The Experts below are selected from a list of 690 Experts worldwide ranked by ideXlab platform
Andrew J Young - One of the best experts on this subject based on the ideXlab platform.
-
the effect of artificial diets on gonad colour and biomass in the edible sea urchin psammechinus miliaris
Aquaculture, 2011Co-Authors: Coleen C Suckling, Rachael C Symonds, Maeve Kelly, Andrew J YoungAbstract:Abstract During two 12 week trials, groups of edible sea urchins, Psammechinus miliaris, were fed artificial diets containing carotenoid pigments. The aim was to improve both the biomass and the colour of the sea urchin gonad in terms of its acceptability as a human food-stuff in the European market place. The pigmented artificial diets, based on the formula used by Robinson et al. (2002) , increased gonad index (GI), pigment deposition and improved gonad colour from that of the initial samples. In Trial I gonad β-carotene levels increased > 2 fold, Echinenone and total carotenoid > 7 fold. Trial II showed greater increases. Diets containing high levels of β-carotene (500 mg per kg dry weight of diet) gave rise to the highest percentages of marketable gonad colours (61–73%), and GI of 17.87–19.81%, (Trial I and II respectively). There was some variation in the results for this particular diet treatment across the two trials presumably reflecting individual urchins varying capacity to ingest, deposit or express the carotenoids in their diet. Providing additional lipids in the diets gave no improvement to gonad colour (56% acceptable) or GI (15.95%) suggesting the lipid content of the basic formulation is adequate. Utilizing an esterified form of lutein and zeaxanthin as a pigment source gave no significant improvement in gonad colour (30–63% acceptable) suggesting that this form of xanthophyll cannot be assimilated by P. miliaris. Female urchins had acceptable gonad colouration more often than males. The dominant carotenoid in the successful diets was β-carotene and this was successfully metabolized into Echinenone, the dominant carotenoid in all gonad samples. Total levels of Echinenone positively correlated with acceptable gonad colour scores. This study demonstrates that 12 weeks is sufficient to effect the desired change in gonad biomass and colour in cultivated P. miliaris.
-
carotenoids in the sea urchin paracentrotus lividus occurrence of 9 cis Echinenone as the dominant carotenoid in gonad colour determination
Comparative Biochemistry and Physiology B, 2007Co-Authors: Rachael C Symonds, Maeve S Kelly, Catherine Carisveyra, Andrew J YoungAbstract:Abstract Regular sampling of wild Paracentrotus lividus was carried out over a 12-month period to examine seasonal effects on the pigment profile and content of the gonads, especially in comparison to gonad colour. The major pigments detected in the gut wall were breakdown products of fucoxanthin, namely fucoxanthinol and amarouciaxanthin A. Lower levels of other dietary carotenoids (lutein and β-carotene) together with some carotenoids not found in the diet, namely isozeaxanthin and Echinenone (∼ 20% total carotenoid) were also detected in the gut wall. The presence of Echinenone in the gut wall demonstrates that this organ acts as a major site of carotenoid metabolism. Echinenone is the dominant carotenoid in the gonads, accounting for approx. 50–60% of the total pigment. Both all-trans and 9′-cis forms of Echinenone were detected in both the gut wall and in the gonad, with levels of the 9′-cis form typically 10-fold greater than the all-trans form in the gonad. The detection of large levels of 9′-cis-Echinenone in wild sea urchins is unexpected due to the absence of 9- or 9′-cis forms of carotenoids in the natural, algal, diet. Whilst Echinenone clearly contributes towards gonad pigmentation, levels of this carotenoid, cannot be directly linked to a qualitative assessment of gonad colour in terms of market acceptability. Indeed, unacceptable gonad colouration can be seen with both very low and high levels of Echinenone and total carotenoid. The presence of 9′-cis-Echinenone as the major carotenoid contributing to the pigmentation/colour of the gonad is an important observation in terms of developing artificial diets for urchin cultivation.
Diana Kirilovsky - One of the best experts on this subject based on the ideXlab platform.
