Heterogeneity in Colicin E2 expression of Escherichia coli
Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
Final Report Abstract
Bacterial interactions, such as competition by toxin release, determine microbial community composition dynamics, which in turn affects human physiology and human health. Stochastic processes strongly influence these bacterial interactions and consequently bacterial interaction dynamics. In this project, we were able to show that stochastic processes play an important role for the spatiotemporal dynamics of ColicinE2 production in bacterial populations and hence affect the competitive success of the ColicinE2 producing bacteria. In combination with mathematical modelling, we were able to describe these complex dynamics of ColicinE2 production. This enabled us to show that the competitive success of the ColicinE2 producing bacteria is dependent on the heterogeneous nature of the toxin production, i.e. a well-adjusted division of labor between toxin producing and reproducing bacteria. Besides the heterogeneous toxin production that is driven by stochastic processes, the time point of toxin release greatly influences population success, as premature release of the toxin negatively affects population growth. In a combined experimental and theoretical study, we were able to show that a time-delay between toxin production and release exists, that is strongly dependent on posttranscriptional regulation by the global carbon storage regulator CsrA, and ensures the release of effective toxin concentrations. The amount of free CsrA is thereby controlled by many different factors. In this context, we were able to discover a yet unknown regulatory component: ssDNA, an intermediate of autonomous ColicinE2 plasmid replication, that is able to bind to CsrA and hence reduces the amount of free CsrA molecules in the bacterial cell. In summary, our work enhanced our understanding on how competition by stochastic driven heterogeneous bacteriocin production can affect the composition dynamics of microbial populations. This important finding of our study was highlighted in an article in Trends in Microbiology.
Publications
- How turbulence regulates biodiversity in systems with cyclic competition. Phys. Rev., E 91, 033009 (2015)
D. Groseli, F. Jenko, and E. Frey
(See online at https://doi.org/10.1103/PhysRevE.91.033009) - Hierarchical Post-transcriptional Regulation of Colicin E2 Expression in Escherichia coli. PLoS Comp. Biol.12(12):e1005243 (2016)
M. Lechner, M. Schwarz, M. Opitz and E. Frey
(See online at https://doi.org/10.1371/journal.pcbi.1005243) - Effects of Stochasticity and Division of Labor in Toxin Production on Two-strain Bacterial Competition in Escherichia coli. Plos Biology, (2017)
B. v. Bronk, S. A. Schaffer, A. Goetz and M. Opitz
(See online at https://doi.org/10.1371/journal.pbio.2001457) - Complex microbial systems across different levels of description. Phys. Biol., 15: 051002 (2018)
B. v. Bronk, A. Goetz and M. Opitz
(See online at https://doi.org/10.1088/1478-3975/aac473) - CsrA and its regulators control ColicinE2 release in Escherichia coli. Scientific Reports, 25;8(1):6537 (2018)
A. Goetz, M. Lechner, A. Mader, B. von Bronk, E. Frey and M. Opitz
(See online at https://doi.org/10.1038/s41598-018-24699-z)
