Molecular Dynamics Simulations of the Effect of the G-Protein and Diffusible Ligands on the β2-Adrenergic Receptor

• Published in: Journal of molecular biology 2011-12, Vol.414 (4), p.611-623
• Main Authors: Goetz, Angela, Lanig, Harald, Gmeiner, Peter, Clark, Timothy
• Format: Article
• Language: English
• Subjects: 7TM receptor activation; Adrenergic beta-2 Receptor Agonists - chemistry; Adrenergic beta-2 Receptor Agonists - pharmacology; agonists; Binding Sites - drug effects; crystal structure; Crystallography, X-Ray - methods; Diffusion; G-protein coupled receptors; G-proteins; GPCR; GTP-Binding Proteins - chemistry; GTP-Binding Proteins - metabolism; isoprenaline; Isoproterenol - chemistry; Isoproterenol - pharmacology; Ligands; Models, Molecular; molecular dynamics; Molecular Dynamics Simulation; molecular dynamics simulations; opsin; Opsins - chemistry; Opsins - metabolism; Propanolamines - chemistry; Propanolamines - pharmacology; Protein Binding - drug effects; Protein Structure, Secondary; protein–receptor interactions; Receptors, Adrenergic, beta-2 - chemistry; Receptors, Adrenergic, beta-2 - metabolism; Receptors, G-Protein-Coupled - chemistry; Receptors, G-Protein-Coupled - metabolism; signal transduction; Signal Transduction - drug effects; X-radiation; β2-adrenergic receptor
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2011.10.015

G-protein-coupled receptors have extraordinary therapeutic potential as targets for a broad spectrum of diseases. Understanding their function at the molecular level is therefore essential. A variety of crystal structures have made the investigation of the inactive receptor state possible. Recently released X-ray structures of opsin and the β 2-adrenergic receptor (β 2AR) have provided insight into the active receptor state. In addition, we have contributed to the crystal structure of an irreversible agonist–β 2 adrenoceptor complex. These extensive studies and biophysical investigations have revealed that agonist binding leads to a low-affinity conformation of the active state that is suggested to facilitate G-protein binding. The high-affinity receptor state, which promotes signal transduction, is only formed in the presence of both agonist and G-protein. Despite numerous crystal structures, it is not yet clear how ligands tune receptor dynamics and G-protein binding. We have now used molecular dynamics simulations to elucidate the distinct impact of agonist and inverse agonist on receptor conformation and G-protein binding by investigating the influence of the ligands on the structure and dynamics of a complex composed of β 2AR and the C-terminal end of the Gα s subunit (GαCT). The simulations clearly showed that the agonist isoprenaline and the inverse agonist carazolol influence the ligand-binding site and the interaction between β 2AR and GαCT differently. Isoprenaline induced an inward motion of helix 5, whereas carazolol blocked the rearrangement of the extracellular part of the receptor. Moreover, in the presence of isoprenaline, β 2AR and GαCT form a stable interaction that is destabilized by carazolol. [Display omitted] ► Agonist binding to β 2AR receptors facilitates binding of G-proteins. ► We present a homology model of the activated β 2AR bound to a G-protein peptide. ► Molecular dynamics shows the ligand impact on the receptor conformation and G-protein binding. ► Simulations differentiate between binding and effects of agonists and antagonists.