-
photoactivation mechanism timing of protein secondary structure dynamics and carotenoid translocation in the orange carotenoid protein
Journal of the American Chemical Society, 2019Co-Authors: Patrick E Konold, Adjélé Wilson, Diana Kirilovsky, Ivo H M Van Stokkum, Fernando Muzzopappa, Marie Louise Groot, John T M KennisAbstract:The orange carotenoid protein (OCP) is a two-domain photoactive protein that noncovalently binds an Echinenone (ECN) carotenoid and mediates photoprotection in cyanobacteria. In the dark, OCP assumes an orange, inactive state known as OCPO; blue light illumination results in the red active state, known as OCPR. The OCPR state is characterized by large-scale structural changes that involve dissociation and separation of C-terminal and N-terminal domains accompanied by carotenoid translocation into the N-terminal domain. The mechanistic and dynamic-structural relations between photon absorption and formation of the OCPR state have remained largely unknown. Here, we employ a combination of time-resolved UV–visible and (polarized) mid-infrared spectroscopy to assess the electronic and structural dynamics of the carotenoid and the protein secondary structure, from femtoseconds to 0.5 ms. We identify a hereto unidentified carotenoid excited state in OCP, the so-called S* state, which we propose to play a key ro...
-
photoactivation mechanism timing of protein secondary structure dynamics and carotenoid translocation in the orange carotenoid protein
Journal of the American Chemical Society, 2019Co-Authors: Patrick E Konold, Adjélé Wilson, Diana Kirilovsky, Fernando Muzzopappa, Marie Louise Groot, Ivo H M Van Stokkum, John T M KennisAbstract:The orange carotenoid protein (OCP) is a two-domain photoactive protein that noncovalently binds an Echinenone (ECN) carotenoid and mediates photoprotection in cyanobacteria. In the dark, OCP assumes an orange, inactive state known as OCPO; blue light illumination results in the red active state, known as OCPR. The OCPR state is characterized by large-scale structural changes that involve dissociation and separation of C-terminal and N-terminal domains accompanied by carotenoid translocation into the N-terminal domain. The mechanistic and dynamic-structural relations between photon absorption and formation of the OCPR state have remained largely unknown. Here, we employ a combination of time-resolved UV–visible and (polarized) mid-infrared spectroscopy to assess the electronic and structural dynamics of the carotenoid and the protein secondary structure, from femtoseconds to 0.5 ms. We identify a hereto unidentified carotenoid excited state in OCP, the so-called S* state, which we propose to play a key ro...
-
Echinenone Vibrational Properties : From Solvents to the Orange Carotenoid Protein.
Biochimica et Biophysica Acta (BBA) - Reviews on Bioenergetics, 2015Co-Authors: Elizabeth Kish, Diana Kirilovsky, M.m. Mendes Pinto, Riccardo Spezia, Bruno RobertAbstract:Orange carotenoid protein (OCP) is a cyanobacterial photoactive protein which binds Echinenone as a chromophore; it is involved in photoprotection of these photosynthetic organisms against intense illumination. In its resting state, OCP appears orange (OCPo), and turns into a red form (OCPr) when exposed to blue-green light. Here we have combined resonance Raman spectroscopy and molecular modeling to investigate the mechanisms underlying the electronic absorption properties of the different forms of OCP. Our results show that there are at least two carotenoid configurations in the OCPo, suggesting that it is quite flexible, and that the OCPo to OCPr transition must involve an increase of the apparent conjugation length of the bound Echinenone. Resonance Raman indicates that this chromophore must be in an all-trans configuration in OCPo. Density functional theory (DFT) calculations, in agreement with the Raman spectra of both OCP forms, show that the OCPo to OCPr transition must involve either an Echinenone s-cis to s-trans isomerization which would affect the position of its conjugated end-chain rings, or a bending of the Echinenone rings which would bring them from out of the plane of the CC conjugated plane in the OCPo form into the CC plane in the OCPr form.
