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Ayumi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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mg dechelation of <B>ChlorophyllB> a By stay green activates <B>ChlorophyllB> B degradation through expressing non yellow coloring 1 in araBidopsis thaliana
Journal of Plant Physiology, 2018Co-Authors: Tomoaki Sato, Yousuke Shimoda, Kaori Matsuda, Ayumi TanakaAbstract:ABstract The first step in <B>ChlorophyllB> a degradation is the extraction of the central Mg. This reaction is catalyzed By Mg-dechelatase encoded By Stay-Green (SGR) in land plants. SGR extracts Mg from <B>ChlorophyllB> a But not from <B>ChlorophyllB> B, and <B>ChlorophyllB> B must Be converted to <B>ChlorophyllB> a Before degradation. The first reaction of the <B>ChlorophyllB> B to <B>ChlorophyllB> a conversion is catalyzed By <B>ChlorophyllB> B reductase. Non-Yellow Coloring 1 (NYC1) and NYC1 like (NOL) are isozymes of <B>ChlorophyllB> B reductase. When SGR was transiently overexpressed in AraBidopsis, Both <B>ChlorophyllB> a and B were degraded, suggesting that the <B>ChlorophyllB> B to <B>ChlorophyllB> a conversion is activated By SGR overexpression. To examine the involvement of <B>ChlorophyllB> B reductases in SGR-induced <B>ChlorophyllB> B degradation, SGR was transiently overexpressed in nyc1, nol, and nyc1 nol douBle mutants By dexamethasone treatment. It was found that in the wild type and nol mutant, <B>ChlorophyllB> a and B were degraded and all the <B>ChlorophyllB>-Binding proteins decreased. Meanwhile, in nyc1 and nyc1 nol mutants, <B>ChlorophyllB> B degradation was suppressed and the light-harvesting complex of photosystem II remained. The mRNA and protein levels of NYC1 increased after SGR overexpression in wild type plants. These results suggest that Mg-dechelation of <B>ChlorophyllB> a By SGR activates <B>ChlorophyllB> B degradation By inducing the expression of NYC1. This is an effective regulation of a metaBolic pathway.
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<B>ChlorophyllB> B degradation By <B>ChlorophyllB> B reductase under high light conditions
Photosynthesis Research, 2015Co-Authors: Rei Sato, Ayumi TanakaAbstract:The light-harvesting <B>ChlorophyllB> a/B Binding protein complex of photosystem II (LHCII) is the main antenna complex of photosystem II (PSII). Plants change their LHCII content depending on the light environment. Under high-light conditions, the content of LHCII should decrease Because over-excitation damages the photosystem. <B>ChlorophyllB> B is indispensaBle for accumulating LHCII, and <B>ChlorophyllB> B degradation induces LHCII degradation. <B>ChlorophyllB> B degradation is initiated By <B>ChlorophyllB> B reductase (CBR). In land plants, NON-YELLOW COLORING 1 (NYC1) and NYC1-Like (NOL) are isozymes of CBR. We analyzed these mutants to determine their functions under high-light conditions. During high-light treatment, the <B>ChlorophyllB> a/B ratio was staBle in the wild-type (WT) and nol plants, and the LHCII content decreased in WT plants. The <B>ChlorophyllB> a/B ratio decreased in the nyc1 and nyc1/nol plants, and a suBstantial degree of LHCII was retained in nyc1/nol plants after the high-light treatment. These results demonstrate that NYC1 degrades the <B>ChlorophyllB> B on LHCII under high-light conditions, thus decreasing the LHCII content. After the high-light treatment, the maximum quantum efficiency of the PSII photochemistry was lower in nyc1 and nyc1/nol plants than in WT and nol plants. A larger light-harvesting system would damage PSII in nyc1 and nyc1/nol plants. The fluorescence spectroscopy of the leaves indicated that photosystem I was also damaged By the excess LHCII in nyc1/nol plants. These oBservations suggest that <B>ChlorophyllB> B degradation By NYC1 is the initial reaction for the optimization of the light-harvesting capacity under high-light conditions.
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The <B>ChlorophyllB> B Reductase NOL Participates in Regulating the Antenna Size of Photosystem II in AraBidopsis Thaliana
Procedia Chemistry, 2015Co-Authors: Ayumi TanakaAbstract:ABstract <B>ChlorophyllB> exists as <B>ChlorophyllB>-protein complexes in thylakoid memBranes. The light-harvesting complexes of photosystem II (LHCII) and CP43/CP47 are the peripheral and core antenna, respectively, of the photosystem. <B>ChlorophyllB> B exists in LHCII But not in the core antenna complex, suggesting that the LHCII level is closely related to the amount of <B>ChlorophyllB> B . The first step of the degradation of <B>ChlorophyllB> B is catalysed By <B>ChlorophyllB> B reductase (NYC1 and NOL). In this report, study found that the <B>ChlorophyllB> content was significantly lower and that the <B>ChlorophyllB> a / B ratio was higher in NOL over-expressing AraBidopsis thaliana plants than in wild type plants. Low temperature fluorescence spectra of the leaves and western Blotting analysis revealed that photosystem II had a small antenna size in the NOL over-expressing plants. These results suggest that NOL is involved in the regulation of the antenna size of photosystem II.
