PubMed:25634239). It antagonises GABA-activated currents with high potency when tested on primary hippocampal neurons (PubMed:25634239). It inhibits recombinantly expressed GABA(A) receptors composed of alpha-2-beta-2-gamma-2 (GABRA2-GABRB2-GABRG2) subunits with high potency (62.3% inhibition at 20 uM of toxin) (PubMed:25634239). It also shows a weaker inhibition on GABA(A) receptors composed of alpha-1-beta-2-gamma-2 (GABRA1-GABRB2-GABRG2) subunits, alpha-4-beta-2-gamma-2 (GABRA4-GABRB2-GABRG2) subunits, and alpha-5-beta-2-gamma-2 (GABRA5-GABRB2-GABRG2) subunits (PubMed:25634239). A very weak inhibition is also observed on GABA(A) receptor composed of alpha-1-beta-3-gamma-2 (GABRA1-GABRB3-GABRG2) (PubMed:26221036). It has also been shown to bind and inhibit recombinant GABA(A) receptor beta-3/GABRB3 subunit (Kd=about 50 nM) (PubMed:16549768). In addition, it blocks the extracellular increase of dopamine evoked by nicotine only at the higher dose (4.2 uM) (PubMed:9840221).[1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSnake-venom alpha-bungarotoxin is a member of the alpha-neurotoxin family that binds with very high affinity to the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction. The structure of the complex between alpha-bungarotoxin and a 13-mer peptide (WRYYESSLEPYPD) that binds the toxin with high affinity, thus inhibiting its interactions with AChR with an IC(50) of 2 nM, has been solved by (1)H-NMR spectroscopy. The bound peptide folds into a beta-hairpin structure created by two antiparallel beta-strands, which combine with the already existing triple-stranded beta-sheet of the toxin to form a five-stranded intermolecular, antiparallel beta-sheet. Peptide residues Y3(P), E5(P), and L8(P) have the highest intermolecular contact area, indicating their importance in the binding of alpha-bungarotoxin; W1(P), R2(P), and Y4(P) also contribute significantly to the binding. A large number of characteristic hydrogen bonds and electrostatic and hydrophobic interactions are observed in the complex. The high-affinity peptide exhibits inhibitory potency that is better than any known peptide derived from AChR, and is equal to that of the whole alpha-subunit of AChR. The high degree of sequence similarity between the peptide and various types of AChRs implies that the binding mode found within the complex might possibly mimic the receptor binding to the toxin. The design of the high-affinity peptide was based on our previous findings: (i) the detection of a lead peptide (MRYYESSLKSYPD) that binds alpha-bungarotoxin, using a phage-display peptide library, (ii) the information about the three-dimensional structure of alpha-bungarotoxin/lead-peptide complex, and (iii) the amino acid sequence analysis of different AChRs. A beta -hairpin structure in a 13-mer peptide that binds alpha -bungarotoxin with high affinity and neutralizes its toxicity.,Scherf T, Kasher R, Balass M, Fridkin M, Fuchs S, Katchalski-Katzir E Proc Natl Acad Sci U S A. 2001 Jun 5;98(12):6629-34. Epub 2001 May 29. PMID:11381118[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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