Comparative study on the chromophore binding sites of rod and red-sensitive cone visual pigments by use of synthetic retinal isomers and analogs

Fukada, Yoshitaka; Okano, Toshiyuki; Shichida, Yoshinori; Yoshizawa, T.; Trehan, Achla; Mead, D.; Denny, Marlene; Asato, Alfred E.; Liu, Robert S. H.

doi:10.1021/bi00464a033

Cited by 60 publications

(41 citation statements)

References 21 publications

(31 reference statements)

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“…As for green, only the decay of meta III (closed triangles) was observed (time constant, 3.9 min) due to a rapid conversion of meta II to meta III intermediates at this temperature. , and red (crosses), among which those of rhodopsin, red, green, and blue are reproduced from previous reports (9,11,31,32,41,42).…”

Section: Discussionsupporting

confidence: 55%

Chimeric Nature of Pinopsin between Rod and Cone Visual Pigments

et al. 1999

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Chicken pineal pinopsin is the first example of extra-retinal opsins, but little is known about its molecular properties as compared with retinal rod and cone opsins. For characterization of extra-retinal photon signaling, we have developed an overexpression system providing a sufficient amount of purified pinopsin. The recombinant pinopsin, together with similarly prepared chicken rhodopsin and green-sensitive cone pigment, was subjected to photochemical and biochemical analyses by using low-temperature spectroscopy and the transducin activation assay. At liquid nitrogen temperature (-196 degrees C), we detected two kinds of photoproducts, bathopinopsin and isopinopsin, having their absorption maxima (lambda(max)) at 527 and approximately 440 nm, respectively, and we observed complete photoreversibility among pinopsin, bathopinopsin, and isopinopsin. A close parallel of the photoreversibility to the rhodopsin system strongly suggests that light absorbed by pinopsin triggers the initial event of cis-trans isomerization of the 11-cis-retinylidene chromophore. Upon warming, bathopinopsin decayed through a series of photobleaching intermediates: lumipinopsin (lambda(max) 461 nm), metapinopsin I (460 nm), metapinopsin II (385 nm), and metapinopsin III (460 nm). Biochemical and kinetic analyses showed that metapinopsin II is a physiologically important photoproduct activating transducin. Detailed kinetic analyses revealed that the formation of metapinopsin II is as fast as that of a chicken cone pigment, green, but that the decay process of metapinopsin II is as slow as that of the rod pigment, rhodopsin. These results indicate that pinopsin is a new type of pigment with a chimeric nature between rod and cone visual pigments in terms of the thermal behaviors of the meta II intermediate. Such a long-lived active state of pinopsin may play a role in the pineal-specific phototransduction process.

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Section: Discussionsupporting

confidence: 55%

Chimeric Nature of Pinopsin between Rod and Cone Visual Pigments

et al. 1999

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“…6 (solid line) must be composed of spectra of the photoproducts of iodopsin, rhodopsin, and the greensensitive pigment, because the sample used for the experi- 6. Relative (Rel.)…”

Section: Discussionmentioning

confidence: 99%

“…Like rhodopsin, iodopsin contains li-cis-retinal as its chromophore. Investigations with retinal isomers and analogs suggested that iodopsin and rhodopsin have similarly shaped chromophore binding sites (6) but the point charges are in different locations (6,7).…”

mentioning

confidence: 99%

Bathoiodopsin, a primary intermediate of iodopsin at physiological temperature.

