Team:ETHZ Basel

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E. lemming

Figure 1. Setup to control E. coli movements. An automatized microscope images the E. lemming. A connected computer system detects and tracks the cells. The direction of movement of the E. lemming is compared to the desired direction defined by the user, e.g. with a joystick. If the direction of movement deviates too much from the desired direction, the digital controller induces tumbling by sending a red light pulse. Otherwise, tumbling is repressed by sending a far-red light pulse.

The core idea of our project is to control chemotaxis of E. coli- by means of light! We'll realize this by hijacking and perturbing the tumbling / directed flagellar movement apparatus. By coupling directed flagellar movement regulating proteins to a novel synthetic light-sensitive spatial localization system, their activity can be controlled reversibly. A light-sensitive dimerizing complex fused to this regulating proteins at a spatially fixed location is induced by light pulses and therefore localization of the two molecules can be manipulated. Tumbling / directed flagellar movement rates are monitored by image processing algorithms, which are linked to the light-pulse generator. This means that E. coli tumbling is induced or suppressed simply by pressing a light switch! This synthetic network enables control of single E. coli cells: We'll make them move like mindless "Lemmings" in the direction they are forced to go!