Structural Insights into Human Acid-sensing Ion Channel 1a Inhibition by Snake Toxin Mambalgin1
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that are involved in diverse neuronal processes including pain sensing. Peptide toxin Mambalgin1 (Mamba1) from black mamba snake venom can reversibly inhibit the conductance of ASICs, showing an analgesic effect. However, the detailed inhibitory mechanism of Mamba1 on ASIC1s, especially how Mamba1 binding to extracellular domain affects the conformational changes of the transmembrane domain of ASICs remains elusive. Here, we present single-particle cryo-EM structures of human ASIC1a (hASIC1a) and hASIC1a-Mamba1 complex at resolutions of 3.56 and 3.90 Å, respectively. The structures revealed the inhibited conformation of hASIC1a upon Mamba1 binding. The combination of the structural and physiological data indicates that Mamba1 prefers to bind hASIC1a in a closed state and reduces the proton sensitivity of the channel, representing a closed-state trapping mechanism.
Data availability
The EM maps for hASIC1a and hASIC1a-Mamba1 complex have been deposited in EMDB (www.ebi.ac.uk/pdbe/emdb/) with accession codes EMD-30346 and EMD-30347. The atomic coordinates for hASIC1a and hASIC1a-Mamba1 complex have been deposited in the Protein Data Bank (www.rcsb.org) with accession codes 7CFS and 7CFT respectively
Article and author information
Author details
Funding
Ministry of Science and Technology of the People's Republic of China (National Key Research and Development Project,2017YFA0505201,2017YFA0505403 and 2016YFA0400903)
- Changlin Tian
Chinese Academy of Sciences (Queensland-Chinese Academy of Sciences (Q-CAS) Collaborative Science Fund,GJHZ201946)
- Changlin Tian
Ministry of Science and Technology of the People's Republic of China (National Key Research and Development Project,2017YFA0505200)
- Lei Liu
National Natural Science Foundation of China (31600601,21778051)
- Demeng Sun
National Natural Science Foundation of China (91753205,21532004)
- Lei Liu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Leon D Islas, Universidad Nacional Autónoma de México, Mexico
Version history
- Received: March 20, 2020
- Accepted: September 10, 2020
- Accepted Manuscript published: September 11, 2020 (version 1)
- Version of Record published: October 13, 2020 (version 2)
Copyright
© 2020, Tian et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 3,557
- views
-
- 654
- downloads
-
- 36
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Further reading
-
- Structural Biology and Molecular Biophysics
The proteasome controls levels of most cellular proteins, and its activity is regulated under stress, quiescence, and inflammation. However, factors determining the proteasomal degradation rate remain poorly understood. Proteasome substrates are conjugated with small proteins (tags) like ubiquitin and Fat10 to target them to the proteasome. It is unclear if the structural plasticity of proteasome-targeting tags can influence substrate degradation. Fat10 is upregulated during inflammation, and its substrates undergo rapid proteasomal degradation. We report that the degradation rate of Fat10 substrates critically depends on the structural plasticity of Fat10. While the ubiquitin tag is recycled at the proteasome, Fat10 is degraded with the substrate. Our results suggest significantly lower thermodynamic stability and faster mechanical unfolding in Fat10 compared to ubiquitin. Long-range salt bridges are absent in the Fat10 structure, creating a plastic protein with partially unstructured regions suitable for proteasome engagement. Fat10 plasticity destabilizes substrates significantly and creates partially unstructured regions in the substrate to enhance degradation. NMR-relaxation-derived order parameters and temperature dependence of chemical shifts identify the Fat10-induced partially unstructured regions in the substrate, which correlated excellently to Fat10-substrate contacts, suggesting that the tag-substrate collision destabilizes the substrate. These results highlight a strong dependence of proteasomal degradation on the structural plasticity and thermodynamic properties of the proteasome-targeting tags.
-
- Biochemistry and Chemical Biology
- Structural Biology and Molecular Biophysics
The articles in this special issue highlight how modern cellular, biochemical, biophysical and computational techniques are allowing deeper and more detailed studies of allosteric kinase regulation.