Due to the lack of genetically encoded probes for fluorine-19 nuclear magnetic resonance spectroscopy ( 19 F NMR), its utility for probing eukaryotic membrane protein dynamics is limited. Here we report an efficient method for the genetic incorporation of an unnatural amino acid (UAA), 3'-trifluoromenthyl-phenylalanine (mtfF), into cannabinoid receptor 1 (CB1) in the Baculovirus Expression System ...
Due to the lack of genetically encoded probes for fluorine-19 nuclear magnetic resonance spectroscopy ( 19 F NMR), its utility for probing eukaryotic membrane protein dynamics is limited. Here we report an efficient method for the genetic incorporation of an unnatural amino acid (UAA), 3'-trifluoromenthyl-phenylalanine (mtfF), into cannabinoid receptor 1 (CB1) in the Baculovirus Expression System. The probe can be inserted at any environmentally sensitive site, while causing minimal structural perturbation to the target protein. Using 19 F NMR and X-ray crystallography methods, we discovered that the allosteric modulator Org27569 and agonists synergistically stabilize a previously unrecognized pre-active state. An allosteric modulation model is proposed to explain Org27569's distinct behavior. We demonstrate that our site-specific 19 F NMR labeling method is a powerful tool in decoding the mechanism of GPCR allosteric modulation. This new method should be broadly applicable for uncovering conformational states for many important eukaryotic membrane proteins.
Organizational Affiliation:
Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China.
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