Structural Insights into the Dynamic Process of β 2 -Adrenergic Receptor Signaling

Manglik, Aashish; Kim, Tae Hun; Masureel, Matthieu; Altenbach, Christian; Yang, Zhongyu; Hilger, Daniel; Lerch, Michael T.; Kobilka, Tong Sun; Thian, Foon Sun; Hubbell, Wayne L.; Prosser, R. Scott; Kobilka, Brian K.

doi:10.1016/j.cell.2015.04.043

Cited by 587 publications

(606 citation statements)

References 39 publications

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“…Furthermore, this places our work in agreement with the transition state theories (recent works: refs. [5][6][7][8]. Physiochemical properties of the ligand-other than vibrational quanta-are likely involved in the activation of both ORs-as suggested for Drosophila receptors by Saberi and Seyed-allaei (91)-and GPCRs in general.…”

Section: Resultsmentioning

confidence: 99%

Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation

Hoehn

Nichols

McCorvy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Recently, an alternative theory concerning the method by which olfactory proteins are activated has garnered attention. This theory proposes that the activation of olfactory G protein-coupled receptors occurs by an inelastic electron tunneling mechanism that is mediated through the presence of an agonist with an appropriate vibrational state to accept the inelastic portion of the tunneling electron's energy. In a recent series of papers, some suggestive theoretical evidence has been offered that this theory may be applied to nonolfactory G protein- O lfaction-and other chemo-sensitive sensory processes-is an important information-gathering technique for organisms of many clades and kingdoms. Specifically, human olfaction is known to occur by activation of olfactory receptors (ORs)-a subclass of G protein-coupled receptors (GPCRs)-located within the nasal epithelium and mediating responses within the olfactory bulb, where it is encoded and conveys information to the amygdala, the orbitofrontal cortex, and the hippocampus (1, 2). The discovery and the cloning of ORs led to the joint 2004 Nobel Prize in Physiology and Medicine to Richard Axel and Linda Buck. (3) GPCRs are 7-helical transmembrane proteins, facilitating communication from extracellular ligand signals to the cellular interior through activation of (interior) G proteins, while maintaining the integrity of the membrane (4). GPCRs are activated by an appropriate agonist moving into the protein's orthosteric binding site, resulting in a conformational change within the helical bundle. This structural change leads to altered conformations of the intracellular loops that couple to appropriate signaling molecules within the cell, e.g., G proteins. A recent series of papers has experimentally determined activated/inactivated states through isotopic-tagged receptors with NMR spectroscopy (5-7). An additional work used molecular dynamics to provide structural insights into how the agonist may assist the interchange between conformations through several proposed peptide sidechain pathways by examining the structures of the activated and inactivated µ-opioid receptor (8). Additionally, photon-induced conformational changes in lightsensitive proteins have also been observed (9, 10).Recently, an iteration of the vibrational theory of olfaction (VTO)-suggested and advocated by Luca Turin (11, 12)-has arisen and has gained both supporters (13-16) and detractors (17, 18); the novelty of this incarnation of the VTO is ascribable to its nonthermal-and nonphoton-based mechanism. Turin's theory is a contemporary reincarnation of the more classical theory proposed by Dyson (19), Wright (20), and Wright and Serenius (21), where the activation of the olfactory receptor is performed-or sensitive to-the molecular vibrations of the olfactant. Dyson suggested that the molecular vibrations of the agonist were exactly responsible for the activation of the protein. These vibrations were entirely thermally excited, as no mechanism for photoexcitation is available within the body. Th...

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Section: Resultsmentioning

confidence: 99%

Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation

Hoehn

Nichols

McCorvy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Nevertheless, high resolution cryo-EM on asymmetric and relatively small membrane proteins (<200 kDa) remains challenging due to the low signal-to-noise ratio that hampers the accuracy of angular determination for 3D reconstructions. This problem is compounded by the intrinsically dynamic character of the 7TM bundle 14, 15 and the relative instability of GPCR complexes, such as with G proteins 16 or arrestins 17 , often resulting in conformational variability or even dissociation during cryo-EM specimen preparation. Notwithstanding these challenges, cryo-EM visualization for GPCR complexes holds tremendous potential for uncovering the various molecular mechanisms involved in signal transduction and regulation of GPCRs and their effector proteins.…”

