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1.
Accumulation of the NON‐YELLOW COLORING 1 protein of the chlorophyll cycle requires chlorophyll b in Arabidopsis thaliana
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Ting Jia Hisashi Ito Xueyun Hu Ayumi Tanaka 《The Plant journal : for cell and molecular biology》2015,81(4):586-596
Chlorophyll a and chlorophyll b are interconverted in the chlorophyll cycle. The initial step in the conversion of chlorophyll b to chlorophyll a is catalyzed by the chlorophyll b reductases NON‐YELLOW COLORING 1 (NYC1) and NYC1‐like (NOL), which convert chlorophyll b to 7‐hydroxymethyl chlorophyll a. This step is also the first stage in the degradation of the light‐harvesting chlorophyll a/b protein complex (LHC). In this study, we examined the effect of chlorophyll 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 chlorophyll b was enhanced by the introduction of a truncated chlorophyllide 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 chlorophyll 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 chlorophyll 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 chlorophyllide a oxygenase suggest that the a feedforward and feedback network is included in chlorophyll cycle. 相似文献
2.
Chlorophyllase activities and chlorophyll degradation during leaf senescence in non-yellowing mutant and wild type of Phaseolus vulgaris L 总被引:6,自引:0,他引:6
The activities of chlorophyllase, contents of pigments including
chlorophyll a and b,
chlorophyllide a and b, and
phaeophorbide a during leaf senescence under low
oxygen (0.5% O2) and control (air) were investigated in a non-yellowing
mutant and wild-type leaves of snap beans (Phaseolus
vulgaris L.). Chlorophyllase from leaf tissues had maximum
activity when incubated at 40C in a mixture
containing 50% acetone. In both mutant and wild type, chlorophyllase
activity was the highest in freshly harvested non-senescent leaves and
decreased sharply in the course of senescence, indicating that the loss of
chlorophylls in senescing leaves is not directly related to the activity of
chlorophyllase and that chlorophyllase activity is not altered in the
mutant. The wild type had higher ratios of chlorophyll
a to chlorophyll b than the
mutant and chlorophyll a : b ratios increased during
senescence in both types. In the senescent mutant leaves, accumulations of
chlorophyllide a and chlorophyllide
b were detected, but no phaeophorbide
a was found. Chlorophyllide b had
a greater accumulation than chlorophyllide a in the
early stage of senescence. Low oxygen treatment not only delayed
chlorophyll degradation but also enhanced the accumulations of
chlorophyllide a and b and
lowered the ratios of chlorophyll a to chlorophyll
b. 相似文献
3.
4.
Optical absorption and fluorescence parameters of chlorophyll a and the phytol-free chlorophyllide a, as well as of their Mg-depleted derivatives, were compared in a series of organic solvents. In contrast to prevailing opinion,
the spectral properties of chlorophyll are not indifferent to the removal of phytol. The electronic absorption spectra of
chlorophyll a and chlorophyllide a differ and display a different dependence on the nature of the solvent, which cannot be explained solely by the location
of a charged carboxylic group in the proximity of the π– electron system. In fact, measurements in media of varying basicity
show that deprotonation of the free carboxylic group in chlorophyllide, i.e., the presence of a negative point charge near
the macrocycle, has no effect on pigment absorption spectra. Analysis of the solvent effect on the QY energies in terms of solvent polarity reveals that the phytyl moiety perturbs the spectral features of chlorophyll, mainly
due to its interactions with the pigment solvation shell. The phytyl residue might also be thus partly involved in controlling
the central metal ligation in chlorophylls. This influence of phytol on the spectral features of chlorophyll should be taken
into account when comparing the spectra in solution with various spectral forms of chlorophyll in vivo.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Rispens T Leeuwen Av Vennegoor A Killestein J Aalberse RC Wolbink GJ Aarden LA 《Analytical biochemistry》2011,(2):271-276
Chlorophyllide a is a metabolite late in the biosynthesis of chlorophylls and bacteriochlorophylls. Isolation procedures for chlorophyllide a from Rhodobacter capsulatus CB1200 and barley (Hordeum vulgare L.) are described and compared. R. capsulatus CB1200 is a double mutant in the bacteriochlorophyllide a biosynthetic pathway, and chlorophyllide a is excreted by the cells when grown in Tween 80-containing liquid medium. It was purified by liquid or solid phase extraction, yielding 7 mg of chlorophyllide a from 1 L of culture. In a second approach, intrinsic chlorophyllase activity was used to dephytylate chlorophyll in an acetonic preparation of leaves of wild-type or chlorophyll b-deficient barley. Purification was achieved by liquid phase extraction, yielding 14 μg of chlorophyllide a per gram of barley leaves. Chlorophyllide a was identified by thin layer chromatography, absorption spectroscopy, and mass spectrometry. 相似文献
6.
