Optocontrol of glutamate receptor activity by single side-chain photoisomerization

• Published in: eLife Vol. 6
• Main Authors: Klippenstein, Viktoria, Hoppmann, Christian, Ye, Shixin, Wang, Lei, Paoletti, Pierre
• Format: Journal Article
• Language: English
• Published: eLife Sciences Publication 23.05.2017
• Subjects: Cognitive science; Neuroscience; azobenzene; ion channel; glutamate receptor; neuroscience; optogenetics; structural biology; unnatural amino acid; none; biophysics; photoswitch
• ISSN: 2050-084X
• DOI: 10.7554/eLife.25808

Engineering light-sensitivity into proteins has wide ranging applications in molecular studies and neuroscience. Commonly used tethered photoswitchable ligands, however, require solvent-accessible protein labeling, face structural constrains, and are bulky. Here, we designed a set of optocontrollable NMDA receptors by directly incorporating single photoswitchable amino acids (PSAAs) providing genetic encodability, reversibility, and site tolerance. We identified several positions within the multi-domain receptor endowing robust photomodulation. PSAA photoisomerization at the GluN1 clamshell hinge is sufficient to control glycine sensitivity and activation efficacy. Strikingly, in the pore domain, flipping of a M3 residue within a conserved transmembrane cavity impacts both gating and permeation properties. Our study demonstrates the first detection of molecular rearrangements in real-time due to the reversible light-switching of single amino acid side-chains, adding a dynamic dimension to protein site-directed mutagenesis. This novel approach to interrogate neuronal protein function has general applicability in the fast expanding field of optopharmacology.