Cited by 453Microbial Metabolic Engineering and BioproductionGene Regulatory Network AnalysisBiochemical and Molecular Research

Metabolite concentrations, fluxes and free energies imply efficient enzyme usage

Open access
Park, Junyoung O, Rubin, Sara A, Xu, Yi-Fan, Amador-Noguez, Daniel, Fan, Jing, Shlomi, Tomer, Rabinowitz, Joshua D·2016·Nature Chemical Biology

Abstract

In metabolism, available free energy is limited and must be divided across pathway steps to maintain a negative ΔG throughout. For each reaction, ΔG is log proportional both to a concentration ratio (reaction quotient to equilibrium constant) and to a flux ratio (backward to forward flux). Here we use isotope labeling to measure absolute metabolite concentrations and fluxes in Escherichia coli, yeast and a mammalian cell line. We then integrate this information to obtain a unified set of concentrations and ΔG for each organism. In glycolysis, we find that free energy is partitioned so as to mitigate unproductive backward fluxes associated with ΔG near zero. Across metabolism, we observe that absolute metabolite concentrations and ΔG are substantially conserved and that most substrate (but not inhibitor) concentrations exceed the associated enzyme binding site dissociation constant (Km or Ki). The observed conservation of metabolite concentrations is consistent with an evolutionary drive to utilize enzymes efficiently given thermodynamic and osmotic constraints.

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  • Average metabolite concentrations generated from the model show reasonable agreement to the values reported by Park et al. (2016) in E. coli, but the cell-to-cell variation in the kinetic models over a cell cycle is broader than the predicted range.

    “In general, average metabolite concentrations generated from the model (Figure 6) show reasonable agreement to the values reported by Park et al. (2016) in E. coli, but the cell-to-cell variation in the kinetic models over a cell cycle is broader than the predicted range.”

    From Fundamental behaviors emerge from simulations of a living minimal cell (2022) · cites this paper as Park et al. (2016)

    Split into 2 atoms — 1 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

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  • The main deviation in glycolysis is the FBA reaction, where the kinetic parameters result in a free energy drop of roughly 25 kJ/mol, which has been reported to be less than 10 kJ/mol.

    “The main deviation here is again with the FBA reaction where the kinetic parameters result in a free energy drop of roughly 25 kJ/mol which has been reported to be less than 10 kJ/mol (Flamholz et al., 2013; Park et al., 2016).”

    From Fundamental behaviors emerge from simulations of a living minimal cell (2022) · cites this paper as Park et al., 2016

    The Results section (‘Integrating metabolite concentrations and free energies’; page unavailable) says aldolase was closer to equilibrium in yeast, supporting a smaller free-energy drop qualitatively. It does not give an aldolase-specific value below 10 kJ/mol. The roughly 25 kJ/mol kinetic estimate is the citing authors’ comparison, not a result attributed to Park et al. (LLM, conf=0.76)

    Experimental — accuracy not yet measured
  • Other studies have reported overall free energy changes through glycolysis from −30 to −70 kJ/mol.

    “Other studies have reported overall free energy changes from −30 to −70 kJ/mol (Flamholz et al., 2013; Park et al., 2016)”

    From Fundamental behaviors emerge from simulations of a living minimal cell (2022) · cites this paper as Park et al., 2016

    The Results section reports an average cumulative glycolytic free-energy change of −46 kJ/mol and says the drop in yeast was nearly double that in mammalian cells. This supports variation in the overall change, but our copy does not give the claimed −30 to −70 kJ/mol endpoints. The measured sequence also runs from phosphoglucose isomerase to pyruvate kinase, rather than including every step of glycolysis. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • Only relative metabolomics data on Syn3A is available, so metabolite concentrations used to initialize simulations were estimated from scaling of an E. coli study and a limited list from M. pneumoniae.

    “At the moment, only relative metabolomics data on Syn3A is available, so the metabolite concentrations used to initialize the simulations of the Syn3A WCM were estimated from a scaling of the comprehensive study done on E. coli (Park et al., 2016) and a limited list from M. pneumoniae (Yus et al., 2009).”

    From Fundamental behaviors emerge from simulations of a living minimal cell (2022) · cites this paper as Park et al., 2016

  • High concentrations of phosphate reported in yeast may be inaccurate for Syn3A.

    “While such high concentrations have been reported in yeast (Park et al., 2016), they may be inaccurate for Syn3A.”

    From Fundamental behaviors emerge from simulations of a living minimal cell (2022) · cites this paper as Park et al., 2016

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Authors
Park, J. O., Rubin, S. A., Xu, Y.-F., Amador-Noguez, D., Fan, J., Shlomi, T., & Rabinowitz, J. D.
Affiliations
  • Princeton University (US)
  • Technion – Israel Institute of Technology (IL)
Corresponding author
Rabinowitz, Joshua D
Venue
Nature Chemical Biology
Published
2016-05-02
Volume
12
Issue
7
Pages
482-489
ISSN
  • 1552-4450 (ISSN-L)
  • 1552-4469
OpenAlex
W2346094579
Cited by
453
References
60
Citations by year
2026: 39 · 2025: 56 · 2024: 53 · 2023: 50 · 2022: 44 · 2021: 43 · 2020: 40 · 2019: 37 · 2018: 43 · 2017: 34 · 2016: 13 · 2014: 1
FWCI
22.17
Type
journal article
Language
en
Open access
Locations
  • Nature Chemical Biology (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
  • Howard Hughes Medical Institute
  • U.S. Department of Energy (DESC0012461)
  • National Institutes of Health
  • National Cancer Institute (R01CA163591)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gene Regulatory Network Analysis
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Biochemical and Molecular Research
Keywords
metabolic flux, metabolite concentrations, enzyme catalytic efficiency, isotopic labeling, glycolysis, reaction quotient, equilibrium constants, Escherichia coli, yeast, thermodynamics of metabolism
MeSH terms
Animals, Cell Line, Enzymes, Escherichia coli, Saccharomyces cerevisiae, Thermodynamics, Mice

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