FBS Colloquia No.239Laboratory of Nano-Biophsics

Simultaneous measurement of intracellular signaling by fluorescence imaging and chemotactic response in a single E. coli cell

E. coli cells have chemotaxis system and control their locomotive organelle flagella, so they can move toward desirable environment. In this system, E. coli moderates the concentration of intracellular signaling molecule, phosphorylated CheY ([CheYp]), according to external stimuli, and CheYp binds to a flagellar motor to induce a switch of rotational direction of motor from counterclockwise to clockwise. [CheYp] and the rotational direction of flagellar motor are closely related, however it’s relation is not quantitatively understood well. Therefore, we tried to simultaneously measure the motor-rotation and [CheYp] in a single cell via Förster Resonance Energy Transfer (FRET) between CheY and CheZ by using binding of CheZ and CheYp during dephosphorylation. By using this measuring system, we succeeded in quantitatively analyzing the process of chemotactic response and adaptation in terms of the concentration of signaling molecule ([CheYp]) and cellular response (rotational direction of flagellar motor). In this colloquium, we will discuss our recent results about the signaling process based on experimental results measured at a single E. coli cell.