Our project

This year, iGEM York are working on a bioremediation project, involving the decontamination of wastewater. Our aim is to increase sulphate uptake in E.coli and chelate Cadmium (a toxic heavy metal) through the use of metal-binding proteins called phytochelatins. Our project is divided into two main approaches that are interconnected:

• The increase of sulphate uptake (using an exogenous sulphate transporter from Bacillus) and its conversion into cysteine by tweaking the cysteine synthesis pathway.

• The increase of cadmium ion uptake (upregulation of cadmium transporters) and chelation (stabilisation of the metal by metal binding proteins).

The metal binding proteins are the link between the two approaches as they contain sulphur rich cysteine residues which will act as sinks for the cysteine overproduction. The metal binding proteins are divided into two main categories:

1. Phytochelatins (synthesized by a phytochelatin synthetase in a stepwise reaction – so we are working with an exogenous Phytochelatin synthetase gene in E coli)

2. Synthetic phytochelatins (engineered and directly translated from the DNA/RNA sequence without the need of a synthase).

Our system is regulated by the metal concentration in the environment. If the concentration reaches the threshold of our cadmium inducible promoter (pYoda) sensitivity then it will activate the whole system. Thus, our system prevents the overproduction of cysteine when Cadmium is not found at high concentrations.