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

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Title: Modulation of the potassium channel KcsA by anionic phospholipids: Role of arginines at the non-annular lipid binding sites
Authors: Poveda, José A. | Giudici, A. Marcela | Renart, M. Lourdes | Millet, Oscar | Morales, Andrés | González-Ros, José M. | Oakes, Victoria | Furini, Simone | Domene, Carmen
Research Group/s: Fisiología de Membranas
Center, Department or Service: Universidad de Alicante. Departamento de Fisiología, Genética y Microbiología
Keywords: Membrane lipid-protein interactions | Ion channel inactivation | Ion channel kinetics | Patch-clamp recordings | Molecular dynamics simulations
Knowledge Area: Fisiología
Issue Date: 1-Oct-2019
Publisher: Elsevier
Citation: Biochimica et Biophysica Acta (BBA) - Biomembranes. 2019, 1861(10): 183029. doi:10.1016/j.bbamem.2019.183029
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.
Sponsor: This work was partly supported by grants PGC2018-093505-B-100, BFU2012-31359 and BFU2015-66612-P from the Spanish MINECO/FEDER (UE), and by BBSRC and Pfizer (BB/L015269/1) through a studentship to V. Oakes.
URI: http://hdl.handle.net/10045/95450
ISSN: 0005-2736 (Print) | 1879-2642 (Online)
DOI: 10.1016/j.bbamem.2019.183029
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2019 Published by Elsevier B.V.
Peer Review: si
Publisher version: https://doi.org/10.1016/j.bbamem.2019.183029
Appears in Collections:INV - Fisiología de Membranas - Artículos de Revistas

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