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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 in the yeast pheromone signaling pathway will be replaced by the human luteinizing hormone receptor (LH/CG), which is the receptor that hCG binds to with high affinity. The yeast strain that will be used contains a yeast/human chimeric Gα subunit, enabling coupling of the receptor with the already existing pheromone pathway in yeast. Consequently, binding of hCG should result in activation of the pathway. The genes tnaA and fmo, encoding tryptophanase and flavin-containing monooxygenase respectively, will also be introduced into the yeast strain. These enzymes catalyze the conversion of tryptophan to indigo. tnaA will be set under the control of the pheromone induced FIG1 promoter and fmo of the constitutive TEF1 promoter. Hence, detection of hCG should result in the production of bio-indigo. Another modification will be the deletion of the gene CWP2, encoding a cell wall mannoprotein, in order to ensure hCG to pass the yeast cell wall.