It is demonstrated that chlorophyll b does not only derive from chlorophyll a , but is also formed separately from an in vivo-occurring chlorophyllide b . The branching point for the latter synthesis is at the level of chlorophyllide, since no protochlorophyllide b was detectable. We have indications that the enzyme oxidizing chlorophyll a to chlorophyll b accepts also non-phytylated 17,18 dihydroporphyrins and is not restricted to chlorophylls. Preparations of chlorophyllide a and chlorophyll a could both be transferred with the same enzyme fraction to chlorophyllide b and chlorophyll b , respectively. Preliminary experiments show this enzyme to be membrane bound and light independent. An updated scheme for chlorophyll b biosynthesis is presented. 相似文献
7.
Yousuke Shimoda Hisashi Ito Ayumi Tanaka 《The Plant journal : for cell and molecular biology》2012,72(3):501-511
Chlorophyll is a deleterious molecule that generates reactive oxygen species and must be converted to non‐toxic molecules during plant senescence. The degradation pathway of chlorophyll a has been determined; however, that of chlorophyll b is poorly understood, and multiple pathways of chlorophyll b degradation have been proposed. In this study, we found that chlorophyll b is degraded by a single pathway, and elucidated the importance of this pathway in avoiding cell death. In order to determine the chlorophyll degradation pathway, we first examined the substrate specificity of 7‐hydroxymethyl chlorophyll a reductase. 7‐hydroxymethyl chlorophyll a reductase reduces 7‐hydroxymethyl chlorophyll a but not 7‐hydroxymethyl pheophytin a or 7‐hydroxymethyl pheophorbide a. These results indicate that the first step of chlorophyll b degradation is its conversion to 7‐hydroxymethyl chlorophyll a by chlorophyll b reductase, although chlorophyll b reductase has broad substrate specificity. In vitro experiments showed that chlorophyll b reductase converted all of the chlorophyll b in the light‐harvesting chlorophyll a/b protein complex to 7‐hydroxymethyl chlorophyll a, but did not completely convert chlorophyll b in the core antenna complexes. When plants whose core antennae contained chlorophyll b were incubated in the dark, chlorophyll b was not properly degraded, and the accumulation of 7‐hydroxymethyl pheophorbide a and pheophorbide b resulted in cell death. This result indicates that chlorophyll 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 chlorophyll b. 相似文献
8.
Biosynthesis of chlorophyll b and the chlorophyll cycle 总被引:6,自引:0,他引:6
Rüdiger W 《Photosynthesis research》2002,74(2):187-193
9.
