Application of Dynamic Flux Analysis in Plant Metabolic Networks
Metabolic networks are composed of metabolic pathways that consist of biochemical reaction steps. The functionality of pathways within a network is determined by metabolic fluxes, defined as the amount of converted metabolite per unit of time, per cell (or per unit mass of tissue), through each biochemical step within a metabolic pathway. The flux through a pathway depends on the kinetic properties of enzymes, as well as on their cellular levels and activities, which are regulated by gene expression, posttranscriptional, translational, and/or posttranslational modifications, and enzyme stability. Metabolic flux analysis (MFA) is a tool that has traditionally been used in microbial systems to assess the effects of environmental and targeted genetic changes on in vivo rates of metabolites synthesis. MFA can be used to gauge the degree of success of specific genetic interventions aimed at diverting metabolic flux to desirable products. The techniques of MFA have therefore become important tools in metabolic engineering and systems biology. To fully understand how a cell functions, analysis needs to include not only a description of its molecular parts, which can be obtained from molecular biology methods, but also a description of flux distributions within the complex and dynamic metabolic networks . As will be discussed in the next section, MFA via computer modeling of metabolism can provide information about the proximity of certain compounds to one another, the contribution of a pathway or part of a pathway to end products, the existence of storage pools, and regulation and reversibility of reactions.
KeywordsPool Size Metabolic Flux Isotopic Abundance Label Pattern Metabolic Flux Analysis
This work is supported by the U.S. National Science Foundation (grant numbers: MCB-0615700 for JAM, ND and DR and BES-0348458 for JAM), the U.S. Department of Agriculture (grant numbers 2003-35318-13619 and 2005-35318-16207 for ND and DR), and the Fred Gloeckner Foundation, Inc (ND).
- 7.Kaminaga Y, Schnepp J, Peel G, Kish CM, Ben-Nissan G, Weiss D, Orlova I, Lavie O, Rhodes D, Wood K, Porterfield DM, Cooper AJL, Schloss JV, Pichersky E, Vainstein A, Dudareva N (2006) Plant phenylacetaldehyde synthase is a bifunctional homotetrameric enzyme that catalyzes phenylalanine decarboxylation and oxidation. J Biol Chem 281:23357–23366.PubMedCrossRefGoogle Scholar
- 9.MacKenzie SL, Tenaschuk D (1979) Quantitative formation of N(O,S)-heptafluorobutyryl isobutyl amino acids for gas chromatographic analysis. I. Esterification. J Chromatography 171:195–208.Google Scholar
- 16.Orlova I, Marshall-Colon A, Schnepp J, Wood B, Varbanova M, Fridman E, Blakeslee JJ, Peer WA, Murphy AS, Rhodes D, Pichersky E, Dudareva N (2006) Reduction of benzenoid synthesis in petunia flowers reveals multiple pathways to benzoic acid and enhancement in auxin transport. Plant Cell 18:3458–3475.PubMedCrossRefGoogle Scholar
- 29.Stephanopoulos GN, Aristidou AA, Nielsen J (1998) Metabolic Engineering Principles and Methodologies. Academic Press, San Diego, CA.Google Scholar