title: Real-time metabolome profiling of the metabolic switch between starvation and growth.
abstract: Metabolic systems are often the first networks to respond to environmental changes, and the ability to monitor metabolite dynamics is key for understanding these cellular responses. Because monitoring metabolome changes is experimentally tedious and demanding, dynamic data on time scales from seconds to hours are scarce. Here we describe real-time metabolome profiling by direct injection of living bacteria, yeast or mammalian cells into a high-resolution mass spectrometer, which enables automated monitoring of about 300 compounds in 15-30-s cycles over several hours. We observed accumulation of energetically costly biomass metabolites in Escherichia coli in carbon starvation-induced stationary phase, as well as the rapid use of these metabolites upon growth resumption. By combining real-time metabolome profiling with modeling and inhibitor experiments, we obtained evidence for switch-like feedback inhibition in amino acid biosynthesis and for control of substrate availability through the preferential use of the metabolically cheaper one-step salvaging pathway over costly ten-step de novo purine biosynthesis during growth resumption.
authors.affiliation: Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland.
authors.forename: Hannes
authors.initials: H
authors.lastname: Link
authors.affiliation: Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Fuhrer
authors.affiliation: Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Gerosa
authors.affiliation: Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Zamboni
authors.affiliation: Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland.
authors.forename: Uwe
authors.initials: U
authors.lastname: Sauer
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001412:Bacillus subtilis; D018533:Biomass; D002244:Carbon / Q000737:chemistry; D002460:Cell Line; D004926:Escherichia coli / Q000502:physiology*; D007477:Ions; D007700:Kinetics; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D055442:Metabolome; D055432:Metabolomics / Q000379:methods*; D051379:Mice; D008962:Models, Theoretical; D011687:Purines / Q000737:chemistry; D012441:Saccharomyces cerevisiae; D015007:Yersinia
chemical_list: D000596:Amino Acids; D007477:Ions; D011687:Purines; D002244:Carbon; D000255:Adenosine Triphosphate