Dynamics of transcription driven by the tetA promoter, one event at a time, in live Escherichia coli cells.
In Escherichia coli, tetracycline prevents translation. When subject to tetracycline, E. coli express TetA to pump it out by a mechanism that is sensitive, while fairly independent of cellular metabolism. We constructed a target gene, PtetA-mRFP1-96BS, with a 96 MS2-GFP binding site array in a single-copy BAC vector, whose expression is controlled by the tetA promoter. We measured the in vivo kinetics of production of individual RNA molecules of the target gene as a function of inducer concentration and temperature. From the distributions of intervals between transcription events, we find that RNA production by PtetA is a sub-Poissonian process. Next, we infer the number and duration of the prominent sequential steps in transcription initiation by maximum likelihood estimation. Under full induction and at optimal temperature, we observe three major steps. We find that the kinetics of RNA production under the control of PtetA, including number and duration of the steps, varies with induction strength and temperature. The results are supported by a set of logical pairwise Kolmogorov-Smirnov tests. We conclude that the expression of TetA is controlled by a sequential mechanism that is robust, whereas sensitive to external signals.
Laboratory of Biosystem Dynamics, Computational Systems Biology Research Group, Department of Signal Processing, Tampere University of Technology, FI-33101 Tampere, Finland.
Anantha-Barathi
AB
Muthukrishnan
Meenakshisundaram
M
Kandhavelu
Jason
J
Lloyd-Price
Fedor
F
Kudasov
Sharif
S
Chowdhury
Olli
O
Yli-Harja
Andre S
AS
Ribeiro
D017920:Antiporters / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics*; D007700:Kinetics; D016013:Likelihood Functions; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D013696:Temperature; D061785:Transcription Initiation, Genetic
D017920:Antiporters; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; C079051:tetA protein, Bacteria