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Krishnamoorthi A, Salom D, Wu A, Palczewski K, Rentzepis PM. Ultrafast transient absorption spectra and kinetics of human blue cone visual pigment at room temperature. Proc Natl Acad Sci U S A 2024; 121:e2414037121. [PMID: 39356673 DOI: 10.1073/pnas.2414037121] [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: 07/12/2024] [Accepted: 09/01/2024] [Indexed: 10/04/2024] Open
Abstract
The ultrafast photochemical reaction mechanism, transient spectra, and transition kinetics of the human blue cone visual pigment have been recorded at room temperature. Ultrafast time-resolved absorption spectroscopy revealed the progressive formation and decay of several metastable photo-intermediates, corresponding to the Batho to Meta-II photo-intermediates previously observed with bovine rhodopsin and human green cone opsin, on the picosecond to millisecond timescales following pulsed excitation. The experimental data reveal several interesting similarities and differences between the photobleaching sequences of bovine rhodopsin, human green cone opsin, and human blue cone opsin. While Meta-II formation kinetics are comparable between bovine rhodopsin and blue cone opsin, the transition kinetics of earlier photo-intermediates and qualitative characteristics of the Meta-I to Meta-II transition are more similar for blue cone opsin and green cone opsin. Additionally, the blue cone photo-intermediate spectra exhibit a high degree of overlap with uniquely small spectral shifts. The observed variation in Meta-II formation kinetics between rod and cone visual pigments is explained based on key structural differences.
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Affiliation(s)
- Arjun Krishnamoorthi
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843
| | - David Salom
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697
- Department of Ophthalmology, School of Medicine, University of California Irvine, Irvine, CA 92697
| | - Arum Wu
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697
- Department of Ophthalmology, School of Medicine, University of California Irvine, Irvine, CA 92697
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697
- Department of Ophthalmology, School of Medicine, University of California Irvine, Irvine, CA 92697
- Department of Chemistry, University of California Irvine, Irvine, CA 92697
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697
| | - Peter M Rentzepis
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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Sato K, Yamashita T, Imamoto Y, Shichida Y. Comparative Studies on the Late Bleaching Processes of Four Kinds of Cone Visual Pigments and Rod Visual Pigment. Biochemistry 2012; 51:4300-8. [DOI: 10.1021/bi3000885] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Keita Sato
- Department of Biophysics,
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Yamashita
- Department of Biophysics,
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yasushi Imamoto
- Department of Biophysics,
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshinori Shichida
- Department of Biophysics,
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Wai MSM, Lorke DE, Kung LS, Yew DTW. Morphogenesis of the different types of photoreceptors of the chicken (Gallus domesticus) retina and the effect of amblyopia in neonatal chicken. Microsc Res Tech 2006; 69:99-107. [PMID: 16456833 DOI: 10.1002/jemt.20279] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Despite the great variety in chicken photoreceptors, existing morphogenetic studies only deal with two types: rods and cones. We have therefore examined by scanning electron microscopy the first appearance and maturation of different retinal photoreceptors in 36 chicken embryos (Gallus domesticus), aged 5-19 days prehatching. On day 5 of incubation, chicken retinae were only composed of proliferating ventricular cells devoid of photoreceptors. On day 8, outer mitotic cells were separated from inner differentiating photoreceptors, by the transient layer of Chievitz. Ball-like protrusions appeared at the ventricular surface, representing the first signs of photoreceptor inner segment formation. From day 10 onward, double cones, single cones, and rods could be clearly distinguished, and occasional cilia were detected at their tip. On day 12, inner segments had increased in length and diameter, and frequently carried a cilium representing the beginning of outer segment formation. On day 14, most photoreceptors displayed a distinct outer segment. On day 19, photoreceptors had essentially assumed adult morphology. Based on the shape of their outer segments, two subtypes of cones and three subtypes of double cones could be distinguished. Throughout development, we observed microvilli close to maturing photoreceptors, either originating from their lateral sides, from their tip, or from Müller cells. Microvillus density peaked between day 12 and 14, indicating an important role in photoreceptor morphogenesis. Unilateral occlusion of the eyes of posthatching chicken reduced the proportion of double cones to single cones in the retina, indicating dependence of retinal morphogenesis upon functional activity of visual cells.
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Affiliation(s)
- Maria Sen Mun Wai
- Department of Anatomy, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
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Guido ME, Carpentieri AR, Garbarino-Pico E. Circadian phototransduction and the regulation of biological rhythms. Neurochem Res 2002; 27:1473-89. [PMID: 12512952 DOI: 10.1023/a:1021696321391] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The vertebrate circadian system that controls most biological rhythms is composed of multiple oscillators with varied hierarchies and complex levels of organization and interaction. The retina plays a key role in the regulation of daily rhythms and light is the main synchronizer of the circadian system. To date, the identity of photoreceptors/photopigments responsible for the entrainment of biological rhythms is still uncertain; however, it is known that phototransduction must occur in the eye because light entrainment is lost with eye removal. The retina is also rhythmic in physiological and metabolic activities as well as in gene expression. Retinal oscillators may act like clocks to induce changes in the visual system according to the phase of the day by predicting environmental changes. These oscillatory and photoreceptive capacities are likely to converge all together on selected retinal cells. The aim of this overview is to present the current knowledge of retinal physiology in relation to the circadian timing system.
