Three Transmembrane Conformations and Sequence-Dependent Displacement of the S4 Domain in Shaker K + Channel Gating

Baker, Oliver S.; Larsson, H. Peter; Mannuzzu, Lidia M.; Isacoff, Ehud Y.

doi:10.1016/s0896-6273(00)80507-3

Cited by 168 publications

(233 citation statements)

References 37 publications

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“…The modification was assayed functionally in two-electrode voltage-clamped oocytes, as described previously (Larsson et al 1996; Baker et al 1998). The applications of the methanethiosulfonate (MTS) reagents were computer controlled, and the MTS reagents were applied either at −80 mV (closed state; S4 in the deactivated state) or at 0 mV or +40 mV depending on the channel type (open/inactivated state; S4 in the activated state).…”

Section: Methodsmentioning

confidence: 99%

“…Cysteine accessibility studies suggest that the positive charges of S4 are either buried in the membrane or in the cytosol when the membrane is held at a hyperpolarized potential, and, in response to a depolarizing voltage pulse, the S4 charges move outward and exposes its three most external charges into the extracellular solution (Larsson et al 1996; Yang et al 1996; Yusaf et al 1996; Baker et al 1998; for review see Keynes and Elinder 1999). S4 is suggested to undergo a large-scale movement during activation of the channels, either a 180° rotation (Papazian and Bezanilla 1997; Cha et al 1999; Glauner et al 1999) or a helical screw motion with both a 180° rotation and a translational motion of 13.5 Å (Catterall 1986; Guy and Seetharamulu 1986; Glauner et al 1999; Keynes and Elinder 1999; Gandhi et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Elinder

Männikkö

Larsson

2001

The Journal of General Physiology

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Voltage-gated ion channels respond to changes in the transmembrane voltage by opening or closing their ion conducting pore. The positively charged fourth transmembrane segment (S4) has been identified as the main voltage sensor, but the mechanisms of coupling between the voltage sensor and the gates are still unknown. Obtaining information about the location and the exact motion of S4 is an important step toward an understanding of these coupling mechanisms. In previous studies we have shown that the extracellular end of S4 is located close to segment 5 (S5). The purpose of the present study is to estimate the location of S4 charges in both resting and activated states. We measured the modification rates by differently charged methanethiosulfonate regents of two residues in the extracellular end of S5 in the Shaker K channel (418C and 419C). When S4 moves to its activated state, the modification rate by the negatively charged sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES−) increases significantly more than the modification rate by the positively charged [2-(trimethylammonium)ethyl] methanethiosulfonate, bromide (MTSET+). This indicates that the positive S4 charges are moving close to 418C and 419C in S5 during activation. Neutralization of the most external charge of S4 (R362), shows that R362 in its activated state electrostatically affects the environment at 418C by 19 mV. In contrast, R362 in its resting state has no effect on 418C. This suggests that, during activation of the channel, R362 moves from a position far away (>20 Å) to a position close (8 Å) to 418C. Despite its close approach to E418, a residue shown to be important in slow inactivation, R362 has no effect on slow inactivation or the recovery from slow inactivation. This refutes previous models for slow inactivation with an electrostatic S4-to-gate coupling. Instead, we propose a model with an allosteric mechanism for the S4-to-gate coupling.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Elinder

Männikkö

Larsson

2001

The Journal of General Physiology

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“…This is the main evidence for the existence of outward movement of the S4 of potassium channels. 49,[57][58][59][60][61] The rest of the transmembrane domains seem to remain mostly static as the S4 moves, providing a physical and electrostatic scaffold. 62,63 Given that the rest of the VSD remains static, as the charged residues in S4 move, they traverse its central portion, which contains an aromatic residue that has been dubbed the charge transfer center.…”

Section: Molecular Mechanism Of Voltage Sensingmentioning

confidence: 99%

Functional diversity of potassium channel voltage-sensing domains

Islas¹

2016

Channels

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Voltage-gated potassium channels or Kv's are membrane proteins with fundamental physiological roles. They are composed of 2 main functional protein domains, the pore domain, which regulates ion permeation, and the voltage-sensing domain, which is in charge of sensing voltage and undergoing a conformational change that is later transduced into pore opening. The voltagesensing domain or VSD is a highly conserved structural motif found in all voltage-gated ion channels and can also exist as an independent feature, giving rise to voltage sensitive enzymes and also sustaining proton fluxes in proton-permeable channels. In spite of the structural conservation of VSDs in potassium channels, there are several differences in the details of VSD function found across variants of Kvs. These differences are mainly reflected in variations in the electrostatic energy needed to open different potassium channels. In turn, the differences in detailed VSD functioning among voltage-gated potassium channels might have physiological consequences that have not been explored and which might reflect evolutionary adaptations to the different roles played by Kv channels in cell physiology.

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“…Of the four segments, S4 plays a pivotal role. When the membrane is depolarized, it moves out of the membrane, thereby carrying its charged residues (arginine and lysine), known as gating charges, across the membrane electric field (11)(12)(13)(14)(15)(16)(17). It is this movement that appears to trigger the opening of the activation gates.…”

mentioning

confidence: 99%

“…We focused our attention on this residue because it occupies a critical position in the channel. It is located within the bilayer yet close to the extracellular boundary (11,12,14,15). This means that when S4 moves out this residue is expected to sever all interactions with the neighboring membrane embedded segments.…”

mentioning

confidence: 99%

Depolarization Induces Intersubunit Cross-linking in a S4 Cysteine Mutant of the Shaker Potassium Channel

Aziz¹,

Partridge²,

Munsey

et al. 2002

Journal of Biological Chemistry

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Voltage-gated potassium (K v ) channels are integral membrane proteins, composed of four subunits, each comprising six (S1-S6) transmembrane segments. S1-S4 comprise the voltage-sensing domain, and S5-S6 with the linker P-loop forms the ion conducting pore domain. During activation, S4 undergoes structural rearrangements that lead to the opening of the channel pore and ion conduction. To obtain details of these structural changes we have used the engineered disulfide bridge approach. For this we have introduced the L361C mutation at the extracellular end of S4 of the Shaker K channel and expressed the mutant channel in Xenopus oocytes. When exposed to mild oxidizing conditions (ambient oxygen or copper phenanthroline), Cys-361 formed an intersubunit disulfide bridge as revealed by the appearance of a dimeric band on Western blotting. As a consequence, the mutant channel suffered a significant loss in conductance (measured by two-electrode voltage clamp). Removal of native cysteines failed to prevent the disulfide formation, indicating that Cys-361 forms a disulfide with its counterpart in the neighboring subunit. The effect was voltage-dependent and occurred during channel activation after Cys-361 has been exposed to the extracellular phase. Although the disulfide bridge reduced the maximal conductance, it caused a hyperpolarizing shift in the conductance-voltage relationship and reduced the deactivation kinetics of the channel. The latter two effects suggest stabilization of the open state of the channel. In conclusion, we report that during activation the intersubunit distance between the N-terminal ends of the S4 segments of the L361C mutant Shaker K channel is reduced.

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Three Transmembrane Conformations and Sequence-Dependent Displacement of the S4 Domain in Shaker K + Channel Gating

Cited by 168 publications

References 37 publications

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Functional diversity of potassium channel voltage-sensing domains

Depolarization Induces Intersubunit Cross-linking in a S4 Cysteine Mutant of the Shaker Potassium Channel

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