NMR structural analysis of alpha-bungarotoxin and its complex with the principal alpha-neurotoxin-binding sequence on the alpha 7 subunit of a neuronal nicotinic acetylcholine receptor

We report a new, higher resolution NMR structure of alpha-bungarotoxin that defines the structure-determining disulfide core and beta-sheet regions. We further report the NMR structure of the stoichiometric complex formed between alpha-bungarotoxin and a recombinantly expressed 19-mer peptide ((178)...

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Bibliographic Details
Published in:The Journal of biological chemistry 2002-04, Vol.277 (14), p.12406-12417
Main Authors: Moise, Leonard, Piserchio, Andrea, Basus, Vladimir J, Hawrot, Edward
Format: Article
Language:English
Subjects:
a-Bungarotoxin
Amino Acid Sequence
Amino Acids - chemistry
Animals
Binding Sites
Bungarotoxins - chemistry
Bungarotoxins - metabolism
Chickens
Disulfides
Kinetics
Ligands
Magnetic Resonance Spectroscopy
Models, Molecular
Molecular Sequence Data
Neurons - metabolism
Peptides - chemistry
Protein Binding
Protein Conformation
Protein Structure, Secondary
Protein Structure, Tertiary
Receptors, Nicotinic - chemistry
Receptors, Nicotinic - metabolism
Sequence Homology, Amino Acid
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Summary:We report a new, higher resolution NMR structure of alpha-bungarotoxin that defines the structure-determining disulfide core and beta-sheet regions. We further report the NMR structure of the stoichiometric complex formed between alpha-bungarotoxin and a recombinantly expressed 19-mer peptide ((178)IPGKRTESFYECCKEPYPD(196)) derived from the alpha7 subunit of the chick neuronal nicotinic acetylcholine receptor. A comparison of these two structures reveals binding-induced stabilization of the flexible tip of finger II in alpha-bungarotoxin. The conformational rearrangements in the toxin create an extensive binding surface involving both sides of the alpha7 19-mer hairpin-like structure. At the contact zone, Ala(7), Ser(9), and Ile(11) in finger I and Arg(36), Lys(38), Val(39), and Val(40) in finger II of alpha-bungarotoxin interface with Phe(186), Tyr(187), Glu(188), and Tyr(194) in the alpha7 19-mer underscoring the importance of receptor aromatic residues as critical neurotoxin-binding determinants. Superimposing the structure of the complex onto that of the acetylcholine-binding protein (1I9B), a soluble homologue of the extracellular domain of the alpha7 receptor, places alpha-bungarotoxin at the peripheral surface of the inter-subunit interface occluding the agonist-binding site. The disulfide-rich core of alpha-bungarotoxin is suggested to be tilted in the direction of the membrane surface with finger II extending into the proposed ligand-binding cavity.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M110320200