Multiple residues specify external tetraethylammonium blockade in voltage-gated potassium channels

Pascual, Juan M.; Shieh, Char‐Chang; Kirsch, Glenn E.; Brown, Arthur M.

doi:10.1016/s0006-3495(95)79915-5

Cited by 38 publications

(35 citation statements)

References 19 publications

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“…Indeed, a similar interaction with a bacterial channel has been modeled with molecular dynamics (Crouzy et al, 2001;Guidoni and Carloni, 2002;Luzhkov et al, 2003) and studied by crystallization with TEA analogs (Lenaeus et al, 2005). However, site-directed mutagenesis and chemical modification results have called this model into question for Kv2.1: although the tyrosine side chain clearly has a role in external TEA block, it may not cage or bind TEA stably or directly in mammalian Kv2.1 channels (Pascual et al, 1995;Andalib et al, 2004). The uncertainty in the mechanism of the TEA block of Kv2.1 makes interpretation of the competition between TEA and 48F10, but not catechol and many derivatives, difficult to interpret in structural terms.…”

Section: Discussionmentioning

confidence: 99%

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Salvador-Recatalà¹,

Kim²,

Zaks-Makhina³

et al. 2006

J Pharmacol Exp Ther

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High-throughput screening led to the identification of a 3-norbornyl derivative of catechol called 48F10 (3-bicyclo[2.2.1]hept-2-yl-benzene-1,2-diol) as a Kv2.1 K ϩ channel inhibitor. By virtue of the involvement of Kv2.1 channels in programmed cell death, 48F10 prevents apoptosis in cortical neurons and enterocytes. This uncharged compound acts with an apparent affinity of 1 M at the tetraethylammonium (TEA) site at the external mouth of the Kv2.1 channel but is ineffective on Kv1.5. Here we investigated the basis of this selectivity with structure-activity studies. We find that catechol (1,2-benzenediol), unlike 48F10, inhibits Kv2.1 currents with a Hill coefficient of 2 and slows channel activation. Furthermore, this inhibition, which requires millimolar concentrations, is unaffected by external TEA or by mutation of the external tyrosine implicated in channel block by TEA and 48F10. In addition, catechol does not distinguish between Kv2.1 and Kv1.5. Thus, catechol acts at conserved sites that are distinct from 48F10. We also tested 11 catechol derivatives based on hydrocarbon adducts including norbornyl substructures, a 48F10 isomer, and a 48F10 diastereomer. These compounds are more potent than catechol, but none replicated the marked selectivity of 48F10 for Kv2.1 over Kv1.5. We conclude that the targeting of 48F10 to the TEA site at the external mouth of the Kv2.1 pore and away from other sites involved in nonselective Kv channel block by catechol requires the norbornyl group in a unique position and orientation on the catechol ring.

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Section: Discussionmentioning

confidence: 99%

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Salvador-Recatalà¹,

Kim²,

Zaks-Makhina³

et al. 2006

J Pharmacol Exp Ther

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“…In dSlo this position is a tyrosine, Y308, and external TEA blocks dSlo channels with high affinity and weak voltage dependence, consistent with its interaction with Y308 on the outer mouth of the pore; in Y308V-substituted channels TEA blocks with an apparent affinity 100 times less than it does the wild-type channel [27]. However, in Shaker-like chan- nels several other residues also affect sensitivity to TEA [20,24]. Inhibition of current by increasing concentrations of external TEA was measured at different membrane potentials ( Fig.…”

Section: Y293w and F294w Dslo Channelsmentioning

confidence: 74%

Aromatic residues affecting permeation and gating in dSlo BK channels

Lagrutta

Shen

Rivard

et al. 1998

Pfl�gers Archiv European Journal of Physiology

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Structural determinants of permeation in large unit conductance calcium-activated potassium channels (BK channels) were investigated. Y293 and F294 in the P-region of dSlo were substituted by tryptophans. Compared to wild-type channels, Y293W channels displayed reduced inward unitary currents while F294W channels exhibited normal inward current amplitudes but flickery kinetics. Both mutations produced changes in current/voltage relations under bi-ionic conditions. Sensitivity to block by external tetraethylammonium (TEA) was affected in both channels, and the voltage dependence of TEA block was increased in F294W channels. Both mutations also affected gating by shifting the half-maximal activation voltage of macroscopic conductance/voltage relations to more positive potentials, and eliminating a slow component of deactivation. The double mutant did not produce ionic currents. These data are consistent with a model in which Y293 contributes to a potassium-binding site close to the outer mouth of the dSlo pore, while F294 contributes to an energy barrier near this site.

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“…[5] The binding of external TEA is critically affected by the presence of one residue present in each of the four subunits, which is located adjacent to the signature sequence within the selectivity filter (GYGD) of K + channels. Channels possessing an aromatic residue, such as a phenylalanine or a tyrosine, for example, Y379 in mKv1.1, [6] Y380 in Kv2.1, [7] Y82 in KcsA, [8] the T449Y mutant of Shaker, [9] or the V515F mutant of rSK3 [5d] are more sensitive to block by TEA. In recent years, an explosion in the number of crystal structures of ion channels, combined with the use of molecular modelling, has led to different assumptions about the type of interaction between TEA and these aromatic residues.…”

Section: Typical Pore Blockmentioning

confidence: 99%

Ion‐Channel Modulators: More Diversity Than Previously Thought

et al. 2011

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Ion-channel function can be modified in various ways. For example, numerous studies have shown that currents through voltage-gated ion channels are affected by pore block or modification of voltage dependence of activation/inactivation. Recent experiments performed on various ion channels show that allosteric modulation is an important mechanism for affecting channel function. For instance, in K(Ca)2 (formerly SK) channels, the prototypic "blocker" apamin prevents conduction by an allosteric mechanism, while TRPV1 channels are prevented from closing by a tarantula toxin, DkTx, through an interaction with residues located away from the selectivity filter. The recent evidence, therefore, suggests that in several ion channels, the region around the outer mouth of the pore is rich in binding sites and could be exploited therapeutically. These discoveries also suggest that the pharmacological vocabulary should be adapted to define these various actions.

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Multiple residues specify external tetraethylammonium blockade in voltage-gated potassium channels

Cited by 38 publications

References 19 publications

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Aromatic residues affecting permeation and gating in dSlo BK channels

Ion‐Channel Modulators: More Diversity Than Previously Thought

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Multiple residues specify external tetraethylammonium blockade in voltage-gated potassium channels

Cited by 38 publications

References 19 publications

Voltage-Gated K+ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K+ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Aromatic residues affecting permeation and gating in dSlo BK channels

Ion‐Channel Modulators: More Diversity Than Previously Thought

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Product

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Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores

Voltage-Gated K⁺ Channel Block by Catechol Derivatives: Defining Nonselective and Selective Pharmacophores