Metabolic flux analysis based on 13C-labeling experiments and integration of the information with gene and protein expression patterns.

The recent progress on metabolic systems engineering was reviewed, in particular focusing on the metabolic flux analysis (MFA) based on the isotopomer distribution obtained using NMR and/or GC-MS. After the brief explanation of how to estimate the metabolic flux distribution (MFD) based on 13C-labeling experiments, the metabolic regulation analysis was made based on the protein expression patterns obtained by two-dimensional electrophoresis (2DE) together with enzyme activity data, and the gene expression patterns obtained by RT-PCR analysis. The particular application was considered for Escherichia coli. The effect of culture conditions such as different carbon sources (glucose, gluconate, glycerol, acetate, etc.) and different dissolved oxygen (DO) concentration, etc. on the metabolism was investigated. The effect of some single-gene knockout such as pgi-, pyk-, and gnd- was also investigated. It was found to be quite useful to integrate the information obtained from metabolic flux analysis, gene and protein expressions as well as intracellular metabolite concentrations to understand the overall picture of metabolic regulation.