1. The single cellular green microalga Botryococcus braunii, race B possesses three distinct 1-deoxy-D-xylulose 5-phosphate synthases.
- Author
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Matsushima D, Jenke-Kodama H, Sato Y, Fukunaga Y, Sumimoto K, Kuzuyama T, Matsunaga S, and Okada S
- Subjects
- Amino Acid Sequence, Chlorophyta genetics, Chlorophyta metabolism, Conserved Sequence, DNA, Complementary genetics, Gene Expression genetics, Gene Expression Regulation, Plant genetics, Gene Library, Kinetics, Microalgae genetics, Microalgae metabolism, Molecular Sequence Data, Phylogeny, Plant Leaves genetics, Plant Leaves metabolism, Plant Proteins genetics, Plant Proteins isolation & purification, Plant Proteins metabolism, Protein Isoforms, Recombinant Proteins, Sequence Alignment, Sequence Analysis, DNA, Temperature, Transferases isolation & purification, Transferases metabolism, Chlorophyta enzymology, Microalgae enzymology, Plant Leaves enzymology, Terpenes metabolism, Transferases genetics
- Abstract
Green algae exclusively use the methylerythritol 4-phosphate (MEP) pathway for the biosynthesis of isoprenoids. The first enzyme of this pathway is 1-deoxy-D-xylulose 5-phosphate synthase (DXS, EC 2.2.1.7). Green algae have been thought to possess only a single DXS, in contrast to land plants, which have at least two isoforms that serve different roles in metabolism. The green microalga Botryococcus braunii has an extraordinary isoprenoid metabolism, as it produces large amounts of triterpene hydrocarbons. Here, we did cDNA cloning of DXSs from B. braunii and examined enzyme activities of the heterologously expressed proteins. Three distinct DXS isoforms were identified, all of which were functional and had similar kinetic properties, whereas the temperature dependence of enzyme activity showed considerable differences. Transcription of the genes was examined by real time quantitative RT-PCR. The three DXS genes were simultaneously expressed, and the expression levels were highest on day six after subculturing. B. braunii is the first green microalga demonstrated to have multiple DXS isoforms like land plants. This difference to other microalgae seems to mirror its special needs for extensive triterpene production by increasing the metabolic flow through the MEP pathway., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2012
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