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Hong JD, Salom D, Choi EH, Du SW, Tworak A, Smidak R, Gao F, Solano YJ, Zhang J, Kiser PD, Palczewski K. Retinylidene chromophore hydrolysis from mammalian visual and non-visual opsins. J Biol Chem 2024; 300:105678. [PMID: 38272218 PMCID: PMC10877631 DOI: 10.1016/j.jbc.2024.105678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/06/2024] [Accepted: 01/13/2024] [Indexed: 01/27/2024] Open
Abstract
Rhodopsin (Rho) and cone opsins are essential for detection of light. They respond via photoisomerization, converting their Schiff-base-adducted 11-cis-retinylidene chromophores to the all-trans configuration, eliciting conformational changes to activate opsin signaling. Subsequent Schiff-base hydrolysis releases all-trans-retinal, initiating two important cycles that maintain continuous vision-the Rho photocycle and visual cycle pathway. Schiff-base hydrolysis has been thoroughly studied with photoactivated Rho but not with cone opsins. Using established methodology, we directly measured the formation of Schiff-base between retinal chromophores with mammalian visual and nonvisual opsins of the eye. Next, we determined the rate of light-induced chromophore hydrolysis. We found that retinal hydrolysis from photoactivated cone opsins was markedly faster than from photoactivated Rho. Bovine retinal G protein-coupled receptor (bRGR) displayed rapid hydrolysis of its 11-cis-retinylidene photoproduct to quickly supply 11-cis-retinal and re-bind all-trans-retinal. Hydrolysis within bRGR in native retinal pigment epithelium microsomal membranes was >6-times faster than that of bRGR purified in detergent micelles. N-terminal-targeted antibodies significantly slowed bRGR hydrolysis, while C-terminal antibodies had no effect. Our study highlights the much faster photocycle of cone opsins relative to Rho and the crucial role of RGR in chromophore recycling in daylight. By contrast, in our experimental conditions, bovine peropsin did not form pigment in the presence of all-trans-retinal nor with any mono-cis retinal isomers, leaving uncertain the role of this opsin as a light sensor.
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Affiliation(s)
- John D Hong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Chemistry, University of California Irvine, Irvine, California, USA
| | - David Salom
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA.
| | - Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Samuel W Du
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Roman Smidak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Yasmeen J Solano
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA
| | - Jianye Zhang
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA; Department of Clinical Pharmacy Practice, University of California Irvine, Irvine, California, USA; Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Chemistry, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA; Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, USA.
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Hong JD, Palczewski K. A short story on how chromophore is hydrolyzed from rhodopsin for recycling. Bioessays 2023; 45:e2300068. [PMID: 37454357 PMCID: PMC10614701 DOI: 10.1002/bies.202300068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 07/18/2023]
Abstract
The photocycle of visual opsins is essential to maintain the light sensitivity of the retina. The early physical observations of the rhodopsin photocycle by Böll and Kühne in the 1870s inspired over a century's worth of investigations on rhodopsin biochemistry. A single photon isomerizes the Schiff-base linked 11-cis-retinylidene chromophore of rhodopsin, converting it to the all-trans agonist to elicit phototransduction through photoactivated rhodopsin (Rho*). Schiff base hydrolysis of the agonist is a key step in the photocycle, not only diminishing ongoing phototransduction but also allowing for entry and binding of fresh 11-cis chromophore to regenerate the rhodopsin pigment and maintain light sensitivity. Many challenges have been encountered in measuring the rate of this hydrolysis, but recent advancements have facilitated studies of the hydrolysis within the native membrane environment of rhodopsin. These techniques can now be applied to study hydrolysis of agonist in other opsin proteins that mediate phototransduction or chromophore turnover. In this review, we discuss the progress that has been made in characterizing the rhodopsin photocycle and the journey to characterize the hydrolysis of its all-trans-retinylidene agonist.