-
Influence of zeaxanthin and Echinenone binding on the activity of the Orange Carotenoid Protein
Biochimica biophysica acta (BBA) - Bioenergetics, 2009Co-Authors: Claire Punginelli, Adjélé Wilson, Jean-marc Routaboul, Diana KirilovskyAbstract:In most cyanobacteria high irradiance induces a photoprotective mechanism that downregulates photosynthesis by increasing thermal dissipation of the energy absorbed by the phycobilisome, the watersoluble antenna. The light activation of a soluble carotenoid protein, the Orange-Carotenoid-Protein (OCP), binding hydroxyEchinenone, a keto carotenoid, is the key inducer of this mechanism. Light causes structural changes within the carotenoid and the protein, leading to the conversion of a dark orange form into a red active form. Here, we tested whether Echinenone or zeaxanthin can replace hydroxyEchinenone in a study in which the nature of the carotenoid bound to the OCP was genetically changed. In a mutant lacking hydroxyEchinenone and Echinenone, the OCP was found to bind zeaxanthin but the stability of the binding appeared to be lower and light was unable to photoconvert the dark form into a red active form. Moreover, in the strains containing zeaxanthin-OCP, blue-green light did not induce the photoprotective mechanism. In contrast, in mutants in which Echinenone is bound to the OCP, the protein is photoactivated and photoprotection is induced. Our results strongly suggest that the presence of the carotenoid carbonyl group that distinguishes Echinenone and hydroxyEchinenone from zeaxanthin is essential for the OCP activity.
Gerhard Sandmann - One of the best experts on this subject based on the ideXlab platform.
-
catalytic properties and reaction mechanism of the crto carotenoid ketolase from the cyanobacterium synechocystis sp pcc 6803
Archives of Biochemistry and Biophysics, 2013Co-Authors: Jurgen Breitenbach, Tanja Gerjets, Gerhard SandmannAbstract:Abstract CrtW and CrtO are two distinct non-homologous β-carotene ketolases catalyzing the formation of Echinenone and canthaxanthin. CrtO belongs to the CrtI family which comprises carotene desaturases and carotenoid oxidases. The CrtO protein from Synechocystis sp. PCC 6803 has been heterologously expressed, extracted and purified. Substrate specificity has been determined in vitro. The enzyme from Synechocystis is basically a mono ketolase. Nevertheless, small amounts of diketo canthaxanthin can be formed. The poor diketolation reaction could be explained by the low relative turnover numbers for the mono keto Echinenone. Also other carotenoids with an unsubstituted β-ionone ring were utilized with low conversion rates by CrtO regardless of the substitutions at the other end of the molecule. The CrtO ketolase was independent of oxygen and utilized an oxidized quinone as co-factor. In common to CrtI-type desaturases, the first catalytic step involved hydride transfer to the quinone. The stabilization reaction of the resulting carbo cation was a reaction with OH− forming a hydroxy group. Finally, the keto group resulted from two subsequent hydroxylations at the same C-atom and water elimination. This reaction mechanism was confirmed by in vitro conversion of the postulated hydroxy intermediates and by their enrichment and identification as trace intermediates during ketolation.
-
a new type of asymmetrically acting β carotene ketolase is required for the synthesis of Echinenone in the cyanobacterium synechocystis sp pcc 6803
Journal of Biological Chemistry, 1997Co-Authors: Blanca Fernandezgonzalez, Gerhard Sandmann, Agustin VioqueAbstract:We have isolated, based on the knowledge of the complete genomic sequence of the cyanobacterium Synechocystis sp. PCC 6803, an open reading frame (slr0088) similar to known bacterial carotene desaturases and have analyzed the function of the encoded protein. Surprisingly, this protein has no detectable desaturase activity with phytoene, hydroxyneurosporene, or ζ-carotene as substrates, but is rather a β-carotene ketolase that acts asymmetrically introducing a keto group on only one of the two β-ionone rings of β-carotene to generate Echinenone. This is in contrast to the so far characterized β-carotene ketolases that act symmetrically, producing the di-keto carotenoid canthaxanthin from β-carotene without significant accumulation of Echinenone. We have designated this new gene crtO The function of the crtO gene product has been demonstrated by 1) the biosynthesis of Echinenone when the crtO gene is expressed in an Escherichia coli strain able to accumulate β-carotene, 2) the in vitro biosynthesis of Echinenone from β-carotene with cell free extracts from E. coli cells that express the crtO gene, and 3) the absence of Echinenone in a Synechocystis strain in which the crtO gene has been insertionally inactivated. The primary structure of the Synechocystis asymmetric ketolase bears no similarity with the known β-carotene ketolases. crtO is not required for normal growth under standard or high light conditions, neither is the photosynthetic activity of the crtO-deficient strain affected.
