The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress

Takahashi, Hiroki; Oshima, Taku; Hobman, Jon L.; Doherty, Neil; Clayton, Selina R.; Iqbal, Mudassar; Hill, Philip J.; Tobe, Toru; Ogasawara, Naotake; Kanaya, Shigehiko; Stekel, Dov J.

Abstract

Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli. We measured the response to zinc of the main specific zinc import and export systems in the wild-type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: first, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments, we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesize that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments

Citation

Takahashi, H., Oshima, T., Hobman, J. L., Doherty, N., Clayton, S. R., Iqbal, M., Hill, P. J., Tobe, T., Ogasawara, N., Kanaya, S., & Stekel, D. J. (2015). The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress. Interface, 12(106), Article 20150069. https://doi.org/10.1098/rsif.2015.0069

• Journal Article Type: Article
• Acceptance Date: Feb 27, 2015
• Online Publication Date: Mar 25, 2015
• Publication Date: May 6, 2015
• Deposit Date: Feb 11, 2016
• Publicly Available Date: Feb 11, 2016
• Journal: Interface
• Electronic ISSN: 1742-5662
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 106
• Article Number: 20150069
• DOI: https://doi.org/10.1098/rsif.2015.0069
• Keywords: Biochemistry, Computational Biology, Systems Biology
• Public URL: https://nottingham-repository.worktribe.com/output/746879
• Publisher URL: http://rsif.royalsocietypublishing.org/content/12/106/20150069
• Contract Date: Feb 11, 2016