Fourier transform IR spectroscopy study for new insights into molecular properties and activation mechanisms of visual pigment rhodopsin

Vogel, Reiner; Siebert, Friedrich

doi:10.1002/bip.10407

Cited by 40 publications

(65 citation statements)

References 81 publications

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“…However, in nanodiscs there are clear shifts in the relative populations of resolved components in the distributions for TM6 and TM7, indicating that these populations are in equilibrium; there are no changes in the distribution monitoring TM5. The general shifts in population are toward the active conformational state as the pH becomes more acidic, as expected (11). At pH 8.0 where the MI population is ∼60% (Fig.…”

Section: For Comparisonsupporting

confidence: 81%

“…In native membranes (5-7) and reconstituted liposomes (8,9), photoactivated rhodopsin within milliseconds reaches a pH-dependent quasi-equilibrium between states designated MI and MII, which are distinguished by their optical absorbance maxima and signature absorbances in the infrared (10)(11)(12). The optically identified MII state has been found to consist of isochromic substates, namely MIIa, MIIb, and MIIbH + (13)(14)(15) (Fig.…”

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confidence: 99%

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Conformational equilibria of light-activated rhodopsin in nanodiscs

Eps

Lydia

Morizumi

et al. 2017

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

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Conformational equilibria of G-protein-coupled receptors (GPCRs) are intimately involved in intracellular signaling. Here conformational substates of the GPCR rhodopsin are investigated in micelles of dodecyl maltoside (DDM) and in phospholipid nanodiscs by monitoring the spatial positions of transmembrane helices 6 and 7 at the cytoplasmic surface using site-directed spin labeling and double electron-electron resonance spectroscopy. The photoactivated receptor in DDM is dominated by one conformation with weak pH dependence. In nanodiscs, however, an ensemble of pH-dependent conformational substates is observed, even at pH 6.0 where the MIIbH + form defined by proton uptake and optical spectroscopic methods is reported to be the sole species present in native disk membranes. In nanodiscs, the ensemble of substates in the photoactivated receptor spontaneously decays to that characteristic of the inactive state with a lifetime of ∼16 min at 20°C. Importantly, transducin binding to the activated receptor selects a subset of the ensemble in which multiple substates are apparently retained. The results indicate that in a native-like lipid environment rhodopsin activation is not analogous to a simple binary switch between two defined conformations, but the activated receptor is in equilibrium between multiple conformers that in principle could recognize different binding partners.G -protein-coupled receptors (GPCRs) are central components of protein-protein interaction networks and can serve as hubs that link the extracellular environment of cells to intracellular signaling events (1). As such, they interact with several intracellular proteins (i.e., arrestins, G proteins, kinases). To obtain such diversity in molecular interaction, GPCRs are thought to be in equilibrium between multiple conformations at the cytoplasmic surface (2-4), enabling conformation-dependent interactions with different partners.The rod photoreceptor rhodopsin has served as a model for members in the class A family of GPCRs. In native membranes (5-7) and reconstituted liposomes (8, 9), photoactivated rhodopsin within milliseconds reaches a pH-dependent quasi-equilibrium between states designated MI and MII, which are distinguished by their optical absorbance maxima and signature absorbances in the infrared (10-12). The optically identified MII state has been found to consist of isochromic substates, namely MIIa, MIIb, and MIIbH + (13-15) (Fig. 1A). MIIbH + , populated at pH 6.0, is thought to be the functionally active substate that recognizes the cognate G-protein transducin (8,15,16).Early data relating global protein structural changes to activation in a GPCR were provided by continuous wave (CW) sitedirected spin labeling (SDSL)-Electron Paramagnetic Resonance (EPR) studies in rhodopsin, where it was shown that a generally outward motion of TM6 and a smaller inward motion of TM7 at the cytoplasmic surface were hallmarks of activation in dodecyl maltoside (DDM) micelles (17, 18). High-resolution distance mapping with SDSL and double electron...

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Section: For Comparisonsupporting

confidence: 81%

mentioning

confidence: 99%

Conformational equilibria of light-activated rhodopsin in nanodiscs

Eps

Lydia

Morizumi

et al. 2017

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

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“…However, under careful data acquisition conditions, the difference between spectra recorded from a protein stabilized in two different conformational states will reveal bands from only those residues whose molecular vibrations, and thus local structures, change during the conformational transition (Vogel and Siebert, 2003;Kö tting and Gerwert, 2005). Difference spectroscopy provides detailed insight into the nature of protein conformational change at the single residue level.…”

Section: Ftir Spectroscopy As a Tool For Monitoring Localmentioning

confidence: 99%

Lipid Composition Alters Drug Action at the Nicotinic Acetylcholine Receptor

Baenziger

Ryan²,

Goodreid³

et al. 2007

Mol Pharmacol

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We tested the hypothesis that membrane lipid composition influences drug action at membrane proteins by studying local anesthetic action at the nicotinic acetylcholine receptor (nAChR). Infrared difference spectra show that concentrations of tetracaine consistent with binding to the ion channel (Ͻ50 M) stabilize a resting-like state when the nAChR is reconstituted into phosphatidylcholine membranes containing the anionic lipid, phosphatidic acid, but have no effect on the nAChR reconstituted into membranes lacking phosphatidic acid, either in the presence or absence of cholesterol. Concentrations of tetracaine above 200 M lead to neurotransmitter site binding in all membranes. In the presence of phosphatidic acid, cholesterol, or both, neurotransmitter site binding leads to the formation of quaternary amine-aromatic interactions between tetracaine and binding site tyrosine/tryptophan residues and the stabilization of a desensitized state. One interpretation suggested by lipid partitioning studies is that phosphatidic acid enhances tetracaine action at the channel pore by increasing the partitioning of tetracaine into the lipid bilayer, thereby enhancing access to the transmembrane pore. However, subtle membrane-dependent variations in the vibrations of tyrosine and tryptophan residues, and agonist analog binding studies indicate that the structures of the agonist-bound neurotransmitter sites of the nAChR in membranes lacking both phosphatidic acid and cholesterol differ from the structures of the agonist-desensitized neurotransmitter sites in the presence of both lipids. Lipid action at the nAChR thus involves more than a simple modulation of the equilibrium between resting and desensitized states.

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“…Friedrich Siebert (Freiburg, Germany) focused his attention on rhodopsin, providing a detailed picture of conformational changes accompanying light-induced activation of the protein. [6] Thomas Elsaesser from the Max-Born-Institute (Berlin, Germany) pointed his femtosecond IR lasers at the very basic problem of hydrogen-bond dynamics, by employing simple dimers of acetic acid as model systems for hydrogen-bonded base pairs in nucleic acids. [7] Using nonlinear optical techniques, he was able to measure coherent vibrational motion along the hydrogen-bond coordinate, as well as to measure the lifetimes of the OH stretching and bending modes.…”

Section: Time-resolved Infrared Spectroscopymentioning

confidence: 99%