Structural plasticity and dynamic selectivity of acid-sensing ion channel-spider toxin complexes

Journal Article · Sun Jul 29 00:00:00 EDT 2012 · Nature (London)

DOI:https://doi.org/10.1038/nature11375· OSTI ID:1054017

Baconguis, Isabelle; Gouaux, Eric ^[1]

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1. Oregon HSU

Acid-sensing ion channels (ASICs) are voltage-independent, amiloride-sensitive channels involved in diverse physiological processes ranging from nociception to taste. Despite the importance of ASICs in physiology, we know little about the mechanism of channel activation. Here we show that psalmotoxin activates non-selective and Na⁺-selective currents in chicken ASIC1a at pH7.25 and 5.5, respectively. Crystal structures of ASIC1a–psalmotoxin complexes map the toxin binding site to the extracellular domain and show how toxin binding triggers an expansion of the extracellular vestibule and stabilization of the open channel pore. At pH7.25 the pore is approximately 10Å in diameter, whereas at pH5.5 the pore is largely hydrophobic and elliptical in cross-section with dimensions of approximately 5 by 7Å, consistent with a barrier mechanism for ion selectivity. These studies define mechanisms for activation of ASICs, illuminate the basis for dynamic ion selectivity and provide the blueprints for new therapeutic agents.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: OTHERNIH
• OSTI ID: 1054017
• Journal Information: Nature (London), Vol. 489; ISSN 0028-0836
• Publisher: Nature Publishing Group
• Country of Publication: United States
• Language: ENGLISH