Rapid Dark Repression of 5-Aminolevulinic Acid Synthesis in Green Barley Leaves

Richter, Andreas; Peter, Enrico; Pörs, Yvonne; Lorenzen, Stephan; Grimm, Bernhard; Czarnecki, Olaf

doi:10.1093/pcp/pcq047

Cited by 69 publications

(69 citation statements)

References 57 publications

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“…11). Nevertheless, a significant rate of ALA formation is observed, which is suggested to provide precursors for the synthesis of heme in darkness (Papenbrock et al, 1999;Richter et al, 2010;Czarnecki et al, 2011). Heme is an essential cofactor of several enzymes, including those that act in the mitochondrial electron transport chain even when light is limiting.…”

Section: Resultsmentioning

confidence: 99%

“…S3C). In dark, the flow of intermediates is rapidly attenuated by the FLU-protochlorophyllide-dependent repression of GluTR activity (Meskauskiene et al, 2001;Meskauskiene and Apel, 2002;Lee et al, 2003;Richter et al, 2010;Kauss et al, 2012). By inhibition of ALA synthesis, the rate-limiting step of TBS, the steady-state levels of MgP and MgPMME, were below the detection limit and protochlorophyllide is the only porphyrin, which accumulates in dark due to the light dependency of protochlorophyllide oxidoreductase (POR).…”

Section: Factors Influencing Gun4 Phosphorylationmentioning

confidence: 99%

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Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms

et al. 2016

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) is a positive regulator of light-dependent chlorophyll biosynthesis. GUN4 activates Mg chelatase (MgCh) that catalyzes the insertion of an Mg 2+ ion into protoporphyrin IX. We show that Arabidopsis (Arabidopsis thaliana) GUN4 is phosphorylated at Ser 264 (S264), the penultimate amino acid residue at the C terminus. While GUN4 is preferentially phosphorylated in darkness, phosphorylation is reduced upon accumulation of Mg porphyrins. Expression of a phosphomimicking GUN4(S264D) results in an incomplete complementation of the white gun4-2 null mutant and a chlorotic phenotype comparable to gun4 knockdown mutants. Phosphorylated GUN4 has a reduced stimulatory effect on MgCh in vitro and in vivo but retains its protein stability and tetrapyrrole binding capacity. Analysis of GUN4 found in oxygenic photosynthetic organisms reveals the evolution of a C-terminal extension, which harbors the phosphorylation site of GUN4 expressed in angiosperms. Homologs of GUN4 from Synechocystis and Chlamydomonas lack the conserved phosphorylation site found in a C-terminal extension of angiosperm GUN4. Biochemical studies proved the importance of the C-terminal extension for MgCh stimulation and inactivation of GUN4 by phosphorylation in angiosperms. An additional mechanism regulating MgCh activity is proposed. In conjunction with the dark repression of 5-aminolevulinic acid synthesis, GUN4 phosphorylation minimizes the flow of intermediates into the Mg branch of the tetrapyrrole metabolic pathway for chlorophyll biosynthesis.

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Section: Resultsmentioning

confidence: 99%

Section: Factors Influencing Gun4 Phosphorylationmentioning

confidence: 99%

Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms

et al. 2016

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“…[See online article for color version of this figure.] chloroplasts were isolated from leaflets in the pea VIGS plants, and Mg chelatase activity was determined by a stopped fluorometric assay as described by Guo et al (1998). For analysis of the ALA synthesizing capacity (Richter et al, 2010), leaf discs with a diameter of 7 mm from different VIGS plants were incubated in 50 mM Tris-HCl, pH 7.2, and 40 mM levulinic acid for 3 h in growing light.…”

Section: Modulation Of Tetrapyrrole Biosynthesis and Photosynthesis Cmentioning

confidence: 99%

“…All of the spectrophotometrical analyses were performed using a Beckman DU-730 spectrophotometer. The maximum quantum yield of PSII photochemistry (calculated as the ratio F v /F m = [F m 2 F 0 ]/F m ) was determined as described by Richter et al (2010).…”

