The heterogeneity of reaction fluxes present in a metabolic network  can be exploited to construct the high-flux fluctuation backbone as a reduced version of metabolism. The backbone maintains all relevant information while displaying a substantially decreased number of interconnections and, hence, it becomes a useful tool to extract relevant metabolic routeswhich unveil important biological information . Here, we disclose the metabolic backbone of Escherichia coli using the computationally predicted fluxes which maximize the growth rate in glucose minimal medium, and we contrast it with the backbone of Mycoplasma pneumoniae, a much URLanism. We find that the core of both backbones are mainly composed of reactions in ancient pathways, meaning that those reactions still retain at present the central role in the evolved metabolism. In E. coli, the analysis of the core reveals a dominant direction with the synthesis of purines and pyrimidines and the metabolism of lipids ensuing after energy metabolism . At the same time, a comparative analysis of the backbone of E. coli in different media leads to the identification of pathways sensitive to environmental changes. The metabolic backbone of URLanism , as a network of metabolites connected by the most relevant fluxes, is thus useful to trace simultaneously both its evolution and adaptation fingerprints.
The heterogeneity of reaction fluxes present in a metabolic network within a single flux state can be exploited to construct the so-called backbone as a reduced version of metabolism. The backbone maintains all significant fluxes producing or consuming metabolites while displaying a substantially decreased number of interconnections and, hence, it becomes a useful tool to extract primary metabolic routes . Here, we disclose the metabolic backbone of Escherichia coli using the computationally predicted fluxes which maximize the growth rate in glucose minimal medium, and we compare it with the backbone of Mycoplasma pneumoniae, a much URLanism. We find that the central core in both backbones is mainly composed of reactions in ancient pathways, still playing at present a key role in energy metabolism. In E. coli, the analysis of the backbone reveals that the synthesis of nucleotides and the metabolism of lipids form smaller cores which rely critically on energy metabolism; but not conversely . At the same time, an analysis of the dependence of this backbone on media composition leads to the identification of pathways sensitive to environmental changes. The metabolic backbone of URLanism is thus useful to trace simultaneously both its evolution and adaptation fingerprints.
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within a single flux state
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high-flux fluctuation
so-called
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relevant information
significant fluxes producing or consuming metabolites
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relevant metabolic routeswhich unveil important biological information
primary metabolic routes
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contrast
compare
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core of both backbones are
central core in both backbones is
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meaning that those reactions still retain at present the central role in the evolved
still playing at present a key role in energy
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core reveals a dominant direction with
backbone reveals that
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purines and pyrimidines and
nucleotides and
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ensuing after energy metabolism
form smaller cores which rely critically on energy metabolism; but not conversely
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a comparative
an
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backbone of E. coli in different media
dependence of this backbone on media composition
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, as a network of metabolites connected by the most relevant fluxes,