Chlorophyll Biosynthesis. Expression of a Second Chl I Gene of Magnesium Chelatase in Arabidopsis Supports Only Limited Chlorophyll Synthesis

We previously demonstrated that maize (Zea mays) locus very oil yellow1 (vey1) encodes a putative cis-regulatory expression polymorphism at the magnesium chelatase subunit I gene (aka oil yellow1) that strongly modifies the chlorophyll content of the semi-dominant Oy1-N1989 mutants. The vey1 allele of Mo17 inbred line reduces chlorophyll content in the mutants leading to reduced photosynthetic output. Oy1-N1989 mutants in B73 reached reproductive maturity four days later than wild-type siblings. Enhancement of Oy1-N1989 by the Mo17 allele at the vey1 QTL delayed maturity further, resulting in detection of a flowering time QTL in two bi-parental mapping populations crossed to Oy1-N1989. The near isogenic lines of B73 harboring the vey1 allele from Mo17 delayed flowering of Oy1-N1989 mutants by twelve days. Just as previously observed for chlorophyll content, vey1 had no effect on reproductive maturity in the absence of the Oy1-N1989 allele. Loss of chlorophyll biosynthesis in Oy1-N1989 mutants and enhancement by vey1 reduced CO2 assimilation. We attempted to separate the effects of photosynthesis on the induction of flowering from a possible impact of chlorophyll metabolites and retrograde signaling by manually reducing leaf area. Removal of leaves, independent of the Oy1-N1989 mutant, delayed flowering but surprisingly reduced chlorophyll contents of emerging leaves. Thus, defoliation did not completely separate the identity of the signal(s) that regulates flowering time from changes in chlorophyll content in the foliage. These findings illustrate the necessity to explore the linkage between metabolism and the mechanisms that connect it to flowering time regulation.

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Regulation der Chlorophyllbiosynthese. Lidit- und entwicklungsbedingte Aktivitätsänderungen von vier aufeinander folgenden Enzymen der Porphyrin- und Chlorophyllbiosynthesekette / Regulation of Chlorophyll Biosynthesis. Changes in Activity of Four Consecutive Enzymes in the Porphyrin and Chlorophyll Biosynthesis Chain during Development and Illumination

Zeitschrift für Naturforschung C ◽

10.1515/znc-1973-1-208 ◽

1973 ◽

Vol 28 (1-2) ◽

pp. 45-58 ◽

Cited By ~ 12

Author(s):

Hansjörg A. W. Schneider

Keyword(s):

Nucleic Acid ◽

Chlorophyll Biosynthesis ◽

Acid Synthesis ◽

Chlorophyll Synthesis ◽

The Other ◽

Tissue Cultures ◽

Leaf Tissues ◽

Porphyrin Synthesis

The activities of enzymes related with chlorophyll and porphyrin synthesis have been examined during development and greening of young corn leaves. The enzymes succinyl-CoA-synthetase (SCoAS), δ-amino-levulinate synthetase (ALAS), δ-amino-levulinate dehydratase (ALAD) and the enzymes involved in porphobilinogenase (PBGA) were under investigaton. When leaves are illuminated and chlorophyll synthesis begins the activity of ALAD is not influenced. The activity of PBGA and SCoAS are slightly higher than in darkness, but the changes are below the range affecting chlorophyll biosynthesis. ALA, however, is only synthetized in the light. Synthesis ceases immediately when illuminiation ist stopped, indicating'that in darkness ALAS is not active. On the other hand ALAS is active in dark grown roots, tubers and other non-leaf tissues. Feeding the plant with succinate, glycine or α-keto-glutarate has no effect on chlorophyll synthesis, but the amount of ALA is reduced, whereas sucrose promotes its accumulation. The results are discussed with completely antitethaal results obtained with tissue cultures of tobacco and are integrated into a scheme which excludes the contrariety of hypotheses deduced from experi- ments with inhibitors of protein and nucleic acid synthesis. It is suggested that the varying results are caused by the action of light on different stages in differentiation of plastids and cells. In contrast to the enzymes SCoAS, ALAD and PBGA whose activities were determined in vitro, ALAS was assayed in vivo by means of the accumulation of (5-amino-levulinate (ALA) after blocking the enzyme ALAD by levulinate (LA). Optimum accumulation is observed when the concentration is about 2 · 10-2 м. LA is not converted to ALA in appreciable amounts. This could be proved by feeding the plants with 14C-LA which was prepared from uniformly labeled 14C-fructose.

