Arachidonic acid effect on the allosteric gating mechanism of BK (Slo1) channels associated with the β1 subunit.

Pedro Martín, Melisa Moncada, Karen Castillo, Federico Orsi, Gerónimo Ducca, José Manuel Fernández-Fernández, Carlos González, Verónica Milesi

Journal: Biochimica et biophysica acta. Biomembranes 2021;1863(9):183550

PMID: 33417967

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Abstract

Arachidonic acid (AA) is a fatty acid involved in the modulation of several ion channels. Previously, we reported that AA activates the high conductance Ca- and voltage-dependent K channel (BK) in vascular smooth muscle depending on the expression of the auxiliary β1 subunit. Here, using the patch-clamp technique on BK channel co-expressed with β1 subunit in a heterologous cell expression system, we analyzed whether AA modifies the three functional modules involved in the channel gating: the voltage sensor domain (VSD), the pore domain (PD), and the intracellular calcium sensor domain (CSD). We present evidence that AA activates BK channel in a direct way, inducing VSD stabilization on its active configuration observed as a significant left shift in the Q-V curve obtained from gating currents recordings. Moreover, AA facilitates the channel opening transitions when VSD are at rest, and the CSD are unoccupied. Furthermore, the activation was independent of the intracellular Ca concentration and reduced when the BK channel was co-expressed with the Y74A mutant of the β1 subunit. These results allow us to present new insigths in the mechanism by which AA modulates BK channels co-expressed with its auxiliary β1 subunit.

Address: Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina. Electronic address: [email protected].; Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina. Electronic address: [email protected].; CINV: Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile. Electronic address: [email protected].; Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina. Electronic address: [email protected].; Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina. Electronic address: [email protected].; Laboratory of Molecular Physiology, Department of Experimental and Health Sciences, University Pompeu Fabra, 08003 Barcelona, Spain. Electronic address: [email protected].; CINV: Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile. Electronic address: [email protected].; Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina. Electronic address: [email protected].

DOI: 10.1016/j.bbamem.2021.183550

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MeSH Terms: Allosteric Regulation, Arachidonic Acid, HEK293 Cells, Humans, Large-Conductance Calcium-Activated Potassium Channel beta Subunits