Conformational dynamics and role of the acidic pocket in ASIC pH-dependent gating

Vullo, Sabrina; Bonifacio, Gaetano; Roy, Sophie; Johner, Niklaus; Bernèche, Simon; Kellenberger, Stephan

doi:10.1073/pnas.1620560114

Cited by 78 publications

(119 citation statements)

References 41 publications

Supporting

Mentioning

104

Contrasting

Order By: Relevance

“…Our results augment previous studies of gating mechanics in ASICs that suggest activation-induced movements at the acidic pocket as well as roles for the lower palm domain and β11-β12 linkers in desensitization 27-29 . By contrast, atomic force microscopy studies 30 indicate that human ASIC1a channels undergo a height increase of the ECD upon activation, a conformational change that has so far not been observed by analysis of x-ray crystallographic and cryo-EM structures of chicken ASIC1a.…”

supporting

confidence: 87%

Gating mechanisms of acid-sensing ion channels

Yoder¹,

Yoshioka²,

Gouaux³

2018

Nature

202

322

View full text Add to dashboard Cite

Acid sensing ion channels (ASICs) are trimeric1, proton-gated2,3 and sodiumselective4,5 members of the epithelial sodium channel/degenerin (ENaC/DEG) superfamily of ion channels6,7 and are expressed throughout vertebrate central and peripheral nervous systems. ASIC gating occurs on a millisecond time scale8 and can be largely described by a simple mechanism composed of three states: high pH resting, low pH open and low pH desensitized9. While previously solved x-ray structures of ASIC1a elucidated the conformations of the open10 and desensitized1,11 states, the structure of the high pH, resting state as well as detailed mechanisms for activation and desensitization have remained elusive. Here we present resting state structures of homotrimeric chicken ASIC1a at high pH determined by x-ray crystallography and single particle cryo-electron microscopy, informing a comprehensive molecular mechanism for proton-dependent gating in ASICs. In the resting state, the thumb domain has moved outward relative to its position in the open and desensitized states, expanding the ‘acidic pocket’. Activation thus involves ‘closure’ of the thumb into the acidic pocket, expansion of the lower palm domain and an iris-like opening of the channel gate. Furthermore, we demonstrate how the β11-β12 linkers demarcating upper and lower palm domains serve as a molecular ‘clutch’, undergoing a simple rearrangement to permit rapid desensitization.

show abstract

supporting

confidence: 87%

Gating mechanisms of acid-sensing ion channels

Yoder¹,

Yoshioka²,

Gouaux³

2018

Nature

202

322

View full text Add to dashboard Cite

show abstract

“…In past studies (Kusama et al, 2013;Li et al, 2012), recovery from desensitization 49 has been well described as a mono-exponential process. This was the case for cASIC1 wild type, 50 however, the L414A mutation was poorly fit by a single exponential function ( Figure 1E (Liechti et al, 2010;MacLean and Jayaraman, 2017;Paukert et al, 2008;Vullo et al, 2017). 62 Therefore, we examined the proton sensitivity of cASIC1 wild type and L414A in outside out 63 patches using fast piezo-driven perfusion ( we observed only a small shift in the pH50 of activation for L414A compared to wild type (wild 66 type: pH50act = 6.43 ± 0.04, n = 6; L414A: pH50act = 6.57 ± 0.03, n = 5, p = 0.027).…”

mentioning

confidence: 84%

β11-12 linker isomerization governs Acid-sensing ion channel desensitization and recovery

Rook¹,

Williamson

Lueck

et al. 2019

Preprint

View full text Add to dashboard Cite

1 Acid-sensing ion channels (ASICs) are neuronal sodium-selective channels activated by reductions 2 in extracellular pH. Structures of the three presumptive functional states, high-pH resting, low-3 pH desensitized, and toxin-stabilized open, have all been solved for chicken ASIC1. These 4 structures, along with prior functional data, suggest that the isomerization or flipping of the β11-5 12 linker in the extracellular, ligand-binding domain is an integral component of the 6 desensitization process.To test this, we combined fast perfusion electrophysiology, molecular 7 dynamics simulations and state-dependent non-canonical amino acid cross-linking. We find that 8 both desensitization and recovery can be accelerated by orders of magnitude by mutating resides 9 in this linker or the surrounding region. Furthermore, desensitization can be suppressed by 10 trapping the linker in the resting state, indicating that isomerization of the β11-12 linker is not 11 merely a consequence of, but a necessity for the desensitization process in ASICs. 12

show abstract

“…Despite the potential pathophysiological relevance of the ASIC-BigDyn interaction (10) is not likely to be the primary proton sensor of ASICs (37,38), side chains in and around the acidic pocket have been shown to modulate proton sensitivity (30,37). A direct binding of BigDyn to this region is therefore expected to alter proton sensing.…”

Section: Mechanism Of Action Of Bigdyn On Asic1amentioning

confidence: 99%

Mechanism and site of action of big dynorphin on ASIC1a

Borg

Braun

Heusser

et al. 2019

Preprint

View full text Add to dashboard Cite

Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to synaptic plasticity, as well as initiation of pain and neuronal death following ischemic stroke.As such, there is a great interest in understanding the in vivo regulation of ASICs, especially by endogenous neuropeptides that potently modulate ASICs. The most potent endogenous ASIC modulator known to date is the opioid neuropeptide big dynorphin (BigDyn). BigDyn is upregulated in chronic pain and increases ASIC-mediated neuronal death during acidosis. Understanding the mechanism and site of action of BigDyn on ASICs could thus enable the rational design of compounds potentially useful in the treatment of pain and ischemic stroke. To this end, we employ a combination of electrophysiology, voltage-clamp fluorometry, synthetic BigDyn analogs and non-canonical amino acidmediated photocrosslinking. We demonstrate that BigDyn binding induces ASIC1a conformational changes that are different from those induced by protonation and likely represent a distinct closed state. Using alanine-substituted BigDyn analogs, we find that the BigDyn modulation of ASIC1a is mediated through electrostatic interactions of basic amino acids in the BigDyn N-terminus. Furthermore, neutralizing acidic amino acids in the ASIC1a extracellular domain reduces BigDyn effects, suggesting a binding site at the acidic pocket. This is confirmed by photocrosslinking using the non-canonical amino acid azidophenylalanine. Overall, our data define the mechanism of how BigDyn modulates ASIC1a, identify the acidic pocket as the binding site for BigDyn and thus highlight this cavity as an important site for the development of ASIC-targeting therapeutics.Note: This manuscript has not been peer-reviewed 3

show abstract

Conformational dynamics and role of the acidic pocket in ASIC pH-dependent gating

Cited by 78 publications

References 41 publications

Gating mechanisms of acid-sensing ion channels

Gating mechanisms of acid-sensing ion channels

β11-12 linker isomerization governs Acid-sensing ion channel desensitization and recovery

Mechanism and site of action of big dynorphin on ASIC1a

Contact Info

Product

Resources

About