scholarly journals Cadmium and Copper Cross-Tolerance. Cu+ Alleviates Cd2 + Toxicity, and Both Cations Target Heme and Chlorophyll Biosynthesis Pathway in Rubrivivax gelatinosus

2020 ◽  
Vol 11 ◽  
Author(s):  
Anne Soisig Steunou ◽  
Anne Durand ◽  
Marie-Line Bourbon ◽  
Marion Babot ◽  
Reem Tambosi ◽  
...  
Keyword(s):  
Chlorophyll Biosynthesis ◽  
Biosynthesis Pathway ◽  
Cross Tolerance ◽  
Rubrivivax Gelatinosus

scholarly journals Plastome Reduction in the Only Parasitic Gymnosperm Parasitaxus Is Due to Losses of Photosynthesis but Not Housekeeping Genes and Apparently Involves the Secondary Gain of a Large Inverted Repeat

2019 ◽  
Vol 11 (10) ◽  
pp. 2789-2796 ◽  
Author(s):  
Xiao-Jian Qu ◽  
Shou-Jin Fan ◽  
Susann Wicke ◽  
Ting-Shuang Yi
Keyword(s):  
Inverted Repeat ◽  
Chlorophyll Biosynthesis ◽  
Housekeeping Genes ◽  
Parasitic Plants ◽  
Structural Features ◽  
Regulation System ◽  
Biosynthesis Pathway ◽  
Plastid Genomes ◽  
Plastome Evolution ◽  
Selection For

Abstract Plastid genomes (plastomes) of parasitic plants undergo dramatic reductions as the need for photosynthesis relaxes. Here, we report the plastome of the only known heterotrophic gymnosperm Parasitaxus usta (Podocarpaceae). With 68 unique genes, of which 33 encode proteins, 31 tRNAs, and four rRNAs in a plastome of 85.3-kb length, Parasitaxus has both the smallest and the functionally least capable plastid genome of gymnosperms. Although the heterotroph retains chlorophyll, all genes for photosynthesis are physically or functionally lost, making photosynthetic energy gain impossible. The pseudogenization of the three plastome-encoded light-independent chlorophyll biosynthesis genes chlB, chlL, and chlN implies that Parasitaxus relies on either only the light-dependent chlorophyll biosynthesis pathway or another regulation system. Nesting within a group of gymnosperms known for the absence of the large inverted repeat regions (IRs), another unusual feature of the Parasitaxus plastome is the existence of a 9,256-bp long IR. Its short length and a gene composition that completely differs from those of IR-containing gymnosperms together suggest a regain of this critical, plastome structure-stabilizing feature. In sum, our findings highlight the particular path of lifestyle-associated reductive plastome evolution, where structural features might provide additional cues of a continued selection for plastome maintenance.

scholarly journals Selenium Regulates Gene Expression for Glucosinolate and Carotenoid Biosynthesis in Arabidopsis

2011 ◽  
Vol 136 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Carl E. Sams ◽  
Dilip R. Panthee ◽  
Craig S. Charron ◽  
Dean A. Kopsell ◽  
Joshua S. Yuan
Keyword(s):  
Gene Expression ◽  
Differentially Expressed Genes ◽  
Plant Species ◽  
Chlorophyll Biosynthesis ◽  
Plant Secondary Metabolites ◽  
Carotenoid Biosynthesis ◽  
Differentially Expressed ◽  
Biosynthesis Pathway ◽  
Tissue Samples ◽  
Expression Of Genes

