title: Metabolic engineering of Arabidopsis for butanetriol production using bacterial genes.
abstract: 1,2,4-butanetriol (butanetriol) is a useful precursor for the synthesis of the energetic material butanetriol trinitrate and several pharmaceutical compounds. Bacterial synthesis of butanetriol from xylose or arabinose takes place in a pathway that requires four enzymes. To produce butanetriol in plants by expressing bacterial enzymes, we cloned native bacterial or codon optimized synthetic genes under different promoters into a binary vector and stably transformed Arabidopsis plants. Transgenic lines expressing introduced genes were analyzed for the production of butanetriol using gas chromatography coupled to mass spectrometry (GC-MS). Soil-grown transgenic plants expressing these genes produced up to 20 µg/g of butanetriol. To test if an exogenous supply of pentose sugar precursors would enhance the butanetriol level, transgenic plants were grown in a medium supplemented with either xylose or arabinose and the amount of butanetriol was quantified. Plants expressing synthetic genes in the arabinose pathway showed up to a forty-fold increase in butanetriol levels after arabinose was added to the medium. Transgenic plants expressing either bacterial or synthetic xylose pathways, or the arabinose pathway showed toxicity symptoms when xylose or arabinose was added to the medium, suggesting that a by-product in the pathway or butanetriol affected plant growth. Furthermore, the metabolite profile of plants expressing arabinose and xylose pathways was altered. Our results demonstrate that bacterial pathways that produce butanetriol can be engineered into plants to produce this chemical. This proof-of-concept study for phytoproduction of butanetriol paves the way to further manipulate metabolic pathways in plants to enhance the level of butanetriol production.
authors.affiliation: Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, CO 80523-1878, USA.
authors.forename: Salah E
authors.initials: SE
authors.lastname: Abdel-Ghany
authors.forename: Irene
authors.initials: I
authors.lastname: Day
authors.forename: Adam L
authors.initials: AL
authors.lastname: Heuberger
authors.forename: Corey D
authors.initials: CD
authors.lastname: Broeckling
authors.forename: Anireddy S N
authors.initials: AS
authors.lastname: Reddy
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D000440:Butanols / Q000378:metabolism*; D005798:Genes, Bacterial; D060847:Metabolic Engineering; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D000440:Butanols; C114589:1,3,4-butanetriol
keywords: 1,2,4-butanetriol; ADG; ADT; Arabidopsis; Arabinose; BFD; BTTN; Butanetriol; DH; GC–MS; MCS; PCA; Phytoproduction; XDG; XDT; Xylose; benzylformate decarboxylase; d, l-butanetriol trinitrate; d-xylose dehydrogenase; dehydrogenase; gas chromatography coupled to mass spectrometry; l-arabinonate dehydratase; l-arabinose dehydrogenase; multiple cloning site; principal component analysis; xylonate dehydratase