The iron–sulfur cluster biosynthesis protein SUFB is required for chlorophyll synthesis,but not phytochrome signaling
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Xueyun Hu Mike T. Page Akihiro Sumida Ayumi Tanaka Matthew J. Terry Ryouichi Tanaka 《The Plant journal : for cell and molecular biology》2017,89(6):1184-1194
Proteins that contain iron–sulfur (Fe–S) clusters play pivotal roles in various metabolic processes such as photosynthesis and redox metabolism. Among the proteins involved in the biosynthesis of Fe–S clusters in plants, the SUFB subunit of the SUFBCD complex appears to be unique because SUFB has been reported to be involved in chlorophyll metabolism and phytochrome‐mediated signaling. To gain insights into the function of the SUFB protein, we analyzed the phenotypes of two SUFB mutants, laf6 and hmc1, and RNA interference (RNAi) lines with reduced SUFB expression. When grown in the light, the laf6 and hmc1 mutants and the SUFB RNAi lines accumulated higher levels of the chlorophyll biosynthesis intermediate Mg‐protoporphyrin IX monomethylester (Mg‐proto MME), consistent with the impairment of Mg‐proto MME cyclase activity. Both SUFC‐ and SUFD‐deficient RNAi lines accumulated the same intermediate, suggesting that inhibition of Fe‐S cluster synthesis is the primary cause of this impairment. Dark‐grown laf6 seedlings also showed an increase in protoporphyrin IX (Proto IX), Mg‐proto, Mg‐proto MME and 3,8‐divinyl protochlorophyllide a (DV‐Pchlide) levels, but this was not observed in hmc1 or the SUFB RNAi lines, nor was it complemented by SUFB overexpression. In addition, the long hypocotyl in far‐red light phenotype of the laf6 mutant could not be rescued by SUFB overexpression and segregated from the pale‐green SUFB‐deficient phenotype, indicating it is not caused by mutation at the SUFB locus. These results demonstrate that biosynthesis of Fe–S clusters is important for chlorophyll biosynthesis, but that the laf6 phenotype is not due to a SUFB mutation. 相似文献
10.
Spectral changes and esterification (presumably with phytol) of newly formed chlorophyllide a in dark-grown leaves of wildtype bean (Phaseolus vulgaris) and barley (Hordeum vulgare) and a number of chloroplast mutants in barley, were studied by spectrofluorimetry on leaves and on solvent extracts. The shift of the fluorescence emission maximum from 692–694 to 678 nm (excitation shift: 682–684 to 672 nm) and esterification of chlorophyllide a have a similar time course, and both processes are temperature dependent in a similar manner. After completion of the spectral shift and esterification, the fluorescence efficiency of chlorophyll a increases with a subsequent reaccumulation of protochlorophyllide. In leaves of mutants where the shift of fluorescence from 692 to 678 nm is lacking, esterification and the subsequent processes are also blocked. In leaves of mutants with a rapid shift of the fluorescence from 692 to 678 nm, or with direct photoconversion to chlorophyllide a with the fluorescence at 678 nm, esterification is also rapid. The results are interpreted as a sequence of molecular events involving a conformational relaxation of the chlorophyllide holochrome and a translocation of chlorophyll a to reaction centers of the photosystems. 相似文献
11.
Summary The rate of chlorophyllide esterification in mustard cotyledons can be increased by a pretreatment with 5 min red light applied 24 h prior to the protochlorophyll(ide)chlorophyll(ide) photoconversion at 60 h after sowing. Simultaneously the red light pulse pretreatment leads to a decrease of the total amount of chlorophyll(ide) a in darkness. It has been proven that phytochrome (Pfr) is the photoeffector for both. Since the amounts of esterified chlorophyllide are determined by the ratio [chlorophyll a]/[chlorophyllide a+chlorophyll a] it is assumed that Pfr increases the rate of esterification indirectly via stimulating the decrease of chlorophyll(ide) a. The regulation of chlorophyll synthesis by Pfr does not seem to involve a control of esterification. The duration of the chlorophyllide esterification differs from the duration of the Shibata shift although both are greatly shortened by the red light pulse pretreatment. The effect of 5 min red light on the duration of the esterification is fully reversible by 5 min far-red light while the reversibility with respect to the Shibata shift is lost within 2 min [Jabben, M. and H. Mohr, Photochem. Photobiol. 22, 55–58 (1975)]. We conclude that the control of the chlorophyllide esterification and the control of the Shibata shift cannot be traced back to the same initial action of Pfr.Abbreviations Chl
chlorophyll
- Chlide
chlorophyllide
- Chl(ide)
sum of Chl and Chlide
- PChl
protochlorophyll
- PChlide
protochlorophyllide
- PChl(ide)
sum of PChl and PChlide
- Pfr
far-red absorbing form of the phytochrome system 相似文献
12.
