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Noise in metabolism and growth at the level of single bacteria.
The small copy number of RNAs and proteins leads to significant fluctuations of their concentration in cells [1]. The resulting noise in cellular components activity can transmit through genetic regulatory networks [2] and give rise to globally coordinated fluctuations in genetic expression [3]. We are interested in exploring how metabolism and growth, which are central to survival and fitness, can be affected by enzyme concentration fluctuations. We measured expression fluctuations of the system controlling lactose degradation, together with the fluctuations in growth rate at the single cell level in growing colonies of E. Coli. Analysis of temporal cross-correlation between growth and enzyme expression reveals that the growth ability of the cells flucutates in time and that the output of metabolism can be affected by noise in a very upstream enzyme. Noise transmission in the cell can be quantitatively understood and predicted according to a simple stochastic model, for different carbon sources and genes.
[1] Stochastic Gene Expression in a Single Cell, Elowitz MB, Levine AJ, Siggia ED, Swain PS, Science 297, 5584 (2002)
[2] Noise propagation in gene networks,J. M. Pedraza and A. van Oudenaarden,Science 307, 1965 (2005).
[3] Quantifying E. coli Proteome and Transcriptome with Single-Molecule Sensitivity in Single Cells, Taniguchi, Yuichi Choi, Paul J. Li, Gene-Wei Chen, Huiyi Babu, Mohan Hearn, Jeremy Emili, Andrew Xie, X. Sunney, Science 239, 5991 (2010)
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Contact : mathilde.reyssat@espci.fr