Glucosinolates (GSs) and carotenoids are important plant secondary metabolites present in several plant species, including arabidopsis (Arabidopsis thaliana). Although genotypic and environmental regulation of GSs and carotenoid compounds has been reported, few studies present data on their regulation at the molecular level. Therefore, the objective of this study was to explore differential expression of genes associated with GSs and carotenoids in arabidopsis in response to selenium fertilization, shown previously to impact accumulations of both classes of metabolites in Brassica species. Arabidopsis was grown under 0.0 or 10.0 μM Na2SeO4 in hydroponic culture. Shoot and root tissue samples were collected before anthesis to measure GSs and carotenoid compounds and conduct gene expression analysis. Gene expression was determined using arabidopsis oligonucleotide chips containing more than 31,000 genes. There were 1274 differentially expressed genes in response to selenium (Se), of which 516 genes were upregulated. Ontology analysis partitioned differentially expressed genes into 20 classes. Biosynthesis pathway analysis using AraCyc revealed that four GSs, one carotenoid, and one chlorophyll biosynthesis pathways were invoked by the differentially expressed genes. Involvement of the same gene in more than one biosynthesis pathway indicated that the same enzyme may be involved in multiple GS biosynthesis pathways. The decrease in carotenoid biosynthesis under Se treatment occurred through the downregulation of phytoene synthase at the beginning of the carotenoid biosynthesis pathway. These findings may be useful to modify the GS and carotenoid levels in arabidopsis and may lead to modification in agriculturally important plant species.

scholarly journals Structure of GUN4 fromChlamydomonas reinhardtii

2015 ◽  
Vol 71 (8) ◽  
pp. 1094-1099 ◽  
Author(s):  
Shabnam Tarahi Tabrizi ◽  
David B. Langley ◽  
Stephen J. Harrop ◽  
Anthony P. Duff ◽  
Robert D. Willows
Keyword(s):  
Crystal Structure ◽  
Chlamydomonas Reinhardtii ◽  
Chlorophyll Biosynthesis ◽  
Conformational Dynamics ◽  
Protoporphyrin Ix ◽  
Biosynthesis Pathway ◽  
Broad Agreement ◽  
Binding Cleft ◽  
Mg Chelatase

The genomes uncoupled 4 (GUN4) protein stimulates chlorophyll biosynthesis by increasing the activity of Mg-chelatase, the enzyme that inserts magnesium into protoporphyrin IX (PPIX) in the chlorophyll biosynthesis pathway. One of the roles of GUN4 is in binding PPIX and Mg-PPIX. In eukaryotes, GUN4 also participates in plastid-to-nucleus signalling, although the mechanism for this is unclear. Here, the first crystal structure of a eukaryotic GUN4, fromChlamydomonas reinhardtii, is presented. The structure is in broad agreement with those of previously solved cyanobacterial structures. Most interestingly, conformational divergence is restricted to several loops which cover the porphyrin-binding cleft. The conformational dynamics suggested by this ensemble of structures lend support to the understanding of how GUN4 binds PPIX or Mg-PPIX.

scholarly journals Important Roles of Key Genes and Transcription Factors in Flower Color Differences of Nicotiana alata

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1976
Author(s):  
Yalin Zheng ◽  
Yudong Chen ◽  
Zhiguo Liu ◽  
Hui Wu ◽  
Fangchan Jiao ◽  
...  
Keyword(s):  
Differential Expression ◽  
Anthocyanin Biosynthesis ◽  
Chlorophyll Biosynthesis ◽  
Enrichment Analysis ◽  
Flower Color ◽  
Nicotiana Alata ◽  
Biosynthesis Pathway ◽  
Color Differences ◽  
Differential Expression Genes ◽  
Horticultural Plant

Nicotiana alata is an ornamental horticultural plant with a variety of flower colors and a long flowering period. The genes in four different colored N. alata (white, purple, red, and lemon green) were analyzed to explain the differences in flower color using transcriptomes. A total of 32 differential expression genes in the chlorophyll biosynthesis pathway and 41 in the anthocyanin biosynthesis pathway were identified. The enrichment analysis showed that the chlorophyll biosynthesis pathway and anthocyanin biosynthesis pathway play critical roles in the color differences of N. alata. The HEMA of the chlorophyll biosynthesis pathway was up-regulated in lemon green flowers. Compared with white flowers, in the red and purple flowers, F3H, F3′5′H and DFR were significantly up-regulated, while FLS was significantly down-regulated. Seventeen differential expression genes homologous to transcription factor coding genes were obtained, and the homologues of HY5, MYB12, AN1 and AN4 were also involved in flower color differences. The discovery of these candidate genes related to flower color differences is significant for further research on the flower colors formation mechanism and color improvements of N. alata.

scholarly journals Spectroscopic and kinetic characterization of the light-dependent enzyme protochlorophyllide oxidoreductase (POR) using monovinyl and divinyl substrates

