title: Molecular cloning, expression profiling and functional analysis of a DXR gene encoding 1-deoxy-D-xylulose 5-phosphate reductoisomerase from Camptotheca acuminata.
abstract: As the second enzyme of the non-mevalonate terpenoid pathway for isopentenyl diphosphate biosynthesis, DXP reductoisomerase (DXR, EC: 1.1.1.267) catalyzes a committed step of the MEP pathway for camptothecin (CPT) biosynthesis. In order to understand more about the role of DXR involved in the CPT biosynthesis at the molecular level, the full-length DXR cDNA sequence (designated as CaDXR) was isolated and characterized for the first time from a medicinal Nyssaceae plant species, Camptotheca acuminata. The full-length cDNA of CaDXR was 1823 bp containing a 1416 bp open reading frame (ORF) encoding a polypeptide of 472 amino acids. Comparative and bioinformatic analyses revealed that CaDXR showed extensive homology with DXRs from other plant species and contained a conserved transit peptide for plastids, an extended Pro-rich region and a highly conserved NADPH binding motif in its N-terminal region owned by all plant DXRs. Phylogenetic analysis indicated that CaDXR was more ancient than other plant DXRs. Tissue expression pattern analysis revealed that CaDXR expressed strongly in stem, weak in leaf and root. CaDXR was found to be an elicitor-responsive gene, which could be induced by exogenous elicitor of methyl jasmonate. The functional color complementation assay indicated that CaDXR could accelerate the biosynthesis of carotenoids in the Escherichia coli transformant, demonstrating that DXP reductoisomerase plays an influential step in isoprenoid biosynthesis.
authors.affiliation: Plant Biotechnology Research Center, Shanghai Key Laboratory of Agrobiotechnology, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, School of Agriculture and Biology, School of Life Science and Technology, Shanghai Jiao Tong University, Shanghai, PRC.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Yao
authors.forename: Yifu
authors.initials: Y
authors.lastname: Gong
authors.forename: Kaijing
authors.initials: K
authors.lastname: Zuo
authors.forename: Hua
authors.initials: H
authors.lastname: Ling
authors.forename: Chengxiang
authors.initials: C
authors.lastname: Qiu
authors.forename: Fei
authors.initials: F
authors.lastname: Zhang
authors.forename: Yechun
authors.initials: Y
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Pi
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Sun
authors.forename: Kexuan
authors.initials: K
authors.lastname: Tang
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D029769:Camptotheca / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics*; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D009097:Multienzyme Complexes; D018749:RNA, Plant; D010088:Oxidoreductases; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; D019747:Aldose-Ketose Isomerases