Journal article
Molecular mechanism of allosteric modification of voltage-dependent sodium channels by local anesthetics
The Journal of general physiology, Vol.136(5), pp.541-554
11/01/2010
DOI: 10.1085/jgp.201010438
PMCID: PMC2964522
PMID: 20937693
Abstract
The hallmark of many intracellular pore blockers such as tetra-alkylammonium compounds and local anesthetics is their ability to allosterically modify the movement of the voltage sensors in voltage-dependent ion channels. For instance, the voltage sensor of domain III is specifically stabilized in the activated state when sodium currents are blocked by local anesthetics. The molecular mechanism underlying this long-range interaction between the blocker-binding site in the pore and voltage sensors remains poorly understood. Here, using scanning mutagenesis in combination with voltage clamp fluorimetry, we systematically evaluate the role of the internal gating interface of domain III of the sodium channel. We find that several mutations in the S4-S5 linker and S5 and S6 helices dramatically reduce the stabilizing effect of lidocaine on the activation of domain III voltage sensor without significantly altering use-dependent block at saturating drug concentrations. In the wild-type skeletal muscle sodium channel, local anesthetic block is accompanied by a 21% reduction in the total gating charge. In contrast, point mutations in this critical intracellular region reduce this charge modification by local anesthetics. Our analysis of a simple model suggests that these mutations in the gating interface are likely to disrupt the various coupling interactions between the voltage sensor and the pore of the sodium channel. These findings provide a molecular framework for understanding the mechanisms underlying allosteric interactions between a drug-binding site and voltage sensors.
Details
- Title: Subtitle
- Molecular mechanism of allosteric modification of voltage-dependent sodium channels by local anesthetics
- Creators
- Manoel Arcisio-Miranda - University of Wisconsin–MadisonYukiko Muroi - University of Wisconsin–MadisonSandipan Chowdhury - University of Wisconsin–MadisonBaron Chanda - University of Wisconsin–Madison
- Resource Type
- Journal article
- Publication Details
- The Journal of general physiology, Vol.136(5), pp.541-554
- DOI
- 10.1085/jgp.201010438
- PMID
- 20937693
- PMCID
- PMC2964522
- NLM abbreviation
- J Gen Physiol
- ISSN
- 0022-1295
- eISSN
- 1540-7748
- Publisher
- Rockefeller Univ Press
- Number of pages
- 14
- Grant note
- R01GM084140 / NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of General Medical Sciences (NIGMS) RO1-GM084140 / National Institutes of Health; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA Shaw Scientist award
- Language
- English
- Date published
- 11/01/2010
- Academic Unit
- Molecular Physiology and Biophysics
- Record Identifier
- 9984297614702771
Metrics
5 Record Views