Retrobiosynthetic nuclear magnetic resonance analysis of amino acid biosynthesis and intermediary metabolism. Metabolic flux in developing maize kernels

Citation
E. Glawischnig et al., Retrobiosynthetic nuclear magnetic resonance analysis of amino acid biosynthesis and intermediary metabolism. Metabolic flux in developing maize kernels, PLANT PHYSL, 125(3), 2001, pp. 1178-1186
Citations number
23
Categorie Soggetti
Plant Sciences","Animal & Plant Sciences
Journal title
PLANT PHYSIOLOGY
ISSN journal
00320889 → ACNP
Volume
125
Issue
3
Year of publication
2001
Pages
1178 - 1186
Database
ISI
SICI code
0032-0889(200103)125:3<1178:RNMRAO>2.0.ZU;2-O
Abstract
Information on metabolic networks could provide the basis for the design of targets for metabolic engineering. To study metabolic flux in cereals, dev eloping maize (Zea mays) kernels were grown in sterile culture on medium co ntaining [U-C-13(6)]glucose or [1,2-C-13(2)]acetate. After growth, amino ac ids, lipids, and sitosterol were isolated from kernels as well as from the cabs, and their C-13 isotopomer compositions were determined by quantitativ e nuclear magnetic resonance spectroscopy. The highly specific labeling pat terns were used to analyze the metabolic pathways leading to amino acids an d the triterpene on a quantitative basis. The data show that serine is gene rated from phosphoglycerate as well as from glycine. Lysine is formed entir ely via the diaminopimelate pathway and sitosterol is synthesized entirely via the mevalonate route. The labeling data of amino acids and sitosterol w ere used to reconstruct the labeling patterns of key metabolic intermediate s (e.g. acetyl-coenzyme A, pyruvate, phosphoenolpyruvate, erythrose 4-phosp hate, and Rib 5-phosphate) that revealed quantitative information about car bon nux m the intermediary metabolism or developing maize Kernels. Exogenou s acetate served as an efficient precursor of sitosterol, as well as of ami no acids of the aspartate and glutamate family; in comparison, metabolites formed in the plastidic compartments showed low acetate incorporation.