Flux analysis of central metabolic pathways in the Fe(III)-reducing organism Geobacter metallireducens via 13C isotopiclabeling
We analyzed the carbon fluxes in the central metabolism ofGeobacter metallireducens strain GS-15 using 13C isotopomer modeling.Acetate labeled in the 1st or 2nd position was the sole carbon source,and Fe-NTA was the sole terminal electron acceptor. The measured labeledacetate uptake rate was 21 mmol/gdw/h in the exponential growth phase.The resulting isotope labeling pattern of amino acids allowed an accuratedetermination of the in vivo global metabolic reaction rates (fluxes)through the central metabolic pathways using a computational isotopomermodel. The model indicated that over 90 percent of the acetate wascompletely oxidized to CO2 via a complete tricarboxylic acid (TCA) cyclewhile reducing iron. Pyruvate carboxylase and phosphoenolpyruvatecarboxykinase were present under these conditions, but enzymes in theglyoxylate shunt and malic enzyme were absent. Gluconeogenesis and thepentose phosphate pathway were mainly employed for biosynthesis andaccounted for less than 3 percent of total carbon consumption. The modelalso indicated surprisingly high reversibility in the reaction betweenoxoglutarate and succinate. This step operates close to the thermodynamicequilibrium possibly because succinate is synthesized via a transferasereaction, and its product, acetyl-CoA, inhibits the conversion ofoxoglutarate to succinate. These findings enable a better understandingof the relationship between genome annotation and extant metabolicpathways in G. metallireducens.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Biological andEnvironmental Research
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 925527
- Report Number(s):
- LBNL-62247; R&D Project: GTL2KK; BnR: KP1102010; TRN: US200809%%786
- Journal Information:
- Applied Environmental Microtiology, Vol. 73, Issue 12; Related Information: Journal Publication Date: June 2007; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
Similar Records
Pathway confirmation and flux analysis of central metabolicpathways in Desulfovibrio vulgaris Hildenborough using gaschromatography-mass spectrometry and fourier transform-ion cyclotronresonance mass spectrometry
Anaerobic central metabolic pathways in Shewanella oneidensis MR-1interpreted in the light of isotopic metabolite labeling, enzymeactivities and genome annotation
Related Subjects
ACETATES
AMINO ACIDS
BINDING ENERGY
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
BYPASSES
CARBON
CARBON SOURCES
CARBOXYLASE
ELECTRONS
ENZYMES
IN VIVO
IRON
METABOLISM
PENTOSES
PHOSPHATES
REACTION KINETICS
STRAINS
THERMODYNAMICS
TRANSFERASES
VALENCE
labeled acetate electron acceptor minimal medium TCA cycleacetyl-CoA transferase