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Affiliation(s)
- John D. Hong
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
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Krishnamoorthi A, Khosh Abady K, Dhankhar D, Rentzepis PM. Ultrafast Transient Absorption Spectra and Kinetics of Rod and Cone Visual Pigments. Molecules 2023; 28:5829. [PMID: 37570798 PMCID: PMC10421382 DOI: 10.3390/molecules28155829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/13/2023] Open
Abstract
Rods and cones are the photoreceptor cells containing the visual pigment proteins that initiate visual phototransduction following the absorption of a photon. Photon absorption induces the photochemical transformation of a visual pigment, which results in the sequential formation of distinct photo-intermediate species on the femtosecond to millisecond timescales, whereupon a visual electrical signal is generated and transmitted to the brain. Time-resolved spectroscopic studies of the rod and cone photo-intermediaries enable the detailed understanding of initial events in vision, namely the key differences that underlie the functionally distinct scotopic (rod) and photopic (cone) visual systems. In this paper, we review our recent ultrafast (picoseconds to milliseconds) transient absorption studies of rod and cone visual pigments with a detailed comparison of the transient molecular spectra and kinetics of their respective photo-intermediaries. Key results include the characterization of the porphyropsin (carp fish rhodopsin) and human green-cone opsin photobleaching sequences, which show significant spectral and kinetic differences when compared against that of bovine rhodopsin. These results altogether reveal a rather strong interplay between the visual pigment structure and its corresponding photobleaching sequence, and relevant outstanding questions that will be further investigated through a forthcoming study of the human blue-cone visual pigment are discussed.
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Affiliation(s)
- Arjun Krishnamoorthi
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Keyvan Khosh Abady
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Dinesh Dhankhar
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
- Thermo Fisher Scientific, Hillsboro, OR 97124, USA
| | - Peter M. Rentzepis
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
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Ultrafast spectra and kinetics of human green-cone visual pigment at room temperature. Proc Natl Acad Sci U S A 2023; 120:e2214276120. [PMID: 36577071 PMCID: PMC9910472 DOI: 10.1073/pnas.2214276120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Rhodopsin is the pigment that enables night vision, whereas cone opsins are the pigments responsible for color vision in bright-light conditions. Despite their importance for vision, cone opsins are poorly characterized at the molecular level compared to rhodopsin. Spectra and kinetics of the intermediate states of human green-cone visual pigment (mid-wavelength sensitive, or MWS opsin) were measured and compared with the intermediates and kinetics of bovine rhodopsin. All the major intermediates of the MWS opsin were recorded in the picosecond to millisecond time range. Several intermediates in MWS opsin appear to have characteristics similar to the intermediates of bovine rhodopsin; however, there are some marked differences. One of the most striking differences is in their kinetics, where the kinetics of the MWS opsin intermediates are slower compared to those of the bovine rhodopsin intermediates.
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Dhankhar D, Nagpal A, Tachibanaki S, Li R, Cesario TC, Rentzepis PM. Comparison of Bovine and Carp Fish Visual Pigment Photo-Intermediates at Room Temperature. Photochem Photobiol 2022; 98:1303-1311. [PMID: 35313014 DOI: 10.1111/php.13621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/17/2022] [Indexed: 11/29/2022]
Abstract
This paper presents room temperature nanoseconds to milliseconds time-resolved spectra and kinetics of the intermediate states and species of bovine and carp fish rhodopsin visual pigments, which also contained ~5% cone pigments. The nanoseconds to milliseconds range cover all the major intermediates in the visual phototransduction process except the formation of bathorhodopsin intermediate which occurs at the femtosecond time scale. The dynamics of these visual pigment intermediates are initiated by excitation with a 532 nm nanosecond laser pulse. The recorded differences between bovine and carp rhodopsin time-resolved spectra of the formation and decay kinetics of their intermediates are presented and discussed. The data show that the carp samples batho intermediate decays faster, nearly by a factor of three, compared to the bovine samples. The formation and decay spectra and kinetics of rhodopsin outer segments and extracted rhodopsin inserted in buffer solution were found to be identical, with very small differences between them in the decay lifetimes of bathorhodopsin and formation of lumirhodopsin.
