Isoprenoid biosynthesis via a mevalonate-independent pathway in plants: cloning and heterologous expression of 1-deoxy-D-xylulose-5-phosphate reductoisomerase from peppermint.
Two distinct pathways are utilized by plants for the biosynthesis of isopentenyl diphosphate, the universal precursor of isoprenoids. The classical acetate/mevalonate pathway operates in the cytosol, whereas plastidial isoprenoids originate via a novel mevalonate-independent route that involves a transketolase-catalyzed condensation of pyruvate and D-glyceraldehyde-3-phosphate to yield 1-deoxy-D-xylulose-5-phosphate as the first intermediate. Based on in vivo feeding experiments, rearrangement and reduction of deoxyxylulose phosphate have been proposed to give rise to 2-C-methyl-D-erythritol-4-phosphate as the second intermediate of this pyruvate/glyceraldehyde-3-phosphate pathway (1-3). The cloning of an Escherichia coli gene encoding an enzyme capable of converting 1-deoxy-D-xylulose-5-phosphate to 2-C-erythritol-4-phosphate was recently reported (4). A cloning strategy was developed for isolating the gene encoding a plant homolog of this enzyme from peppermint (Mentha x piperita), and the identity of the resulting cDNA was confirmed by heterologous expression in E. coli. Unlike the microbial reductoisomerase, the plant ortholog encodes a preprotein bearing an N-terminal plastidial transit peptide that directs the enzyme to plastids where the mevalonate-independent pathway operates in plants. The peppermint gene comprises an open reading frame of 1425 nucleotides which, when the plastidial targeting sequence is excluded, encodes a deduced enzyme of approximately 400 amino acid residues with a mature size of about 43.5 kDa.
Lange
B M
BM
Institute of Biological Chemistry, and Department of Biochemistry and Biophysics, Washington State University, Pullman, Washington 99164-6340, USA.
Croteau
R
R
D019747:Aldose-Ketose Isomerases / Q000235:genetics*; D000595:Amino Acid Sequence; D004896:Erythritol / Q000031:analogs & derivatives / Q000378:metabolism; D045782:Hemiterpenes; D019686:Lamiaceae / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009943:Organophosphorus Compounds / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics*; D010428:Pentosephosphates / Q000378:metabolism; D018087:Plastids / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013403:Sugar Phosphates / Q000378:metabolism; D013729:Terpenes / Q000378:metabolism*
C109460:1-deoxylulose 5-phosphate; C114232:2-C-methylerythritol 4-phosphate; D045782:Hemiterpenes; D009097:Multienzyme Complexes; D009943:Organophosphorus Compounds; D010428:Pentosephosphates; D013403:Sugar Phosphates; D013729:Terpenes; C004809:isopentenyl pyrophosphate; D010088:Oxidoreductases; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; D019747:Aldose-Ketose Isomerases; D004896:Erythritol