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Bioluminescence resonance energy transfer assays reveal ligand-specific conformational changes within preformed signaling complexes containing delta-opioid receptors and heterotrimeric G proteins.

ABSTRACT: Heptahelical receptors communicate extracellular information to the cytosolic compartment by binding an extensive variety of ligands. They do so through conformational changes that propagate to intracellular signaling partners as the receptor switches from a resting to an active conformation. This active state has been classically considered unique and responsible for regulation of all signaling pathways controlled by a receptor. However, recent functional studies have challenged this notion and called for a paradigm where receptors would exist in more than one signaling conformation. This study used bioluminescence resonance energy transfer assays in combination with ligands of different functional profiles to provide in vivo physical evidence of conformational diversity of delta-opioid receptors (DORs). DORs and alpha(i1)beta(1)gamma(2) G protein subunits were tagged with Luc or green fluorescent protein to produce bioluminescence resonance energy transfer pairs that allowed monitoring DOR-G protein interactions from different vantage points. Results showed that DORs and heterotrimeric G proteins formed a constitutive complex that underwent structural reorganization upon ligand binding. Conformational rearrangements could not be explained by a two-state model, supporting the idea that DORs adopt ligand-specific conformations. In addition, conformational diversity encoded by the receptor was conveyed to the interaction among heterotrimeric subunits. The existence of multiple active receptor states has implications for the way we conceive specificity of signal transduction.

SUBMITTER: Audet N

PROVIDER: S-EPMC3258885 | biostudies-other | 2008 May

REPOSITORIES: biostudies-other

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Bioluminescence resonance energy transfer assays reveal ligand-specific conformational changes within preformed signaling complexes containing delta-opioid receptors and heterotrimeric G proteins.

Audet Nicolas N Galés Céline C Archer-Lahlou Elodie E Vallières Marc M Schiller Peter W PW Bouvier Michel M Pineyro Graciela G

The Journal of biological chemistry 20080401 22

Heptahelical receptors communicate extracellular information to the cytosolic compartment by binding an extensive variety of ligands. They do so through conformational changes that propagate to intracellular signaling partners as the receptor switches from a resting to an active conformation. This active state has been classically considered unique and responsible for regulation of all signaling pathways controlled by a receptor. However, recent functional studies have challenged this notion and ...[more]

PMID: 18381293

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Project description:BackgroundArabidopsis, 7-transmembrane Regulator of G signaling protein 1 (AtRGS1) modulates canonical G protein signaling by promoting the inactive state of heterotrimeric G protein complex on the plasma membrane. It is known that plant leucine-rich repeat receptor-like kinases (LRR RLKs) phosphorylate AtRGS1 in vitro but little is known about the in vivo interaction, molecular dynamics, or the cellular consequences of this interaction.MethodsTherefore, a subset of the known RLKs that phosphorylate AtRGS1 were selected for elucidation, namely, BAK1, BIR1, FLS2. Several microscopies for both static and dynamic protein-protein interactions were used to follow in vivo interactions between the RLKs and AtRGS1 after the presentation of the Pathogen-associated Molecular Pattern, Flagellin 22 (Flg22). These microscopies included Förster Resonance Energy Transfer, Bimolecular Fluoresence Complementation, and Cross Number and Brightness Fluorescence Correlation Spectroscopy. In addition, reactive oxygen species and calcium changes in living cells were quantitated using luminometry and R-GECO1 microscopy.ResultsThe LRR RLKs BAK1 and BIR1, interact with AtRGS1 at the plasma membrane. The RLK ligand flg22 sets BAK1 in motion toward AtRGS1 and BIR1 away, both returning to the baseline orientations by 10 minutes. The C-terminal tail of AtRGS1 is important for the interaction with BAK1 and for the tempo of the AtRGS1/BIR1 dynamics. This window of time corresponds to the flg22-induced transient production of reactive oxygen species and calcium release which are both attenuated in the rgs1 and the bak1 null mutants.ConclusionsA temporal model of these interactions is proposed. flg22 binding induces nearly instantaneous dimerization between FLS2 and BAK1. Phosphorylated BAK1 interacts with and enables AtRGS1 to move away from BIR1 and AtRGS1 becomes phosphorylated leading to its endocytosis thus leading to de-repression by permitting AtGPA1 to exchange GDP for GTP. Finally, the G protein complex becomes dissociated thus AGB1 interacts with its effector proteins leading to changes in reactive oxygen species and calcium.

Dataset Information

Bioluminescence resonance energy transfer assays reveal ligand-specific conformational changes within preformed signaling complexes containing delta-opioid receptors and heterotrimeric G proteins.

Publications

Bioluminescence resonance energy transfer assays reveal ligand-specific conformational changes within preformed signaling complexes containing delta-opioid receptors and heterotrimeric G proteins.

Similar Datasets

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