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Characterization of the magnesium chelatase from Thermosynechococcus elongatus

Biochemical Journal ◽

10.1042/bj20130834 ◽

2013 ◽

Vol 457 (1) ◽

pp. 163-170 ◽

Cited By ~ 9

Author(s):

Nathan B. P. Adams ◽

Christopher J. Marklew ◽

Amanda A. Brindley ◽

C. Neil Hunter ◽

James D. Reid

Keyword(s):

Chlorophyll Biosynthesis ◽

Thermostable Enzyme ◽

Enzyme Complex ◽

Magnesium Chelatase

Magnesium chelatase is the ‘gatekeeper’ multi-subunit enzyme complex that initiates chlorophyll biosynthesis; we present the first characterization of an active thermostable enzyme complex and we use hybrid mesophilic/thermophilic chelatase complexes to reveal that Mg2+ co-operativity resides in the ChlD subunit.

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Chlorophyll a biosynthesis

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1976.0010 ◽

1976 ◽

Vol 273 (924) ◽

pp. 207-225 ◽

Cited By ~ 10

Keyword(s):

Chlorophyll A ◽

Chlorophyll Biosynthesis ◽

Protoporphyrin Ix ◽

Chlorophyll Synthesis ◽

Synthesis Reaction ◽

Etiolated Leaves ◽

Regulatory Aspects ◽

Vinyl Group ◽

Chlorophyll A Biosynthesis ◽

Monomethyl Ester

Protoporphyrin IX is believed to be an intermediate common to both haem and chlorophyll biosynthesis. The pathway specific to chlorophyll starts with magnesium protoporphyrin and its monomethyl ester. Two routes have been proposed for conversion of the latter compound to protochlorophyllide: A, formation of the isocyclic ring followed by reduction of the 4-vinyl group, or B, reduction of the 4-vinyl group followed by formation of the isocyclic ring. Membranes prepared from isolated barley etioplasts are found to convert magnesium 2,4-divinylphaeoporphyrin a 5 monomethyl ester to chlorophyllide a at a rate equal to that of chlorophyll synthesis in intact leaves: this result supports route A. NADPH is necessary to maintain the two successive reductive steps: reduction of the 4-vinyl group and then the photoreduction of ring IV to yield chlorophyllide. The prohaem content of etiolated leaves does not increase during the phase of active chlorophyll synthesis although evidence is presented that suggests that the ALA synthesis reaction that regulates chlorophyll synthesis is common to both pathways. This and other regulatory aspects are discussed.

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Photocatalytic plant LPOR forms helical lattices that shape membranes for chlorophyll synthesis

10.1101/2020.08.19.257774 ◽

2020 ◽

Author(s):

Henry C. Nguyen ◽

Arthur A. Melo ◽

Jerzy Kruk ◽

Adam Frost ◽

Michal Gabruk

Keyword(s):