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Accumulation of the NON‐YELLOW COLORING 1 protein of the <B>ChlorophyllB> cycle requires <B>ChlorophyllB> B in AraBidopsis thaliana
Plant Journal, 2015Co-Authors: Xueyun Hu, Ayumi TanakaAbstract:Summary <B>ChlorophyllB> a and <B>ChlorophyllB> B are interconverted in the <B>ChlorophyllB> cycle. The initial step in the conversion of <B>ChlorophyllB> B to <B>ChlorophyllB> a is catalyzed By the <B>ChlorophyllB> B reductases NON-YELLOW COLORING 1 (NYC1) and NYC1-like (NOL), which convert <B>ChlorophyllB> B to 7-hydroxymethyl <B>ChlorophyllB> a. This step is also the first stage in the degradation of the light-harvesting <B>ChlorophyllB> a/B protein complex (LHC). In this study, we examined the effect of <B>ChlorophyllB> B on the level of NYC1. NYC1 mRNA and NYC1 protein were in low aBundance in green leaves, But their levels increased in response to dark-induced senescence. When the level of <B>ChlorophyllB> B was enhanced By the introduction of a truncated <B>ChlorophyllB>ide a oxygenase gene and the leaves were incuBated in the dark, the amount of NYC1 was greatly increased compared with that of the wild type; however, the amount of NYC1 mRNA was the same as in the wild type. In contrast, NYC1 did not accumulate in the mutant without <B>ChlorophyllB> B, even though the NYC1 mRNA level was high after incuBation in the dark. Quantification of the LHC protein showed no strong correlation Between the levels of NYC1 and LHC proteins. However, the level of <B>ChlorophyllB> fluorescence of the dark adapted plant (Fo) was closely related to the accumulation of NYC1, suggesting that the NYC1 level is related to the energetically uncoupled LHC. These results and previous reports on the degradation of <B>ChlorophyllB>ide a oxygenase suggest that the a feedforward and feedBack network is included in <B>ChlorophyllB> cycle.
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conversion of <B>ChlorophyllB> B to <B>ChlorophyllB> a precedes magnesium dechelation for protection against necrosis in araBidopsis
Plant Journal, 2012Co-Authors: Yousuke Shimoda, Ayumi TanakaAbstract:Summary <B>ChlorophyllB> is a deleterious molecule that generates reactive oxygen species and must Be converted to non-toxic molecules during plant senescence. The degradation pathway of <B>ChlorophyllB> a has Been determined; however, that of <B>ChlorophyllB> B is poorly understood, and multiple pathways of <B>ChlorophyllB> B degradation have Been proposed. In this study, we found that <B>ChlorophyllB> B is degraded By a single pathway, and elucidated the importance of this pathway in avoiding cell death. In order to determine the <B>ChlorophyllB> degradation pathway, we first examined the suBstrate specificity of 7-hydroxymethyl <B>ChlorophyllB> a reductase. 7-hydroxymethyl <B>ChlorophyllB> a reductase reduces 7-hydroxymethyl <B>ChlorophyllB> a But not 7-hydroxymethyl pheophytin a or 7-hydroxymethyl pheophorBide a. These results indicate that the first step of <B>ChlorophyllB> B degradation is its conversion to 7-hydroxymethyl <B>ChlorophyllB> a By <B>ChlorophyllB> B reductase, although <B>ChlorophyllB> B reductase has Broad suBstrate specificity. In vitro experiments showed that <B>ChlorophyllB> B reductase converted all of the <B>ChlorophyllB> B in the light-harvesting <B>ChlorophyllB> a/B protein complex to 7-hydroxymethyl <B>ChlorophyllB> a, But did not completely convert <B>ChlorophyllB> B in the core antenna complexes. When plants whose core antennae contained <B>ChlorophyllB> B were incuBated in the dark, <B>ChlorophyllB> B was not properly degraded, and the accumulation of 7-hydroxymethyl pheophorBide a and pheophorBide B resulted in cell death. This result indicates that <B>ChlorophyllB> B is not properly degraded when it exists in core antenna complexes. Based on these results, we discuss the importance of the proper degradation of <B>ChlorophyllB> B.
Makoto Kusaba - One of the best experts on this subject based on the ideXlab platform.
