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O Hisatomi

Publications and source records attributed to O Hisatomi.

33 records · Page 2Linked to original sources
PubMed1997

Functional expression and site-directed mutagenesis of photoactive yellow protein.

The gene encoding photoactive yellow protein (PYP) was isolated from Ectothiorhodospira halophila, and a high-level expression system for PYP was constructed in Escherichia coli. The molecular weight and the absorption spectrum of PYP expressed in E. coli were identical with those of the native PYP isolated from E. halophila. The amino acid residues which might interact with the chromophore (Tyr42, Glu46, Thr50, Arg52, and Cys69) were mutated by site-directed mutagenesis and the absorption spectra of these mutants were examined to study the chromophore/protein interaction in PYP. The former three substitutions (Y42F, E46Q, and T50V) brought about red-shifts of the absorption spectra, but the substitution of Arg52 (R52Q) brought about no change and that of Cys69 (C69S) led to no formation of pigments. These results suggest that Tyr42, Glu46, and Thr50 strongly interact with the chromophore, while Arg52 does not contribute the color tuning of PYP.

Amino Acid Sequence↗
PubMed1997

Characterization of lamprey rhodopsin by isolation from lamprey retina and expression in mammalian cells.

A visual pigment was extracted from lamprey retina and was expressed in cultured mammalian cells (293S) using a cDNA fragment isolated from lamprey retina. The extracted pigment, a putative lamprey rhodopsin, had an absorption maximum at 503 nm. The recombinant lamprey rhodopsin, reconstituted with 11-cis-retinal, showed an absorption maximum at about 500 nm. Both pigments reacted with an anti-bovine rhodopsin antibody (Rh29), which recognizes the short photoreceptor cells in lamprey retina. Unlike rhodopsins of higher vertebrates, the lamprey rhodopsin bleached gradually in the presence of 100 mM hydroxylamine even in the dark. Our results suggest that, despite its high similarities with other vertebrate rhodopsins, lamprey rhodopsin has a character different from those of higher vertebrates.

Animals↗
PubMed1996

Photoreceptor protein s26, a cone homologue of S-modulin in frog retina.

A frog retinal protein named s26 is a 26-kDa protein found during purification of S-modulin in frog retina (Kawamura, S. (1992) Photochem. Photobiol. 56, 1173-1180). To identify its role in frog retina, first s26 was purified to nearly homogeneity with three chromatographical steps. Based on the partial amino acid sequences of the proteolysed fragments of s26, we isolated cDNAs that encode s26. The analysis of its amino acid sequence revealed that s26 is an S-modulin-like protein, while it shows higher homology to visinin. Visinin is a Ca2+-binding protein reported to be present in chicken cones, but its localization in the retina had been a subject in dispute. The present study showed that s26 is present in cone photoreceptors. The study also showed that s26 inhibits phosphorylation of rhodopsin after a light flash at high Ca2+ concentrations as S-modulin does. From these results, we concluded that s26 is a cone homologue of S-modulin. The result is consistent with the idea that each type of photoreceptors expresses each cell-type specific version of phototransduction proteins.

Amino Acid Sequence↗
PubMed1996

Molecular properties of chimerical mutants of gecko blue and bovine rhodopsin.

In spite of the high similarity in amino acid sequence between rod visual pigment rhodopsin and gecko blue-sensitive pigment (gecko blue), not only the spectral sensitivities but also the thermal decay rates of the meta II- and III-intermediates are noticeably different from one another [Kojima et al. (1995) Biochemistry 34, 1096-1106]. In order to identify the protein region(s) that contain(s) key residue being responsible for the functional difference, we constructed six chimerical mutants derived from gecko blue and bovine rhodopsin, with the aid of protein production in a human embryonic kidney cell line (293S). While the absorption maximum of every mutant was located in between gecko blue (466 nm) and bovine rhodopsin (500 nm), a large blue-shift (18 nm) was observed when the helices I-III of rhodopsin were replaced with those of gecko blue. A time resolved spectroscopic study demonstrated that this replacement also accelerated the decay rate of the meta II-intermediate. The decay of the meta III-intermediate of the mutants became faster as the compartment of gecko blue was increased. Thus, the faster decay of the meta II-intermediate of gecko blue is largely attributed to residues within helices I-III, while the decay of the meta III-intermediate apparently depends on the overall structure of the protein.

