Properties of Slo1 K
            <sup>+</sup>
            channels with and without the gating ring

Budelli, Gonzalo; Geng, Yanyan; Butler, Alice; Magleby, Karl L.; Salkoff, Lawrence

doi:10.1073/pnas.1313433110

Cited by 49 publications

(67 citation statements)

References 47 publications

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“…This description is meant to capture an important property of the structures; that the voltage sensor communicates with the Ca 2+ sensor. However, experiments under extreme conditions of voltage and Ca 2+ have shown that each sensor to some degree can work independently to regulate the pore 4,23,24 .…”

Section: Discussionmentioning

confidence: 99%

“…The S4–S5 linker is one of the key structural elements on the TMD side of the interface and therefore movements of S4 helices should directly impinge on movements of the RCK1 N-lobes on the gating ring. The interface also contains a Mg 2+ ion, whose binding site was predicted by mutagenesis studies 10,15,18,19,20,21,22,23 . In the Ca 2+ structure the Mg 2+ ion mediates multiple interactions that bridge the RCK1 N-lobe to the TMD via helix S0’ and the S2–S3 linker (Fig.…”

Section: Regulation By Voltagementioning

confidence: 99%

See 1 more Smart Citation

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Hite

Tao

MacKinnon

2016

Nature

177

324

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The precise control of an ion channel’s gate by environmental stimuli is crucial to the fulfillment of its biological role. The gate in Slo1 channels is regulated by two separate stimuli, intracellular Ca2+ concentration and membrane voltage. Thus, Slo1 is central to understanding the relationship between intracellular Ca2+ and membrane excitability. Here we present the Slo1 structure in the absence of Ca2+ and compare it with the Ca2+-bound channel. Ca2+ binding at two unique binding sites per subunit stabilizes an expanded conformation of the Ca2+ sensor gating ring. These conformational changes are propagated from the gating ring to the pore through covalent linkers and through protein interfaces formed between the gating ring and the voltage sensors. The gating ring and voltage sensors are directly connected through these interfaces, which allow membrane voltage to regulate gating of the pore by influencing the Ca2+ sensors.

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Section: Discussionmentioning

confidence: 99%

Section: Regulation By Voltagementioning

confidence: 99%

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Hite

Tao

MacKinnon

2016

Nature

177

324

View full text Add to dashboard Cite

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“…Ca 2+ binding through these domains is transduced to the transmembrane domain via the S6/RCK1 linker (12,17). Recent evidence (18) supports the idea that the cytosolic domain of this channel is responsible for sensing Ca 2+ , because truncated BK channels lacking the C terminus are insensitive to Ca…”

Section: +mentioning

confidence: 93%

Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: Involvement of the S4/S5 linker and the S6 segment

Webb

Kshatri

Large

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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GoSlo-SR-5-6 is a novel large-conductance Ca 2+ -activated K + (BK) channel agonist that shifts the activation V 1/2 of these channels in excess of −100 mV when applied at a concentration of 10 μM. Although the structure-activity relationship of this family of molecules has been established, little is known about how they open BK channels. To help address this, we used a combination of electrophysiology, mutagenesis, and mathematical modeling to investigate the molecular mechanisms underlying the effect of GoSlo-SR-5-6. Our data demonstrate that the effects of this agonist are practically abolished when three point mutations are made: L227A in the S4/S5 linker in combination with S317R and I326A in the S6C region. Our data suggest that GoSlo-SR-5-6 interacts with the transmembrane domain of the channel to enhance pore opening. The Horrigan-Aldrich model suggests that GoSlo-SR-5-6 works by stabilizing the open conformation of the channel and the activated state of the voltage sensors, yet decouples the voltage sensors from the pore gate.

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“…Left shift of G-V (V0.5 Table 1: C-linker scrambling mutations and measured V0.5 in the full-length and Core-MT BK channels at [Ca 2+ ] = 0 and [Mg 2+ ] = 0. The Core-MT constructs are based on the TMD, C-linker of mSlo1, and an 11-residue tail from KV 1.4 of the mouse Shaker family (19,20). The location of the nearest Tyr to the S6 C-terminal is highlighted in green.…”

Section: Sequence Scrambling Of the C-linker Dramatically Modulates Bmentioning

confidence: 99%

Nonspecific membrane interactions can modulate BK channel activation

Yazdani

Zhang

Jia

et al. 2020

Preprint

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One-sentence summary: The covalent linker between BK intracellular and transmembrane domains is likely a part of the sensing apparatus that regulates the channel activation. # Equal contributions * Corresponding Authors: Jianmin Cui: Phone: (314) 935-8896; AbstractLarge-conductance potassium (BK) channels are transmembrane (TM) proteins that can be synergistically and independently activated by membrane voltage and intracellular Ca 2+ . The only covalent connection between the cytosolic Ca 2+ sensing domain and the TM pore and voltage sensing domains is a 15-residue "C-linker". To determine the linker's role in BK activation, we designed a series of linker sequence scrambling mutants to suppress potential complex interplay of specific interactions with the rest of the protein. The results revealed a surprising sensitivity of BK activation to the linker sequence. Combing atomistic simulations and further mutagenesis experiments, we demonstrated that nonspecific interactions of the linker with membrane alone could directly modulate BK activation. The C-linker thus plays more direct roles in mediating allosteric coupling between BK domains than previously assumed. Our results also suggest that covalent linkers could directly modulate TM protein function and should be considered an integral component of the sensing apparatus.Widely distributed in nerve and muscle cells, large-conductance potassium (BK) channels are characterized by a large single-channel conductance (~ 100 -300 pS) (1-5) and dual activation by both intracellular Ca 2+ and membrane voltage (6-8), thus an ideal model system for understanding the gating and sensor-pore coupling in ion channels. BK channels are involved in numerous vital physiological processes including intracellular ion homeostasis and membrane excitation, and are associated with pathogenesis of many diseases such as epilepsy, stroke, autism and hypertension (9). Functional BK channels are homo-tetramers, each containing three distinct domains (Figure 1a). The voltage sensor domain (VSD) detects membrane potential, the pore-gate domain (PGD) controls the K + selectivity and permeation, and the cytosolic tail domain (CTD) senses various intracellular ligands including Ca 2+ . The VSD and the CTD also form a Mg 2+ binding site for Mg 2+ dependent activation (Yang 2008 NSMB). The tetrameric assembly of CTD domains is also referred to as the "gating ring". VSD and PGD together form the trans-membrane domain (TMD) of BK channels. Previous studies on mouse BK channels (10) and recent atomistic structures of full-length Aplysia californica BK channel (aSlo1) (11, 12) reveal that CTD of each subunit reside beneath the TMD of the neighboring subunit in a surprising domain-swapped arrangement ( Figure S1a).The only covalent connection between CTD and TMD of BK channels is a 15-residue peptide referred to as the "C-linker" (R329 to K343 in the human BK channel, hSlo1) (green in Figure 1a).This linker directly connects the pore lining S6 helices in the PGD (yellow in Figure S1b) to the Nterminus...

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Properties of Slo1 K ⁺ channels with and without the gating ring

Cited by 49 publications

References 47 publications

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: Involvement of the S4/S5 linker and the S6 segment

Nonspecific membrane interactions can modulate BK channel activation

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Properties of Slo1 K + channels with and without the gating ring

Cited by 49 publications

References 47 publications

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Structural basis for gating the high-conductance Ca2+-activated K+ channel

Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: Involvement of the S4/S5 linker and the S6 segment

Nonspecific membrane interactions can modulate BK channel activation

Contact Info

Product

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Properties of Slo1 K ⁺ channels with and without the gating ring