Engineered orthogonal quorum sensing systems for synthetic gene regulation

Abstract

Gene regulators that are controlled by membranepermeable compounds called Homoserine lactones (HSLs) have become popular tools for building synthetic gene networks that coordinate behaviors across populations of engineered bacteria. Synthetic HSLsignaling systems are derived from natural DNA and protein elements from microbial quorum signaling pathways. Crosstalk, where a single HSL can activate multiple regulators, can lead to faults in networks composed of parallel signaling pathways. Here, we report an investigation of quorum sensing components to identify synthetic pathways that exhibit little to no crosstalk in liquid and solid cultures. In previous work, we characterized the response of a single regulator (LuxR) to ten distinct HSLsynthase enzymes. Our current study determined the responses of five different regulators (LuxR, LasR, TraR, BjaR, and AubR) to the same set of synthases. We identified two sets of orthogonal synthaseregulator pairs (BjaI/BjaR + EsaI/TraR and LasI/LasR + EsaI/TraR) that show little to no crosstalk when they are expressed in Escherichia coli BL21. These results expand the toolbox of characterized components for engineering microbial communities.

DNA as Features

“…For this research question we ask questions related to application engineering. We use the 2017 iGEM team project from Arizona State University [2,33] introduced in our motivating example. Because this team built a quorum sensing network, which is a type of cellto-cell signaling, it helps us validate the results from RQ1 from an application engineering perspective.…”