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

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Giuseppe Deganutti ◽  
Yi-Lynn Liang ◽  
Xin Zhang ◽  
Maryam Khoshouei ◽  
Lachlan Clydesdale ◽  
...  
Keyword(s):  
G Protein ◽  
Transmembrane Domain ◽  
Protein Activation ◽  
G Protein Activation ◽  
Binding Cavity ◽  
Transient Interactions ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Dynamics Simulations ◽  
Peptide Agonist

AbstractThe 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 combine cryo-electron microscopy, molecular dynamics simulations, receptor mutagenesis and pharmacological assays, to interrogate the mechanism and consequences of GLP-1R binding to four peptide agonists; glucagon-like peptide-1, oxyntomodulin, exendin-4 and exendin-P5. These data reveal 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.

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

2021 ◽  
Author(s):  
Giuseppe Deganutti ◽  
Yi-Lynn Liang ◽  
Xin Zhang ◽  
Maryam Khoshouei ◽  
Lachlan Clydesdale ◽  
...  
Keyword(s):  
G Protein ◽  
Transmembrane Domain ◽  
Protein Activation ◽  
G Protein Activation ◽  
Binding Cavity ◽  
Transient Interactions ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Dynamics Simulations ◽  
Peptide Agonist

ABSTRACTThe 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.

scholarly journals Structural Determinants for G Protein Activation and Selectivity in the Second Intracellular Loop of the Thyrotropin Receptor

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 477-485 ◽  
Author(s):  
Susanne Neumann ◽  
Gerd Krause ◽  
Maren Claus ◽  
Ralf Paschke
Keyword(s):  
G Protein ◽  
Transmembrane Domain ◽  
Point Mutations ◽  
Hydrophobic Residue ◽  
Intracellular Loop ◽  
Structural Determinants ◽  
Protein Activation ◽  
G Protein Activation ◽  
Potential Interactions ◽  
Receptor Domain

The TSH receptor (TSHR) activates mainly two signal transduction pathways, cAMP production and phosphoinositide turnover, mediated by Gs and Gq coupling, respectively. Several activating deletion and point mutations within intracellular loop 3 (ICL3) and the adjacent portion of transmembrane domain 6 (TM6) support a direct G protein activation by this receptor domain. The ICL3, however, is predicted by modeling to interact with other receptor domains, primarily ICL2, to form a pocket for G protein binding and to allow optimum interaction. Systematic mutagenesis was used to identify important sites within ICL2 and potential interactions between ICL2 and ICL3 of the TSHR required for G protein coupling. Deletions of four or five residues and their corresponding multiple alanine substitutions were introduced into ICL2. Residues I523-D530, comprising mainly the N-terminal half of ICL2, appeared to be critical for Gs- and Gq-mediated signaling. A single alanine substitution screening within ICL2 revealed hydrophobic residue M527 in particular and, to lesser extents, F525, R528, L529, and D530 as residues that selectively abolished or strongly impaired Gq activation. Molecular modeling suggests that F525 interacts with ICL3. To test this hypothesis, ICL2/ICL3 double mutants introducing strong complementary properties were constructed and tested for functional rescue of Gq-mediated signaling. Our results indicate that ICL2 interacts with ICL3 in close vicinity to F525 and T607, suggesting a conformational cooperation between ICL2 and ICL3 during Gq activation by TSHR.

scholarly journals Structures of metabotropic GABAB receptor

2020 ◽  
Author(s):  
Makaía M. Papasergi-Scott ◽  
Michael J. Robertson ◽  
Alpay B. Seven ◽  
Ouliana Panova ◽  
Jesper M. Mathiesen ◽  
...  
Keyword(s):  
Ligand Binding ◽  
G Protein ◽  
Cellular Response ◽  
Transmembrane Domain ◽  
Gabab Receptor ◽  
Rational Drug Design ◽  
Protein Activation ◽  
Brain Physiology ◽  
Rational Drug ◽  
G Protein Activation

