Shikimate Kinase from Spinach Chloroplasts

Schmidt, Christian; Danneel, Hans-Jürgen; Schultz, Gernot; Buchanan, Bob B.

doi:10.1104/pp.93.2.758

Cited by 35 publications

(10 citation statements)

References 26 publications

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“…It is very unlikely that BSA functions as a protease inhibitor in its protection against inactivation of QA hydrolyase, since no protease inhibitor or thiol reagent could replace it. We could explain the BSA function, and a similar function of ovalbumin, through protein-protein interactions, as described for SK kinase from spinach leaves (Schmidt et al, 1990). This finding is consistent with results obtained from gel filtration.…”

Section: Discussionmentioning

confidence: 77%

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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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Section: Discussionmentioning

confidence: 77%

“…SDS-PAGE was performed according to Laemmli (1970) with 3% acrylamide for the stacking gel and 12% for the resolving gel. Proteins on gels were visualized by silver staining (Schmidt et al, 1990).…”

Section: Sds-pagementioning

confidence: 99%

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

1995

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“…This would allow for the regulation of the shikimate pathway by light. A light stimulation of the overall activity of the shikimate pathway, in vivo or in isolated chloroplasts, has been reported earlier ( 19,20), but light-regulated enzymes have not been identified yet (29).…”

Section: Monoq Chromatographymentioning

confidence: 91%

Purification and Characterization of Chorismate Synthase from Euglena gracilis

Schaller¹,

Afferden²,

Windhofer³

et al. 1991

Plant Physiol.

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Chorismate synthase was purified 1200-fold from Euglena gracilis. The molecular mass of the native enzyme is in the range of 110 to 138 kilodaltons as judged by gel filtration. The molecular mass of the subunit was determined to be 41.7 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified chorismate synthase is associated with an NADPH-dependent flavin mononucleotide reductase that provides in vivo the reduced flavin necessary for catalytic activity. In vitro, flavin reduction can be mediated by either dithionite or light. The enzyme obtained from E. gracilis was compared with chorismate synthases purified from a higher plant (Corydalis sempervirens), a bacterium (Escherichia co/i), and a fungus (Neurospora crassa).These four chorismate synthases were found to be very similar in terms of cofactor specificity, kinetic properties, isoelectric points, and pH optima. All four enzymes react with polyclonal antisera directed against chorismate synthases from C. sempervirens and E. coli. The closely associated flavin mononucleotide reductase that is present in chorismate synthase preparations from E. gracilis and N. crassa is the main difference between those synthases and the monofunctional enzymes from C. sempervirens and E. coli.The three aromatic amino acids are synthesized via the shikimate pathway in microorganisms and plants (Fig. 1). Although the reaction sequence in the prechorismate pathway is identical in all organisms investigated so far, there are considerable differences in enzyme organization, as well as regulation, between organisms of different taxonomic groups. In Escherichia coli, the seven enzymatic activities of the prechorismate pathway are associated with monofunctional polypeptides. In contrast, in (reviewed in ref. 4). In Euglena gracilis, the organization of the prechorismate pathway appears to resemble that found in fungi. The first and the last steps are catalyzed by single enzymes (DAHP-synthase and chorismate synthase, respectively), whereas activities 2 to 6 form a large complex resembling the fungal arom complex (27). Euglena and fungi are strikingly similar in other biochemical pathways as well. Thus, both groups of organisms use the L-a-aminoadipate pathway for lysine biosynthesis, whereas bacteria, algae, and plants follow the diaminopimelate route (30). On the basis of such findings, a close evolutionary relationship was proposed for euglenoids and fungi. But aromatic biosynthesis shows several features that, among all organisms studied so far, are unique for E. gracilis. Anthranilate synthase, the first enzyme in the tryptophan branch ( Fig. 1), is monomeric in Euglena, whereas in all other anthranilate synthases characterized so far the chorismate and glutamine binding sites reside on distinct polypeptide chains (16). The synthesis of tryptophan from anthranilate is catalyzed by a single protein in Euglena (17), but in all other known examples tryptophan synthase is separable from the other activities of the tryptophan branch (17). Unlike ot...

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“…It has been suggested that plant SKs act as regulatory points for the shikimate pathway, facilitating metabolic flux towards specific secondary metabolite pools [3]. This is supported by observations of rapid induction of plant SK transcripts by fungal elicitors [4], the significant sensitivity of plant SK activity to cellular ATP energy charge [5], and the differential expression of the three rice SK genes during specific developmental stages and biotic stress response [6].…”

Section: Introductionmentioning

confidence: 91%

Evolutionary Diversification of Plant Shikimate Kinase Gene Duplicates

2008

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Shikimate kinase (SK; EC 2.7.1.71) catalyzes the fifth reaction of the shikimate pathway, which directs carbon from the central metabolism pool to a broad range of secondary metabolites involved in plant development, growth, and stress responses. In this study, we demonstrate the role of plant SK gene duplicate evolution in the diversification of metabolic regulation and the acquisition of novel and physiologically essential function. Phylogenetic analysis of plant SK homologs resolves an orthologous cluster of plant SKs and two functionally distinct orthologous clusters. These previously undescribed genes, shikimate kinase-like 1 (SKL1) and -2 (SKL2), do not encode SK activity, are present in all major plant lineages, and apparently evolved under positive selection following SK gene duplication over 400 MYA. This is supported by functional assays using recombinant SK, SKL1, and SKL2 from Arabidopsis thaliana (At) and evolutionary analyses of the diversification of SK-catalytic and -substrate binding sites based on theoretical structure models. AtSKL1 mutants yield albino and novel variegated phenotypes, which indicate SKL1 is required for chloroplast biogenesis. Extant SKL2 sequences show a strong genetic signature of positive selection, which is enriched in a protein–protein interaction module not found in other SK homologs. We also report the first kinetic characterization of plant SKs and show that gene expression diversification among the AtSK inparalogs is correlated with developmental processes and stress responses. This study examines the functional diversification of ancient and recent plant SK gene duplicates and highlights the utility of SKs as scaffolds for functional innovation.

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Shikimate Kinase from Spinach Chloroplasts

Cited by 35 publications

References 26 publications

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

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

Purification and Characterization of Chorismate Synthase from Euglena gracilis

Evolutionary Diversification of Plant Shikimate Kinase Gene Duplicates

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