Conformational Plasticity in the KcsA Potassium Channel Pore Helix Revealed by Homo-FRET Studies

Overview

Journal Sci Rep

Specialty Science

Date 2019 Apr 19

PMID 30996281

Citations 12

Authors

M Lourdes Renart

A Marcela Giudici

Jose A Poveda

Aleksander Fedorov

Mario N Berberan-Santos

Manuel Prieto

Clara Diaz-Garcia

Jose M Gonzalez-Ros

Ana Coutinho

Affiliations

Soon will be listed here.

Abstract

Potassium channels selectivity filter (SF) conformation is modulated by several factors, including ion-protein and protein-protein interactions. Here, we investigate the SF dynamics of a single Trp mutant of the potassium channel KcsA (W67) using polarized time-resolved fluorescence measurements. For the first time, an analytical framework is reported to analyze the homo-Förster resonance energy transfer (homo-FRET) within a symmetric tetrameric protein with a square geometry. We found that in the closed state (pH 7), the W67-W67 intersubunit distances become shorter as the average ion occupancy of the SF increases according to cation type and concentration. The hypothesis that the inactivated SF at pH 4 is structurally similar to its collapsed state, detected at low K, pH 7, was ruled out, emphasizing the critical role played by the S2 binding site in the inactivation process of KcsA. This homo-FRET approach provides complementary information to X-ray crystallography in which the protein conformational dynamics is usually compromised.

Citing Articles

pH-induced conformational changes in the selectivity filter of a potassium channel lead to alterations in its selectivity and permeation properties.

Coll-Diez C, Giudici A, Potenza A, Gonzalez-Ros J, Poveda J Front Pharmacol. 2025; 15():1499383.

PMID: 39834826 PMC: 11743430. DOI: 10.3389/fphar.2024.1499383.

Conformational Dynamic Studies of Prokaryotic Potassium Channels Explored by Homo-FRET Methodologies.

Coutinho A, Poveda J, Renart M Methods Mol Biol. 2024; 2796:35-72.

PMID: 38856894 DOI: 10.1007/978-1-0716-3818-7_3.

Anionic Phospholipids Shift the Conformational Equilibrium of the Selectivity Filter in the KcsA Channel to the Conductive Conformation: Predicted Consequences on Inactivation.

Renart M, Giudici A, Coll-Diez C, Gonzalez-Ros J, Poveda J Biomedicines. 2023; 11(5).

PMID: 37239046 PMC: 10216125. DOI: 10.3390/biomedicines11051376.

Molecular rearrangements in S6 during slow inactivation in Shaker-IR potassium channels.

Szanto T, Papp F, Zakany F, Varga Z, Deutsch C, Panyi G J Gen Physiol. 2023; 155(7).

PMID: 37212728 PMC: 10202832. DOI: 10.1085/jgp.202313352.

Silica/Proteoliposomal Nanocomposite as a Potential Platform for Ion Channel Studies.

Esquembre R, Renart M, Poveda J, Mateo C Molecules. 2022; 27(19).

PMID: 36235195 PMC: 9571612. DOI: 10.3390/molecules27196658.

References

Kratochvil H, Carr J, Matulef K, Annen A, Li H, Maj M . Instantaneous ion configurations in the K+ ion channel selectivity filter revealed by 2D IR spectroscopy. Science. 2016; 353(6303):1040-1044. PMC: 5544905. DOI: 10.1126/science.aag1447. View

Devaraneni P, Komarov A, Costantino C, Devereaux J, Matulef K, Valiyaveetil F . Semisynthetic K+ channels show that the constricted conformation of the selectivity filter is not the C-type inactivated state. Proc Natl Acad Sci U S A. 2013; 110(39):15698-703. PMC: 3785774. DOI: 10.1073/pnas.1308699110. View

Thaler C, Koushik S, Puhl 3rd H, Blank P, Vogel S . Structural rearrangement of CaMKIIalpha catalytic domains encodes activation. Proc Natl Acad Sci U S A. 2009; 106(15):6369-74. PMC: 2669344. DOI: 10.1073/pnas.0901913106. View

Liu S, Focke P, Matulef K, Bian X, Moenne-Loccoz P, Valiyaveetil F . Ion-binding properties of a K+ channel selectivity filter in different conformations. Proc Natl Acad Sci U S A. 2015; 112(49):15096-100. PMC: 4679001. DOI: 10.1073/pnas.1510526112. View