Shinichi Takaichi - One of the best experts on this subject based on the ideXlab platform.
-
zeaxanthin and Echinenone protect the repair of photosystem ii from inhibition by singlet oxygen in synechocystis sp pcc 6803
Plant and Cell Physiology, 2015Co-Authors: Yuri Kusama, Shinichi Takaichi, Shuhei Inoue, Haruhiko Jimbo, Kintake Sonoike, Yukako Hihara, Yoshitaka NishiyamaAbstract:Carotenoids are important components of antioxidative systems in photosynthetic organisms. We investigated the roles of zeaxanthin and Echinenone in the protection of PSII from photoinhibition in Synechocystis sp. PCC 6803, using mutants of the cyanobacterium that lack these carotenoids. The activity of PSII in mutant cells deficient in either zeaxanthin or Echinenone was more sensitive to strong light than the activity in wild-type cells, and the activity in mutant cells deficient in both carotenoids was hypersensitive to strong light, indicating that the absence of these carotenoids increased the extent of photoinhibition. Nonetheless, the rate of photodamage to PSII, as measured in the presence of chloramphenicol, which blocks the repair of PSII, was unaffected by the absence of either carotenoid, suggesting that these carotenoids might act by protecting the repair of PSII. Knockout of the gene for the so-called orange carotenoid protein (OCP), in which the 3'-hydroxyEchinenone cofactor, a derivative of Echinenone, is responsible for the thermal dissipation of excitation energy, increased the extent of photoinhibition but did not affect photodamage, suggesting that thermal dissipation also protects the repair of PSII. In mutant cells lacking OCP, as well as those lacking zeaxanthin and Echinenone, the production of singlet oxygen was stimulated and the synthesis de novo of various proteins, including the D1 protein, was markedly suppressed under strong light. These observations suggest that the carotenoids and thermal dissipation might protect the repair of photodamaged PSII by depressing the levels of singlet oxygen that inhibits protein synthesis.
-
the cyanobacterium anabaena sp pcc 7120 has two distinct β carotene ketolases crto for Echinenone and crtw for ketomyxol synthesis
FEBS Letters, 2005Co-Authors: Mari Mochimaru, Hajime Masukawa, Shinichi TakaichiAbstract:Two β-carotene ketolases, CrtW and CrtO, are widely distributed in bacteria, although they show no significant sequence homology with each other. The cyanobacterium Anabaena sp. PCC 7120 was found to have two homologous genes. In the crtW deleted mutant, myxol 2′-fucoside was present, but ketomyxol 2′-fucoside was absent. In the crtO deleted mutant, β-carotene was accumulated, and the amount of Echinenone was decreased. Therefore, CrtW catalyzed myxol 2′-fucoside to ketomyxol 2′-fucoside, and CrtO catalyzed β-carotene to Echinenone. This cyanobacterium was the first species found to have both enzymes, which functioned in two distinct biosynthetic pathways.
-
the cyanobacterium gloeobacter violaceus pcc 7421 uses bacterial type phytoene desaturase in carotenoid biosynthesis
FEBS Letters, 2005Co-Authors: Tohru Tsuchiya, Takashi Maoka, Norihiko Misawa, Shinichi Takaichi, Hideaki Miyashita, Mamoru MimuroAbstract:Carotenoid composition and its biosynthetic pathway in the cyanobacterium Gloeobacter violaceus PCC 7421 were investigated. β-Carotene and (2S,2′S)-oscillol 2,2′-di(α-l-fucoside), and Echinenone were major and minor carotenoids, respectively. We identified two unique genes for carotenoid biosynthesis using in vivo functional complementation experiments. In Gloeobacter, a bacterial-type phytoene desaturase (CrtI), rather than plant-type desaturases (CrtP and CrtQ), produced lycopene. This is the first demonstration of an oxygenic photosynthetic organism utilizing bacterial-type phytoene desaturase. We also revealed that Echinenone synthesis is catalyzed by CrtW rather than CrtO. These findings indicated that Gloeobacter retains ancestral properties of carotenoid biosynthesis.
