Comparative studies of l- and d-methionine metabolism in lower and higher plants

Pokorný, Miroslav; Marčenko, Elena; Keglević, Dina

doi:10.1016/s0031-9422(00)85382-0

Cited by 37 publications

(14 citation statements)

References 25 publications

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“…As with Met transamination, a small capacity to convert MTOB to MTHB may be widespread, because MTHB (of undetermined configuration) has been detected as a metabolite of radiotracer Met or MTOB in diverse higher and lower plants, including algae that lack DMSP (Pokorny et al, 1970;Kushad et al, 1983;Miyazaki and Yang, 1987). However, MTHB formation in these cases may be just a reversible side reaction of the Met salvage pathway (Miyazaki and Yang, 1987), which would be expected to carry very little flux compared with DMSP synthesis.…”

Section: Discussionmentioning

confidence: 99%

Identification and Stereospecificity of the First Three Enzymes of 3-Dimethylsulfoniopropionate Biosynthesis in a Chlorophyte Alga1

et al. 1998

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Many marine algae produce 3-dimethylsulfoniopropionate (DMSP), a potent osmoprotective compound whose degradation product dimethylsulfide plays a central role in the biogeochemical S cycle. Algae are known to synthesize DMSP via the four-step pathway, L-Met 3 4-methylthio-2-oxobutyrate 3 4-methylthio-2-hydroxybutyrate 3 4-dimethylsulfonio-2-hydroxy-butyrate (DM-SHB) 3 DMSP. Substrate-specific enzymes catalyzing the first three steps in this pathway were detected and partially characterized in cell-free extracts of the chlorophyte alga Enteromorpha intestinalis. The first is a 2-oxoglutarate-dependent aminotransferase, the second an NADPH-linked reductase, and the third an S-adenosylmethioninedependent methyltransferase. Sensitive radiometric assays were developed for these enzymes, and used to show that their activities are high enough to account for the estimated in vivo flux from Met to DMSP. The activities of these enzymes in other DMSP-rich chlorophyte algae were at least as high as those in E. intestinalis, but were >20-fold lower in algae without DMSP. The reductase and methyltransferase were specific for the D-enantiomer of 4-methylthio-2-hydroxybutyrate in vitro, and both the methyltransferase step and the step(s) converting DMSHB to DMSP were shown to prefer D-enantiomers in vivo. The intermediate DMSHB was shown to act as an osmoprotectant, which indicates that the first three steps of the DMSP synthesis pathway may be sufficient to confer osmotolerance.

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Section: Discussionmentioning

confidence: 99%

Identification and Stereospecificity of the First Three Enzymes of 3-Dimethylsulfoniopropionate Biosynthesis in a Chlorophyte Alga1

et al. 1998

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“…DMSP biosynthesis has been studied in higher plants and marine algae by in vivo radiotracer methods. In the green alga Ulva lactuca the carbon skeleton, the sulfur and the methyl groups of DMSP are derived from methionine (Greene, 1962;Kahn, 1964); this is probably also so in the red alga Chondria coerulescens (Chillemi et al, 1990), in brown algae (Pokorny et al, 1970), and in Wedelia biflora (Hanson and Rivoal, unpublished (Mudd and Datko, 1990;Pokorny et al, 1970).…”

Section: -Alanine Betainementioning

confidence: 99%

Evolution and Metabolic Engineering of Osmoprotectant Accumulation in Higher Plants

Hanson

Burnet

1994

Biochemical and Cellular Mechanisms of Stress Tolerance in Plants

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Glycine betaine can act an osmoprotectant in many organisms.The capacity to accumulate glycine betaine in response to drought or salt stress is widespread in angiosperms, and probably appeared early in the evolution of this group. Despite the efficacy of glycine betaine, diverse angiosperm taxa have evolved a range of structurally analogous compounds which supplement or replace it.These compounds include choline-Osulfate, dimethylsulfoniopropionate, and the betaines of Balanine, proline and hydroxyproline.This phytochemical diversity may reflect biosynthetic innovation driven by three types of· selective forces: the need for effective osmoprotection, the interaction between osmotic and co-occurring physicochemical stresses, and the action of herbivores and pathogens. The evolution of the biosynthetic pathways for alternative osmoprotectants to glycine betaine suggests new opportunities for the metabolic engineering of stress tolerance.

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“…Furthermore, there are several reports of D-amino acid toxicity towards plants (Valdovinos and Muir, 1965;Aldag and Young, 1970;Manabe and Ohira, 1981). Available information suggests that some D-amino acids can be conjugated with appropriate compounds to form N-malonyl and N-acetyl conjugates by a wide array of different plants (Pokorny et al, 1970). It has been suggested that the conjugation of D-amino acids and their compartmentalization in the vacuole provides a way to neutralise these potentially toxic compounds (Gamburg and Rekoslavskaya, 1991).…”

Section: Introductionmentioning

confidence: 99%

The dsdA gene from Escherichia coli provides a novel selectable marker for plant transformation

2005

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Plants are sensitive to D-serine, but functional expression of the dsdA gene, encoding D-serine ammonia lyase, from Escherichia coli can alleviate this toxicity. Plants, in contrast to many other organisms, lack the common pathway for oxidative deamination of D-amino acids. This difference in metabolism has major consequences for plant responses to D-amino acids, since several D-amino acids are toxic to plants even at relatively low concentrations. Therefore, introducing an enzyme specific for a phytotoxic D-amino acid should generate a selectable characteristic that can be screened. Here we present the use of the dsdA gene as a selectable marker for transformation of Arabidopsis. D-serine ammonia lyase catalyses the deamination of D-serine into pyruvate, water and ammonium. dsdA transgenic seedlings can be clearly distinguished from wild type, having an unambiguous phenotype immediately following germination when selected on D-serine containing medium. The dsdA marker allows flexibility in application of the selective agent: it can be applied in sterile plates, in foliar sprays or in liquid culture. Selection with D-serine resistance was compared with selection based on kanamycin resistance, and was found to generate similar transformation frequencies but also to be more unambiguous, more rapid and more versatile with respect to the way the selective agent can be supplied.

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Comparative studies of l- and d-methionine metabolism in lower and higher plants

Cited by 37 publications

References 25 publications

Identification and Stereospecificity of the First Three Enzymes of 3-Dimethylsulfoniopropionate Biosynthesis in a Chlorophyte Alga1

Identification and Stereospecificity of the First Three Enzymes of 3-Dimethylsulfoniopropionate Biosynthesis in a Chlorophyte Alga1

Evolution and Metabolic Engineering of Osmoprotectant Accumulation in Higher Plants

The dsdA gene from Escherichia coli provides a novel selectable marker for plant transformation

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