AbstractGABA (γ-aminobutyric acid) stimulation of the metabotropic GABAB receptor results in prolonged inhibition of neurotransmission that is central to brain physiology. GABAB belongs to the Family C of G protein-coupled receptors (GPCRs), which operate as dimers to relay synaptic neurotransmitter signals into a cellular response through the binding and activation of heterotrimeric G proteins. GABAB, however, is unique in its function as an obligate heterodimer in which agonist binding and G protein activation take place on distinct subunits. Here we show structures of heterodimeric and homodimeric full-length GABAB receptors. Complemented by cellular signaling assays and atomistic simulations, the structures reveal an essential role for the GABAB extracellular loop 2 (ECL2) in relaying structural transitions by ordering the linker connecting the extracellular ligand-binding domain to the transmembrane region. Furthermore, the ECL2 of both GABAB subunits caps and interacts with the hydrophilic head of a phospholipid occupying the extracellular half of the transmembrane domain, thereby providing a potentially crucial link between ligand binding and the receptor core that engages G protein. These results provide a starting framework to decipher mechanistic modes of signal transduction mediated by GABAB dimers and have important implications for rational drug design targeting these receptors.

scholarly journals Bile acids drive colonic secretion of glucagon-like-peptide 1 and peptide-YY in rodents

2019 ◽  
Vol 316 (5) ◽  
pp. G574-G584 ◽  
Author(s):  
Charlotte Bayer Christiansen ◽  
Samuel Addison Jack Trammell ◽  
Nicolai Jacob Wewer Albrechtsen ◽  
Kristina Schoonjans ◽  
Reidar Albrechtsen ◽  
...  
Keyword(s):  
Bile Acids ◽  
G Protein ◽  
Peptide Yy ◽  
Whole Body ◽  
Rat Colon ◽  
G Protein Coupled Receptor ◽  
L Cells ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
G Protein Coupled

A large number of glucagon-like-peptide-1 (GLP-1)- and peptide-YY (PYY)-producing L cells are located in the colon, but little is known about their contribution to whole body metabolism. Since bile acids (BAs) increase GLP-1 and PYY release, and since BAs spill over from the ileum to the colon, we decided to investigate the ability of BAs to stimulate colonic GLP-1 and PYY secretion. Using isolated perfused rat/mouse colon as well as stimulation of the rat colon in vivo, we demonstrate that BAs significantly enhance secretion of GLP-1 and PYY from the colon with average increases of 3.5- and 2.9-fold, respectively. Furthermore, we find that responses depend on BA absorption followed by basolateral activation of the BA-receptor Takeda-G protein-coupled-receptor 5. Surprisingly, the apical sodium-dependent BA transporter, which serves to absorb conjugated BAs, was not required for colonic conjugated BA absorption or conjugated BA-induced peptide secretion. In conclusion, we demonstrate that BAs represent a major physiological stimulus for colonic L-cell secretion.NEW & NOTEWORTHY By the use of isolated perfused rodent colon preparations we show that bile acids are potent and direct promoters of colonic glucagon-like-peptide 1 and peptide-YY secretion. The study provides convincing evidence that basolateral Takeda-G protein-coupled-receptor 5 activation is mediating the effects of bile acids in the colon and thus add to the existing literature described for L cells in the ileum.

Opioid-Activated Postsynaptic, Inward Rectifying Potassium Currents in Whole Cell Recordings in Substantia Gelatinosa Neurons

1998 ◽  
Vol 80 (6) ◽  
pp. 2954-2962 ◽  
Author(s):  
S. P. Schneider ◽  
W. A. Eckert ◽  
A. R. Light
Keyword(s):  
Membrane Potential ◽  
G Protein ◽  
Potassium Currents ◽  
Substantia Gelatinosa ◽  
Opioid Agonist ◽  
Membrane Hyperpolarization ◽  
Whole Cell ◽  
Protein Activation ◽  
G Protein Activation ◽  
Whole Cell Recordings