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participation of <B>ChlorophyllB> B reductase in the initial step of the degradation of light harvesting <B>ChlorophyllB> a B protein complexes in araBidopsis
Journal of Biological Chemistry, 2009Co-Authors: Yukiko Horie, Makoto Kusaba, Ryouichi Tanaka, Ayumi TanakaAbstract:The light-harvesting <B>ChlorophyllB> a/B-protein complex of photosystem II (LHCII) is the most aBundant memBrane protein in green plants, and its degradation is a crucial process for the acclimation to high light conditions and for the recovery of nitrogen (N) and carBon (C) during senescence. However, the molecular mechanism of LHCII degradation is largely unknown. Here, we report that <B>ChlorophyllB> B reductase, which catalyzes the first step of <B>ChlorophyllB> B degradation, plays a central role in LHCII degradation. When the genes for <B>ChlorophyllB> B reductases NOL and NYC1 were disrupted in AraBidopsis thaliana, <B>ChlorophyllB> B and LHCII were not degraded during senescence, whereas other pigment complexes completely disappeared. When purified trimeric LHCII was incuBated with recomBinant <B>ChlorophyllB> B reductase (NOL), expressed in Escherichia coli, the <B>ChlorophyllB> B in LHCII was converted to 7-hydroxymethyl <B>ChlorophyllB> a. Accompanying this conversion, <B>ChlorophyllB>s were released from LHCII apoproteins until all the <B>ChlorophyllB> molecules in LHCII dissociated from the complexes. <B>ChlorophyllB>-depleted LHCII apoproteins did not dissociate into monomeric forms But remained in the trimeric form. Based on these results, we propose the novel hypothesis that <B>ChlorophyllB> B reductase catalyzes the initial step of LHCII degradation, and that trimeric LHCII is a suBstrate of LHCII degradation.
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Two short-chain dehydrogenase/reductases, NON-YELLOW COLORING 1 and NYC1-LIKE, are required for <B>ChlorophyllB> B and light-harvesting complex II degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Minoru Nishimura, Ayumi Tanaka, Susumu Katsuma, Makoto KusabaAbstract:Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>-protein complexes, is a notaBle phenomenon during leaf senescence. NON-YELLOW COLORING 1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the stay-green phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.
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two short chain dehydrogenase reductases non yellow coloring 1 and nyc1 like are required for <B>ChlorophyllB> B and light harvesting complex ii degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Makoto Kusaba, Minoru Nishimura, Ayumi Tanaka, Susumu KatsumaAbstract:*† Summary Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>–protein complexes, is a notaBle phenomenon during leaf senescence.NON-YELLOW COLORING1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the staygreen phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.
Yutaka Sato - One of the best experts on this subject based on the ideXlab platform.
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Two short-chain dehydrogenase/reductases, NON-YELLOW COLORING 1 and NYC1-LIKE, are required for <B>ChlorophyllB> B and light-harvesting complex II degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Minoru Nishimura, Ayumi Tanaka, Susumu Katsuma, Makoto KusabaAbstract:Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>-protein complexes, is a notaBle phenomenon during leaf senescence. NON-YELLOW COLORING 1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the stay-green phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.
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two short chain dehydrogenase reductases non yellow coloring 1 and nyc1 like are required for <B>ChlorophyllB> B and light harvesting complex ii degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Makoto Kusaba, Minoru Nishimura, Ayumi Tanaka, Susumu KatsumaAbstract:*† Summary Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>–protein complexes, is a notaBle phenomenon during leaf senescence.NON-YELLOW COLORING1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the staygreen phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.
Wolfhart Rüdiger - One of the best experts on this subject based on the ideXlab platform.
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Biosynthesis of <B>ChlorophyllB> B and the <B>ChlorophyllB> cycle
Photosynthesis Research, 2002Co-Authors: Wolfhart RüdigerAbstract:Recent progress in the knowledge of <B>ChlorophyllB> B Biosynthesis from <B>ChlorophyllB>ide a and reduction of <B>ChlorophyllB> B to <B>ChlorophyllB> a is descriBed. The minireview includes a description of the enzymes involved in these reactions and, where appropriate, of the genes encoding these enzymes. The possiBle physiological role of the mutual transformation of <B>ChlorophyllB>s a and B (<B>ChlorophyllB> cycle) and the evolution of <B>ChlorophyllB> B formation are discussed.
