Molecular cloning and characterization of two cDNAs encoding 1-deoxy- d-xylulose 5-phosphate reductoisomerase from Hevea brasiliensis

• Published in: Journal of plant physiology 2008-01, Vol.165 (9), p.991-1002
• Main Authors: Seetang-Nun, Yortyot, Sharkey, Thomas D., Suvachittanont, Wallie
• Format: Article
• Language: English
• Subjects: 1-Deoxy- d-xylulose 5-phosphate reductoisomerase; alcohol oxidoreductases; Aldose-Ketose Isomerases - chemistry; Aldose-Ketose Isomerases - genetics; Amino Acid Sequence; amino acid sequences; Biological and medical sciences; Clone Cells; Cloning, Molecular; complementary DNA; DNA, Complementary - genetics; Enzymes; Escherichia coli; ethylene; Ethylene or ethephon; Ethylenes - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Dosage - drug effects; Gene Expression Profiling; gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes, Plant; Hevea - drug effects; Hevea - enzymology; Hevea - genetics; Hevea basiliensis; Hevea brasiliensis; Isoprenoid biosynthesis; isoprenoids; Latex; messenger RNA; Metabolism; methyl-D-erythritol 4-phosphate; Models, Molecular; molecular cloning; Molecular Sequence Data; Multienzyme Complexes - chemistry; Multienzyme Complexes - genetics; Oxidoreductases - chemistry; Oxidoreductases - genetics; Phylogeny; Plant physiology and development; Protein Structure, Secondary; RNA, Messenger - genetics; RNA, Messenger - metabolism; Rubber biosynthesis; sequence analysis; Sequence Analysis, DNA; signal transduction
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2007.06.014

1-Deoxy- d-xylulose 5-phosphate reductoisomerase (DXR, EC: 1.1.1.267) is the second enzyme in the 2 C-methyl- d-erythritol 4-phosphate (MEP) pathway, one of the two pathways in plants that can produce isoprenoids. The MEP pathway is the source of isoprene emitted from leaves, but rubber production is believed to result primarily from the mevalonic acid (MVA) pathway. Two cDNAs for DXR designated HbDXR1 and HbDXR2 were isolated from leaves and latex of rubber tree using RT-PCR based methods. Both cDNAs contain an open reading frame (ORF) of 1416 bp encoding 471 amino acids with a molecular mass of about 51 kDa. The deduced HbDXRs show extensive sequence similarities to that of other plant DXRs (73–87% identity). Molecular modeling revealed that the two HbDXRs contain all typical characteristics of DXR and share spatial structures, which are very similar to that of Escherichia coli DXR. Phylogenetic and DNA gel blot analyses suggested that a duplication of the DXR gene has occurred in the rubber tree. Semi-quantitative RT-PCR analysis showed that the HbDXR genes are differentially regulated in various tissues of the rubber tree. The HbDXR2 was more highly expressed in clone RRIM 600 than in the wild type, and this is consistent with higher rubber content of this clone. While 2-chloroethane phosphonic acid (ethephon) significantly increased latex yield, it only transiently induced the HbDXR2 gene. The expression of HbDXR2 in the latex suggests its important role in isoprenoid biosynthesis by substrate molecules, indicating that the MEP pathway may have some indirect roles in the biosynthesis of rubber.