title: Induction kinetics of a conditional pH stress response system in Escherichia coli.
abstract: The analysis of stress response systems in microorganisms can reveal molecular strategies for regulatory control and adaptation. In this study, we focused on the Cad module, a subsystem of Escherichia coli's response to acidic stress that is conditionally activated at low pH only when lysine is available. When expressed, the Cad system counteracts the elevated H(+) concentration by converting lysine to cadaverine under the consumption of H(+) and exporting cadaverine in exchange for external lysine. Surprisingly, the cad operon displays a transient response, even when the conditions for its induction persist. To quantitatively characterize the regulation of the Cad module, we experimentally recorded and theoretically modeled the dynamics of important system variables. We established a quantitative model that adequately describes and predicts the transient expression behavior for various initial conditions. Our quantitative analysis of the Cad system supports negative feedback by external cadaverine as the origin of the transient response. Furthermore, the analysis puts causal constraints on the precise mechanism of signal transduction via the regulatory protein CadC.
authors.affiliation: Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Fritz
authors.forename: Christiane
authors.initials: C
authors.lastname: Koller
authors.forename: Korinna
authors.initials: K
authors.lastname: Burdack
authors.forename: Larissa
authors.initials: L
authors.lastname: Tetsch
authors.forename: Ina
authors.initials: I
authors.lastname: Haneburger
authors.forename: Kirsten
authors.initials: K
authors.lastname: Jung
authors.forename: Ulrich
authors.initials: U
authors.lastname: Gerland
mesh_terms: D015152:Blotting, Northern; D002103:Cadaverine / Q000378:metabolism; D002262:Carboxy-Lyases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008954:Models, Biological; D008962:Models, Theoretical; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
chemical_list: D002262:Carboxy-Lyases; C021520:lysine decarboxylase; D002103:Cadaverine