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Atomic basis for therapeutic activation of neuronal potassium channels.

Kim RY, Yau MC, Galpin JD, Seebohm G, Ahern CA, Pless SA, Kurata HT - Nat Commun (2015)

Bottom Line: Introduction of a non-natural isosteric H-bond-deficient Trp analogue abolishes channel potentiation, indicating that retigabine effects rely strongly on formation of a H-bond with the conserved pore Trp.In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators.These findings functionally pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3.

ABSTRACT
Retigabine is a recently approved anticonvulsant that acts by potentiating neuronal M-current generated by KCNQ2-5 channels, interacting with a conserved Trp residue in the channel pore domain. Using unnatural amino-acid mutagenesis, we subtly altered the properties of this Trp to reveal specific chemical interactions required for retigabine action. Introduction of a non-natural isosteric H-bond-deficient Trp analogue abolishes channel potentiation, indicating that retigabine effects rely strongly on formation of a H-bond with the conserved pore Trp. Supporting this model, substitution with fluorinated Trp analogues, with increased H-bonding propensity, strengthens retigabine potency. In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators. These findings functionally pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators.

No MeSH data available.


ML-213 exhibits a stronger electrostatic surface potential and higher potency than retigabine for KCNQ3* activation.(a,b) Chemical structures and electrostatic surface potentials for retigabine and ML-213. Note the increased negative surface potential in the vicinity of the carbonyl oxygen atom in ML-213. The scale for electrostatic surface potential representation is red: −80 kcal, yellow: 0 kcal, blue: +80 kcal. (c) Concentration–response curves for retigabine and ML-213 (n=5) effects on KCNQ3* channels (n=5). Error bars represent s.e.m.
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f6: ML-213 exhibits a stronger electrostatic surface potential and higher potency than retigabine for KCNQ3* activation.(a,b) Chemical structures and electrostatic surface potentials for retigabine and ML-213. Note the increased negative surface potential in the vicinity of the carbonyl oxygen atom in ML-213. The scale for electrostatic surface potential representation is red: −80 kcal, yellow: 0 kcal, blue: +80 kcal. (c) Concentration–response curves for retigabine and ML-213 (n=5) effects on KCNQ3* channels (n=5). Error bars represent s.e.m.

Mentions: We further investigated the mechanism of H-bonding with Trp265 by seeking potential H-bond acceptors in the retigabine molecule, a task facilitated by the availability of numerous retigabine analogues. We first considered the analogue ML-213 because it has a simplified chemical scaffold compared with retigabine and a reduced number of possible H-bond acceptors (Fig. 6a,b). We found that ML-213 is a more potent activator of KCNQ3* compared with retigabine (EC50=3.6±0.2 μM, n=5, versus 11.6±0.4 μM, n=5, respectively, Fig. 6c, ± indicates s.e.). We have also included the calculated electrostatic surface potentials for retigabine and ML-213, illustrating that the negative surface potential around the carbonyl oxygen is more pronounced for ML-213 (red protrusion, Fig. 6a,b).


Atomic basis for therapeutic activation of neuronal potassium channels.

Kim RY, Yau MC, Galpin JD, Seebohm G, Ahern CA, Pless SA, Kurata HT - Nat Commun (2015)

ML-213 exhibits a stronger electrostatic surface potential and higher potency than retigabine for KCNQ3* activation.(a,b) Chemical structures and electrostatic surface potentials for retigabine and ML-213. Note the increased negative surface potential in the vicinity of the carbonyl oxygen atom in ML-213. The scale for electrostatic surface potential representation is red: −80 kcal, yellow: 0 kcal, blue: +80 kcal. (c) Concentration–response curves for retigabine and ML-213 (n=5) effects on KCNQ3* channels (n=5). Error bars represent s.e.m.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561856&req=5

f6: ML-213 exhibits a stronger electrostatic surface potential and higher potency than retigabine for KCNQ3* activation.(a,b) Chemical structures and electrostatic surface potentials for retigabine and ML-213. Note the increased negative surface potential in the vicinity of the carbonyl oxygen atom in ML-213. The scale for electrostatic surface potential representation is red: −80 kcal, yellow: 0 kcal, blue: +80 kcal. (c) Concentration–response curves for retigabine and ML-213 (n=5) effects on KCNQ3* channels (n=5). Error bars represent s.e.m.
Mentions: We further investigated the mechanism of H-bonding with Trp265 by seeking potential H-bond acceptors in the retigabine molecule, a task facilitated by the availability of numerous retigabine analogues. We first considered the analogue ML-213 because it has a simplified chemical scaffold compared with retigabine and a reduced number of possible H-bond acceptors (Fig. 6a,b). We found that ML-213 is a more potent activator of KCNQ3* compared with retigabine (EC50=3.6±0.2 μM, n=5, versus 11.6±0.4 μM, n=5, respectively, Fig. 6c, ± indicates s.e.). We have also included the calculated electrostatic surface potentials for retigabine and ML-213, illustrating that the negative surface potential around the carbonyl oxygen is more pronounced for ML-213 (red protrusion, Fig. 6a,b).

Bottom Line: Introduction of a non-natural isosteric H-bond-deficient Trp analogue abolishes channel potentiation, indicating that retigabine effects rely strongly on formation of a H-bond with the conserved pore Trp.In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators.These findings functionally pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3.

ABSTRACT
Retigabine is a recently approved anticonvulsant that acts by potentiating neuronal M-current generated by KCNQ2-5 channels, interacting with a conserved Trp residue in the channel pore domain. Using unnatural amino-acid mutagenesis, we subtly altered the properties of this Trp to reveal specific chemical interactions required for retigabine action. Introduction of a non-natural isosteric H-bond-deficient Trp analogue abolishes channel potentiation, indicating that retigabine effects rely strongly on formation of a H-bond with the conserved pore Trp. Supporting this model, substitution with fluorinated Trp analogues, with increased H-bonding propensity, strengthens retigabine potency. In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators. These findings functionally pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators.

No MeSH data available.