Optimal tracers for parallel labeling experiments and13C metabolic flux analysis: A new precision and synergy scoring system.
13C-Metabolic flux analysis (13C-MFA) is a widely used approach in metabolic engineering for quantifying intracellular metabolic fluxes. The precision of fluxes determined by13C-MFA depends largely on the choice of isotopic tracers and the specific set of labeling measurements. A recent advance in the field is the use of parallel labeling experiments for improved flux precision and accuracy. However, as of today, no systemic methods exist for identifying optimal tracers for parallel labeling experiments. In this contribution, we have addressed this problem by introducing a new scoring system and evaluating thousands of different isotopic tracer schemes. Based on this extensive analysis we have identified optimal tracers for13C-MFA. The best single tracers were doubly13C-labeled glucose tracers, including [1,6-13C]glucose, [5,6-13C]glucose and [1,2-13C]glucose, which consistently produced the highest flux precision independent of the metabolic flux map (here, 100 random flux maps were evaluated). Moreover, we demonstrate that pure glucose tracers perform better overall than mixtures of glucose tracers. For parallel labeling experiments the optimal isotopic tracers were [1,6-13C]glucose and [1,2-13C]glucose. Combined analysis of [1,6-13C]glucose and [1,2-13C]glucose labeling data improved the flux precision score by nearly 20-fold compared to widely use tracer mixture 80% [1-13C]glucose +20% [U-13C]glucose.
Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark DE 19716, USA.
Scott B
SB
Crown
Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark DE 19716, USA.
Christopher P
CP
Long
Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark DE 19716, USA. Electronic address: mranton@udel.edu.
Maciek R
MR
Antoniewicz
D053898:Biosynthetic Pathways / Q000502:physiology; D002247:Carbon Isotopes / Q000493:pharmacokinetics*; D066241:Carbon-13 Magnetic Resonance Spectroscopy / Q000379:methods*; D003198:Computer Simulation; D004926:Escherichia coli / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007553:Isotope Labeling / Q000379:methods*; D060847:Metabolic Engineering / Q000379:methods; D064688:Metabolic Flux Analysis / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000502:physiology*; D008954:Models, Biological
D002247:Carbon Isotopes; D005947:Glucose
E. coli; GC–MS; Integrated flux analysis; Isotopic labeling; Optimal tracer experiment design