Albert Huff 《Phytochemistry》1982,21(2):261-265
Chlorophyll is effectively bleached by H2O2 in the presence of certain phenols and peroxidase (EC 1.11.1.7) extracted from acetone powders of orange flavedo (Citrus sinensis). Optimal conditions for chlorophyll: hydrogen peroxide oxidoreductase include: pH, 5.9; [H2O2] 222 μM; ionic strength 0.11. A phenol is required and resorcinol is the most effective. Catechol and hydroquinone are inhibitory. Chlorophyll a, chlorophyllide a, and chlorophyll b all have similar Vmax but Km for chlorophyll a is about one-third that of chlorophyll b, while the Km for chlorophyllide a is about one-half that of chlorophyll a. Pheophytin a was much less reactive than chlorophyll a, and Mg2+ included in the reaction system did not affect rates of pheophytin destruction. 相似文献
13.
BEL1‐LIKE HOMEODOMAIN 11 regulates chloroplast development and chlorophyll synthesis in tomato fruit
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Lanhuan Meng Zhongqi Fan Qiang Zhang Cuicui Wang Ying Gao Yikang Deng Benzhong Zhu Hongliang Zhu Jianye Chen Wei Shan Xueren Yin Silin Zhong Donald Grierson Cai‐Zhong Jiang Yunbo Luo Da‐Qi Fu 《The Plant journal : for cell and molecular biology》2018,94(6):1126-1140
14.
Illumination of etiolated maize leaves with low-intensity light produces a chlorophyll/pheophytin-containing complex. The complex contains two native chlorophyll forms Chl 671/668 and Chl 675/668 as well as pheophytin Pheo 679/675 (with chlorophyll/pheophytin ratio of 2/1). The complex is formed in the course of two successive reactions: reaction of protochlorophyllide Pchlde 655/650 photoreduction resulted in chlorophyllide Chlde 684/676 formation, and the subsequent dark reaction of Chlde 684/676 involving Mg substitution by H2 in pigment chromophore and pigment esterification by phytol. Out data show that the reaction leading to chlorophyll/pheophytin-containing complex formation is not destructive. The reaction is in fact biosynthetic, and is competitive with the known reactions of biosynthesis of the bulk of chlorophyll molecules. The relationship between chlorophyll and pheophytin biosynthesis reactions is controlled by temperature, light intensity and exposure duration.The native complex containing pheophytin a and chlorophyll a is supposed to be a direct precursor of the PS II reaction centre in plant leaves.Abbreviations Chl
chlorophyll
- Chlde
chlorophyllide
- Pchl
protochlorophyll
- Pchlde
protochloropyllide
- Pheo
pheophytin
- PS II RC
Photosystem II reaction centres. Abbreviations for native pigment forms: the first number after pigment symbol corresponds to the maximum position of low-temperature fluorescence band (nm); the second number corresponds to the maximum position of long wave absorption band 相似文献
15.
L. A. S. Silva V. F. Sampaio L. C. S. Barbosa M. Machado D. N. A. Flores‐Borges J. F. Sales D. C. de Oliveira J. L. S. Mayer V. C. Kuster D. I. Rocha 《Plant biology (Stuttgart, Germany)》2020,22(5):761-768
- The partial or complete loss of chlorophylls, or albinism, is a rare phenomenon in plants. In the present study, we provide the first report of the occurrence in albino Delonix regia seedlings and describe the morpho‐physiological changes associated with albinism.
