A Scalable Peptide/GPCR Communication Language

As synthetic biology transitions from single cell engineering to the creation of multi-cell consortia, a scalable signaling language for communication within diverse communities will become necessary for information transfer. Bacterial quorum sensing and electrical communication are two such examples of engineering cell-cell communication. However, the number of specific ion channels and unique small-molecule signals available to use as a signaling language is small, and not easily expanded or diversified. Fungi, however, have already evolved a scalable signaling system in the form of their small peptide pheromone/GPCR pairs used for mating. Through fungal genome mining we have identified hundreds of extant peptide/GPCR pairs that can be further diversified through directed evolution. Additionally, we have chosen the well-studied baker’s yeast Saccharomyces cerevisiae to serve as a genetically tractable host with an extremely well-characterized mating pathway. Using a common downstream transduction MAPK pathway in S. cerevisiae, we have developed a “plug-and-play” system whereby data-mined GPCR and peptide ligand modules may be easily substituted into the yeast mating and peptide secretion pathways. We have also engineered S. cerevisiae strains with GPCR-controlled outputs including fluorescence and colored pigment production in order to provide a quantitative readout of receptor activation. We are working to couple GPCR activation to the expression of an essential gene in our engineered strains, allowing us to establish a cyclic communication system whereby interdependent growth is controlled by peptide signaling between strains and have developed a model to describe the behavior of our engineered consortia and predict consequences of culture perturbations. As we expand our repertoire of fully characterized peptide/GPCR pairs, we aim to establish this system in additional output species including Saccharomyces boulardii and Schizosaccharomyces pombe as well. Such consortia could serve as a new biosensor paradigm and as independent hosts for the biosynthesis of modular metabolites such as polyketides.