Neutralisation of a single voltage sensor affects gating determinants in all four pore-forming S6 segments of CaV1.2: a cooperative gating modelReport as inadecuate




Neutralisation of a single voltage sensor affects gating determinants in all four pore-forming S6 segments of CaV1.2: a cooperative gating model - Download this document for free, or read online. Document in PDF available to download.

Pflügers Archiv - European Journal of Physiology

, Volume 464, Issue 4, pp 391–401

First Online: 02 September 2012Received: 27 July 2012Revised: 14 August 2012Accepted: 16 August 2012

Abstract

Voltage sensors trigger the closed–open transitions in the pore of voltage-gated ion channels. To probe the transmission of voltage sensor signalling to the channel pore of CaV1.2, we investigated how elimination of positive charges in the S4 segments charged residues were replaced by neutral glutamine modulates gating perturbations induced by mutations in pore-lining S6 segments. Neutralisation of all positively charged residues in IIS4 produced a functional channel IIS4N, while replacement of the charged residues in IS4, IIIS4 and IVS4 segments resulted in nonfunctional channels. The IIS4N channel displayed activation kinetics similar to wild type. Mutations in a highly conserved structure motif on S6 segments -GAGA ring-: G432W in IS6, A780T in IIS6, G1193T in IIIS6 and A1503G in IVS6 induce strong left-shifted activation curves and decelerated channel deactivation kinetics. When IIS4N was combined with these mutations, the activation curves were shifted back towards wild type and current kinetics were accelerated. In contrast, 12 other mutations adjacent to the GAGA ring in IS6–IVS6, which also affect activation gating, were not rescued by IIS4N. Thus, the rescue of gating distortions in segments IS6–IVS6 by IIS4N is highly position-specific. Thermodynamic cycle analysis supports the hypothesis that IIS4 is energetically coupled with the distantly located GAGA residues. We speculate that conformational changes caused by neutralisation of IIS4 are not restricted to domain II IIS6 but are transmitted to gating structures in domains I, III and IV via the GAGA ring.

KeywordsCalcium channel Voltage sensor Pore Mutational analysis Channel gating Electronic supplementary materialThe online version of this article doi:10.1007-s00424-012-1144-5 contains supplementary material, which is available to authorized users.

Download fulltext PDF



Author: Stanislav Beyl - Katrin Depil - Annette Hohaus - Anna Stary-Weinzinger - Tobias Linder - Eugen Timin - Steffen Hering

Source: https://link.springer.com/







Related documents