Mutagenesis facilitated crystallization of GLP-1R

IUCrJ. 2019 Oct 17;6(Pt 6):996-1006. doi: 10.1107/S2052252519013496. eCollection 2019 Nov 1.

Abstract

The class B family of G-protein-coupled receptors (GPCRs) has long been a paradigm for peptide hormone recognition and signal transduction. One class B GPCR, the glucagon-like peptide-1 receptor (GLP-1R), has been considered as an anti-diabetes drug target and there are several peptidic drugs available for the treatment of this overwhelming disease. The previously determined structures of inactive GLP-1R in complex with two negative allosteric modulators include ten thermal-stabilizing mutations that were selected from a total of 98 designed mutations. Here we systematically summarize all 98 mutations we have tested and the results suggest that the mutagenesis strategy that strengthens inter-helical hydro-phobic interactions shows the highest success rate. We further investigate four back mutations by thermal-shift assay, crystallization and molecular dynamic simulations, and conclude that mutation I1962.66bF increases thermal stability intrinsically and that mutation S2714.47bA decreases crystal packing entropy extrinsically, while mutations S1932.63bC and M2333.36bC may be dispensable since these two cysteines are not di-sulfide-linked. Our results indicate intrinsic connections between different regions of GPCR transmembrane helices and the current data suggest a general mutagenesis principle for structural determination of GPCRs and other membrane proteins.

Keywords: G-protein-coupled receptors; crystallization; glucagon-like peptide-1 receptor; membrane proteins; molecular dynamic simulations; mutations.

Grant support

This work was funded by Beijing Computational Research Center grant . National Natural Science Foundation of China grants 11575021 and 31770898. Key Technologies Research and Development Program grant 2018YFA0507001.