Copper is an element, which is essential for cell functioning and survival, but becomes toxic at high concentrations.
Organisms like Baker's yeast, Saccharomyces cerevisiae, have developed mechanisms for regulating internal concentration of copper. S. cerevisiae is adapted to live and grow in environments ranging from having trace amounts of copper to concentrations of Cu2+ in the millimolar range.
In this work we show how the inflow/outflow framework can be used to model the homeostatic control of copper in S. cerevisiae. We then extend the operative range of copper homeostasis by adding an outflow controller. Using synthetic biology we integrate the gene of a copper transporting P-type ATPase from Candida albicans (Crp) into the genome of S. cerevisiae together with a copper dependent promoter.
We show that the added outflow controller increases the copper tolerance of S. cerevisiae. The controller action is examined by fusing the copper ATPase to a green fluorescent protein, EGFP. The controller is only active when the internal concentration of copper in the cell is too high, and the action increases with increasing internal copper concentration.