Metal AND

Our system consists of a hybrid promoter which contains binding sites for two transcription factors that act as repressors, CzrA and ArsR. In the presence of Met1, CzrA losses affinity for its binding site.

Similarly, if there is Met2 in the cell, ArsR also dissociates itself from its binding site. Taking into account these facts, unless Met1 and Met2 are present in the culture, we can say that the genes under this hybrid promoter will be repressed, just like a AND gate should function!

Repressors

Inputs

Kappa

There is no metal catabolism, so metals just reach an equilibrium and non-toxic concentration within the cell through exporting it out of the cytosol, maintaining the concentration constant. This makes the behavior of a single burst or a continuous dose similar, because the metal levels in just one dose will be constant since metals won’t be degraded.