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Identification of an essential binding site for local anesthetics in the ‘side pockets´ of Kv1 channels
  • +11
  • Aytug Kiper,
  • Sarah Stalke,
  • Stefanie Marzian,
  • Mauricio BedoyaOrcid,
  • David Ramírez,
  • Alicia De la Cruz,
  • Diego Alberto Peraza,
  • José Márquez Montesinos,
  • Bárbara Arévalo Ramos,
  • Susanne Rinné,
  • Teresa Gonzalez,
  • Carmen Valenzuela,
  • Wendy Gonzalez,
  • Niels Decher
Aytug Kiper
University of Marburg, Germany
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Sarah Stalke
University of Marburg, Germany
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Stefanie Marzian
University of Marburg, Germany
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Mauricio Bedoya
Orcid
University of Talca
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David Ramírez
University of Chile
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Alicia De la Cruz
Instituto de Investigaciones Biomédicas Alberto Sols
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Diego Alberto Peraza
Instituto de Investigaciones Biomedicas
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José Márquez Montesinos
Instituto de Investigaciones Biomédicas Alberto Sols
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Bárbara Arévalo Ramos
University of Talca
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Susanne Rinné
University of Marburg, Germany
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Teresa Gonzalez
Instituto de Investigaciones Biomedicas
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Carmen Valenzuela
Instituto de Investigaciones Biomedicas
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Wendy Gonzalez
Universidad de Talca
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Niels Decher
University of Marburg, Germany
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Peer review status:IN REVISION

31 Mar 2020Submitted to British Journal of Pharmacology
01 Apr 2020Assigned to Editor
01 Apr 2020Submission Checks Completed
04 Apr 2020Reviewer(s) Assigned
11 May 2020Editorial Decision: Revise Minor

Abstract

Background and Purpose: Local anesthetics block sodium and a variety of potassium channels. Although previous studies identified a residue in the pore signature sequence together with three residues in the S6 segment as a putative binding site, the precise molecular basis of Kv potassium channel inhibition by local anesthetics remained unknown. Kv crystal structures predict that some of these residues point away from the central cavity and face into a drug binding site called ‘side pockets´. Thus, the question arises whether the binding site of local anesthetics is exclusively located in the central cavity or also involves the ‘side pockets´. Experimental Approach: A systematic functional alanine mutagenesis approach, scanning 58 mutants, in concert with in silico docking experiments and molecular dynamics simulations were utilized to elucidate the binding site of bupivacaine and ropivacaine. Key Results: Kv1.5 inhibition by local anesthetics requires binding to the central cavity and the ‘side pockets´, where the latter requires interactions with residues of the S5 and the backside of the S6 segment. Mutations in the ‘side pockets´ remove stereoselectivity of Kv1.5 inhibition by bupivacaine. Strikingly, while we found that binding to the ‘side pockets´ is conserved for the different local anesthetics, the binding mode in the central cavity and the ‘side pockets´ shows considerable variations. Conclusion and Implications: Local anesthetics bind to the central cavity and the ‘side pockets´ which provides a crucial key for the molecular understanding of their Kv channel affinity and stereoselectivity, as well as their spectrum of side effects.