Schneider, S. P., W. A. Eckert III, and A. R. Light. Opioid-activated postsynaptic, inward rectifying potassium currents in whole cell recordings in substantia gelatinosa neurons. J. Neurophysiol. 80: 2954–2962, 1998. Using tight-seal, whole cell recordings from isolated transverse slices of hamster and rat spinal cord, we investigated the effects of the μ-opioid agonist (d-Ala2, N-Me-Phe4,Gly5-ol)-enkephalin (DAMGO) on the membrane potential and conductance of substantia gelatinosa (SG) neurons. We observed that bath application of 1–5 μM DAMGO caused a robust and repeatable hyperpolarization in membrane potential ( V m) and decrease in neuronal input resistance ( R N) in 60% (27/45) of hamster neurons and 39% (9/23) of rat neurons, but significantly only when ATP (2 mM) and guanosine 5′-triphosphate (GTP; 100 μM) were included in the patch pipette internal solution. An ED50 of 50 nM was observed for the hyperpolarization in rat SG neurons. Because G-protein mediation of opioid effects has been shown in other systems, we tested if the nucleotide requirement for opioid hyperpolarization in SG neurons was due to G-protein activation. GTP was replaced with the nonhydrolyzable GTP analogue guanosine-5′- O-(3-thiotriphosphate) (GTP-γ-S; 100 μM), which enabled DAMGO to activate a nonreversible membrane hyperpolarization. Further, intracellular application of guanosine-5′- O-(2-thiodiphosphate) (GDP-β-S; 500 μM), which blocks G-protein activation, abolished the effects of DAMGO. We conclude that spinal SG neurons are particularly susceptible to dialysis of GTP by whole cell recording techniques. Moreover, the depletion of GTP leads to the inactivation of G-proteins that mediate μ-opioid activation of an inward-rectifying, potassium conductance in these neurons. These results explain the discrepancy between the opioid-activated hyperpolarization in SG neurons observed in previous sharp electrode experiments and the more recent failures to observe these effects with whole cell patch techniques.

scholarly journals Residues within the Transmembrane Domain of the Glucagon-Like Peptide-1 Receptor Involved in Ligand Binding and Receptor Activation: Modelling the Ligand-Bound Receptor

2011 ◽  
Vol 25 (10) ◽  
pp. 1804-1818 ◽  
Author(s):  
K. Coopman ◽  
R. Wallis ◽  
G. Robb ◽  
A. J. H. Brown ◽  
G. F. Wilkinson ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Structural Model ◽  
Transmembrane Domain ◽  
Transmembrane Helix ◽  
Receptor Activation ◽  
Agonist Affinity ◽  
Camp Generation ◽  
N Terminus ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

The C-terminal regions of glucagon-like peptide-1 (GLP-1) bind to the N terminus of the GLP-1 receptor (GLP-1R), facilitating interaction of the ligand N terminus with the receptor transmembrane domain. In contrast, the agonist exendin-4 relies less on the transmembrane domain, and truncated antagonist analogs (e.g. exendin 9–39) may interact solely with the receptor N terminus. Here we used mutagenesis to explore the role of residues highly conserved in the predicted transmembrane helices of mammalian GLP-1Rs and conserved in family B G protein coupled receptors in ligand binding and GLP-1R activation. By iteration using information from the mutagenesis, along with the available crystal structure of the receptor N terminus and a model of the active opsin transmembrane domain, we developed a structural receptor model with GLP-1 bound and used this to better understand consequences of mutations. Mutation at Y152 [transmembrane helix (TM) 1], R190 (TM2), Y235 (TM3), H363 (TM6), and E364 (TM6) produced similar reductions in affinity for GLP-1 and exendin 9–39. In contrast, other mutations either preferentially [K197 (TM2), Q234 (TM3), and W284 (extracellular loop 2)] or solely [D198 (TM2) and R310 (TM5)] reduced GLP-1 affinity. Reduced agonist affinity was always associated with reduced potency. However, reductions in potency exceeded reductions in agonist affinity for K197A, W284A, and R310A, while H363A was uncoupled from cAMP generation, highlighting critical roles of these residues in translating binding to activation. Data show important roles in ligand binding and receptor activation of conserved residues within the transmembrane domain of the GLP-1R. The receptor structural model provides insight into the roles of these residues.

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