2006 ◽  
Vol 394 (1) ◽  
pp. 243-248 ◽  
Author(s):  
Derren J. Heyes ◽  
Jerzy Kruk ◽  
C. Neil Hunter
Keyword(s):  
Rhodobacter Capsulatus ◽  
Chlorophyll Biosynthesis ◽  
Kinetic Properties ◽  
Biosynthesis Pathway ◽  
Kinetic Characterization ◽  
Protochlorophyllide Oxidoreductase ◽  
Substrate Analogues ◽  
Steady State Kinetic ◽  
State Kinetic

The enzyme POR [Pchlide (protochlorophyllide) oxidoreductase] catalyses the reduction of Pchlide to chlorophyllide, which is a key step in the chlorophyll biosynthesis pathway. This light-dependent reaction has previously been studied in great detail but recent reports suggest that a mixture of MV (monovinyl) and DV (divinyl) Pchlides may have influenced some of these properties of the reaction. Low-temperature absorbance and fluorescence spectroscopy have revealed several spectral differences between MV and DV Pchlides, which were purified from a Rhodobacter capsulatus strain that was shown to contain a mixture of the two pigments. A thorough steady-state kinetic characterization using both Pchlide forms demonstrates that neither pigment appears to affect the kinetic properties of the enzyme. The reaction has also been monitored following illumination at low temperatures and was shown to consist of an initial photochemical step followed by four ‘dark’ steps for both pigments. However, minor differences were observed in the spectral properties of some of the intermediates, although the temperature dependency of each step was nearly identical for the two pigments. This work provides the first detailed kinetic and spectroscopic study of this unique enzyme using biologically important MV and DV substrate analogues. It also has significant implications for the DV reductase enzyme, which is responsible for converting DV pigments into their MV counterparts, and its position in the sequence of reactions that comprise the chlorophyll biosynthesis pathway.

Role of the antioxidant system in the regulation of the chlorophyll biosynthesis pathway in the vascular plant Cucumis sativus

2018 ◽  
Vol 45 (4) ◽  
pp. 464
Author(s):  
Aarti Dhepe ◽  
Komal Joshi
Keyword(s):  
Cucumis Sativus ◽  
Antioxidant System ◽  
Chlorophyll Biosynthesis ◽  
Vascular Plant ◽  
Protoporphyrin Ix ◽  
Thioredoxin Reductase ◽  
Ros Generation ◽  
Biosynthesis Pathway ◽  
Cucumis Sativus L

In this study, the role of the antioxidant system has been examined in the regulation of the chlorophyll biosynthesis pathway in the vascular plant Cucumis sativus L. To generate reactive oxygen species (ROS), etiolated (E) and green (G) cucumber cotyledons were treated with methyl viologen (MV) or were exposed to high light (HL, 400–500 µE m–2 s–1). ROS generation was confirmed by measuring proline and H2O2 concentrations. With the effects of the MV- and HL-induced oxidative stress, it was observed that the chlorophyll biosynthesis pathway was severely affected in the HL-treated etiolated cotyledons (E-HL), MV-treated etiolated cotyledons (E-MV) and in MV-treated green cotyledons (G-MV) at 5-amino levulinic acid (ALA) as well as at protoporphyrin IX and Mg-protoporphyrin IX monomethyl ester levels. The antioxidant assays conducted showed that the ascorbate peroxidase (APX) activity had decreased in the E-HL, E-MV and G-MV cotyledons along with the levels of ascorbate and lutein. A decrease in the NADPH-dependent thioredoxin reductase (NTRC) was also observed in the MV-treated cotyledons with a significant impairment of the catalase activity in the E-HL cotyledons. Conversely, in the HL-treated green i.e. G-HL cotyledons, where the accumulation of H2O2 and the inhibition of chlorophyll biosynthesis were not observed, an increase in the levels of APX, NTRC, peroxiredoxin, ascorbate, glutathione and lutein was noted. Thus, the results obtained suggested that the antioxidant system could influence the flow of the chlorophyll biosynthesis pathway through maintaining the levels of H2O2.

