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bioRxiv · 10.1101/2020.07.03.173997

Mutational analysis to explore long-range allosteric coupling and decoupling in a pentameric channel receptor

Lefebvre, S. N.·Taly, A.·Menny, A.·Medjebeur, K.·Corringer, P.-J.
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Abstract

Pentameric ligand-gated ion channels (pLGICs) mediate chemical signaling through a succession of allosteric transitions that are yet not completely understood. On the prototypic bacterial channel GLIC, we explored the conformational landscape of the protein during pH-gating. To this aim, we introduced a series of allosteric mutations, and characterized the protein conformation over a broad pH range. We combined electrophysiological recordings, fluorescence quenching experiments monitoring key quaternary reorganizations, and simulations by normal mode analysis. Moderate loss-of-function mutations and the allosteric modulator propofol displace allosteric equilibria involved in pre-activation and pore opening processes, highlighting long-range allosteric coupling between distant regions of the protein. In contrast, total loss-of-function mutations stabilize the protein in unique intermediate conformations where motions are decoupled. Altogether, our data show that the protein can access a wide conformational landscape, raising the possibility of multiple conformational pathways during gating.Competing Interest StatementThe authors have declared no competing interest.View Full Text

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Lefebvre, S. N., Taly, A., Menny, A., Medjebeur, K., Corringer, P.-J.. 2020-07-04. Mutational analysis to explore long-range allosteric coupling and decoupling in a pentameric channel receptor. https://doi.org/10.1101/2020.07.03.173997

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