Original Paper Biochemistry and Molecular Biology	Planta Med 2006; 72: 329-335 DOI: 10.1055/s-2005-916234
© Georg Thieme Verlag KG Stuttgart · New York
Molecular Cloning and Expression Profile Analysis of Ginkgo biloba DXS Gene Encoding 1-Deoxy-D-xylulose 5-Phosphate Synthase, the First Committed Enzyme of the 2-C-Methyl-D-erythritol 4-Phosphate Pathway
Yi-fu Gong1, 2, Zhi-hua Liao3, 4, Bin-hui Guo1, Xiao-fen Sun3, Ke-xuan Tang1, 3
1 Plant Biotechnology Research Center, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, School of Agriculture and Biology, School of Life Science and Technology, Shanghai Jiao Tong University, Shanghai, P. R. China 2 Faculty of Life Science and Biotechnology, Ningbo University, Ningbo, P. R. China 3 State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Morgan-Tan International Center for Life Sciences, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, Fudan University, Shanghai, P. R. China 4 School of Life Sciences, Laboratory of Natural Products and Metabolic Engineering, Institute of Biotechnology, Institute of Modern Biopharmaceuticals, Southwest China Normal University, Chongqing, P. R. China

Abstract

Plant diterpenes such as ginkgolides are biosynthesized via the recently discovered 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. The initial step of the MEP pathway is the formation of 1-deoxy-D-xylulose 5-phosphate (DXP) catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS, EC: 4.1.3.37), which may thus be considered the first committed step of the MEP pathway for ginkgolides biosynthesis. The full-length cDNA of DXS was isolated and characterized from the gymnosperm plant species, Ginkgo biloba. The full-length cDNA of GbDXS was 2795 bp containing a 2154 bp open reading frame (ORF) encoding 717 amino acids. Comparative and bioinformatic analyses revealed that GbDXS has extensive homology with DXSs from other plant species and, like these, contains a conserved transit peptide for plastid import, histidine residue, a putative thiamine diphosphate-binding site and a transketolase motif. Phylogenetic analysis indicates that GbDXS belongs to the plant DXS1 cluster and suggests it to be more ancient than other plant DXSs. GbDXS was found to be expressed in all tested tissues including roots, stems, leaves, pericarps and seeds. Expression profiling analyses revealed that GbDXS expression was induced by exogenous elicitors including methyl jasmonate, arachidonic acid, acetylsalicylic acid and ceric ammonium sulfate, and showed that the transcription levels were correlated with ginkgolide accumulation, suggesting that DXS might play a regulatory role in ginkgolide biosynthesis in cell culture of G. biloba at the transcriptional level.

Key words

1-Deoxy-D-xylulose 5-phosphate synthase (DXS) - Ginkgo biloba - ginkgolides - biosynthesis - elicitor