MGDG, PG and SQDG regulate the activity of light-dependent protochlorophyllide oxidoreductase

2017 ◽  
Vol 474 (7) ◽  
pp. 1307-1320 ◽  
Author(s):  
Michal Gabruk ◽  
Beata Mysliwa-Kurdziel ◽  
Jerzy Kruk
Keyword(s):  
Molecular Mechanisms ◽  
Chlorophyll Biosynthesis ◽  
Fluorescence Emission ◽  
Lipid Binding ◽  
Site Directed Mutagenesis ◽  
Biosynthesis Pathway ◽  
Amino Acid Residues ◽  
Protochlorophyllide Oxidoreductase ◽  
Emission Maximum ◽  
Identify Amino Acid

Light-dependent protochlorophyllide oxidoreductase (POR) is a plant enzyme involved in the chlorophyll biosynthesis pathway. POR reduces one of the double bonds of the protochlorophyllide (Pchlide) using NADPH and light. In the present study, we found out that phosphatidylglycerol and sulfoquinovosyl diacylglycerol are allosteric regulators of the nucleotide binding, which increase the affinity towards NADPH a 100-fold. Moreover, we showed for the first time that NADH can, like NADPH, form active complexes with Pchlide and POR, however, at much higher concentrations. Additionally, monogalactosyldiacylglycerol (MGDG) was shown to be the main factor responsible for the red shift of the fluorescence emission maximum of Pchlide:POR:NADPH complexes. Importantly, the emission maximum at 654 nm was obtained only for the reaction mixtures supplemented with MGDG and at least one of the negatively charged plant lipids. Moreover, the site-directed mutagenesis allowed us to identify amino acid residues that may be responsible for lipid binding and Pchlide coordination. Our experiments allowed us to identify six different Pchlide:POR complexes that differ in the fluorescence emission maxima of the pigment. The results presented here reveal the contribution of thylakoid lipids in the regulation of the chlorophyll biosynthesis pathway; however, the molecular mechanisms of this process are to be clarified.

Distribution and Functional Analysis of the Two Types of 8-vinyl Reductase Involved in Chlorophyll Biosynthesis in Marine Cyanobacteria

2021 ◽  
Author(s):  
Haruka Suehiro ◽  
Ryouichi Tanaka ◽  
Hisashi Ito
Keyword(s):  
Chlorophyll Biosynthesis ◽  
Marine Cyanobacteria ◽  
Biosynthesis Pathway ◽  
Genomic Comparison ◽  
Marine Cyanobacterium ◽  
Photosynthetic Organisms ◽  
Chlorophyll Precursor ◽  
Vinyl Group ◽  
Vinyl Reductase

Abstract In the chlorophyll biosynthesis pathway, the 8-vinyl group of the chlorophyll precursor is reduced to an ethyl group by 8-vinyl reductase. Two isozymes of 8-vinyl reductase have been described in oxygenic photosynthetic organisms: one encoded by BciA and another by BciB. Only BciB contains an [Fe-S] cluster and most cyanobacteria harbor this form; whereas a few contain BciA. Given this disparity in distribution, cyanobacterial BciA has remained largely overlooked, which has limited understanding of chlorophyll biosynthesis in these microorganisms. Here, we reveal that cyanobacterial BciA encodes a functional 8-vinyl reductase, as evidenced by measuring the in vitro activity of recombinant Synechococcus and Acaryochloris BciA. Genomic comparison revealed that BciB had been replaced by BciA during evolution of the marine cyanobacterium Synechococcus, and coincided with replacement of Fe-superoxide dismutase (SOD) with Ni-SOD. These findings imply that the acquisition of BciA confers an adaptive advantage to cyanobacteria living in low-iron oceanic environments.

Oxygen-dependent copper toxicity: targets in the chlorophyll biosynthesis pathway identified in the copper efflux ATPase CopA deficient mutant

2015 ◽  
Vol 17 (6) ◽  
pp. 1963-1976 ◽  
Author(s):  
Sylviane Liotenberg ◽  
Anne-Soisig Steunou ◽  
Anne Durand ◽  
Marie-Line Bourbon ◽  
David Bollivar ◽  
...  
Keyword(s):  
Chlorophyll Biosynthesis ◽  
Copper Toxicity ◽  
Biosynthesis Pathway ◽  
Deficient Mutant
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