ELECTRO-STERIC MECHANISM OF CLC-2 CHLORIDE CHANNEL ACTIVATION

De Jesus-Perez, J. J.; Mendez-Maldonado, G. A.; Gonzalez-Hernandez, I. L.; De la Rosa, V.; Gastelum-Garibaldi, R.; Sanchez-Rodriguez, J. E.; Arreola, J.

doi:10.1101/2020.06.12.148783

bioRxiv · 10.1101/2020.06.12.148783

ELECTRO-STERIC MECHANISM OF CLC-2 CHLORIDE CHANNEL ACTIVATION

De Jesus-Perez, J. J.·Mendez-Maldonado, G. A.·Gonzalez-Hernandez, I. L.·De la Rosa, V.·Gastelum-Garibaldi, R.·Sanchez-Rodriguez, J. E.·Arreola, J.

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Abstract

Two-pore voltage-gated CLC chloride channels control neuronal and muscle excitability. They share a dimeric structure but their activation mechanism remains unresolved. Here we determine the step-by-step activation mechanism of the broadly expressed CLC-2 channel using homology modelling, molecular dynamic simulations and functional studies. We establish that a two-leaf gate formed by Tyr561-H2O-Glu213 flanked by Lys568/Glu174 and Lys212 closes the canonical pore. Activation begins when a hyperpolarization-propelled intracellular chloride occupies the pore and splits Tyr561-H2O-Glu213 by electrostatic/steric repulsion. Unrestrained Glu213 rotates outwardly to bind Lys212 but the pore remains closed. Protonation breaks the Glu213-Lys212 interaction while another chloride occupies the pore thus catalysing chloride exit via Lys212. Also, we found that the canonical pore is uncoupled from a cytosolic cavity by a Tyr561-containing hydrophobic gate that prevents Glu213 protonation by intracellular protons. Our data provide atomistic details about CLC-2 activation but this mechanism might be common to other CLC channels.Competing Interest StatementThe authors have declared no competing interest.View Full Text

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De Jesus-Perez, J. J., Mendez-Maldonado, G. A., Gonzalez-Hernandez, I. L., De la Rosa, V., Gastelum-Garibaldi, R., Sanchez-Rodriguez, J. E., Arreola, J.. 2020-06-13. ELECTRO-STERIC MECHANISM OF CLC-2 CHLORIDE CHANNEL ACTIVATION. https://doi.org/10.1101/2020.06.12.148783

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