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Regulatory switch at the cytoplasmic interface controls TRPV channel gating.

ABSTRACT: Temperature-sensitive transient receptor potential vanilloid (thermoTRPV) channels are activated by ligands and heat, and are involved in various physiological processes. ThermoTRPV channels possess a large cytoplasmic ring consisting of N-terminal ankyrin repeat domains (ARD) and C-terminal domains (CTD). The cytoplasmic inter-protomer interface is unique and consists of a CTD coiled around a ?-sheet which makes contacts with the neighboring ARD. Despite much existing evidence that the cytoplasmic ring is important for thermoTRPV function, the mechanism by which this unique structure is involved in thermoTRPV gating has not been clear. Here, we present cryo-EM and electrophysiological studies which demonstrate that TRPV3 gating involves large rearrangements at the cytoplasmic inter-protomer interface and that this motion triggers coupling between cytoplasmic and transmembrane domains, priming the channel for opening. Furthermore, our studies unveil the role of this interface in the distinct biophysical and physiological properties of individual thermoTRPV subtypes.

SUBMITTER: Zubcevic L

PROVIDER: S-EPMC6538378 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Regulatory switch at the cytoplasmic interface controls TRPV channel gating.

Zubcevic Lejla L Borschel William F WF Hsu Allen L AL Borgnia Mario J MJ Lee Seok-Yong SY

eLife 20190509

Temperature-sensitive transient receptor potential vanilloid (thermoTRPV) channels are activated by ligands and heat, and are involved in various physiological processes. ThermoTRPV channels possess a large cytoplasmic ring consisting of N-terminal ankyrin repeat domains (ARD) and C-terminal domains (CTD). The cytoplasmic inter-protomer interface is unique and consists of a CTD coiled around a β-sheet which makes contacts with the neighboring ARD. Despite much existing evidence that the cytoplas ...[more]

PMID: 31070581

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Project description:The intracellular tetramerization domain (T1) of most eukaryotic voltage-gated potassium channels (Kv channels) exists as a "hanging gondola" below the transmembrane regions that directly control activation gating via the electromechanical coupling between the S4 voltage sensor and the main S6 gate. However, much less is known about the putative contribution of the T1 domain to Kv channel gating. This possibility is mechanistically intriguing because the T1-S1 linker connects the T1 domain to the voltage-sensing domain. Previously, we demonstrated that thiol-specific reagents inhibit Kv4.1 channels by reacting in a state-dependent manner with native Zn(2+) site thiolate groups in the T1-T1 interface; therefore, we concluded that the T1-T1 interface is functionally active and not protected by Zn(2+) (Wang, G., M. Shahidullah, C.A. Rocha, C. Strang, P.J. Pfaffinger, and M. Covarrubias. 2005. J. Gen. Physiol. 126:55-69). Here, we co-expressed Kv4.1 channels and auxiliary subunits (KChIP-1 and DPPX-S) to investigate the state and voltage dependence of the accessibility of MTSET to the three interfacial cysteines in the T1 domain. The results showed that the average MTSET modification rate constant (k(MTSET)) is dramatically enhanced in the activated state relative to the resting and inactivated states (approximately 260- and approximately 47-fold, respectively). Crucially, under three separate conditions that produce distinct activation profiles, k(MTSET) is steeply voltage dependent in a manner that is precisely correlated with the peak conductance-voltage relations. These observations strongly suggest that Kv4 channel gating is tightly coupled to voltage-dependent accessibility changes of native T1 cysteines in the intersubunit Zn(2+) site. Furthermore, cross-linking of cysteine pairs across the T1-T1 interface induced substantial inhibition of the channel, which supports the functionally dynamic role of T1 in channel gating. Therefore, we conclude that the complex voltage-dependent gating rearrangements of eukaryotic Kv channels are not limited to the membrane-spanning core but must include the intracellular T1-T1 interface. Oxidative stress in excitable tissues may perturb this interface to modulate Kv4 channel function.

Dataset Information

Regulatory switch at the cytoplasmic interface controls TRPV channel gating.

Publications

Regulatory switch at the cytoplasmic interface controls TRPV channel gating.

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