Kandori

Mizukami

Okada

et al. 1990

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

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Measurement of the primary photochemical reaction of iodopsin, a chicken red-sensitive cone visual pigment, was carried out at room temperature by using picosecond (ps) laser photolysis. Excitation of iodopsin with a ps green pulse (pulse width, 21 ps) caused the instantaneous formation of a bathochromic product, which was stable on a ps time scale. This product may correspond to "bathoiodopsin," which was detected by low-temperature spectrophotometry. Although bathoiodopsin produced at the temperature of liquid nitrogen or helium reverted to the original pigment (iodopsin) on warming (above -170'C), the bathoiodopsin produced at physiological temperature decayed to all-trans-retinal and R-photopsin (the protein moiety of iodopsin) presumably through several intermediates. The absorption maximum of bathoiodopsin at room temperature was at 625 nm, a wavelength slightly shorter than that measured at low temperature (A4., 640 nm). The extinction coefficient of bathoiodopsin at room temperature was lower than that at low temperature and close to that of the original iodopsin at room temperature.The vertebrate retina contains two kinds of photoreceptor cells, rods and cones. A rod is a photoreceptor cell that has evolutionally acquired an extremely high photosensitivity so as to act under twilight conditions. The visual pigment in rods is called rhodopsin. Cones, however, act under daylight conditions and have a photoresponse with a wider dynamic range and a faster latency (1). Since there are at least three types of cones, each with its own distinct visual pigment possessing characteristic absorption maximum (2), integration of the photoresponses from cones generates the sensation of color in the visual cortex.The primary photoreceptive mechanism in visual transduction has been extensively investigated in rods, which contain rhodopsin as the visual pigment. Rhodopsin has an 11-cis-retinylidene chromophore attached by a protonated Schiff base linkage to a specific lysine residue of the apoprotein opsin. The primary photochemical event in rhodopsin is an isomerization around the C11=C12 bond of the 11-cisretinylidene chromophore to form photorhodopsin, a highly twisted all-trans photoproduct (3,4 (6, 7).On absorption of light, iodopsin bleaches to all-transretinal and R-photopsin (the protein moiety of iodopsin) by way of lumiiodopsin and then metaiodopsin, according to low-temperature spectrophotometry (8). Yoshizawa and Wald (9) observed that irradiation of iodopsin at the temperature of liquid nitrogen produced bathoiodopsin. Prolonged irradiation of this sample formed a steady-state photo mixture composed of iodopsin, isoiodopsin, and bathoiodopsin. This photochemical behavior of iodopsin is very similar to that of rhodopsin (Fig. 1). On warming, however, an unexpected difference between iodopsin and rhodopsin was observed; unlike bathorhodopsin, bathoiodopsin was not thermally converted to lumiiodopsin but reverted back to iodopsin above -170°C. Thus the question arises whether bathoiodopsin is a physiolo...

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“…The membrane was then washed four times with 200 µL of washing buffer (20 mM Tris–HCl, 100 mM NaCl, and 25 mM MgCl 2 , pH 7.4) to diminish free [ 35 S] GTPγS, and put into 0.9 mL of scintillator (ACS II, GE Healthcare) to measure the radioactivity by a liquid scintillation counter. Gt (α and βγ subunits) was purified from bovine retina as described in literature [34], [35], while Go and Gi were mixtures of Goα [36] and Giα [37] with Gβγ from brain [36].…”

Section: Methodsmentioning

confidence: 99%

UV-Sensitive Photoreceptor Protein OPN5 in Humans and Mice

et al. 2011

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A variety of animal species utilize the ultraviolet (UV) component of sunlight as their environmental cues, whereas physiological roles of UV photoreception in mammals, especially in human beings, remain open questions. Here we report that mouse neuropsin (OPN5) encoded by the Opn5 gene exhibited an absorption maximum (λmax) at 380 nm when reconstituted with 11-cis-retinal. Upon UV-light illumination, OPN5 was converted to a blue-absorbing photoproduct (λmax 470 nm), which was stable in the dark and reverted to the UV-absorbing state by the subsequent orange light illumination, indicating its bistable nature. Human OPN5 also had an absorption maximum at 380 nm with spectral properties similar to mouse OPN5, revealing that OPN5 is the first and hitherto unknown human opsin with peak sensitivity in the UV region. OPN5 was capable of activating heterotrimeric G protein Gi in a UV-dependent manner. Immuno-blotting analyses of mouse tissue extracts identified the retina, the brain and, unexpectedly, the outer ears as the major sites of OPN5 expression. In the tissue sections of mice, OPN5 immuno-reactivities were detected in a subset of non-rod/non-cone retinal neurons as well as in the epidermal and muscle cells of the outer ears. Most of these OPN5-immuno-reactivities in mice were co-localized with positive signals for the alpha-subunit of Gi. These results demonstrate the first example of UV photoreceptor in human beings and strongly suggest that OPN5 triggers a UV-sensitive Gi-mediated signaling pathway in the mammalian tissues.

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Comparative study on the chromophore binding sites of rod and red-sensitive cone visual pigments by use of synthetic retinal isomers and analogs

Cited by 60 publications

References 21 publications

Chimeric Nature of Pinopsin between Rod and Cone Visual Pigments

Chimeric Nature of Pinopsin between Rod and Cone Visual Pigments

Bathoiodopsin, a primary intermediate of iodopsin at physiological temperature.

UV-Sensitive Photoreceptor Protein OPN5 in Humans and Mice

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