Interaction of storage carbohydrates and other cyclic fluxes with central metabolism: A quantitative approach by non-stationary 13 C metabolic flux analysis

• Published in: Metabolic engineering communications Vol. 3; pp. 52 - 63
• Main Authors: Suarez-Mendez, C.A., Hanemaaijer, M., ten Pierick, Angela, Wolters, J.C., Heijnen, J.J., Wahl, S.A.
• Format: Journal Article
• Language: English
• Published: Netherlands 01.12.2016
• Subjects: GLU, glutamate; PYK, pyruvate kinase; T6P, trehalose-6-phosphate; FBP, fructose-1,6-bis-phosphate; Flux estimation; PGM, phosphoglucomutase; LEU, leucine; FUM, fumarate; GLN, glutamine; PFK, 6-phosphofructokinase; X5P, xylulose-5-phosphate; GLY, glycine; E4P, erythrose-4-phosphate; S7P, sedoheptulose-7-phosphate; DO, dissolved oxygen; UDPG, UDP-glucose; OAA, oxaloacetate; MAL, malate; FMH, fumarate hydratase; RPI, ribose-5-phosphate isomerase; ASP, aspartate; PEP, phospho-enol-pyruvate; DHAP, dihydroxy acetone phosphate; PRO, proline; PYR, pyruvate; RPE, ribulose-phosphate 3-epimerase; UTP, uridine-5-triphosphate; TCA, tricarboxylic acid cycle; PPP, pentose phosphate pathway; LYS, lysine; Ribu5P, ribulose-5-phosphate; F6P, fructose-6-phosphate; Rib5P, ribose-5-phosphate; ALA, alanine; TPP, trehalose- phosphatase; Trehalose; α-KG, oxoglutarate; GAP, glyceraldehyde-3-phosphate; Amino acids; PGI, glucose-6-phosphate isomerase; ENO, phosphopyruvate hydratase; 2PG, 2-phosphoglycerate; GAPDH&PGK, glyceraldehyde-3-phosphate dehydrogenase+phosphoglycerate kinase; GPM, phosphoglycerate mutase; 3PG, 3-phosphoglycerate; 6PG, 6-phospho gluconate; CoA, coenzyme-A; G6P, glucose-6-phosphate; TPS, alpha,alpha-trehalose-phosphate synthase; Iso-Cit, isocitrate; PMI, mannose-6-phosphate isomerase; G1P, glucose-1-phosphate; G6PDH, glucose-6-phosphate dehydrogenase; ACO, aconitate hydratase; Glycogen; Non-stationary 13C labeling; OUR, Oxygen uptake rate; SUC, succinate; FBA, fructose-bisphosphate aldolase; SER, serine; METH, methionine; IDMS, Isotope dilution mass spectrometry; UDP, uridine-5-diphosphate; AK, adenylate kinase
• ISSN: 2214-0301; 2214-0301
• DOI: 10.1016/j.meteno.2016.01.001

C labeling experiments in aerobic glucose limited cultures of at four different growth rates (0.054; 0.101, 0.207, 0.307 h ) are used for calculating fluxes that include intracellular cycles (e.g., storage carbohydrate cycles, exchange fluxes with amino acids), which are rearranged depending on the growth rate. At low growth rates the impact of the storage carbohydrate recycle is relatively more significant than at high growth rates due to a higher concentration of these materials in the cell (up to 560-fold) and higher fluxes relative to the glucose uptake rate (up to 16%). Experimental observations suggest that glucose can be exported to the extracellular space, and that its source is related to storage carbohydrates, most likely via the export and subsequent extracellular breakdown of trehalose. This hypothesis is strongly supported by C-labeling experimental data, measured extracellular trehalose, and the corresponding flux estimations.