Serotonin GPCR-based biosensing modalities in yeast

Summary Serotonin is a key neurotransmitter involved in numerous physiological processes and serves as an important precursor for manufacturing bioactive indoleamines and alkaloids used in the treatment of human pathologies. In humans, serotonin sensing and signaling can occur by 12 G protein-coupled receptors (GPCRs) coupled to G proteins. To systematically assess serotonin GPCR signaling, we characterized reporter gene expression of a 144-sized library encoding all 12 human serotonin GPCRs in combination with 12 different Gα proteins in yeast exposed to serotonin. For the 5-HT4 receptor, we observe 25- and 64-fold changes in EC 50 values and dynamic reporter gene outputs, respectively. Furthermore, we show that optimal biosensing designs enable high-resolution sensing of serotonin produced in yeast, as well as provide a platform for characterization of 19 serotonin GPCR polymorphisms found in human populations. Taken together, our study highlights serotonin biosensing modalities of relevance to both biotechnological and human health applications. Highlights Human serotonin G protein-coupled receptors display promiscuous Gα coupling in yeast Gα-coupled serotonin receptors display up to 64-fold changes in reporter expression output Differences in Gα protein evokes 25- and 2-fold difference in EC 50 and sensitivity, respectively Serotonin receptor 5-HT4 and human SNP variants display physiologically relevant EC 50 values in yeast 5-HT4 can be applied for high-resolution biosensing of serotonin produced from yeast