Reaction Mechanisms ◽

Spectral Properties ◽

Chlorophyll Biosynthesis ◽

3D Structure ◽

Chlorophyll Synthesis ◽

Protochlorophyllide Oxidoreductase ◽

Photosynthetic Membrane ◽

Life On Earth ◽

Outer Membrane Leaflet ◽

Chl Biosynthesis

AbstractChlorophyll (Chl) biosynthesis, crucial to life on Earth, is tightly regulated because its precursors are phototoxic1. In flowering plants, the enzyme Light-dependent Protochlorophyllide OxidoReductase (LPOR) captures photons to catalyze the penultimate reaction: the reduction of a double-bond within protochlorophyllide (Pchlide) to generate chlorophyllide (Chlide)2,3. In darkness, LPOR oligomerizes to facilitate photon energy transfer and catalysis4,5. However, the complete 3D structure of LPOR, the higher-order architecture of LPOR oligomers, and the implications of these self-assembled states for catalysis, including how LPOR positions Pchlide and the cofactor NADPH, remain unknown. Here we report the atomic structure of LPOR assemblies by electron cryo-microscopy (cryoEM). LPOR polymerizes with its substrates into helical filaments around constricted lipid bilayer tubes. Portions of LPOR and Pchlide insert into the outer membrane leaflet, targeting the product, Chlide, to the membrane for the final reaction site of chlorophyll biosynthesis. In addition to its crucial photocatalytic role, we show that in darkness LPOR filaments directly shape membranes into high-curvature tubules with the spectral properties of the prolammelar body, whose light-triggered disassembly provides lipids for thylakoid assembly. Our structure of the catalytic site, moreover, challenges previously proposed reaction mechanisms6. Together, our results reveal a new and unexpected synergy between photosynthetic membrane biogenesis and chlorophyll synthesis in plants orchestrated by LPOR.

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iTRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

10.21203/rs.3.rs-36055/v4 ◽

2020 ◽

Author(s):

Hao Sun ◽

Jie Yu ◽

Fan Zhang ◽

Junmei Kang ◽

Mingna Li ◽

...

Keyword(s):

Leaf Development ◽

Proteomic Analysis ◽

Regulatory Networks ◽

Carbon Fixation ◽

Chlorophyll Biosynthesis ◽

Chlorophyll Synthesis ◽

Phenylpropanoid Pathway ◽

Chlorophyll Metabolism ◽

Phenylpropanoid Biosynthesis ◽

Proteomic Study

Abstract Background: To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves.Results: Based on fold-change thresholds of >1.20 or <0.83 (p<0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially enriched proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins. Conclusion: Enhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

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A Very Oil Yellow1 modifier of the Oil Yellow1-N1989 allele uncovers a cryptic phenotypic impact of cis-regulatory variation in maize

10.1101/230375 ◽

2017 ◽

Author(s):

Rajdeep S. Khangura ◽

Sandeep Marla ◽

Bala P. Venkata ◽

Nicholas J. Heller ◽

Gurmukh S. Johal ◽

...

Keyword(s):

Natural Variation ◽

Chlorophyll Biosynthesis ◽

Transcript Abundance ◽

Forward Genetics ◽

Expression Level ◽

Dna Polymorphisms ◽

Regulatory Sequence ◽

Chlorophyll Metabolism ◽

Magnesium Chelatase ◽

Regulatory Variation

AbstractForward genetics determines the function of genes underlying trait variation by identifying the change in DNA responsible for changes in phenotype. Detecting phenotypically-relevant variation outside protein coding sequences and distinguishing this from neutral variants is not trivial; partly because the mechanisms by which DNA polymorphisms in the intergenic regions affect gene regulation are poorly understood. Here we utilized a dominant genetic marker with a convenient phenotype to investigate the effect of cis and trans-acting regulatory variation. We performed a forward genetic screen for natural variation that suppress or enhance the semi-dominant mutant allele Oy1-N1989, encoding the magnesium chelatase subunit I of maize. This mutant permits rapid phenotyping of leaf color as a reporter for chlorophyll accumulation, and mapping of natural variation in maize affecting chlorophyll metabolism. We identified a single modifier locus segregating between B73 and Mo17 that was linked to the reporter gene itself, which we call very oil yellow1. Based on the variation in OY1 transcript abundance and genome-wide association data, vey1 is predicted to consist of multiple cis-acting regulatory sequence polymorphisms encoded at the wild-type oy1 alleles. The vey1 allele appears to be a common polymorphism in the maize germplasm that alters the expression level of a key gene in chlorophyll biosynthesis. These vey1 alleles have no discernable impact on leaf chlorophyll in the absence of the Oy1-N1989 reporter. Thus, use of a mutant as a simple and efficient reporter for magnesium chelatase activity resulted in the detection of expression-level polymorphisms not readily visible in the laboratory.

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Bilin-dependent regulation of chlorophyll biosynthesis by GUN4

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2104443118 ◽

2021 ◽

Vol 118 (20) ◽

pp. e2104443118

Author(s):

Weiqing Zhang ◽

Robert D. Willows ◽

Rui Deng ◽

Zheng Li ◽

Mengqi Li ◽

...

