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Revision as of 10:58, 22 September 2010

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In the classic video game “Lemmings” the player has to lead a colony of lemmings with suicidal tendencies safely through a perilous world. Our project is about implementing the basic idea of this video game of spatial movement control into the biological system of Escherichia coli. We would like to guide an individual E. coli bacterium along a path.

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!