Chemotaxis is the movement of an organism in response to an external chemical stimulus. The bacterial chemotaxis system is characterized by specific responses, high sensitivity and a dynamic range (1). This system enables bacteria to sense their immediate environment and quickly adapt to changes in its chemical composition - thus fleeing from repellents or moving towards attractants. The key to this system and the first link in the chain is the bacterial chemoreceptor - a membrane protein that binds the effector and transduces the signal down the line. Despite it's advantages this system is still rather limited, bacterial chemoreceptors have evolved to sense specific materials that either benefit or harm the cell in some way. The specificity of a receptor is determined by its ligand binding domain. This domain is the focus of project S.Tar.

Fig. 1: A bacterial sense of direction.

The S.Tar platform offers the means to decide what substance will trigger a chemotactic response- controlled chemotaxis. The base of our project and the source of our name is the Tar chemoreceptor, one of four E. coli receptors. By changing Tar’s ligand binding domain to that of other receptors or by mutating it, we show that E. coli can be engineered to respond to completely new materials.