Cuello L, Jogini V, Cortes D, Perozo E . Structural mechanism of C-type inactivation in K(+) channels. Nature. 2010; 466(7303):203-8. PMC: 3033749. DOI: 10.1038/nature09153. View

Valeur B, Weber G . Resolution of the fluorescence excitation spectrum of indole into the 1La and 1Lb excitation bands. Photochem Photobiol. 1977; 25(5):441-4. DOI: 10.1111/j.1751-1097.1977.tb09168.x. View

Cordero-Morales J, Cuello L, Perozo E . Voltage-dependent gating at the KcsA selectivity filter. Nat Struct Mol Biol. 2006; 13(4):319-22. DOI: 10.1038/nsmb1070. View

Shealy R, Murphy A, Ramarathnam R, Jakobsson E, Subramaniam S . Sequence-function analysis of the K+-selective family of ion channels using a comprehensive alignment and the KcsA channel structure. Biophys J. 2003; 84(5):2929-42. PMC: 1302856. DOI: 10.1016/S0006-3495(03)70020-4. View

Cheng W, McCoy J, Thompson A, Nichols C, Nimigean C . Mechanism for selectivity-inactivation coupling in KcsA potassium channels. Proc Natl Acad Sci U S A. 2011; 108(13):5272-7. PMC: 3069191. DOI: 10.1073/pnas.1014186108. View

10.

Zhou Y, Kaufman A, Mackinnon R . Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution. Nature. 2001; 414(6859):43-8. DOI: 10.1038/35102009. View

11.

Yohannan S, Hu Y, Zhou Y . Crystallographic study of the tetrabutylammonium block to the KcsA K+ channel. J Mol Biol. 2007; 366(3):806-14. DOI: 10.1016/j.jmb.2006.11.081. View

12.

Cordero-Morales J, Jogini V, Chakrapani S, Perozo E . A multipoint hydrogen-bond network underlying KcsA C-type inactivation. Biophys J. 2011; 100(10):2387-93. PMC: 3093550. DOI: 10.1016/j.bpj.2011.01.073. View

13.

Renart M, Triano I, Poveda J, Encinar J, Fernandez A, Ferrer-Montiel A . Ion binding to KcsA: implications in ion selectivity and channel gating. Biochemistry. 2010; 49(44):9480-7. DOI: 10.1021/bi101235v. View

14.

Renart M, Montoya E, Fernandez A, Molina M, Poveda J, Encinar J . Contribution of ion binding affinity to ion selectivity and permeation in KcsA, a model potassium channel. Biochemistry. 2012; 51(18):3891-900. DOI: 10.1021/bi201497n. View

15.

Li J, Ostmeyer J, Boulanger E, Rui H, Perozo E, Roux B . Chemical substitutions in the selectivity filter of potassium channels do not rule out constricted-like conformations for C-type inactivation. Proc Natl Acad Sci U S A. 2017; 114(42):11145-11150. PMC: 5651753. DOI: 10.1073/pnas.1706983114. View

16.

Giudici A, Molina M, Ayala J, Montoya E, Renart M, Fernandez A . Detergent-labile, supramolecular assemblies of KcsA: relative abundance and interactions involved. Biochim Biophys Acta. 2012; 1828(2):193-200. DOI: 10.1016/j.bbamem.2012.09.020. View

17.

Chan F, Kaminski C, Kaminski Schierle G . HomoFRET fluorescence anisotropy imaging as a tool to study molecular self-assembly in live cells. Chemphyschem. 2011; 12(3):500-9. DOI: 10.1002/cphc.201000833. View

18.

Ogielska E, Aldrich R . Functional consequences of a decreased potassium affinity in a potassium channel pore. Ion interactions and C-type inactivation. J Gen Physiol. 1999; 113(2):347-58. PMC: 2223370. DOI: 10.1085/jgp.113.2.347. View

19.

Cordero-Morales J, Cuello L, Zhao Y, Jogini V, Cortes D, Roux B . Molecular determinants of gating at the potassium-channel selectivity filter. Nat Struct Mol Biol. 2006; 13(4):311-8. DOI: 10.1038/nsmb1069. View

20.

Zhou Y, MacKinnon R . The occupancy of ions in the K+ selectivity filter: charge balance and coupling of ion binding to a protein conformational change underlie high conduction rates. J Mol Biol. 2003; 333(5):965-75. DOI: 10.1016/j.jmb.2003.09.022. View