- Wild‐type (WT) and albino seedlings were characterized. Leaflets samples were processed following common procedures for analysis with light, scanning and transmission electron microscopy. The chlorophyll a fluorescence parameters and the carbohydrate, lipid and soluble protein content were also determined in leaf and cotyledon samples of both albino and WT seedlings.
- Albino seedlings showed reduced growth. They also had lower chlorophyll and protein content in foliar tissues than WT seedlings, in addition to lower concentrations of lipids and carbohydrates stored in cotyledons. The chloroplasts of albino seedlings were poorly developed, with an undefined internal membrane system and the presence of plastoglobules. Wild‐type seedlings had a uniseriate and hypoestomatic epidermis. The mesophyll was dorsiventral, consisting of a layer of palisade parenchyma and two to four layers of spongy parenchyma. In albino seedlings, the spongy parenchyma was compact, with few intercellular spaces, and the thickness of the mesophyll was larger, resulting in increased thickness of the leaf blade. Albino seedlings had higher stomatal density and number of pavement cells, although the stomata had smaller dimensions.
- In addition to the partial loss of chlorophylls, albino D. regia showed changes at physiological and structural levels, demonstrating the crucial nature of photosynthetic pigments during the development and differentiation of plant leaf tissues/cells.
16.
Castelfranco PA 《Photosynthesis research》2007,91(1):25-36
Our research on chlorophyll biosynthesis, over a period of approximately twenty years, has been described, emphasizing those
areas in which our laboratory made significant and timely contributions. References to some of our most important articles
are included. Portions of the chlorophyll biosynthetic pathway, in which our own laboratory was not involved, for example,
the reduction of protochlorophyllide to chlorophyllide and the phytylation of the latter to yield chlorophyll a, have not been covered in this article. Those events which preceded my involvement with chlorophyll biosynthesis, but which
contributed to the formation of my own scientific personality, are mentioned briefly in the Introduction. My non-scientific
avocations have been included at the request of the reviewers and Govindjee. 相似文献
17.
Absorption and low temperature fluorescence emission spectra were measured on chloroplast thylakoids and on purified reaction center chlorophyll a-protein complexes of photosystem I, CP-a1. A clear association between the presence of ß-carotene and the occurrence of far red absorbing and emitting chlorophyll a components of the reaction center antennae of photosystem I was demonstrated. For this study chloroplasts and CP-a1 were obtained from normal and carotenoid deficient plant material of various sources. The experimental material included 1) lyophilized pea chloroplasts extracted with petroleum ether, 2) the carotenoid deficient mutant C-6E of Scenedesmus obliquus and 3) wheat chloroplasts derived from normal and SAN-9789 treated plants. Removal of carotenoids, most likely principally ß-carotene, caused a loss of long wavelength absorbing chlorophylls in chloroplasts and purified CP-a1, and the loss or diminution of the long wavelength peak seen in the low temperature fluorescence emission spectrum. This association between ß-carotene and special chlorophyll a forms may explain both the photoprotective and antenna functions ascribed to ß-carotene. In the absence of carotenoids in wheat and in the Scenedesmus mutant, the chlorophyll a antenna of photosystem I was extremely photosensitive. A triplet-triplet resonance energy transfer from chlorophyll a to ß-carotene and a singlet-singlet energy transfer from excited ß-carotene to chlorophyll would explain the photoprotective and antenna functions, respectively. The role of this association in determining some of the fluorescence properties of photosystem I is also discussed. 相似文献
18.
