A GPCR-Based Yeast Biosensor for Biomedical, Biotechnological and Point-of-Use Cannabinoid Determination

The growing interest in cannabinoids as therapeutics and the decriminalization of cannabis for self-medication and recreational use have created an urgent need for convenient methods to discover and evaluate novel synthetic and natural cannabinoids and also monitor cannabinoid levels in patients or users. The human receptors targeted by cannabinoids, CB1 and CB2, are G-protein coupled receptors (GPCRs). Although GPCRs are the most powerful and versatile means by which eukaryotes sense their environment, biosensors employing GPCRs are still largely missing. Here, we hijack the Saccharomyces cerevisiae pheromone pathway to develop a GPCR-based biosensor platform and then equip this platform with the CB2 receptor, optimize it to achieve up to 10 pM cannabinoid sensitivity and a 10^3:1 dynamic range, and test it in three real-life applications.

First, we screen a library of synthetic compounds for novel cannabinoids. We discover two novel synthetic CB2 agonists and antagonists and prove that our biosensor can democratize drug screening by permitting the low-cost, high-throughput screening of thousands of compounds per day without the need for expensive equipment or specialist personnel.

Subsequently, we apply it in bioprospecting, the discovery of bioactive compounds from complex natural extracts, by enabling bioactivity-based fractionation and purification. We screened extracts from 54 different plants and discovered a novel phytocannabinoid, dugesia lactone.

Finally, we develop a robust portable biosensor for use by non-specialists outside lab settings. We analyze body fluid samples and achieve the rapid and confident detection of illicit drugs such as “Spice”/“K2”.

In conclusion, we demonstrate a whole-cell GPCR-based biosensor with unprecedented sensitivity and robustness that enables various real-life applications. Taking advantage of the modularity of the developed platform and the extensive sensing repertoire of GPCRs in different organisms opens up the possibilities to develop similar systems for various applications and numerous other compounds beyond cannabinoids.