Circuit containing hydrolases

A seven-species model was used to model the spatiotemporal behaviour of our multicellular sender–receiver system. The model was based on differential equations with Hill functions that captured the activation of protein synthesis as a function of the concentration of the signalling molecule.

For the agar plate and mine cells modules, we use the system of equations and parameters set of the previous simulation.

Mine Cells

The PDEs for the states involved in the sender module are given below:

Equation system 1: System of Differential equations for mine cells.

Agar Plate

The PDE for OHHL in the agar plate is given below:

Equation 2: Processes taking place on the agar plate: diffusion and decay of OHHL

Receiver Cells

Receivers are engineered to respond differently to two OHHL concentration levels. Basically, cells should be capable of produce a visible response for the player, in order to discriminate between the presence of 0, 1 or 2 adjacent mine cells. To achieve this goal, we incorporate two enzymatic reporters, under the control of P_lux promoters, in our circuit, (GusA and AES). Such enzymes can catalyze the hydrolysis of various chromogenic compounds to give rise to a relatively quick coloured response.

In addition to new proteins incorporated to the circuit, it is important to remain that the grid was changed to a three neighbours setup.

</p> The intracellular species of interest in the receiver cells included LuxR, AHL, LuxR/AHL complex (denoted as R) and the hydrolases (GusA and AES).

Figure 4: Differential equations of the receiver cells

To distinguish between AHL-levels, the expression of the hydrolases is controlled by PLuxR promoters mutants, which are sensitive to different concentration of the dimer LuxR-AHL (denoted as R) given by the number of surrounding mines.

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