Design of an engineered Gαq protein for high-yield expression and NMR isotope labeling in E. coli

G protein-coupled receptors (GPCRs) are pivotal therapeutic targets that signal through heterotrimeric G proteins. While structural insights into Gα s and Gα i/o subfamilies have advanced significantly, characterizing the Gα q/11 subfamily remains challenging due to poor soluble expression in prokaryotic systems, precluding high-yield isotope labeling needed for NMR studies. Here, we present an efficient expression strategy for Gα q protein in Escherichia coli . We identified the H5 helix as a critical determinant of folding and solubility. By swapping this helix with its Gα i/o counterpart and employing low-temperature co-expression with bacterial chaperones, we significantly enhance soluble yields while retaining GTPase activity. The 15 N-labeled protein exhibited well-dispersed 1 H– 15 N HSQC spectra, validating the suitability of this expression strategy for future high-resolution NMR investigations. Download: Download high-res image (183KB) Download: Download full-size image