Hiroshi Yamatani Yutaka Sato Yu Masuda Yusuke Kato Ryouhei Morita Kenji Fukunaga Yoshiaki Nagamura Minoru Nishimura Wataru Sakamoto Ayumi Tanaka Makoto Kusaba 《The Plant journal : for cell and molecular biology》2013,74(4):652-662
Yellowing/chlorophyll breakdown is a prominent phenomenon in leaf senescence, and is associated with the degradation of chlorophyll – protein complexes. From a rice mutant population generated by ionizing radiation, we isolated nyc4‐1, a stay‐green mutant with a defect in chlorophyll breakdown during leaf senescence. Using gene mapping, nyc4‐1 was found to be linked to two chromosomal regions. We extracted Os07g0558500 as a candidate for NYC4 via gene expression microarray analysis, and concluded from further evidence that disruption of the gene by a translocation‐related event causes the nyc4 phenotype. Os07g0558500 is thought to be the ortholog of THF1 in Arabidopsis thaliana. The thf1 mutant leaves show variegation in a light intensity‐dependent manner. Surprisingly, the Fv/Fm value remained high in nyc4‐1 during the dark incubation, suggesting that photosystem II retained its function. Western blot analysis revealed that, in nyc4‐1, the PSII core subunits D1 and D2 were significantly retained during leaf senescence in comparison with wild‐type and other non‐functional stay‐green mutants, including sgr‐2, a mutant of the key regulator of chlorophyll degradation SGR. The role of NYC4 in degradation of chlorophyll and chlorophyll – protein complexes during leaf senescence is discussed. 相似文献
19.
A comparative study of reciprocal conversions of chlorophylls a and b (Chl aand Chl b) in etiolated and post-etiolated rye seedlings (Secale cereale L.) was performed. The production of these pigments was initiated by infiltration of exogenous chlorophyllides a and b (Chlide a and b). It was shown that Chlide b, when infiltrated into etiolated rye seedlings, was esterified, producing Chl b. A major portion of Chl b (more than 80%) was transformed into Chl aduring long-term seedling dark exposure. The high rate of Chl b conversion into Chl a in the pool of pigments of exogenous origin was also observed during the lag-phase when there was no chlorophyll formation from endogenous precursors. The infiltration of Chlide a resulted in Chl a formation. The efficiency of its conversion into Chl b was low (about 1%) in the etiolated seedlings but increased during their greening. In the post-etiolated seedlings infiltrated with Chlide b, which were preliminary illuminated for 6–12 h, the Chl /Chl a ratio was almost similar in the pools of pigments synthesized from both exogenous and endogenous precursors. The rates of direct and reverse reactions responsible for the interconversion of Chl aand Chl b depended on the stage of the formation of the photosynthetic apparatus during greening of etiolated seedlings, when the particular structural components are formed in a definite sequence. 相似文献
20.
In plants, chlorophyll is actively synthesized from glutamate in the developmental phase and is degraded into non-fluorescent
chlorophyll catabolites during senescence. The chlorophyll metabolism must be strictly regulated because chlorophylls and
their intermediate molecules generate reactive oxygen species. Many mechanisms have been proposed for the regulation of chlorophyll
synthesis including gene expression, protein stability, and feedback inhibition. However, information on the regulation of
chlorophyll degradation is limited. The conversion of chlorophyll b to chlorophyll a is the first step of chlorophyll degradation. In order to understand the regulatory mechanism of this reaction, we isolated
a mutant which accumulates 7-hydroxymethyl chlorophyll a (HMChl), an intermediate molecule of chlorophyll b to chlorophyll a conversion, and designated the mutant hmc1. In addition to HMChl, hmc1 accumulated pheophorbide a, a chlorophyll degradation product, when chlorophyll degradation was induced by dark incubation. These results indicate that
the activities of HMChl reductase (HAR) and pheophorbide a oxygenase (PaO) are simultaneously down-regulated in this mutant. We identified a mutation in the AtNAP1 gene, which encodes a subunit of the complex for iron–sulfur cluster formation. HAR and PaO use ferredoxin as a reducing
power and PaO has an iron-sulfur center; however, there were no distinct differences in the protein levels of ferredoxin and
PaO between wild type and hmc1. The concerted regulation of chlorophyll degradation is discussed in relation to the function of AtNAP1. 相似文献