scholarly journals Position and motions of the S4 helix during opening of the Shaker potassium channel

2010 ◽  
Vol 136 (6) ◽  
pp. 629-644 ◽  
Author(s):  
L. Revell Phillips ◽  
Kenton J. Swartz
Keyword(s):  
Potassium Channel ◽  
Open Channels ◽  
Shaker Potassium Channel ◽  
Voltage Sensors ◽  
Voltage Gated ◽  
Kv Channels ◽  
Close Proximity ◽  
Pore Domain ◽  
Significant Distance ◽  
Average Position

The four voltage sensors in voltage-gated potassium (Kv) channels activate upon membrane depolarization and open the pore. The location and motion of the voltage-sensing S4 helix during the early activation steps and the final opening transition are unresolved. We studied Zn2+ bridges between two introduced His residues in Shaker Kv channels: one in the R1 position at the outer end of the S4 helix (R362H), and another in the S5 helix of the pore domain (A419H or F416H). Zn2+ bridges readily form between R362H and A419H in open channels after the S4 helix has undergone its final motion. In contrast, a distinct bridge forms between R362H and F416H after early S4 activation, but before the final S4 motion. Both bridges form rapidly, providing constraints on the average position of S4 relative to the pore. These results demonstrate that the outer ends of S4 and S5 remain in close proximity during the final opening transition, with the S4 helix translating a significant distance normal to the membrane plane.

Structural model of a voltage-gated potassium channel based on spectroscopic data

2001 ◽  
Vol 29 (4) ◽  
pp. 589-593 ◽  
Author(s):  
P. I. Haris
Keyword(s):  
Potassium Channel ◽  
Structural Model ◽  
Structural Data ◽  
Theoretical Models ◽  
Shaker Potassium Channel ◽  
Voltage Gated ◽  
Folded Structure ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Pore Domain

It is estimated that membrane proteins comprise as much as 30% of most genomes. Yet our knowledge of membrane-protein folding is still in its infancy. Consequently, there is a great need for developing approaches that can further advance our understanding of how peptides and proteins interact with membranes and thereby attain their folded structure. An approach that we have been exploring involves dissecting voltage-gated ion channels into simple peptide domains for the purpose of determining their structure in different media using physical techniques. We have synthesized peptides corresponding to the six membrane-spanning segments, as well as the pore domain, of the Shaker channel and characterized their secondary structures. From these studies we have developed a model for the transmembrane structure of the Shaker potassium channel that is constructed from α-helices. The hard structural data obtained from these studies lends support to the recent theoretical models of this channel protein that have been developed by others.

scholarly journals Dynamics of Pore Domain Affected by Single Mutations in S4 Segment of Shaker Potassium Channel

2019 ◽  
Vol 116 (3) ◽  
pp. 101a
Author(s):  
Carlos Alberto ◽  
Z. Bassetto Jr ◽  
Joao Luis Carvalho-de-Souza ◽  
Francisco Bezanilla
Keyword(s):  
Potassium Channel ◽  
Shaker Potassium Channel ◽  
Pore Domain ◽  
S4 Segment

Genetic mapping of the voltage-gated shaker potassium channel beta subunit Kcnab1 to mouse Chromosome 3

1998 ◽  
Vol 9 (3) ◽  
pp. 260-260 ◽  
Author(s):  
J. M. Jones ◽  
E. Bentley ◽  
M. H. Meisler ◽  
Susan M. Darling
Keyword(s):  
Genetic Mapping ◽  
Potassium Channel ◽  
Mouse Chromosome ◽  
Beta Subunit ◽  
Chromosome 3 ◽  
Shaker Potassium Channel ◽  
Voltage Gated

Voltage clamp fluorimetry studies of mammalian voltage-gated K+ channel gating

2007 ◽  
Vol 35 (5) ◽  
pp. 1080-1082 ◽  
Author(s):  
T.W. Claydon ◽  
D. Fedida
Keyword(s):  
Ion Channel ◽  
Potassium Channel ◽  
Real Time ◽  
Voltage Clamp ◽  
Conformational Changes ◽  
Channel Gating ◽  
K Channel ◽  
Voltage Gated ◽  
Kv Channels ◽  
Health And Disease

VCF (voltage clamp fluorimetry) provides a powerful technique to observe real-time conformational changes that are associated with ion channel gating. The present review highlights the insights such experiments have provided in understanding Kv (voltage-gated potassium) channel gating, with particular emphasis on the study of mammalian Kv1 channels. Further applications of VCF that would contribute to our understanding of the modulation of Kv channels in health and disease are also discussed.

scholarly journals Insights into the molecular mechanism for hyperpolarization-dependent activation of HCN channels

2018 ◽  
Vol 115 (34) ◽  
pp. E8086-E8095 ◽  
Author(s):  
Galen E. Flynn ◽  
William N. Zagotta
Keyword(s):  
Ion Channels ◽  
Cyclic Nucleotide ◽  
Electromechanical Coupling ◽  
Canonical Model ◽  
Hcn Channels ◽  
Voltage Gated ◽  
Kv Channels ◽  
Recovery From Inactivation ◽  
Voltage Dependent ◽  
Pore Domain