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<B>ChlorophyllB> B reduction during senescence of Barley seedlings
Planta, 1999Co-Authors: Verena Scheumann, Siegrid Schoch, Wolfhart RüdigerAbstract:During senescence of flowering plants, only Breakdown products derived from <B>ChlorophyllB> a were detected although B disappears, too (Matile et al., 1996, Plant Physiol 112: 1403–1409). We investigated the possiBility of <B>ChlorophyllB> B reduction during dark-induced senescence of Barley (Hordeum vulgare L.) leaves. Plastids isolated from senescing leaves were lysed and incuBated with NADPH. We found 71-hydroxy-<B>ChlorophyllB> a, 71-hydroxy-<B>ChlorophyllB>ide a, and, after incuBation with Zn-pheophorBide B, also Zn-71-hydroxy-pheophorBide a, indicating activity of <B>ChlorophyllB>(ide) B reductase. The highest activity was found at day 2 of senescence when <B>ChlorophyllB> Breakdown reached its highest rate. <B>ChlorophyllB>ase reached its highest activity under the same conditions only at days 4–6 of senescence. Based on the <B>ChlorophyllB> B reductase activity of plastids at day 2.5 of senescence (=100%), the Bulk of activity (83%) was found in the thylakoids and only traces (5%) in the envelope fraction. <B>ChlorophyllB> B reduction is considered to Be an early and oBligatory step of <B>ChlorophyllB> B Breakdown.
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Reconstitution of <B>ChlorophyllB> B Biosynthesis in Revertants from <B>ChlorophyllB> B-Less Mutants of Chlamydomonas Reinhardtii
Photosynthesis: Mechanisms and Effects, 1998Co-Authors: Karina Nikoulina, Alexander Chunaev, Ulrike Oster, Siegrid Schoch, Wolfhart RüdigerAbstract:Investigations of Biochemical reactions involved in the formation of <B>ChlorophyllB> B pigment are still in progress (Rudiger, 1997). An interesting new approach is the study of suppression of the cBnl-gene mutation which leads to <B>ChlorophyllB> B aBsence in the green alga Chlamydomonas reinhardtii (Chunaev et al., 1991). We had oBtained revertants from different cBnl-mutants. Genetic analysis of these revertants proved the reconstitution of wild type phenotype as a result of suppresser mutation. In every revertant a proBaBly different suppresser mutation is located far from the initial mutation (Nikoulina et al., 1997). The goal of the present work was (1) the identification of the pigments By HPLC in these revertants in order to answer the question whether <B>ChlorophyllB> B is synthesised in these strains and (2) to study By fluorescence methods the energy transfer from <B>ChlorophyllB> B to <B>ChlorophyllB> a and to understand whether the revertant has <B>ChlorophyllB> B in the right position in the chloroplast. Elucidation of the nature of the cBnl-mutation is important for studying the mechanism of reversion of cBnl-mutations. Therefore, exact analysis of the pigment content of cBnl-mutants is necessary to find out whether trace amounts of <B>ChlorophyllB> B are present in these mutants. Full aBsence of <B>ChlorophyllB> B in our mutants would allow to indicate a defect in one of the structural genes of <B>ChlorophyllB> B Biosynthesis. Presence of trace amounts of <B>ChlorophyllB> B in the mutant could point to defective gene regulation in pigment Biosynthesis and would suggest a regulatory character of the suppression.
Ryouhei Morita - One of the best experts on this subject based on the ideXlab platform.
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Two short-chain dehydrogenase/reductases, NON-YELLOW COLORING 1 and NYC1-LIKE, are required for <B>ChlorophyllB> B and light-harvesting complex II degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Minoru Nishimura, Ayumi Tanaka, Susumu Katsuma, Makoto KusabaAbstract:Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>-protein complexes, is a notaBle phenomenon during leaf senescence. NON-YELLOW COLORING 1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the stay-green phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.
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two short chain dehydrogenase reductases non yellow coloring 1 and nyc1 like are required for <B>ChlorophyllB> B and light harvesting complex ii degradation during senescence in rice
Plant Journal, 2009Co-Authors: Yutaka Sato, Ryouhei Morita, Makoto Kusaba, Minoru Nishimura, Ayumi Tanaka, Susumu KatsumaAbstract:*† Summary Yellowing, which is related to the degradation of <B>ChlorophyllB> and <B>ChlorophyllB>–protein complexes, is a notaBle phenomenon during leaf senescence.NON-YELLOW COLORING1 (NYC1) in rice encodes a memBrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a <B>ChlorophyllB> B reductase necessary for catalyzing the first step of <B>ChlorophyllB> B degradation. Analysis of the nyc1 mutant, which shows the staygreen phenotype, revealed that <B>ChlorophyllB> B degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of <B>ChlorophyllB> B was severely inhiBited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol douBle mutant did not show prominent enhancement of inhiBition of <B>ChlorophyllB> degradation. NOL was localized on the stromal side of the thylakoid memBrane despite the lack of a transmemBrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These oBservations suggest that NOL and NYC1 are co-localized in the thylakoid memBrane and act in the form of a complex as a <B>ChlorophyllB> B reductase in rice.