Journal: Cell Discov / Year: 2018 Title: Cryo-EM structure of the ASIC1a-mambalgin-1 complex reveals that the peptide toxin mambalgin-1 inhibits acid-sensing ion channels through an unusual allosteric effect. Authors: Demeng Sun / You Yu / Xiaobin Xue / Man Pan / Ming Wen / Siyu Li / Qian Qu / Xiaorun Li / Longhua Zhang / Xueming Li / Lei Liu / Maojun Yang / Changlin Tian / Abstract: Acid-sensing ion channels (ASICs) are neuronal voltage-independent Na channels that are activated by extracellular acidification. ASICs play essential roles in a wide range of physiological ...Acid-sensing ion channels (ASICs) are neuronal voltage-independent Na channels that are activated by extracellular acidification. ASICs play essential roles in a wide range of physiological processes, including sodium homeostasis, synaptic plasticity, neurodegeneration, and sensory transduction. Mambalgins, a family of three-finger toxins isolated from black mamba venom, specifically inhibit ASICs to exert strong analgesic effects in vivo, thus are thought to have potential therapeutic values against pain. However, the interaction and inhibition mechanism of mambalgin on ASICs remains elusive. Here, we report a cryo-electron microscopy (cryo-EM) structure of chicken ASIC1a (cASIC1a) in complex with mambalgin-1 toxin at 5.4 Å resolution. Our structure provides the first experimental evidence that mambalgin-1 interacts directly with the extracellular thumb domain of cASIC1a, rather than inserting into the acid-sensing pocket, as previously reported. Binding of mambalgin-1 leads to relocation of the thumb domain that could disrupt the acidic pocket of cASIC1a, illustrating an unusual inhibition mechanism of toxins on ASIC channels through an allosteric effect. These findings establish a structural basis for the toxicity of the mambalgins, and provide crucial insights for the development of new optimized inhibitors of ASICs.
History
Deposition
Dec 14, 2017
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Header (metadata) release
Jun 13, 2018
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Map release
Jun 13, 2018
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Update
Jun 20, 2018
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Current status
Jun 20, 2018
Processing site: RCSB / Status: Released
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