- Observation of thiamin-bound intermediates and microscopic rate constants for their interconversion on 1-deoxy- d -xylulose 5-phosphate synthase: 600-Fold rate acceleration of pyruvate decarboxylation by d -glyceraldehyde-3-phosphate.
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The thiamin diphosphate (ThDP)-dependent enzyme 1-deoxy-d-xylulose 5-phosphate (DXP) synthase carries out the condensation of pyruvate as a 2-hydroxyethyl donor with d-glyceraldehyde-3-phosphate (d-GAP) as acceptor forming DXP. Toward understanding catalysis of this potential anti-infective drug target, we examined the pathway of the enzyme using steady state and presteady state kinetic methods. It was found that DXP synthase stabilizes the ThDP-bound predecarboxylation intermediate formed between ThDP and pyruvate (C2α-lactylThDP or LThDP) in the absence of d-GAP, while addition of d-GAP enhanced the rate of decarboxylation by at least 600-fold. We postulate that decarboxylation requires formation of a ternary complex with both LThDP and d-GAP bound, and the central enzyme-bound enamine reacts with d-GAP to form DXP. This appears to be the first study of a ThDP enzyme where the individual rate constants could be evaluated by time-resolved circular dichroism spectroscopy, and the results could have relevance to other ThDP enzymes in which decarboxylation is coupled to a ligation reaction. The acceleration of the rate of decarboxylation of enzyme-bound LThDP in the presence of d-GAP suggests a new approach to inhibitor design.
- Patel, Hetalben,Nemeria, Natalia S.,Jordan, Frank,Brammer, Leighanne A.,Freel Meyers, Caren L.
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p. 18374 - 18379,6
(2012)
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- Determination of the Activity of 1-Deoxy-d-Xylulose 5-Phosphate Synthase by Pre-column Derivatization-HPLC Using 1,2-Diamino-4,5-Methylenedioxybenzene as a Derivatizing Reagent
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α-Ketoacids can be determined by HPLC through pre-column derivatization with 1,2-diamino-4,5-methylenedioxybenzene (DMB) as a derivatizing reagent. Using this method, the specific activity and the steady-state kinetic of 1-deoxy-d-xylulose-5-phosphate synthase (DXS) were measured. Firstly, DXS substrate pyruvate was derivatized with DMB in acidic solution; then the corresponding quinoxalinone was elucidated by LC–ESI–MS and quantified by HPLC-UV. The optimum derivatization conditions were as follows: aqueous medium at pH 1.0, reaction temperature 80?°C, reaction time 60?min, molar ratio of DMB to pyruvate 10:1. The HPLC was run with isocratic elution using the mixture of methanol and water (60:40, v/v) as a mobile phase. The detective limit and the linear correlation range of the method were 0.05?μM and 0.002?1.0?mM (R = 0.994), respectively. The relative standard deviation (RSD) of six determinations was 2.48%. The steady-state kinetic parameters of DXS for pyruvate determined with the method were identical to the reported data. The established method is a practical route for evaluation of DXS activity, especially in the research and development of DXS inhibitors.
- Liang, Yan-Fei,Liu, Hui,Li, Heng,Gao, Wen-Yun
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- An improved preparation of D-glyceraldehyde 3-phosphate and its use in the synthesis of 1-deoxy-D-xylulose 5-phosphate
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D-Glyceraldehyde 3-phosphate (=D-GAP; 2) was prepared by an improved chemical method (Scheme 2), and it was then employed to synthesize 1-deoxy-d-xylulose 5-phosphate (=DXP; 3) which is enzymatically one of the key intermediates in the MEP (4) terpenoid b
- Li, Heng,Tian, Jie,Wang, Hui,Yang, Shao-Qing,Gao, Wen-Yun
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- Targeting DXP synthase in human pathogens: Enzyme inhibition and antimicrobial activity of butylacetylphosphonate
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The unique methylerythritol phosphate pathway for isoprenoid biosynthesis is essential in most bacterial pathogens. The first enzyme in this pathway, 1-deoxy-D-xylulose 5-phosphate (DXP) synthase, catalyzes a distinct thiamin diphosphate (ThDP)-dependent reaction to form DXP from D-glyceraldehyde 3-phosphate (D-GAP) and pyruvate and represents a potential anti-infective drug target. We have previously demonstrated that the unnatural bisubstrate analog, butylacetylphosphonate (BAP), exhibits selective inhibition of Escherichia coli DXP synthase over mammalian ThDP-dependent enzymes. Here, we report the selective inhibition by BAP against recombinant DXP synthase homologs from Mycobacterium tuberculosis, Yersinia pestis and Salmonella enterica. We also demonstrate antimicrobial activity of BAP against both Gram-negative and Gram-positive strains (including E. coli, S. enterica and Bacillus anthracis), and several clinically isolated pathogens. Our results suggest a mechanism of action involving inhibition of DXP synthase and show that BAP acts synergistically with established antimicrobial agents, highlighting a potential strategy to combat emerging resistance in bacterial pathogens.