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Affiliation(s)
- Dinesh Dhankhar
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Anushka Nagpal
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Shuji Tachibanaki
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Runze Li
- School of Physical Science and Technology, Shanghai Tech University, Shanghai, China
| | | | - Peter M Rentzepis
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
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Salom D, Jin H, Gerken TA, Yu C, Huang L, Palczewski K. Human red and green cone opsins are O-glycosylated at an N-terminal Ser/Thr-rich domain conserved in vertebrates. J Biol Chem 2019; 294:8123-8133. [PMID: 30948514 DOI: 10.1074/jbc.ra118.006835] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/15/2019] [Indexed: 12/28/2022] Open
Abstract
There are fundamental differences in the structures of outer segments between rod and cone photoreceptor cells in the vertebrate retina. Visual pigments are the only essential membrane proteins that differ between rod and cone outer segments, making it likely that they contribute to these structural differences. Human rhodopsin is N-glycosylated on Asn2 and Asn15, whereas human (h) red and green cone opsins (hOPSR and hOPSG, respectively) are N-glycosylated at Asn34 Here, utilizing a monoclonal antibody (7G8 mAB), we demonstrate that hOPSR and hOPSG from human retina also are O-glycosylated with full occupancy. We determined that 7G8 mAB recognizes the N-terminal sequence 21DSTQSSIF28 of hOPSR and hOPSG from extracts of human retina, but only after their O-glycans have been removed with O-glycosidase treatment, thus revealing this post-translational modification of red and green cone opsins. In addition, we show that hOPSR and hOPSG from human retina are recognized by jacalin, a lectin that binds to O-glycans, preferentially to Gal-GalNAc. Next, we confirmed the presence of O-glycans on OPSR and OPSG from several vertebrate species, including mammals, birds, and amphibians. Finally, the analysis of bovine OPSR by MS identified an O-glycan on Ser22, a residue that is semi-conserved (Ser or Thr) among vertebrate OPSR and OPSG. These results suggest that O-glycosylation is a fundamental feature of red and green cone opsins, which may be relevant to their function or to cone cell development, and that differences in this post-translational modification also could contribute to the different morphologies of rod and cone photoreceptors.
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Affiliation(s)
- David Salom
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, Irvine, California 92697; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106.
| | - Hui Jin
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Thomas A Gerken
- Department of Biochemistry and Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, Irvine, California 92697; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106.
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Breyton C, Javed W, Vermot A, Arnaud CA, Hajjar C, Dupuy J, Petit-Hartlein I, Le Roy A, Martel A, Thépaut M, Orelle C, Jault JM, Fieschi F, Porcar L, Ebel C. Assemblies of lauryl maltose neopentyl glycol (LMNG) and LMNG-solubilized membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:939-957. [PMID: 30776334 DOI: 10.1016/j.bbamem.2019.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/08/2019] [Accepted: 02/08/2019] [Indexed: 12/11/2022]
Abstract
Laurylmaltose neopentylglycol (LMNG) bears two linked hydrophobic chains of equal length and two hydrophilic maltoside groups. It arouses a strong interest in the field of membrane protein biochemistry, since it was shown to efficiently solubilize and stabilize membrane proteins often better than the commonly used dodecylmaltopyranoside (DDM), and to allow structure determination of some challenging membrane proteins. However, LMNG was described to form large micelles, which could be unfavorable for structural purposes. We thus investigated its auto-assemblies and the association state of different membrane proteins solubilized in LMNG by analytical ultracentrifugation, size exclusion chromatography coupled to light scattering, centrifugation on sucrose gradient and/or small angle scattering. At high concentrations (in the mM range), LMNG forms long rods, and it stabilized the membrane proteins investigated herein, i.e. a bacterial multidrug transporter, BmrA; a prokaryotic analogous of the eukaryotic NADPH oxidases, SpNOX; an E. coli outer membrane transporter, FhuA; and the halobacterial bacteriorhodopsin, bR. BmrA, in the Apo and the vanadate-inhibited forms showed reduced kinetics of limited proteolysis in LMNG compared to DDM. Both SpNOX and BmrA display an increased specific activity in LMNG compared to DDM. The four proteins form LMNG complexes with their usual quaternary structure and with usual amount of bound detergent. No heterogeneous complexes related to the large micelle size of LMNG alone were observed. In conditions where LMNG forms assemblies of large size, FhuA crystals diffracting to 4.0 Å were obtained by vapor diffusion. LMNG large micelle size thus does not preclude membrane protein homogeneity and crystallization.
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Affiliation(s)
- Cécile Breyton
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Waqas Javed
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France; University of Lyon, CNRS, UMR5086, Molecular Microbiology and Structural Biochemistry, IBCP, Lyon 69367, France
| | - Annelise Vermot
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Charles-Adrien Arnaud
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Christine Hajjar
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Jérôme Dupuy
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Isabelle Petit-Hartlein
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Aline Le Roy
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Anne Martel
- Institut Max Von Laue Paul Langevin, 38042 Grenoble, France
| | - Michel Thépaut
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Cédric Orelle
- University of Lyon, CNRS, UMR5086, Molecular Microbiology and Structural Biochemistry, IBCP, Lyon 69367, France
| | - Jean-Michel Jault
- University of Lyon, CNRS, UMR5086, Molecular Microbiology and Structural Biochemistry, IBCP, Lyon 69367, France
| | - Franck Fieschi
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France
| | - Lionel Porcar
- Institut Max Von Laue Paul Langevin, 38042 Grenoble, France
| | - Christine Ebel
- Univ. Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), 38000 Grenoble, France.
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