Single-cell FRET imaging of phosphatase activity in the Escherichia coli chemotaxis system

Ady Vaknin, Howard C. Berg

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


Two-component signaling systems, in which a receptor-coupled kinase is used to control the phosphorylation level of a response regulator, are commonly used in bacteria to sense their environment. In the chemotaxis system of Escherichia coli, the receptors, and thus the kinase, are clustered on the inner cell membrane. The phosphatase of this system also is recruited to receptor clusters, but the reason for this association is not clear. By using FRET imaging of single cells, we show that in vivo the phosphatase activity is substantially larger at the cluster, indicating that the signaling source (the kinase) and the signaling sink (the phosphatase) tend to be located at the same place in the cell. When this association is disrupted, a gradient in the concentration of the phosphorylated response regulator appears, and the chemotactic response is degraded. Such colocalization is inevitable in systems in which the activity of the kinase and the phosphatase are produced by the same enzyme. Evidently, this design enables a more rapid and spatially uniform response.

Original languageAmerican English
Pages (from-to)17072-17077
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number49
StatePublished - 7 Dec 2004


  • Bacteria
  • Cyan fluorescence protein
  • Signal transduction
  • Yellow fluorescence protein


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