title: Kinetics of the cellular intake of a gene expression inducer at high concentrations.
abstract: From in vivo single-event measurements of the transient and steady-state transcription activity of a single-copy lac-ara-1 promoter in Escherichia coli, we characterize the intake kinetics of its inducer (IPTG) from the media. We show that the empirical data are well-fit by a model of intake assuming a bilayer membrane, with the passage through the second layer being rate-limiting, coupled to a stochastic, sub-Poissonian, multi-step transcription process. Using this model, we show that for a wide range of extracellular inducer levels (up to 1.25 mM) the intake process is diffusive-like, suggesting unsaturated membrane permeability. Inducer molecules travel from the periplasm to the cytoplasm in, on average, 31.7 minutes, strongly affecting cells' response time. The novel methodology followed here should aid the study of cellular intake mechanisms at the single-event level.
authors.affiliation: Laboratory of Biosystem Dynamics, Department of Signal Processing, Tampere University of Technology, FI-33101 Tampere, Finland. andre.ribeiro@tut.fi.
authors.forename: Huy
authors.initials: H
authors.lastname: Tran
authors.forename: Samuel M D
authors.initials: SM
authors.lastname: Oliveira
authors.forename: Nadia
authors.initials: N
authors.lastname: Goncalves
authors.forename: Andre S
authors.initials: AS
authors.lastname: Ribeiro
mesh_terms: D000465:Algorithms; D001692:Biological Transport; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D007425:Intracellular Membranes / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000378:metabolism / Q000494:pharmacology; D008954:Models, Biological; D009876:Operon; D012097:Repressor Proteins / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D012097:Repressor Proteins; D007544:Isopropyl Thiogalactoside