Section: Determination Of Pigment Contents and F V /F M Ratiosmentioning

confidence: 99%

Thioredoxin Redox Regulates ATPase Activity of Magnesium Chelatase CHLI Subunit and Modulates Redox-Mediated Signaling in Tetrapyrrole Biosynthesis and Homeostasis of Reactive Oxygen Species in Pea Plants

et al. 2012

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The chloroplast thioredoxins (TRXs) function as messengers of redox signals from ferredoxin to target enzymes. In this work, we studied the regulatory impact of pea (Pisum sativum) TRX-F on the magnesium (Mg) chelatase CHLI subunit and the enzymatic activation of Mg chelatase in vitro and in vivo. In vitro, reduced TRX-F activated the ATPase activity of pea CHLI and enhanced the activity of Mg chelatase reconstituted from the three recombinant subunits CHLI, CHLD, and CHLH in combination with the regulator protein GENOMES UNCOUPLED4 (GUN4). Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that TRX-F physically interacts with CHLI but not with either of the other two subunits or GUN4. In vivo, virus-induced TRX-F gene silencing (VIGS-TRX-F) in pea plants did not result in an altered redox state of CHLI. However, simultaneous silencing of the pea TRX-F and TRX-M genes (VIGS-TRX-F/TRX-M) resulted in partially and fully oxidized CHLI in vivo. VIGS-TRX-F/TRX-M plants demonstrated a significant reduction in Mg chelatase activity and 5-aminolevulinic acid synthesizing capacity as well as reduced pigment content and lower photosynthetic capacity. These results suggest that, in vivo, TRX-M can compensate for a lack of TRX-F and that both TRXs act as important redox regulators of Mg chelatase. Furthermore, the silencing of TRX-F and TRX-M expression also affects gene expression in the tetrapyrrole biosynthesis pathway and leads to the accumulation of reactive oxygen species, which may also serve as an additional signal for the transcriptional regulation of photosynthesis-associated nuclear genes.

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“…The list of vitamins and cofactors included biotin, thiamin diphosphate, NAD and derivatives, FAD and FMN, coenzyme A, 4-phosphopantetheine, tetrahydrofolate and its derivatives, α-tocopherol, ascorbate, ubiquinone-9, lipoic acid, heme, and pyridoxal-5 ′ -phosphate (Cameron and Teas, 1948;Teas, 1954;Giri et al, 1960;Ingle et al, 1965;Metz et al, 1970;Weber, 1987;Battey and Ohlrogge, 1990;Shannon et al, 1996;Szal et al, 2003;Tumaney et al, 2004;Shi et al, 2005;Drozak and Romanowska, 2006;Hu et al, 2006;Naqvi et al, 2009;Perez-Lopez et al, 2010;Richter et al, 2010;Enami et al, 2011;Spielbauer et al, 2013;Seaver et al, 2014).…”

Section: Vitamins and Cofactorsmentioning

confidence: 99%

Improved Evidence-Based Genome-Scale Metabolic Models for Maize Leaf, Embryo, and Endosperm

Seaver¹,

Bradbury²,

Frelin³

et al. 2016

Crop Breeding

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There is a growing demand for genome-scale metabolic reconstructions for plants, fueled by the need to understand the metabolic basis of crop yield and by progress in genome and transcriptome sequencing. Methods are also required to enable the interpretation of plant transcriptome data to study how cellular metabolic activity varies under different growth conditions or even within different organs, tissues, and developmental stages. Such methods depend extensively on the accuracy with which genes have been mapped to the biochemical reactions in the plant metabolic pathways. Errors in these mappings lead to metabolic reconstructions with an inflated number of reactions and possible generation of unreliable metabolic phenotype predictions. Here we introduce a new evidence-based genome-scale metabolic reconstruction of maize, with significant improvements in the quality of the gene-reaction associations included within our model. We also present a new approach for applying our model to predict active metabolic genes based on transcriptome data. This method includes a minimal set of reactions associated with low expression genes to enable activity of a maximum number of reactions associated with high expression genes. We apply this method to construct an organ-specific model for the maize leaf, and tissue specific models for maize embryo and endosperm cells. We validate our models using fluxomics data for the endosperm and embryo, demonstrating an improved capacity of our models to fit the available fluxomics data. All models are publicly available via the DOE Systems Biology Knowledgebase and PlantSEED, and our new method is generally applicable for analysis transcript profiles from any plant, paving the way for further in silico studies with a wide variety of plant genomes.

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Rapid Dark Repression of 5-Aminolevulinic Acid Synthesis in Green Barley Leaves

Cited by 69 publications

References 57 publications

Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms

Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms

Thioredoxin Redox Regulates ATPase Activity of Magnesium Chelatase CHLI Subunit and Modulates Redox-Mediated Signaling in Tetrapyrrole Biosynthesis and Homeostasis of Reactive Oxygen Species in Pea Plants

Improved Evidence-Based Genome-Scale Metabolic Models for Maize Leaf, Embryo, and Endosperm

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