Keyword(s):

Enzymatic Activity ◽

Heme Oxygenase ◽

Chlorophyll Biosynthesis ◽

Protoporphyrin Ix ◽

Common Trunk ◽

Magnesium Chelatase ◽

Photosynthetic Eukaryotes ◽

Linear Tetrapyrroles ◽

Oxygenic Phototrophs ◽

Binding Component

Biosyntheses of chlorophyll and heme in oxygenic phototrophs share a common trunk pathway that diverges with insertion of magnesium or iron into the last common intermediate, protoporphyrin IX. Since both tetrapyrroles are pro-oxidants, it is essential that their metabolism is tightly regulated. Here, we establish that heme-derived linear tetrapyrroles (bilins) function to stimulate the enzymatic activity of magnesium chelatase (MgCh) via their interaction with GENOMES UNCOUPLED 4 (GUN4) in the model green alga Chlamydomonas reinhardtii. A key tetrapyrrole-binding component of MgCh found in all oxygenic photosynthetic species, CrGUN4, also stabilizes the bilin-dependent accumulation of protoporphyrin IX-binding CrCHLH1 subunit of MgCh in light-grown C. reinhardtii cells by preventing its photooxidative inactivation. Exogenous application of biliverdin IXα reverses the loss of CrCHLH1 in the bilin-deficient heme oxygenase (hmox1) mutant, but not in the gun4 mutant. We propose that these dual regulatory roles of GUN4:bilin complexes are responsible for the retention of bilin biosynthesis in all photosynthetic eukaryotes, which sustains chlorophyll biosynthesis in an illuminated oxic environment.

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iTRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

BMC Plant Biology ◽

10.1186/s12870-020-02671-2 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Hao Sun ◽

Jie Yu ◽

Fan Zhang ◽

Junmei Kang ◽

Mingna Li ◽

...

Keyword(s):

Leaf Development ◽

Proteomic Analysis ◽

Regulatory Networks ◽

Carbon Fixation ◽

Chlorophyll Biosynthesis ◽

Chlorophyll Synthesis ◽

Phenylpropanoid Pathway ◽

Chlorophyll Metabolism ◽

Phenylpropanoid Biosynthesis ◽

Proteomic Study

Abstract Background To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves. Results Based on fold-change thresholds of > 1.20 or < 0.83 (p < 0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially enriched proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins. Conclusion Enhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

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Chemical Regulation of Plastid Development. I. Inhibition of Chlorophyll Biosynthesis in Detached Pumpkin Cotyledons by CPTA. A Pigment and Ultrastructual Study

Functional Plant Biology ◽

10.1071/pp9740119 ◽

1974 ◽

Vol 1 (1) ◽

pp. 119 ◽

Cited By ~ 3

Author(s):

DJ Simpson ◽

CO Chichester ◽

TH Lee

Keyword(s):

Light Intensity ◽

Chlorophyll Biosynthesis ◽

Carotenoid Biosynthesis ◽

Chlorophyll Synthesis ◽

High Light Intensity ◽

High Light ◽

Trimethylammonium Chloride ◽

Plastid Development ◽

Plastid Ultrastructure ◽

Chlorophyll Accumulation

The effects of 2-(4-chlorophenylthio)ethyldiethylammonium chloride (CPTA) on chlorophyll accumulation, carotenoid biosynthesis and plastid ultrastructure were examined in expanding excised pumpkin cotyledons. CPTA in the dark caused an increased synthesis of non-photoconvertible protochlorophyll but had no effect on the ultrastructure of the starch-containing plastids. In the light, CPTA was a powerful inhibitor of chlorophyll synthesis in greening cotyledons, especially at high light intensity, and induced the accumulation of lycopene. When applied to the greened cotyledons, CPTA caused the transformation of the chloroplasts to chromoplast-like organelles containing osmiophilic globules and lycopene crystalloids. Two other structurally similar compounds,diethyl[4-{3'-(4"-methylphenyl)-3-oxoprop-2' -enyl}phenoxyethyl]ammonium chloride (SK&F 13831) and (2-chloroethyl)trimethylammonium chloride (chlormequat), also caused lycopene accumulation and inhibited chlorophyll synthesis. It is possible that CPTA can induce the formation of chromoplasts from proplastids and chloroplasts in tissue that does not normally contain such organelles.

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