Selective polypeptide ligand binding to the extracellular surface of the transmembrane domains of the class B GPCRs GLP-1R and GCGR

Huixia Wang; Wanhui Hu; Tiandan Xu; Ya Yuan; Dongsheng Liu; Kurt Wüthrich

doi:10.1016/j.isci.2023.106918

Selective polypeptide ligand binding to the extracellular surface of the transmembrane domains of the class B GPCRs GLP-1R and GCGR

iScience. 2023 May 19;26(6):106918. doi: 10.1016/j.isci.2023.106918. eCollection 2023 Jun 16.

Authors

Huixia Wang^{1

2

3

4}, Wanhui Hu¹, Tiandan Xu^{1

2

3

4}, Ya Yuan¹, Dongsheng Liu¹, Kurt Wüthrich^{1

3

5}

Affiliations

¹ IHuman Institute, ShanghaiTech University, Shanghai 201210, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
⁴ Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
⁵ Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92037, USA.

Abstract

Crystal and cryo-EM structures of the glucagon-like peptide-1 receptor (GLP-1R) and glucagon receptor (GCGR) bound with their peptide ligands have been obtained with full-length constructs, indicating that the extracellular domain (ECD) is indispensable for specific ligand binding. This article complements these data with studies of ligand recognition of the two receptors in solution. Paramagnetic NMR relaxation enhancement measurements using dual labeling with fluorine-19 probes on the receptor and nitroxide spin labels on the peptide ligands provided new insights. The glucagon-like peptide-1 (GLP-1) was found to interact with GLP-1R by selective binding to the extracellular surface. The ligand selectivity toward the extracellular surface of the receptor was preserved in the transmembrane domain (TMD) devoid of the ECD. The dual labeling approach further provided evidence of cross-reactivity of GLP-1R and GCGR with glucagon and GLP-1, respectively, which is of interest in the context of medical treatments using combinations of the two polypeptides.

Keywords: Biological sciences; molecular biology; molecular interaction; molecular structure.