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Affiliation(s)
- Mario E Guido
- CIQUIBIC (CONICET)-Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Cuidad Universitaria, 5000 Córdoba, Argentina.
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Wai SM, Yew DT. A cytological study on the development of the different types of visual cells in the chicken (Gallus domesticus). Cell Mol Neurobiol 2002; 22:57-85. [PMID: 12064518 DOI: 10.1023/a:1015393729005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The formation of visual cells and their intracellular organelles was studied in the embryonic chicken (Gallus domesticus) between stage 36 and hatching. Cilia formation was observed at stage 30 and by stage 42, outer segment formation from the cilia was evident. The inner segments appeared as buddings at stage 36. By stage 37, the buddings of double cones were observed clearly and such buddings elongated by stage 42. Both the single cones and rods appeared as buddings by stage 38 and elongation of the buddings was seen by stage 42. Oil droplets initially appeared by stage 39 in accessory cones and were observed in other cones by stage 42. Glycogen bodies were demonstrated firstly in rods and accessory cones at stage 43 and their development was completed by stage 45. In essence, all the essential elements of the visual cells were fully developed by hatching.
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Affiliation(s)
- Sen Mun Wai
- Department of Anatomy, The Chinese University of Hong Kong, Shatin, New Territories
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Larkin P, Semple-Rowland SL. A null mutation in guanylate cyclase-1 alters the temporal dynamics and light entrainment properties of the iodopsin rhythm in cone photoreceptor cells. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 92:49-57. [PMID: 11483241 DOI: 10.1016/s0169-328x(01)00136-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Guanylate cyclase-1 (GC1) plays a critical role in visual phototransduction and its absence severely compromises the ability of the photoreceptor cells to transduce light for vision. In this study we sought to determine if the absence of GC1 has any effect on light entrainment of the circadian oscillators located in these cells. We compared the rhythmic changes in transcript levels of iodopsin, a photoreceptor-specific gene whose expression is regulated by circadian oscillators, in retinas of normal chickens and GUCY1*B (*B) chickens that carry a null mutation in GC1. Our results show that iodopsin rhythms are present in *B retinas and that they can be entrained to light; however, the rise and fall of iodopsin transcript levels in *B retina under cyclic light conditions is significantly more rapid than that observed in normal retina, and under constant dark conditions, the phase of the iodopsin rhythm in *B retina is advanced by 6 h relative to that observed in normal retina. In addition, the rate of entrainment of the iodopsin rhythm in *B retina to a reversal of the light cycle is significantly slower than normal. The results of our study show that a functioning visual phototransduction cascade is not essential for light entrainment of the oscillators that drive the iodopsin rhythm in photoreceptor cells. We propose that the abnormal synthesis of cGMP in *B photoreceptors underlies the irregular iodopsin rhythms observed in post-hatch *B retina.
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Affiliation(s)
- P Larkin
- Department of Neuroscience, McKnight Brain Institute, University of Florida, 100 S. Newell Dr., Gainesville, FL 32610-0244, USA
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McBee JK, Palczewski K, Baehr W, Pepperberg DR. Confronting complexity: the interlink of phototransduction and retinoid metabolism in the vertebrate retina. Prog Retin Eye Res 2001; 20:469-529. [PMID: 11390257 DOI: 10.1016/s1350-9462(01)00002-7] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Absorption of light by rhodopsin or cone pigments in photoreceptors triggers photoisomerization of their universal chromophore, 11-cis-retinal, to all-trans-retinal. This photoreaction is the initial step in phototransduction that ultimately leads to the sensation of vision. Currently, a great deal of effort is directed toward elucidating mechanisms that return photoreceptors to the dark-adapted state, and processes that restore rhodopsin and counterbalance the bleaching of rhodopsin. Most notably, enzymatic isomerization of all-trans-retinal to 11-cis-retinal, called the visual cycle (or more properly the retinoid cycle), is required for regeneration of these visual pigments. Regeneration begins in rods and cones when all-trans-retinal is reduced to all-trans-retinol. The process continues in adjacent retinal pigment epithelial cells (RPE), where a complex set of reactions converts all-trans-retinol to 11-cis-retinal. Although remarkable progress has been made over the past decade in understanding the phototransduction cascade, our understanding of the retinoid cycle remains rudimentary. The aim of this review is to summarize recent developments in our current understanding of the retinoid cycle at the molecular level, and to examine the relevance of these reactions to phototransduction.
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Affiliation(s)
- J K McBee
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
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Degrip W, Rothschild K. Chapter 1 Structure and mechanism of vertebrate visual pigments. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1383-8121(00)80004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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