Animals↗
PubMed1996

Molecular cloning and characterization of the putative ultraviolet-sensitive visual pigment of goldfish.

A cDNA full length encoding a putative ultraviolet (UV)-sensitive visual pigment of goldfish was isolated. The deduced amino acid sequence shows 64% identity to those of human blue and chicken violet, and less identity (40-49%) to those of other vertebrate visual pigment. The mRNA is localized in the miniature short single cone cells, which are known to have a sensitivity maximum in the near UV-region.

Amino Acid Sequence↗
PubMed1996

Lectin cytochemical analysis of glycoconjugates in photoreceptor cell membranes of Lampetra japonica.

Seven types of ferritinized lectin were used to examine the distribution of glycoconjugates on the outer segment membranes of lamprey photoreceptor cells. Ultrastructural pre-embedding labeling revealed that peanut agglutinin, soybean agglutinin and Ricinus communis agglutinin I were preferentially bound to the proximal, lateral and luminal surfaces of the long cell outer segments, whereas Griffonia simplicifolia agglutinin II and concanavalin A agglutinin were bound to the corresponding surfaces of the short cell outer segments. The results indicate that there is marked difference in the composition of glycoconjugates over the outer segment membranes between long and short photoreceptors.

Animals↗
PubMed1996

Two opsins from the compound eye of the crab Hemigrapsus sanguineus

The primary structures of two opsins from the brachyuran crab Hemigrapsus sanguineus were deduced from the cDNA nucleotide sequences. Both deduced proteins were composed of 377 amino acid residues and included residues highly conserved in visual pigments of other species, and the proteins were 75 % identical to each other. The distribution of opsin transcripts in the compound eye, determined by in situ hybridization, suggested that the mRNAs of the two opsins were expressed simultaneously in all of the seven retinular cells (R1-R7) forming the main rhabdom in each ommatidium. Two different visual pigments may be present in one photoreceptor cell in this brachyuran crab. The spectral sensitivity of the compound eye was also determined by recording the electroretinogram. The compound eye was maximally sensitive at about 480 nm. These and previous findings suggest that both opsins of this brachyuran crab produce visual pigments with maximal absorption in the blue-green region of the spectrum. Evidence is presented that crustaceans possess multiple pigment systems for vision.

Journal Article↗
PubMed1996

Temporal expression of rod and cone opsins in embryonic goldfish retina predicts the spatial organization of the cone mosaic.

PURPOSE: Cone photoreceptors in teleost fish retina are organized into a precise, crystalline mosaic in which the four spectral subtypes have a consistent position relative to each other. The objective of the current study was to describe the spatial and temporal progression of photoreceptor differentiation in the embryonic goldfish retina to understand how the retinal cone mosaic might be produced. METHODS: To identify developing photoreceptors when they first begin to express a specific opsin, the authors used in situ hybridization with cRNA probes generated from cDNA for rod opsin and red, green, blue, and ultraviolet cone opsins from goldfish (Carassius auratus). RESULTS: In the retina, rod opsin was expressed first, and it was restricted to a small patch of regularly spaced, precocious rods located near the ventronasal edge of the retina, close to the choroid fissure. The patch enlarged by recruitment of additional rods in a circular path, moving from ventral to nasal to dorsal to temporal retina. Expression of cone opsins began approximately 10 hours after rod opsin was first expressed, and differentiation of cone photoreceptors followed the spatial pattern laid down by the early rods. The temporal order of onset of cone opsin expression was red, then green, then blue, then ultraviolet. When rod and red cone opsin probes were combined, the number of labeled cells was additive, suggesting that these two opsins are expressed in separate populations of photoreceptors. CONCLUSIONS: The onset of opsin expression in goldfish retina follows a highly ordered spatio-temporal pattern. Early differentiation and regular spacing of the precocious rods was unexpected and suggested that they may play a role in cone mosaic patterning. The order of subsequent cone opsin expression was related to the relative positions of cone subtype in the mosaic, suggesting the possibility that inductive interactions among developing photoreceptors may be responsible for patterning the cone mosaic array.

Animals↗
PubMed1995

Cloning and expression of frog rhodopsin cDNA.

