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Binding Sites and the Mechanism of Action of Propofol and a Photoreactive Analogue in Prokaryotic Voltage-Gated Sodium Channels
- Source :
- ACS chemical neuroscience. 12(20)
- Publication Year :
- 2021
-
Abstract
- Propofol, one of the most commonly used intravenous general anesthetics, modulates neuronal function by interacting with ion channels. The mechanisms that link propofol binding to the modulation of distinct ion channel states, however, are not understood. To tackle this problem, we investigated the prokaryotic ancestors of eukaryotic voltage-gated Na+ channels (Navs) using unbiased photoaffinity labeling (PAL) with a diazirine derivative of propofol (AziPm), electrophysiological methods, and mutagenesis. AziPm inhibits Nav function in a manner that is indistinguishable from that of the parent compound by promoting activation-coupled inactivation. In several replicates (8/9) involving NaChBac and NavMs, we found adducts at residues located at the C-terminal end of the S4 voltage sensor, the S4-S5 linker, and the N-terminal end of the S5 segment. However, the non-inactivating mutant NaChBac-T220A yielded adducts that were different from those found in the wild-type counterpart, which suggested state-dependent changes at the binding site. Then, using molecular dynamics simulations to further elucidate the structural basis of Nav modulation by propofol, we show that the S4 voltage sensors and the S4-S5 linkers shape two distinct propofol binding sites in a conformation-dependent manner. Supporting the PAL and MD simulation results, we also found that Ala mutations of a subset of adducted residues have distinct effects on gating modulation of NaChBac and NavMs by propofol. The results of this study provide direct insights into the structural basis of the mechanism through which propofol binding promotes activation-coupled inactivation to inhibit Nav channel function.
- Subjects :
- Binding Sites
Photoaffinity labeling
Physiology
Chemistry
Cognitive Neuroscience
Sodium channel
Anesthetics, General
Mutagenesis
Cell Biology
General Medicine
Gating
Voltage-Gated Sodium Channels
Biochemistry
Ion Channels
chemistry.chemical_compound
Mechanism of action
Diazirine
Biophysics
medicine
Binding site
medicine.symptom
Propofol
Ion channel
Subjects
Details
- ISSN :
- 19487193
- Volume :
- 12
- Issue :
- 20
- Database :
- OpenAIRE
- Journal :
- ACS chemical neuroscience
- Accession number :
- edsair.doi.dedup.....e1ab9656de65b55cd38807b1e1b70d33