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Shikimate Pathway (shikimate + pathway)
Selected AbstractsOverexpression of the Wounding-Responsive Gene AtMYB15 Activates the Shikimate Pathway in ArabidopsisJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2006Yanhui Chen Abstract The MYB transcription factor genes play important roles in many developmental processes and various defense responses of plants. The shikimate pathway is a major biosynthetic pathway for the production of three aromatic amino acids and other aromatic compounds that are involved in multiple responses of plants, including protection against UV and defense. Herein, we describe the characterization of the R2R3-MYB gene AtMYB15 as an activator of the shikimate pathway in Arabidopsis. The AtMYB15 protein is nuclear localized and a transcriptional activation domain is found in its C-terminal portion. Northern blots showed that AtMYB15 is an early wounding-inducible gene. Resutls of microarray analysis, confirmed using quantitative real-time polymerase chain reaction, showed that overexpression of AtMYB15 in transgenic plants resulted in elevated expression of almost all the genes involved in the shikimate pathway. Bioinformatics analysis showed that one or more AtMYB15-binding AC elements were detected in the promoters of these upregulated genes. Furthermore, these genes in the shikimate pathway were also found to be induced by wounding. These data suggest an important role of AtMYB15 as a possible direct regulator of the Arabidopsis shikimate pathway in response to wounding. (Managing editor: Ya-Qin Han) [source] Biochemical characterization and inhibitor discovery of shikimate dehydrogenase from Helicobacter pyloriFEBS JOURNAL, Issue 20 2006Cong Han Shikimate dehydrogenase (SDH) is the fourth enzyme involved in the shikimate pathway. It catalyzes the NADPH-dependent reduction of 3-dehydroshikimate to shikimate, and has been developed as a promising target for the discovery of antimicrobial agent. In this report, we identified a new aroE gene encoding SDH from Helicobacter pylori strain SS1. The recombinant H. pylori shikimate dehydrogenase (HpSDH) was cloned, expressed, and purified in Escherichia coli system. The enzymatic characterization of HpSDH demonstrates its activity with kcat of 7.7 s,1 and Km of 0.148 mm toward shikimate, kcat of 7.1 s,1 and Km of 0.182 mm toward NADP, kcat of 5.2 s,1 and Km of 2.9 mm toward NAD. The optimum pH of the enzyme activity is between 8.0 and 9.0, and the optimum temperature is around 60 °C. Using high throughput screening against our laboratory chemical library, five compounds, curcumin (1), 3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H -chromen-7-yl 3-chlorobenzoate (2), butyl 2-{[3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H -chromen-7-yl]oxy}propanoate (3), 2-({2-[(2-{[2-(2,3-dimethylanilino)-2-oxoethyl]sulfanyl}-1,3-benzothiazol-6-yl)amino]-2-oxoethyl}sulfanyl)- N -(2-naphthyl)acetamide (4), and maesaquinone diacetate (5) were discovered as HpSDH inhibitors with IC50 values of 15.4, 3.9, 13.4, 2.9, and 3.5 µm, respectively. Further investigation indicates that compounds 1, 2, 3, and 5 demonstrate noncompetitive inhibition pattern, and compound 4 displays competitive inhibition pattern with respect to shikimate. Compounds 1, 4, and 5 display noncompetitive inhibition mode, and compounds 2 and 3 show competitive inhibition mode with respect to NADP. Antibacterial assays demonstrate that compounds 1, 2, and 5 can inhibit the growth of H. pylori with MIC of 16, 16, and 32 µg·mL,1, respectively. This current work is expected to favor better understanding the features of SDH and provide useful information for the development of novel antibiotics to treat H. pylori -associated infection. [source] Ubiquinone biosynthesis in microorganismsFEMS MICROBIOLOGY LETTERS, Issue 2 2001R Meganathan Abstract The quinoid nucleus of the benzoquinone, ubiquinone (coenzyme Q; Q), is derived from the shikimate pathway in bacteria and eukaryotic microorganisms. Ubiquinone is not considered a vitamin since mammals synthesize it from the essential amino acid tyrosine. Escherichia coli and other Gram-negative bacteria derive the 4-hydroxybenzoate required for the biosynthesis of Q directly from chorismate. The yeast, Saccharomyces cerevisiae, can either form 4-hydroxybenzoate from chorismate or tyrosine. However, unlike mammals, S. cerevisiae synthesizes tyrosine in vivo by the shikimate pathway. While the reactions of the pathway leading from 4-hydroxybenzoate to Q are the same in both organisms the order in which they occur differs. The 4-hydroxybenzoate undergoes a prenylation, a decarboxylation and three hydroxylations alternating with three methylation reactions, resulting in the formation of Q. The methyl groups for the methylation reactions are derived from S -adenosylmethionine. While the prenyl side chain is formed by the 2- C -methyl- d -erythritol 4-phosphate (non-mevalonate) pathway in E. coli, it is formed by the mevalonate pathway in the yeast. [source] Overexpression of the Wounding-Responsive Gene AtMYB15 Activates the Shikimate Pathway in ArabidopsisJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2006Yanhui Chen Abstract The MYB transcription factor genes play important roles in many developmental processes and various defense responses of plants. The shikimate pathway is a major biosynthetic pathway for the production of three aromatic amino acids and other aromatic compounds that are involved in multiple responses of plants, including protection against UV and defense. Herein, we describe the characterization of the R2R3-MYB gene AtMYB15 as an activator of the shikimate pathway in Arabidopsis. The AtMYB15 protein is nuclear localized and a transcriptional activation domain is found in its C-terminal portion. Northern blots