Protonation controls ASIC1a activity via coordinated movements in multiple domains.

Détails

Ressource 1Télécharger: BIB_7DDBEAA9023B.P001.pdf (3940.39 [Ko])
Etat: Serval
Version: Final published version
ID Serval
serval:BIB_7DDBEAA9023B
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Protonation controls ASIC1a activity via coordinated movements in multiple domains.
Périodique
Journal of General Physiology
Auteur(s)
Bonifacio G., Lelli C.I., Kellenberger S.
ISSN
1540-7748 (Electronic)
ISSN-L
0022-1295
Statut éditorial
Publié
Date de publication
2014
Volume
143
Numéro
1
Pages
105-118
Langue
anglais
Résumé
Acid-sensing ion channels (ASICs) are neuronal Na(+)-conducting channels activated by extracellular acidification. ASICs are involved in pain sensation, expression of fear, and neurodegeneration after ischemic stroke. Functional ASICs are composed of three identical or homologous subunits, whose extracellular part has a handlike structure. Currently, it is unclear how protonation of residues in extracellular domains controls ASIC activity. Knowledge of these mechanisms would allow a rational development of drugs acting on ASICs. Protonation may induce conformational changes that control the position of the channel gate. We used voltage-clamp fluorometry with fluorophores attached to residues in different domains of ASIC1a to detect conformational changes. Comparison of the timing of fluorescence and current signals identified residues involved in movements that preceded desensitization and may therefore be associated with channel opening or early steps leading to desensitization. Other residues participated in movements intimately linked to desensitization and recovery from desensitization. Fluorescence signals of all mutants were detected at more alkaline pH than ionic currents. Their midpoint of pH dependence was close to that of steady-state desensitization, whereas the steepness of the pH fluorescence relationship was closer to that of current activation. A sequence of movements was observed upon acidification, and its backward movements during recovery from desensitization occurred in the reverse order, indicating that the individual steps are interdependent. Furthermore, the fluorescence signal of some labeled residues in the finger domain was strongly quenched by a Trp residue in the neighboring β-ball domain. Upon channel activation, their fluorescence intensity increased, indicating that the finger moved away from the β ball. This extensive analysis of activity-dependent conformational changes in ASICs sheds new light on the mechanisms by which protonation controls ASIC activity.
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2014 19:37
Dernière modification de la notice
08/05/2019 20:58
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