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels are both voltage- and ligand-activated membrane proteins that contribute to electrical excitability and pace-making activity in cardiac and neuronal cells. These channels are members of the voltage-gated Kv channel superfamily and cyclic nucleotide-binding domain subfamily of ion channels. HCN channels have a unique feature that distinguishes them from other voltage-gated channels: the HCN channel pore opens in response to hyperpolarizing voltages instead of depolarizing voltages. In the canonical model of electromechanical coupling, based on Kv channels, a change in membrane voltage activates the voltage-sensing domains (VSD) and the activation energy passes to the pore domain (PD) through a covalent linker that connects the VSD to the PD. In this investigation, the covalent linkage between the VSD and PD, the S4-S5 linker, and nearby regions of spHCN channels were mutated to determine the functional role each plays in hyperpolarization-dependent activation. The results show that: (i) the S4-S5 linker is not required for hyperpolarization-dependent activation or ligand-dependent gating; (ii) the S4 C-terminal region (S4C-term) is not necessary for ligand-dependent gating but is required for hyperpolarization-dependent activation and acts like an autoinhibitory domain on the PD; (iii) the S5N-term region is involved in VSD–PD coupling and holding the pore closed; and (iv) spHCN channels have two voltage-dependent processes, a hyperpolarization-dependent activation and a depolarization-dependent recovery from inactivation. These results are inconsistent with the canonical model of VSD–PD coupling in Kv channels and elucidate the mechanism for hyperpolarization-dependent activation of HCN channels.

scholarly journals Can Shaker Potassium Channels be Locked in the Deactivated State?

2004 ◽  
Vol 124 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Youshan Yang ◽  
Yangyang Yan ◽  
Fred J. Sigworth
Keyword(s):  
Xenopus Oocytes ◽  
Voltage Dependence ◽  
Voltage Sensor ◽  
Structural Studies ◽  
Gating Currents ◽  
Shaker Potassium Channel ◽  
Voltage Sensors ◽  
Voltage Gated ◽  
Gated Channel ◽  
Shaker Potassium Channels

For structural studies it would be useful to constrain the voltage sensor of a voltage-gated channel in its deactivated state. Here we consider one Shaker potassium channel mutant and speculate about others that might allow the channel to remain deactivated at zero membrane potential. Ionic and gating currents of F370C Shaker, expressed in Xenopus oocytes, were recorded in patches with internal application of the methanethiosulfonate reagent MTSET. It appears that the voltage dependence of voltage sensor movement is strongly shifted by reaction with internal MTSET, such that the voltage sensors appear to remain deactivated even at positive potentials. A disadvantage of this construct is that the rate of modification of voltage sensors by MTSET is quite low, ∼0.17 mM−1·s−1 at −80 mV, and is expected to be much lower at depolarized potentials.

scholarly journals The S4 Voltage Sensor Packs Against the Pore Domain in the KAT1 Voltage-Gated Potassium Channel

Neuron ◽  
2005 ◽  
Vol 47 (3) ◽  
pp. 395-406 ◽  
Author(s):  
Helen C. Lai ◽  
Michael Grabe ◽  
Yuh Nung Jan ◽  
Lily Yeh Jan
Keyword(s):  
Potassium Channel ◽  
Voltage Sensor ◽  
Voltage Gated ◽  
Pore Domain

scholarly journals The trajectory of discrete gating charges in a voltage-gated potassium channel

2020 ◽  
Author(s):  
Michael F. Priest ◽  
Elizabeth E.L. Lee ◽  
Francisco Bezanilla
Keyword(s):  
Potassium Channel ◽  
Voltage Sensor ◽  
Drive Voltage ◽  
Shaker Potassium Channel ◽  
Voltage Gated ◽  
Charged Amino Acids ◽  
Voltage Gated Ion Channels ◽  
Sensing Membrane ◽  
Positively Charged ◽  
Gating Charges

AbstractPositively-charged amino acids respond to membrane potential changes to drive voltage sensor movement in voltage-gated ion channels, but determining the trajectory of voltage sensor gating charges has proven difficult. We optically tracked the movement of the two most extracellular charged residues (R1, R2) in the Shaker potassium channel voltage sensor using a fluorescent positively-charged bimane derivative (qBBr) that is strongly quenched by tryptophan. By individually mutating residues to tryptophan within the putative trajectory of gating charges, we observed that the charge pathway during activation is a rotation and a tilted translation that differs between R1 and R2 and is distinct from their deactivation pathway. Tryptophan-induced quenching of qBBr also indicates that a crucial residue of the hydrophobic plug is linked to the Cole-Moore shift through its interaction with R1. Finally, we show that this approach extends to additional voltage-sensing membrane proteins using the Ciona intestinalis voltage sensitive phosphatase (CiVSP).

scholarly journals Tracking the movement of discrete gating charges in a voltage-gated potassium channel

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Michael F Priest ◽  
Elizabeth EL Lee ◽  
Francisco Bezanilla
Keyword(s):  
Potassium Channel ◽  
Voltage Sensor ◽  
Charge Motion ◽  
Shaker Potassium Channel ◽  
Voltage Gated ◽  
Charged Amino Acids ◽  
Voltage Gated Ion Channels ◽  
Sensing Membrane ◽  
Positively Charged ◽  
Gating Charges

Positively-charged amino acids respond to membrane potential changes to drive voltage sensor movement in voltage-gated ion channels, but determining the displacements of voltage sensor gating charges has proven difficult. We optically tracked the movement of the two most extracellular charged residues (R1, R2) in the Shaker potassium channel voltage sensor using a fluorescent positively-charged bimane derivative (qBBr) that is strongly quenched by tryptophan. By individually mutating residues to tryptophan within the putative pathway of gating charges, we observed that the charge motion during activation is a rotation and a tilted translation that differs between R1 and R2. Tryptophan-induced quenching of qBBr also indicates that a crucial residue of the hydrophobic plug is linked to the Cole-Moore shift through its interaction with R1. Finally, we show that this approach extends to additional voltage-sensing membrane proteins using the Ciona intestinalis voltage sensitive phosphatase (CiVSP) (Murata et al., 2005a).

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