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confidence: 99%

Cryo-EM structure of the activated GLP-1 receptor in complex with a G protein

Zhang

Sun

Feng

et al. 2017

Nature

503

568

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Summary Glucagon-like peptide-1 (GLP-1) is a hormone with essential roles in regulating insulin secretion, carbohydrate metabolism and appetite. GLP-1 effects are mediated through binding to GLP-1R, a family B G protein-coupled receptor (GPCR) signaling primarily through the stimulatory G protein Gs. Family B GPCRs are important therapeutic targets, however our understanding of their mechanism of action is limited by the lack of structural information on activated and full-length receptors. Here we show the electron cryo-microscopy structure of the peptide-activated GLP-1R:Gs complex at near atomic resolution. The peptide is clasped between the N-terminal domain and transmembrane core of the receptor, further stabilized by extracellular loops. Conformational changes in the transmembrane domain result in a sharp kink in the middle of transmembrane helix 6, which pivots its intracellular half outward to accommodate the α5 helix of GαsRas. These results provide a structural framework for understanding family B receptor activation through hormone binding.

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“…Interestingly, the dynamic equilibrium of receptors remains heterogeneous even in the presence of saturating concentrations of full agonists and always contains a fraction of receptors in inactive states (19,(21)(22)(23). In fact, agonists alone are not sufficient to stabilize the fully active receptor state as seen in the crystal structures (19 -24).…”

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confidence: 99%

“…Recent biophysical studies on various receptors (Class A and Class C) have shown that GPCRs reside in a dynamic equilibrium of distinct receptor conformations comprising inactive and active receptor states (19 -22). These studies suggest a common mechanism for agonist efficacy: agonists shift the preexisting equilibrium of different receptor conformations toward more active states (21,22).…”

mentioning

confidence: 99%

Ligand Binding Ensembles Determine Graded Agonist Efficacies at a G Protein-coupled Receptor

Böck

Bermudez

Krebs

et al. 2016

Journal of Biological Chemistry

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G protein-coupled receptors constitute the largest family of membrane receptors and modulate almost every physiological process in humans. Binding of agonists to G protein-coupled receptors induces a shift from inactive to active receptor conformations. Biophysical studies of the dynamic equilibrium of receptors suggest that a portion of receptors can remain in inactive states even in the presence of saturating concentrations of agonist and G protein mimetic. However, the molecular details of agonist-bound inactive receptors are poorly understood.Here we use the model of bitopic orthosteric/allosteric (i.e. dualsteric) agonists for muscarinic M 2 receptors to demonstrate the existence and function of such inactive agonist⅐receptor complexes on a molecular level. Using all-atom molecular dynamics simulations, dynophores (i.e. a combination of static three-dimensional pharmacophores and molecular dynamics-based conformational sampling), ligand design, and receptor mutagenesis, we show that inactive agonist⅐receptor complexes can result from agonist binding to the allosteric vestibule alone, whereas the dualsteric binding mode produces active receptors. Each agonist forms a distinct ligand binding ensemble, and different agonist efficacies depend on the fraction of purely allosteric (i.e. inactive) versus dualsteric (i.e. active) binding modes. We propose that this concept may explain why agonist⅐receptor complexes can be inactive and that adopting multiple binding modes may be generalized also to small agonists where binding modes will be only subtly different and confined to only one binding site.Specific and coordinated cell-to-cell communication regulates the flow of information between cells, and proper information processing ensures physiological functions of biological systems. G protein-coupled receptors (GPCRs), 8 constituting the largest class of membrane proteins in mammals, are essential mediators of chemically and light-encoded information (1-4). GPCRs sense a great variety of extracellular stimuli, e.g. neurotransmitters and hormones, and subsequently translate this information into an intracellular response via G proteins, ␤-arrestins, and possibly GPCR-interacting proteins (2-5). Because of their abundance and relevance in regulating the majority of (patho-)physiological processes in humans, GPCRs have for a long time represented the most important drug targets being addressed by at least a third of all currently marketed drugs (6, 7).Agonist binding leads to receptor activation, which is followed by intracellular G protein recruitment and subsequent cell signaling. Breakthroughs in GPCR crystallography have led to inactive and active crystal structures of the same receptor protein. Among these are rhodopsin (8 -10) and more recently the ␤ 2 -adrenergic (11-14), M 2 muscarinic (15, 16), and -opioid receptors (17, 18). These structures most likely represent energetically favored, relatively stable inactive and active receptor⅐ligand complexes. Despite the diversity of crystallized receptors, a common...

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Structural Insights into the Dynamic Process of β 2 -Adrenergic Receptor Signaling

Cited by 587 publications

References 39 publications

Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation

Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation

Cryo-EM structure of the activated GLP-1 receptor in complex with a G protein

Ligand Binding Ensembles Determine Graded Agonist Efficacies at a G Protein-coupled Receptor

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