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Modulation of the potassium channel KcsA by anionic phospholipids: Role of arginines at the non-annular lipid binding sites.

Authors
  • Poveda, José A1
  • Giudici, A Marcela1
  • Renart, M Lourdes1
  • Millet, Oscar2
  • Morales, Andrés3
  • González-Ros, José M4
  • Oakes, Victoria5
  • Furini, Simone6
  • Domene, Carmen7
  • 1 Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE) and Instituto de Biología Molecular y Celular (IBMC), Universidad Miguel Hernández, Elche, E-03202, Alicante, Spain. , (Spain)
  • 2 Structural Biology Unit, CICbioGUNE, Bizkaia Technology Park, Derio, 48160, Vizcaya, Spain. , (Spain)
  • 3 Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, E-03080 Alicante, Spain. , (Spain)
  • 4 Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE) and Instituto de Biología Molecular y Celular (IBMC), Universidad Miguel Hernández, Elche, E-03202, Alicante, Spain. Electronic address: [email protected] , (Spain)
  • 5 Department of Chemistry, University of Bath, 1 South Bldg., Claverton Down, Bath BA2 7AY, United Kingdom. , (United Kingdom)
  • 6 Department of Medical Biotechnologies, University of Siena, Siena, Italy. , (Italy)
  • 7 Department of Chemistry, University of Bath, 1 South Bldg., Claverton Down, Bath BA2 7AY, United Kingdom; Department of Chemistry, University of Oxford, Oxford OX1 3TA, Oxford, United Kingdom. Electronic address: [email protected] , (United Kingdom)
Type
Published Article
Journal
Biochimica et biophysica acta. Biomembranes
Publication Date
Oct 01, 2019
Volume
1861
Issue
10
Pages
183029–183029
Identifiers
DOI: 10.1016/j.bbamem.2019.183029
PMID: 31351058
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

The role of arginines R64 and R89 at non-annular lipid binding sites of KcsA, on the modulation of channel activity by anionic lipids has been investigated. In wild-type (WT) KcsA reconstituted into asolectin lipid membranes, addition of phosphatidic acid (PA) drastically reduces inactivation in macroscopic current recordings. Consistent to this, PA increases current amplitude, mean open time and open probability at the single channel level. Moreover, kinetic analysis reveals that addition of PA causes longer open channel lifetimes and decreased closing rate constants. Effects akin to those of PA on WT-KcsA are observed when R64 and/or R89 are mutated to alanine, regardless of the added anionic lipids. We interpret these results as a consequence of interactions between the arginines and the anionic PA bound to the non-annular sites. NMR data shows indeed that at least R64 is involved in binding PA. Moreover, molecular dynamics (MD) simulations predict that R64, R89 and surrounding residues such as T61, mediate persistent binding of PA to the non-annular sites. Channel inactivation depends on interactions within the inactivation triad (E71-D80-W67) behind the selectivity filter. Therefore, it is expected that such interactions are affected when PA binds the arginines at the non-annular sites. In support of this, MD simulations reveal that PA binding prevents interaction between R89 and D80, which seems critical to the effectiveness of the inactivation triad. This mechanism depends on the stability of the bound lipid, favoring anionic headgroups such as that of PA, which thrive on the positive charge of the arginines. Copyright © 2019. Published by Elsevier B.V.

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