Rachael C Symonds - One of the best experts on this subject based on the ideXlab platform.
-
the effect of artificial diets on gonad colour and biomass in the edible sea urchin psammechinus miliaris
Aquaculture, 2011Co-Authors: Coleen C Suckling, Rachael C Symonds, Maeve Kelly, Andrew J YoungAbstract:Abstract During two 12 week trials, groups of edible sea urchins, Psammechinus miliaris, were fed artificial diets containing carotenoid pigments. The aim was to improve both the biomass and the colour of the sea urchin gonad in terms of its acceptability as a human food-stuff in the European market place. The pigmented artificial diets, based on the formula used by Robinson et al. (2002) , increased gonad index (GI), pigment deposition and improved gonad colour from that of the initial samples. In Trial I gonad β-carotene levels increased > 2 fold, Echinenone and total carotenoid > 7 fold. Trial II showed greater increases. Diets containing high levels of β-carotene (500 mg per kg dry weight of diet) gave rise to the highest percentages of marketable gonad colours (61–73%), and GI of 17.87–19.81%, (Trial I and II respectively). There was some variation in the results for this particular diet treatment across the two trials presumably reflecting individual urchins varying capacity to ingest, deposit or express the carotenoids in their diet. Providing additional lipids in the diets gave no improvement to gonad colour (56% acceptable) or GI (15.95%) suggesting the lipid content of the basic formulation is adequate. Utilizing an esterified form of lutein and zeaxanthin as a pigment source gave no significant improvement in gonad colour (30–63% acceptable) suggesting that this form of xanthophyll cannot be assimilated by P. miliaris. Female urchins had acceptable gonad colouration more often than males. The dominant carotenoid in the successful diets was β-carotene and this was successfully metabolized into Echinenone, the dominant carotenoid in all gonad samples. Total levels of Echinenone positively correlated with acceptable gonad colour scores. This study demonstrates that 12 weeks is sufficient to effect the desired change in gonad biomass and colour in cultivated P. miliaris.
-
carotenoids in the sea urchin paracentrotus lividus occurrence of 9 cis Echinenone as the dominant carotenoid in gonad colour determination
Comparative Biochemistry and Physiology B, 2007Co-Authors: Rachael C Symonds, Maeve S Kelly, Catherine Carisveyra, Andrew J YoungAbstract:Abstract Regular sampling of wild Paracentrotus lividus was carried out over a 12-month period to examine seasonal effects on the pigment profile and content of the gonads, especially in comparison to gonad colour. The major pigments detected in the gut wall were breakdown products of fucoxanthin, namely fucoxanthinol and amarouciaxanthin A. Lower levels of other dietary carotenoids (lutein and β-carotene) together with some carotenoids not found in the diet, namely isozeaxanthin and Echinenone (∼ 20% total carotenoid) were also detected in the gut wall. The presence of Echinenone in the gut wall demonstrates that this organ acts as a major site of carotenoid metabolism. Echinenone is the dominant carotenoid in the gonads, accounting for approx. 50–60% of the total pigment. Both all-trans and 9′-cis forms of Echinenone were detected in both the gut wall and in the gonad, with levels of the 9′-cis form typically 10-fold greater than the all-trans form in the gonad. The detection of large levels of 9′-cis-Echinenone in wild sea urchins is unexpected due to the absence of 9- or 9′-cis forms of carotenoids in the natural, algal, diet. Whilst Echinenone clearly contributes towards gonad pigmentation, levels of this carotenoid, cannot be directly linked to a qualitative assessment of gonad colour in terms of market acceptability. Indeed, unacceptable gonad colouration can be seen with both very low and high levels of Echinenone and total carotenoid. The presence of 9′-cis-Echinenone as the major carotenoid contributing to the pigmentation/colour of the gonad is an important observation in terms of developing artificial diets for urchin cultivation.
