11-<i>cis</i>- and All-<i>trans</i>-Retinols Can Activate Rod Opsin: Rational Design of the Visual Cycle

Kono, Masahiro; Goletz, Patrice; Crouch, Rosalie K.

doi:10.1021/bi800357b

Cited by 34 publications

(32 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several groups have shown a dose response for ATR-induced G protein activation and arrestin binding (26,27), and the ability of ATR to bind to active-stabilized opsins has also been shown (8,14,(28)(29)(30). Our results with WT protein (Fig.…”

Section: After Rhodopsin Photoactivation An Equilibrium Of Atr Releasupporting

confidence: 70%

Decay of an active GPCR: Conformational dynamics govern agonist rebinding and persistence of an active, yet empty, receptor state

Schafer

Fay

Janz

et al. 2016

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

View full text Add to dashboard Cite

Here, we describe two insights into the role of receptor conformational dynamics during agonist release (all-trans retinal, ATR) from the visual G protein-coupled receptor (GPCR) rhodopsin. First, we show that, after light activation, ATR can continually release and rebind to any receptor remaining in an active-like conformation. As with other GPCRs, we observe that this equilibrium can be shifted by either promoting the active-like population or increasing the agonist concentration. Second, we find that during decay of the signaling state an active-like, yet empty, receptor conformation can transiently persist after retinal release, before the receptor ultimately collapses into an inactive conformation. The latter conclusion is based on timeresolved, site-directed fluorescence labeling experiments that show a small, but reproducible, lag between the retinal leaving the protein and return of transmembrane helix 6 (TM6) to the inactive conformation, as determined from tryptophan-induced quenching studies. Accelerating Schiff base hydrolysis and subsequent ATR dissociation, either by addition of hydroxylamine or introduction of mutations, further increased the time lag between ATR release and TM6 movement. These observations show that rhodopsin can bind its agonist in equilibrium like a traditional GPCR, provide evidence that an active GPCR conformation can persist even after agonist release, and raise the possibility of targeting this key photoreceptor protein by traditional pharmaceutical-based treatments.T he superfamily of G protein-coupled receptors (GPCRs) is one of the largest targets of pharmaceutical drugs in the human genome. Classically, GPCR signaling occurs when a diffusible ligand (such as a drug) binds to the receptor and stabilizes conformations that can couple with and activate intracellular proteins. Our understanding of this process has built on the classical "ternary complex" model of receptor-ligand-G protein interaction (1), a model that, with revisions, has continued to guide our knowledge of how this critical event occurs.However, this paradigm has faced problems when applied to rhodopsin, the dim-light visual receptor. Rhodopsin is kept in an "off" state by a covalently bound inverse agonist, 11-cis retinal (11CR). Light converts the 11CR to an agonist, all-trans retinal (ATR), which enables the receptor to activate its G protein, transducin (G t ) (2, 3). The active receptor, metarhodopsin II (MII), continues signaling until the Schiff base linking ATR to the receptor is hydrolyzed, resulting in the release of ATR and the decay of MII into an inactive apoprotein, opsin (4, 5). Binding of a new 11CR to opsin reforms the dark state (DS), enabling another round of photon detection (6).Due to this unusual light-activated, covalently bound ligand, rhodopsin has usually been considered "different" from the larger superfamily of diffusible ligand-binding GPCRs. However, we recently discovered that rhodopsin behaves more like a traditional ligand-binding GPCR than previously thought (7). Our expe...

show abstract

Section: After Rhodopsin Photoactivation An Equilibrium Of Atr Releasupporting

confidence: 70%

Decay of an active GPCR: Conformational dynamics govern agonist rebinding and persistence of an active, yet empty, receptor state

Schafer

Fay

Janz

et al. 2016

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

View full text Add to dashboard Cite

show abstract

“…Second, it seems likely that interference of G90D with the site of retinal attachment also increases the rate of thermal isomerization. Several retinal isomers, including all-trans and 11-cis-retinal, can transiently activate opsin until SB formation with K296 deactivates the protein [31,32]. Interference of CSNB mutations with SB formation and stability can lead to increased background activity in the presence of non-covalently bound cis-retinal, as evidenced in our structure (Fig 3).…”

Section: Relevance To Csnbmentioning

confidence: 64%

Insights into congenital stationary night blindness based on the structure of G90D rhodopsin

et al. 2013

View full text Add to dashboard Cite

We present active-state structures of the G protein-coupled receptor (GPCRs) rhodopsin carrying the disease-causing mutation G90D. Mutations of G90 cause either retinitis pigmentosa (RP) or congenital stationary night blindness (CSNB), a milder, non-progressive form of RP. Our analysis shows that the CSNBcausing G90D mutation introduces a salt bridge with K296. The mutant thus interferes with the E113Q-K296 activation switch and the covalent binding of the inverse agonist 11-cis-retinal, two interactions that are crucial for the deactivation of rhodopsin. Other mutations, including G90V causing RP, cannot promote similar interactions. We discuss our findings in context of a model in which CSNB is caused by constitutive activation of the visual signalling cascade.

show abstract

“…On the other hand, opsin is exposed to the retinoids present in the ROS membrane, many of which are agonists for opsin, with ATR as the most potent one (34). The activity of ATR/opsin noncovalent complex (~0.03 to 0.14 of Meta-II) is five orders of magnitude higher than that of free opsin (35,36).…”

Section: The Physiological Implications Of Free Opsin In Rod Cell Sigmentioning

confidence: 99%

Measurement of Slow Spontaneous Release of 11-cis-Retinal from Rhodopsin

Tian

Sakmar

Huber

2017

Biophysical Journal

View full text Add to dashboard Cite

The vertebrate visual photoreceptor rhodopsin (Rho) is a unique G protein-coupled receptor as it utilizes a covalently tethered inverse agonist (11-cis-retinal) as the native ligand. Previously, electrophysiological studies showed that ligand binding of 11-cis-retinal in dark-adapted Rho was essentially irreversible with a half-life estimated to be 420 years, until after thermal isomerization to all-trans-retinal, which then slowly dissociates. This long lifetime of 11-cis-retinal binding was considered to be physiologically important for minimizing background signal (dark noise) of the visual system. However, in vitro biochemical studies on the thermal stability of Rho showed that Rho decays with a half-life on the order of days. In this study, we resolve the discrepancy by measuring the chromophore exchange rate of the bound 11-cis-retinal chromophore with free 9-cis-retinal from Rho in an in vitro phospholipid/detergent bicelle system. We conclude that the thermal decay of Rho primarily proceeds through spontaneous breaking of the covalent linkage between opsin and 11-cis-retinal, which was overlooked in the electrophysiological recording. We estimate that this slow spontaneous release of 11-cis-retinal from Rho should result in 10 4 to 10 5 free opsin molecules in a dark-adapted rod cell-a number that is three orders of magnitude higher than previously expected. We also discuss the physiological implications of these findings on the basal activity of opsins and the associated dark noise in the visual system.

show abstract

11-cis- and All-trans-Retinols Can Activate Rod Opsin: Rational Design of the Visual Cycle

Cited by 34 publications

References 40 publications

Decay of an active GPCR: Conformational dynamics govern agonist rebinding and persistence of an active, yet empty, receptor state

Decay of an active GPCR: Conformational dynamics govern agonist rebinding and persistence of an active, yet empty, receptor state

Insights into congenital stationary night blindness based on the structure of G90D rhodopsin

Measurement of Slow Spontaneous Release of 11-cis-Retinal from Rhodopsin

Contact Info

Product

Resources

About