- Smith, Jessica M.,Warrington, Nicole V.,Vierling, Ryan J.,Kuhn, Misty L.,Anderson, Wayne F.,Koppisch, Andrew T.,Freel Meyers, Caren L.
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- Formation of 4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol from 2-C- methyl-D-erythritol 4-phosphate by 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase, a new enzyme in the nonmevalonate pathway
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2-C-Methyl,D-erythritol 4-phosphate is transformed to 4-(cytidine 5'- diphospho)-2-C-methyl-D-erythritol in the presence of cytidine 5'- triphosphate by a novel Escherichia coli enzyme, 2-C-methyl-D-erythritol 4- phosphate cytidylyltransferase, involved in the nonmevalonate pathway. (C) 2000 Elsevier Science Ltd.
- Kuzuyama, Tomohisa,Takagi, Motoki,Kaneda, Kazuhide,Dairi, Tohru,Seto, Haruo
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- Molecular cloning, expression and characterization of the first three genes in the mevalonate-independent isoprenoid pathway in Streptomyces coelicolor
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The mevalonate-independent biosynthetic pathway to isopentenyl diphosphate and dimethylallyl diphosphate, the universal precursors to the isoprenoids, operates in eubacteria, including Escherichia coli, in algae, and in the plastids of higher plants. A search of the Sanger Centre Streptomyces coelicolor genome database revealed open reading frames with ca. 40-50% identity at the deduced amino acid level to the first three E. coli enzymes of this pathway, corresponding to deoxyxylulose phosphate synthase, deoxyxylulose phosphate reductoisomerase and 2-C-methyl erythritol 4-phosphate cytidyltransferase. The coelicolor genes have been cloned and expressed in E. coli, and the recombinant proteins characterized physically and kinetically. The presence of the corresponding enzyme activities in Extracts of S. coelicolor CH999 further supports the operation of the mevalonate-independent pathway in this organism. Copyright
- Cane, David E,Chow, Cathy,Lillo, Antonietta,Kang, Ilgu
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- DXP synthase-catalyzed c-n bond formation: Nitroso substrate specificity studies guide selective inhibitor design
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1-Deoxy-D-xylulose 5-phosphate (DXP) synthase catalyzes the first step in the nonmammalian isoprenoid biosynthetic pathway to form DXP from pyruvate and D-glyceraldehyde 3-phosphate (D-GAP) in a thiamin diphosphate-dependent manner. Its unique structure and mechanism distinguish DXP synthase from its homologues and suggest that it should be pursued as an anti-infective drug target. However, few reports describe any development of selective inhibitors of this enzyme. Here, we reveal that DXP synthase catalyzes C-N bond formation and exploit aromatic nitroso substrates as active site probes. Substrate specificity studies reveal a high affinity of DXP synthase for aromatic nitroso substrates compared to the related ThDP-dependent enzyme pyruvate dehydrogenase (PDH). Results from inhibition and mutagenesis studies indicate that nitroso substrates bind to E. coli DXP synthase in a manner distinct from that of D-GAP. Our results suggest that the incorporation of aryl acceptor substrate mimics into unnatural bisubstrate analogues will impart selectivity to DXP synthase inhibitors. As a proof of concept, we show selective inhibition of DXP synthase by benzylacetylphosphonate (BnAP).
- Morris, Francine,Vierling, Ryan,Boucher, Lauren,Bosch, Juergen,Freel Meyers, Caren L.
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p. 1309 - 1315
(2013/08/23)
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- Revealing substrate promiscuity of 1-deoxy-D-xylulose 5-phosphate synthase
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A study of DXP synthase has revealed flexibility In the acceptor substrate binding pocket for nonpolar substrates and has uncovered new details of the catalytic mechanism to show that pyruvate can act as both donor and acceptor substrate.
- Brammer, Leighanne A.,Meyers, Caren Freel
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supporting information; experimental part
p. 4748 - 4751
(2010/02/28)
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