showed that AtMYB15 is an early wounding-inducible gene. Resutls of microarray analysis, confirmed using quantitative real-time polymerase chain reaction, showed that overexpression of AtMYB15 in transgenic plants resulted in elevated expression of almost all the genes involved in the shikimate pathway. Bioinformatics analysis showed that one or more AtMYB15-binding AC elements were detected in the promoters of these upregulated genes. Furthermore, these genes in the shikimate pathway were also found to be induced by wounding. These data suggest an important role of AtMYB15 as a possible direct regulator of the Arabidopsis shikimate pathway in response to wounding. (Managing editor: Ya-Qin Han) [source] Global transcript profiling of primary stems from Arabidopsis thaliana identifies candidate genes for missing links in lignin biosynthesis and transcriptional regulators of fiber differentiationTHE PLANT JOURNAL, Issue 5 2005Jürgen Ehlting Summary Different stages of vascular and interfascicular fiber differentiation can be identified along the axis of bolting stems in Arabidopsis. To gain insights into the metabolic, developmental, and regulatory events that control this pattern, we applied global transcript profiling employing an Arabidopsis full-genome longmer microarray. More than 5000 genes were differentially expressed, among which more than 3000 changed more than twofold, and were placed into eight expression clusters based on polynomial regression models. Within these, 182 upregulated transcription factors represent candidate regulators of fiber development. A subset of these candidates has been associated with fiber development and/or secondary wall formation and lignification in the literature, making them targets for functional studies and comparative genomic analyses with woody plants. Analysis of differentially expressed phenylpropanoid genes identified a set known to be involved in lignin biosynthesis. These were used to anchor co-expression analyses that allowed us to identify candidate genes encoding proteins involved in monolignol transport and monolignol dehydrogenation and polymerization. Similar analyses revealed candidate genes encoding enzymes that catalyze missing links in the shikimate pathway, namely arogenate dehydrogenase and prephenate aminotransferase. [source] Crystallization and preliminary X-ray crystallographic analysis of chorismate synthase from Mycobacterium tuberculosisACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2004Marcio Vinicius Bertacine Dias The enzymes of the shikimate pathway are potential targets for the development of new therapies because they are essential for bacteria but absent from mammals. The last step in this pathway is performed by chorismate synthase (CS), which catalyzes the conversion of 5-enolpyruvylshikimate-3-phosphate to chorismate. Optimization of crystallization trials allowed the crystallization of homogeneous recombinant CS from Mycobacterium tuberculosis (MtCS). The crystals of MtCS belong to space group P6422 (or P6222) and diffract to 2.8,Å resolution, with unit-cell parameters a = b = 129.7, c = 156.8,Å. There are two molecules in the asymmetric unit. Molecular-replacement trials were not sucessful. Heavy-atom derivative screening is in progress. [source] A novel noncovalent complex of chorismate mutase and DAHP synthase from Mycobacterium tuberculosis: protein purification, crystallization and X-ray diffraction analysisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Mats Ökvist Chorismate mutase catalyzes a key step in the shikimate-biosynthetic pathway and hence is an essential enzyme in bacteria, plants and fungi. Mycobacterium tuberculosis contains two chorismate mutases, a secreted and an intracellular one, the latter of which (MtCM; Rv0948c; 90 amino-acid residues; 10,kDa) is the subject of this work. Here are reported the gene expression, purification and crystallization of MtCM alone and of its complex with another shikimate-pathway enzyme, DAHP synthase (MtDS; Rv2178c; 472 amino-acid residues; 52,kDa), which has been shown to enhance the catalytic efficiency of MtCM. The MtCM,MtDS complex represents the first noncovalent enzyme complex from the common shikimate pathway to be structurally characterized. Soaking experiments with a transition-state analogue are also reported. The crystals of MtCM and the MtCM,MtDS complex diffracted to 1.6 and 2.1,Å resolution, respectively. [source] Effects of the magnesium and chloride ions and shikimate on the structure of shikimate kinase from Mycobacterium tuberculosisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2007Marcio Vinicius Bertacine Dias Bacteria, fungi and plants can convert carbohydrate and phosphoenolpyruvate into chorismate, which is the precursor of various aromatic compounds. The seven enzymes of the shikimate pathway are responsible for this conversion. Shikimate kinase (SK) is the fifth enzyme in this pathway and converts shikimate to shikimate-3-phosphate. In this work, the conformational changes that occur on binding of shikimate, magnesium and chloride ions to SK from Mycobacterium tuberculosis (MtSK) are described. It was observed that both ions and shikimate influence the conformation of residues of the active site of MtSK. Magnesium influences the conformation of the shikimate hydroxyl groups and the position of the side chains of some of the residues of the active site. Chloride seems to influence the affinity of ADP and its position in the active site and the opening length of the LID domain. Shikimate binding causes a closing of the LID domain and also seems to influence the crystallographic packing of SK. The results shown here could be useful for understanding the catalytic mechanism of SK and the role of ions in the activity of this protein. 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