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  • Structure of the Native Mus...
    Rahman, Md. Mahfuzur; Teng, Jinfeng; Worrell, Brady T.; Noviello, Colleen M.; Lee, Myeongseon; Karlin, Arthur; Stowell, Michael H.B.; Hibbs, Ryan E.

    Neuron (Cambridge, Mass.), 06/2020, Letnik: 106, Številka: 6
    Journal Article

    The nicotinic acetylcholine receptor, a pentameric ligand-gated ion channel, converts the free energy of binding of the neurotransmitter acetylcholine into opening of its central pore. Here we present the first high-resolution structure of the receptor type found in muscle-endplate membrane and in the muscle-derived electric tissues of fish. The native receptor was purified from Torpedo electric tissue and functionally reconstituted in lipids optimal for cryo-electron microscopy. The receptor was stabilized in a closed state by the binding of α-bungarotoxin. The structure reveals the binding of a toxin molecule at each of two subunit interfaces in a manner that would block the binding of acetylcholine. It also reveals a closed gate in the ion-conducting pore, formed by hydrophobic amino acid side chains, located ∼60 Å from the toxin binding sites. The structure provides a framework for understanding gating in ligand-gated channels and how mutations in the acetylcholine receptor cause congenital myasthenic syndromes. •High-resolution structure of a native muscle-type nicotinic acetylcholine receptor•Previously unresolved structural elements contribute to neurotoxin binding•Channel is stabilized in a closed conformation by α-bungarotoxin from snake venom•Transduction mechanism and myasthenic disease mutations Rahman et al. report the high-resolution single-particle cryo-EM structure of a native muscle-type nicotinic acetylcholine receptor from the Torpedo electric ray, in complex with α-bungarotoxin from the banded krait. The structure was obtained in a lipidic environment shown to support channel function and reveals a closed, hydrophobic ion channel gate.