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Large-scale in vivo flux analysis shows rigidity and suboptimal performance of Bacillus subtilis metabolism. Ref: Eliane Fischer & Uwe Sauer, Nature Genetics 37:636 Presented by Shenghua Liang. Bow-tie 13 C technology
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Large-scale in vivo flux analysis shows rigidity and suboptimal performance of Bacillus subtilis metabolism Ref: Eliane Fischer & Uwe Sauer, Nature Genetics 37:636 Presented by Shenghua Liang
Bow-tie • 13C technology • For the first time, a large-scale experimental analysis of intracellular flux distributions.
Experiments • 137 mutants in 9 groups covering all major functional categories • Central carbon metabolism • Biosynthetic reactions • Catabolic reactions and transport • Transcriptional regulators • Signal transduction • Inorganic ion transport and metabolism • Energy production and conversion • Other functions • Unknown or general function
Conclusions - 1 • In contrast to peripheral biosynthetic network, no kinetic effect modulates the distribution of central metabolic fluxes • Neither flux into PPP nor that into TCA is driven by the biosynthetic demand for the cofactors of NADPH and ATP • Maximal energy yield is not a relevant metabolic objective during exponential growth phase of B. subtilis
Conclusions - 2 • Control architecture of central metabolism is designed to provide a rigid flux distribution that is independent of the rate and yield of biomass formation • B. subtilis maintains a stable metabolic state under a given environmental condition • The state is robust against random genetic perturbations because the exclusive flexible acetyl-CoA branch point provide sufficient flexibility • At the expense of optimal biomass productivity, metabolic fluxes are fine-tuned by developmental regulators that control adaptive responses. • B. subtilis maintains in a standby mode that allows rapid responses to variations in environmental conditions.