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Mechanisms of noncovalent β subunit regulation of NaV channel gating

Zhu, Wandi and Voelker, Taylor L. and Varga, Zoltán and Schubert, Angela R. and Nerbonne, Jeanne M. and Silva, Jonathan R. (2017) Mechanisms of noncovalent β subunit regulation of NaV channel gating. The Journal of General Physiology. pp. 813-831. ISSN 1540-7748

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Abstract

Voltage-gated Na(+) (NaV) channels comprise a macromolecular complex whose components tailor channel function. Key components are the non-covalently bound β1 and β3 subunits that regulate channel gating, expression, and pharmacology. Here, we probe the molecular basis of this regulation by applying voltage clamp fluorometry to measure how the β subunits affect the conformational dynamics of the cardiac NaV channel (NaV1.5) voltage-sensing domains (VSDs). The pore-forming NaV1.5 α subunit contains four domains (DI-DIV), each with a VSD. Our results show that β1 regulates NaV1.5 by modulating the DIV-VSD, whereas β3 alters channel kinetics mainly through DIII-VSD interaction. Introduction of a quenching tryptophan into the extracellular region of the β3 transmembrane segment inverted the DIII-VSD fluorescence. Additionally, a fluorophore tethered to β3 at the same position produced voltage-dependent fluorescence dynamics strongly resembling those of the DIII-VSD. Together, these results provide compelling evidence that β3 binds proximally to the DIII-VSD. Molecular-level differences in β1 and β3 interaction with the α subunit lead to distinct activation and inactivation recovery kinetics, significantly affecting NaV channel regulation of cell excitability.

Item Type: Article
Subjects: R Medicine / orvostudomány > R1 Medicine (General) / orvostudomány általában > R850-854 Experimental medicine / kisérleti orvostudomány
Depositing User: Dr Zoltan Varga
Date Deposited: 27 Sep 2017 10:34
Last Modified: 27 Sep 2017 10:34
URI: http://real.mtak.hu/id/eprint/63987

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