L-deoxy-D-xylulose-5-phosphate

D-glyceraldehyde-3-phosphate, pyruvate (G3P) l-deoxy-D-xylulose-5-phosphate (DXP) 2C-methyl-D-erythritol-4-phosphate (MEP) 4-diphosph-2C-methyl-D-erythritol (CDP-ME) 4-diphosphocytidyl-2C-methyl-D-erythritol-2-phophate (CDP-MEP)... 

Lichtenthaler, H.K., The l-deoxy-d-xylulose-5-phosphate pathway of isoprenoid biosynthesis in plants, Anna. Rev. Plant Physiol. Plant Mol. Biol. 50, 47, 1999. 

Estevez, J.M. et al., l-Deoxy-D-xylulose-5-phosphate synthase, a limiting enzyme for plastidic isoprenoid biosynthesis in plants, J. Biol. Chem. 276, 22901, 2001. 

The enzymatic conversion of l-deoxy-D-xylulose-5-phosphate to pyridoxol phosphate (Vitamin B6) in E. coli was demonstrated <99JA7722>. 

Singh N, Cheve G, Avery MA, McCurdy CR (2006) Comparative protein modeling of l-deoxy-D-xylulose-5-phosphate reductoi-somerase enzyme from Plasmodium falciparum a potential target for antimalarial drug discovery. J Chem Inf Model 46(3) 1360-1370... 

R,4S)-3,4-Dihydroxy-5-oxohexylphosphonic acid (282), an isosteric analogue of l-deoxy-D-xylulose-5-phosphate (DXP), the first C5 intermediate in the MEP pathway for isoprenoid biosynthesis has been synthesized from (+)2,3-0-benzylidene-D-threitol (283) by a seven step reaction sequence. This phosphonate (282) was next enzymatically converted into (3R,4R)-3,4,5-trihy-droxyphosphonic acid (284), an isosteric analogue of 2-C-methyl-D-erythritol-4-phosphate (Scheme 72). 

The thiamin biosynthetic pathway is outlined in Fig. 22 [88]. Overall the pathway involves the separate synthesis of the thiazole 111 and the pyrimidine 114 which are then coupled. l-Deoxy-D-xylulose-5-phosphate (see sections 11 and 12 of this review) is the precursor to the five carbon unit of the thiazole [89], cysteine is the sulfur source [90, 91], and the C2-N3 atoms of the thiazole are derived from the a-carbon and the amino group of tyrosine [92-94]. The pyrimidine is derived from 5-aminoimidazole riboside (AIRs), an intermediate on the purine biosynthetic pathway. This reaction involves a complex rearrangement in which the C4 carbon of AIRs is inserted into the C4-C5 imidazole double bond, converting the imidazole to a pyrimidine, and the C2 carbon of AIRs is used to methylate the C2 position of the imidazole [95-98]. 

Complex xylulose structures can also be synthesized by RAMA1741. Employing a one-pot, three-enzyme system with RAMA, triose phosphate isomerase, and l-deoxy-D-xylulose-5-phosphate synthase, l-deoxy-D-xylulose-5-phosphate could be obtained in 47 % yield[75]. Furthermore, a four-enzyme, one-pot system employing FDP-aldolase from S. camosus furnished 5-deoxy-5-ethyl-D-xylulose1761. 

Levin EY, BlochK (1964) Absence of sterols in blue-green algae. Nature 202 90-91 Lichtenthaler HK, Schwender J, Disch A, Rohmer M (1997) Biosynthesis of isoprenoids in higher plant chloroplasts proceeds via a mevalonate-independent pathway. FEBS Letters 400 271-274 Lichtenthaler HK (1999) The l-deoxy-D-xylulose-5-phosphate pathway of isoprenoid biosynthesis in plants. Ann Rev Plant Physiol Plant Mol Biol 50 47-65 Luo Y, Sternberg L (1991) Deuterium heterogeneity in starch and cellulose nitrate of CAM and C3 plants. Phytochemistry 30 1095-1098... 

A proposal for the formation of l-deoxy-D-xylulose-5-phosphate and its conversion to isopentenyl pyrophosphate is outlined in Fig. 43 [183,185]. None of the enzymes involved have yet been cloned or characterized. 

The first specific precursor for terpenoids in the cytoplasma is the Cg molecule mevalonic acid (MVA), which is built via the classical acetate/mevalonate pathway and converted by a series of phosphorylating and decarboxylation reactions into C5 isopentenyldiphosphate (IPP), the universal building block for chain elongation up to C20. In the chloroplasts, the biosynthesis of IPP starts from glyceraldehyde-3-phosphate and pyruvate to give l-deoxy-D-xylulose-5-phosphate (DOXP) via the non-mevalonate pathway as a recently detected alternative IPP route [19]. The reaction is catalyzed by the enzyme DOXP synthase and can be inhibited by a breakdown product of the herbicide clomazone [12]. 

In spike lavender, an additional copy of the l-deoxy-D-xylulose-5-phosphate synthase gene (DXS), the first enzymatic step in the methylerythritol phosphate (MEP) pathway leading to the precursors of monoterpenes, from Arabidopsis thaliam was introduced and led to an increase of the essential oil of the leaves of up to 360% and of the essential oil of flowers of up to 74% (Munoz-Bertomeu et al., 2006). 

Munoz-Bertomeu, J., I. Arrillaga, R. Ros, and J. Segura, 2006. Up-regulation of l-deoxy-D-xylulose-5-phosphate synthase enhances production of essential oils in transgenic spike lavender. Plant Phys., 142 890-900. 

A pathway to pyridoxal itself from l-deoxy-D-xylulose-5-phosphate and 4-hydroxy-L-threonine 4-phosphate will be elaborated upon in the discussion of cofactors. 

Hans J, Hause B, Strack D, Walter MH (2004) Cloning, characterization, and immunoloca-lization of a mycorrhiza inducible l-deoxy-D-xylulose-5-phosphate reductoisomerase in arbuscule-containing cells of maize. Plant Physiol 134 614-624... 

In this pathway (Pig. 88.4), D-glyceraldehyde-3-phosphate initially condenses with pyruvate to yield l-deoxy-D-xylulose-5-phosphate (DOXP) through... 

IPP, a Cs-compound, is the source of carotenoids, isoprenoids, terpenes, quinones, and phytol of BChls and Chls. There are two known independent pathways of IPP synthesis the classical mevalonate (MVA) pathway and the alternative, non-mevalonate, l-deoxy-D-xylulose-5-phosphate (DOXP) pathway [19, 20]. In the MVA pathway, acetyl-coenzyme A is converted to IPP through mevalonate. The enzymes and genes involved in this pathway are well studied [21]. The DOXP pathway was found in the 1990s, and in this pathway, pyruvate and glyceraldehyde are converted to IPP. 

Fig. 117.9 An overview of the cytosolic mevalonate pathway and plastidial mevalonate-independent pathway for the biosynthesis of terpenoids (isoprenoids) in plant cells [99] (DMAPP, dimethylallyl diphosphate DXP, l-deoxy-D-xylulose-5-phosphate DXS, DXP synthase DXR, DXP reductoisomerase MEP, 2-C-methyl-D-erythritol 4-phosphate GASP, gfyc-eraldehyde-3-phosphate HMG-CoA, 3-hydroxy-3-methylglutaryl-CoA HMGR, HMGR-CoA reductase IPP, isopentenyl diphosphate. Mevinolin and fosmidomycin are inhibitors of HMGR and DXR, respectively)...

---