Fine-Tuning of Chemotactic Response in E. coli Determined by High-Throughput Capillary Assay

Current Microbiology - Tập 62 - Trang 764-769 - 2010
Heungwon Park1, Calin C. Guet2, Thierry Emonet3, Philippe Cluzel2,4
1The Department of Physics, The James Franck Institute, The Institute for Biophysical Dynamics, University of Chicago, Chicago, USA
2Department of Molecular and Cellular Biology, FAS Center for Systems Biology, Harvard University, Cambridge, USA
3Departments of Molecular, Cellular, and Developmental Biology & Physics, Yale University, New Haven, USA
4School of Engineering and Applied Sciences, Harvard University, Cambridge, USA

Tóm tắt

In E. coli, chemotactic behavior exhibits perfect adaptation that is robust to changes in the intracellular concentration of the chemotactic proteins, such as CheR and CheB. However, the robustness of the perfect adaptation does not explicitly imply a robust chemotactic response. Previous studies on the robustness of the chemotactic response relied on swarming assays, which can be confounded by processes besides chemotaxis, such as cellular growth and depletion of nutrients. Here, using a high-throughput capillary assay that eliminates the effects of growth, we experimentally studied how the chemotactic response depends on the relative concentration of the chemotactic proteins. We simultaneously measured both the chemotactic response of E. coli cells to l-aspartate and the concentrations of YFP-CheR and CheB-CFP fusion proteins. We found that the chemotactic response is fine-tuned to a specific ratio of [CheR]/[CheB] with a maximum response comparable to the chemotactic response of wild-type behavior. In contrast to adaptation in chemotaxis, that is robust and exact, capillary assays revealed that the chemotactic response in swimming bacteria is fined-tuned to wild-type level of the [CheR]/[CheB] ratio.

Tài liệu tham khảo

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