title: Deoxyxylulose 5-Phosphate Synthase Controls Flux through the Methylerythritol 4-Phosphate Pathway in Arabidopsis.
abstract: The 2-C-methylerythritol 4-phosphate (MEP) pathway supplies precursors for plastidial isoprenoid biosynthesis including carotenoids, redox cofactor side chains, and biogenic volatile organic compounds. We examined the first enzyme of this pathway, 1-deoxyxylulose 5-phosphate synthase (DXS), using metabolic control analysis. Multiple Arabidopsis (Arabidopsis thaliana) lines presenting a range of DXS activities were dynamically labeled with13CO2in an illuminated, climate-controlled, gas exchange cuvette. Carbon was rapidly assimilated into MEP pathway intermediates, but not into the mevalonate pathway. A flux control coefficient of 0.82 was calculated for DXS by correlating absolute flux to enzyme activity under photosynthetic steady-state conditions, indicating that DXS is the major controlling enzyme of the MEP pathway. DXS manipulation also revealed a second pool of a downstream metabolite, 2-C-methylerythritol-2,4-cyclodiphosphate (MEcDP), metabolically isolated from the MEP pathway. DXS overexpression led to a 3- to 4-fold increase in MEcDP pool size but to a 2-fold drop in maximal labeling. The existence of this pool was supported by residual MEcDP levels detected in dark-adapted transgenic plants. Both pools of MEcDP are closely modulated by DXS activity, as shown by the fact that the concentration control coefficient of DXS was twice as high for MEcDP (0.74) as for 1-deoxyxylulose 5-phosphate (0.35) or dimethylallyl diphosphate (0.34). Despite the high flux control coefficient for DXS, its overexpression led to only modest increases in isoprenoid end products and in the photosynthetic rate. Diversion of flux via MEcDP may partly explain these findings and suggests new opportunities to engineer the MEP pathway.
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.) michael.phillips@cragenomica.es lwright@ice.mpg.de.
authors.forename: Louwrance P
authors.identifier: http://orcid.org/0000-0001-5998-6079
authors.initials: LP
authors.lastname: Wright
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Johann M
authors.initials: JM
authors.lastname: Rohwer
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Andrea
authors.initials: A
authors.lastname: Ghirardo
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Almuth
authors.initials: A
authors.lastname: Hammerbacher
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Miriam
authors.initials: M
authors.lastname: Ortiz-Alcaide
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Bettina
authors.initials: B
authors.lastname: Raguschke
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Jörg-Peter
authors.initials: JP
authors.lastname: Schnitzler
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.).
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.affiliation: Department of Biochemistry, Max Plank Institute for Chemical Ecology, 07745 Jena, Germany (L.P.W., A.H., B.R., J.G.);Department of Biochemistry, Stellenbosch University, 7602 Stellenbosch, South Africa (J.M.R.);Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Helmholtz Zentrum, 85764 Neuherberg, Germany (A.G., J.-P.S.); andPlant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (Consorci CSIC-IRTA-UAB-UB), 08193 Bellaterra, Barcelona, Spain (M.O., M.A.P.) michael.phillips@cragenomica.es lwright@ice.mpg.de.
authors.forename: Michael A
authors.identifier: http://orcid.org/0000-0001-7276-119X
authors.initials: MA
authors.lastname: Phillips