Differential expression of tomato (Lycopersicon esculentum L.) genes encoding shikimate pathway isoenzymes. II. Chorismate synthase

Görlach, Jörn; Schmid, Jürg; Amrhein, Nikolaus

doi:10.1007/bf00021526

Cited by 35 publications

(21 citation statements)

References 30 publications

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“…Besides DAHP synthase and AS, CS is the third enzyme of the shikimate pathway known to be encoded by two distinct genes which respond differentially to pathogen-derived stress factors. The differential expression of the two tomato CS genes in response to elicitor was not expected in this case, since both genes exhibit the same organ-specific expression pattern (14,21). In this respect the two CS genes clearly differ from the two DAHP synthase genes of tomato.…”

Section: Resultsmentioning

confidence: 77%

“…It was previously shown that Pmg induces PAL activity and ethylene biosynthesis in tomato cells (10,16) and, furthermore, that the induction of PAL activity by YIE was independent of ethylene biosynthesis (17). Of (18,19,21). To link the expression patterns of these genes with those of the general phenylpropanoid pathway, the expression of the PAL gene family was also analyzed.…”

Section: Resultsmentioning

confidence: 99%

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Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Görlach

Raesecke

Rentsch

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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The accumulation of phenylalanine-derived phenolic compounds is a well-known element of a plant's defense in response to pathogen attack Phenylalanine, as well as the other two aromatic amino acids, tyrosine and tryptophan, is synthesized by way of the shikimate pathway. The first seven steps of the shikimate pathway (the prechorismate pathway) are common for the biosynthesis of all three aromatic amino acids. We have studied transcript levels of six genes-i.e., two 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase genes, one shikimate kinase gene, one 5-enolpyruvylshikimate 3-phosphate synthase gene, and two chorismate synthase genes-corresponding to four steps of the prechorismate pathway, in cultured tomato cells exposed to fungal elicitors.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Görlach

Raesecke

Rentsch

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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“…Very recent studies on the organ-specific expression of genes encoding SK pathway isoenzymes in green and nongreen tissues (Eberhard et al, 1993;Gorlach et al, 1993a, 199310) suggest an organ-specific regulation of AAA synthesis. Of interest is the elevated transcription of genes of SK pathway enzymes in nongreen parts (Gorlach et al, 1994). Such elevated transcription could mean an intensive synthesis in these parts and an export of surplus prearomatic and aromatic compounds.…”

Section: Discussionmentioning

confidence: 99%

The Metabolism of Quinate in Pea Roots (Purification and Partial Characterization of a Quinate Hydrolyase)

1995

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QA and SK are compounds that often occur in relatively high concentrations in green and nongreen tissues of herbaceous (Yoshida et al., 1975) and woody angiosperms (Boudet, 1973). For example, in the spring, high amounts of QA are formed in developing coniferous needles (2-10% of dry weight) in the course of photosynthetic C02 fixation (Dittrich and Kandler, 1971). This QA pool is metabolized during the lignification process in the summer. QA is also a precursor for chlorogenic acids and is converted into other secondary products like protocatechuic acid (Haslam, 1974). Although QA is formed by a QA:NAD(P)+ oxidoreductase from DHQ, an intermediate in the SK pathway (Bentley, 1990), its involvement in AAA biosynthesis is not clear. 14C-labeled QA is incorporated into free and proteinbound AAA in different herbaceous species and members of the Rosaceae (Weinstein et al., 1959(Weinstein et al., , 1961 and in mung bean (Minamikawa et al., 1969). However, the actual enzymatic steps for channeling QA into the SK pathway are not known.In pea (Pisum sativum L.) epicotyls, an irreversible conversion of QA into SK has been found (Tazaki et al., 1974), whereas the reaction appears to be reversible in mung bean (Minamikawa et al

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“…Initially, native gradient (8-25%) gel electrophoresis of matCS (Fig. 5) conserved among all known CSs (Gorlach et al, 1993), deleterious consequences upon enzyme activity due to relatively large additions adjacent to this region are not surprising. At the plant level, we would conclude from these data that activity of plant CS, as defined by our assay conditions, is dependent on import into plastids.…”

Section: Complementation Of E Coli Cs Mutant Ab2849mentioning

confidence: 99%

Only the Mature Form of the Plastidic Chorismate Synthase Is Enzymatically Active

1995

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Coding regions of a cDNA for precursor and mature chorismate synthase (CS), a plastidic enzyme, from Corydalis sempervirens were expressed in Escherichia coli as translational fusions to glutathione-S-transferase. Fusion proteins were purified, and precursor and mature forms of CS were then released by proteolytic cleavage with factor Xa. Although mature CS was enzymatically active afier release, activity could be detected neither for the precursor CS nor for corresponding glutathione-S-transferase fusion proteins. I n contrast, two other shikimate pathway enzymes (shikimate kinase and 5-enol-pyruvylshikimate-3-phosphate synthase) have previously been shown to be as enzymatically active as their respective higher molecular weight precursors. By expression of unfused, mature CS from C. sempervirens in E. coli, it was possible to obtain large quantities of enzymatically active CS protein compared to yields from plant cell cultures. Expression levels i n E. coli approached 1% of total soluble protein. No differences were found between authentic CS isolated from cell cultures and CS expressed in and purified from E. coli, which made possible a more detailed biochemical characterization of CS. Quaternary structure analysis of the purified mature CS indicated that the enzyme exists as a dimer, i n contrast to the active tetrameric structures determined for E. coli and Neurospora crassa enzymes.CS catalyzes the unusual trans 1,4-elimination of orthophosphate from EPSP to form chorismate, the last common intermediate in the synthesis of the aromatic amino acids Phe, Tyr, and Trp. CSs from a11 sources studied, including the higher plant Corydalis sempervirens, have an absolute requirement for reduced flavin. The actual role of flavin is not immediately obvious, since no net redox change occurs. Recently, however, it has been shown with the Escherichia coli CS that the flavin undergoes a change during catalysis that is observable spectrophotometrically and possibly involves a C(4a)-flavin adduct/charge transfer intermediate, indicating direct involvement of flavin in the reaction mechanism (Ramjee et al., 1991(Ramjee et al., , 1992.After the initial demonstration of CS activity in a cell-free extract from a higher plant (Mousdale and Coggins, 1986), plant CS was first purified to homogeneity from a C. sempervirens cell culture (Schaller et al., 1990). The protein is monofunctional, lacking the ability to generate reduced flavin with NADPH by an intrinsic "diaphorase" activity (Schaller et al., 1990). A cDNA encoding CS was cloned from C. sempervirens. The deduced amino acid sequence revealed that the cDNA encodes a precursor polypeptide with an N-terminal plastid transit peptide domain (Schaller et al., 1991a).In higher plants, aromatic amino acid biosynthetic enzymes including CS activity have been localized to plastids Coggins, 1985, 1986). However, cytosolic activities for at least two steps of the pathway, 3-deoxy-~-arabino-heptulosonate-7-phosphate synthase and chorismate mutase, have been detected (Hrazdina and Jen...

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Differential expression of tomato (Lycopersicon esculentum L.) genes encoding shikimate pathway isoenzymes. II. Chorismate synthase

Cited by 35 publications

References 30 publications

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

The Metabolism of Quinate in Pea Roots (Purification and Partial Characterization of a Quinate Hydrolyase)

Only the Mature Form of the Plastidic Chorismate Synthase Is Enzymatically Active

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