Figure 2.

Coordinated switching of multiple flagellar motors in a single E. coli cell. (a) Schematic diagram of the measurement system. Polystyrene beads (ϕ=0.5 μm) were attached to sticky flagellar stubs. Phase-contrast images of each bead were recorded with a high-speed CCD camera, and the angular velocity and rotational direction were estimated from the position of the bead for every recorded frame. The chemoreceptor patch was observed via the intracellular localization of GFP-CheW. (b) Time course of the rotational speeds of two motors on the same cell. Plus and minus values represent CCW and CW rotations, respectively. Lines indicate the speed of the motor closer to (red) and farther from (blue) the chemoreceptor patch. The motor closer to the patch switched rotational direction before the more distant motor, in both CCW-to-CW and CW-to-CCW switching. (c) Correlation analysis of the switching between the two motors depicted in Fig. 2b (blue line). The green line shows the correlation between two motors on a different cell. Delay of the peak was defined as Δτ, which represents the difference in the time of switching between two motors. (d) The relationship between Δτ and M2²–M1², where M1 and M2 are the distances from the chemoreceptor patch to the closer and further motors, respectively. Correlations were analyzed based on the motor closer to the major chemoreceptor patch. Part b, c, and d of the figure was reused with permission from reference 40.