The cDNA encoding the putative rhodopsin of frog (Rana catesbeiana) was cloned and expressed in cultured cells. The deduced amino acid sequence (354 residues) has more than 90% identity with the rhodopsins of two other frogs (Rana pipiens and Xenopus laevis) and 80% identity with other vertebrate rhodopsins. The isoelectric point calculated from the sequence was about 8.2, which is intermediate between rhodopsins and the cone visual pigments of higher vertebrates. The cloned cDNA was expressed in cultured mammalian cells. The difference absorbance maximum before and after photobleaching was about 500 nm, the same as that observed in the retina, demonstrating that the cloned cDNA does indeed encode functional rhodopsin.

Amino Acid Sequence↗
PubMed1994

Phylogenetic relationships among vertebrate visual pigments.

Genomic DNA fragments in exon 4 of chicken, goldfish and salmon visual pigments were amplified by polymerase chain reaction, using oligonucleotide mixtures as primers, and hypothetical phylogenetic trees were drawn up from the deduced amino acid sequences. The results suggest that vertebrate visual pigments have evolved along at least five lines, and that these lines diverged from an ancestral gene before the bony fishes diverged from the rest of the higher vertebrates.

Amino Acid Sequence↗
PubMed1993

Recoverin has S-modulin activity in frog rods.

In vertebrate photoreceptors, light induces hydrolysis of cGMP by activating cGMP phosphodiesterase (PDE), which results in closure of the cGMP-activated cation channel. During light adaptation, the cytoplasmic Ca2+ concentration decreases, and this decrease is one of the underlying mechanisms of light adaptation. Sensitivity-modulating protein (S-modulin) is a Ca(2+)-binding protein involved in light adaptation in frog rods; it regulates both the light sensitivity of PDE and the lifetime of activated PDE by controlling rhodopsin phosphorylation in a Ca(2+)-dependent manner. Recoverin has been reported as a Ca(2+)-dependent regulator of guanylate cyclase in bovine rods (Dizhoor, A. M., Ray, S., Kumar, S., Niemi, G., Spencer, M., Brolley, D., Walsh, K. A. Philipov, P. P., Hurley, J. B., and Stryer, L. (1991) Science 251, 915-918). Here, we show that recoverin has similar activity as S-modulin, and the amino acid sequences of both proteins are similar. The results strongly suggest that recoverin is bovine S-modulin and regulates PDE activation.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1991

Isolation and characterization of lamprey rhodopsin cDNA.

Genomic DNA fragments coding a visual pigment of the lamprey were amplified by polymerase chain reaction, using oligonucleotide mixtures as primers. The complete coding region of the cDNA was obtained by separate amplification of both cDNA ends. The deduced amino acid sequence of the coding region showed 78-82% identity with those of rhodopsins of higher vertebrates, but only 43-47% identity with those of human color pigments. The cloned DNA appears to be the cDNA of a lamprey rhodopsin, which is expressed in the "short" photoreceptor cell.

Amino Acid Sequence↗
PubMed1989

Demonstration by lectin cytochemistry of rod and cone photoreceptors in the lamprey retina.

Lectin cytochemical analysis was undertaken to examine the distribution of glycoconjugates associated with the short and long photoreceptor cells in the lamprey retina. Concanavalin A bound preferentially to the outer segment region of the short cells. Wheat germ agglutinin bound weakly to both long and short cells. The outer segment regions of the long cells were stained intensely with peanut agglutinin. Pretreatment with neuraminidase to remove sialic acid resulted in decreased binding of wheat germ agglutinin throughout the retina and increased binding of peanut agglutinin to the outer segment region of the short cells and the region of myoid process of the long cells. These results suggest that there is a difference in the distribution of glycoconjugate residues between the long and short cells. A rod-like character of the short cell and a cone-like character of the long are tentatively discussed. Lectin-binding patterns in other retinal regions is also examined.

Animals↗
PubMed1982

Electron microscopic observation on phase transition of purple membrane.

Structural changes during the thermal phase transition of purple membrane were observed by freeze-fracture electron microscopy. Native Halobacterium halobium cells contain broad purple membrane areas about 1 micron in diameter. The boundary separating purple and red membranes is obvious. On warming at 80 degrees C, particles of red membrane spread out beyond the boundary. Then a purple membrane area is eventually divided into small areolae of similar size, about 0.1 micron in diameter. By cooling down slowly, the purple membrane area is reformed and the crystalline arrangement also restored.

Bacteriorhodopsins↗