Biology subjects

Truong, T. T.

Publications and source records attributed to Truong, T. T..

3 recordsLinked to original sources

bioRxiv2021

Dynamics of GLP-1R peptide agonist engagement are correlated with kinetics of G protein activation

The glucagon-like peptide-1 receptor (GLP-1R) has broad physiological roles and is a validated target for treatment of metabolic disorders. Despite recent advances in GLP-1R structure elucidation, detailed mechanistic understanding of how different peptides generate profound differences in G protein-mediated signalling is still lacking. Here we have combined cryo-electron microscopy, molecular dynamics simulations, receptor mutagenesis and pharmacological assays, to interrogate the mechanism and consequences of GLP-1R binding by four peptide agonists; glucagon-like peptide-1, oxyntomodulin, exendin-4 and exendin-P5. These data revealed that distinctions in peptide N-terminal interactions and dynamics with the GLP-1R transmembrane domain are reciprocally associated with differences in the allosteric coupling to G proteins. In particular, transient interactions with residues at the base of the binding cavity correlate with enhanced kinetics for G protein activation, providing a rationale for differences in G protein-mediated signalling efficacy from distinct agonists.

biochemistry↗

bioRxiv2021

Structural and Functional Diversity among Agonist-Bound States of the GLP-1 Receptor

Recent advances in G protein-coupled receptor (GPCR) structural elucidation have strengthened previous hypotheses that multi-dimensional signal propagation mediated by these receptors is, in part, dependent on their conformational mobility. However, the relationship between receptor function and static structures determined via crystallography or cryo-electron microscopy is not always clear. This study examines the contribution of peptide agonist conformational plasticity to activation of the glucagon-like peptide-1 receptor (GLP-1R), an important clinical target. We employ variants of the peptides GLP-1 and exendin-4 to explore the interplay between helical propensity near the agonist N-terminus and the ability to bind to and activate the receptor. Cryo-EM analysis of a complex involving an exendin-4 analogue, the GLP-1R and Gs protein revealed two receptor conformers with distinct modes of peptide-receptor engagement. Our functional and structural data suggest that receptor conformational dynamics associated with flexibility of the peptide N-terminal activation domain may be a key determinant of agonist efficacy.

pharmacology and toxicology↗

bioRxiv2020

Differential GLP-1R binding and activation by peptide and non-peptide agonists

Peptide drugs targeting class B1 GPCRs can treat multiple diseases, however there remains substantial interest in the development of orally delivered non-peptide drugs. Here we reveal unexpected overlap between signalling and regulation of the glucagon-like peptide-1 (GLP-1) receptor by the non-peptide agonist, PF 06882961, and GLP-1 that was not observed for another compound, OWL-833. Both compounds are currently in clinical trials for treatment of type 2 diabetes. High resolution cryo-EM structures reveal the binding sites for PF-06882961 and GLP-1 substantially overlap, whereas OWL-833 adopts a unique binding mode with a more open receptor conformation at the extracellular face. Structural differences involving extensive water-mediated hydrogen bond networks could be correlated to functional data to understand how PF 06882961, but not OWL-833, can closely mimic the pharmacological properties of GLP-1. These findings will facilitate rational structure-based discovery of non-peptide agonists targeting class B GPCRs.

pharmacology and toxicology↗