Expression, Functional Characterization, and Solid-State NMR Investigation of the G Protein-Coupled GHS Receptor in Bilayer Membranes

• Published in: Scientific reports 2017-04, Vol.7 (1), p.46128-46128, Article 46128
• Main Authors: Schrottke, Stefanie, Kaiser, Anette, Vortmeier, Gerrit, Els-Heindl, Sylvia, Worm, Dennis, Bosse, Mathias, Schmidt, Peter, Scheidt, Holger A., Beck-Sickinger, Annette G., Huster, Daniel
• Format: Article
• Language: English
• Subjects: 101/6; 631/535/878/1264; 631/57/2272/2276; 82; 82/80; Dimyristoylphosphatidylcholine - chemistry; E coli; Ghrelin; Ghrelin - metabolism; Growth hormones; Humanities and Social Sciences; Humans; Lipid Bilayers - chemistry; Magnetic Resonance Spectroscopy; Membranes; multidisciplinary; NMR; Nuclear magnetic resonance; Phosphatidylcholines - chemistry; Receptors, Ghrelin - agonists; Receptors, Ghrelin - chemistry; Receptors, Ghrelin - metabolism; Recombinant Proteins - metabolism; Rotational diffusion; Science; Spectroscopy; Spectrum analysis
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep46128

The expression, functional reconstitution and first NMR characterization of the human growth hormone secretagogue (GHS) receptor reconstituted into either DMPC or POPC membranes is described. The receptor was expressed in E. coli . refolded, and reconstituted into bilayer membranes. The molecule was characterized by 15 N and 13 C solid-state NMR spectroscopy in the absence and in the presence of its natural agonist ghrelin or an inverse agonist. Static 15 N NMR spectra of the uniformly labeled receptor are indicative of axially symmetric rotational diffusion of the G protein-coupled receptor in the membrane. In addition, about 25% of the 15 N sites undergo large amplitude motions giving rise to very narrow spectral components. For an initial quantitative assessment of the receptor mobility, 1 H- 13 C dipolar coupling values, which are scaled by molecular motions, were determined quantitatively. From these values, average order parameters, reporting the motional amplitudes of the individual receptor segments can be derived. Average backbone order parameters were determined with values between 0.56 and 0.69, corresponding to average motional amplitudes of 40–50° of these segments. Differences between the receptor dynamics in DMPC or POPC membranes were within experimental error. Furthermore, agonist or inverse agonist binding only insignificantly influenced the average molecular dynamics of the receptor.