Team:Chalmers-Gothenburg/Biodetection of hCG
From 2012.igem.org
Biodetection of hCG hormone
Saccharomyces cerevisiae will be modified in such a way that the yeast cell should function as a biosensor for the human chorionic gonadotropin hormone (hCG). This hormone is produced in the body during pregnancy and consequently, the idea for the biosensor is to function as a simple pregnancy test. To construct the biosensor, the Ste2 receptor, member of the G protein-coupled receptor (GPCR) family, in the yeast pheromone signaling pathway will be replaced by the human luteinizing hormone receptor (LH/CG). The LH/CG receptor binds to hCG with high affinity. As an output signal, the expression of indigo producing enzymes will be coupled with the pheromone pathway.
The yeast strain that will be used is provided by the Kondo group from Kobe University in Japan. It has the endogenous GPCR Ste2 deleted in order to prevent it from isolating G proteins in inactive complexes. Sst2, a negative feedback regulator of the pheromone pathway is also knocked out. The strain contains a yeast/human chimeric Gα subunit which should ensure the interaction of the human GPCR with the yeast pheromone pathway. Binding of hCG to the LH/CG receptor will result in the activation of the chimeric G protein, the activation of the pheromone pathway and consequently the expression of indigo synthesizing enzymes.