(164x) Engineering Ligand-Specific Biosensors for Aromatic Amino Acids, Neurochemicals, and Other Structurally Similar Compounds

Microbial biosensors have diverse applications in metabolic engineering and medicine (1, 2). Specific and accurate quantification of chemical concentrations allows for adaptive regulation of enzymatic pathways and temporally-precise expression of diagnostic reporters. Although biosensors should differentiate structurally similar ligands with distinct biological functions, such specific sensors are rarely found in nature and challenging to create. Using E. coli Nissle 1917, a generally regarded as safe microbe, we characterized two biosensor systems that promiscuously recognize aromatic amino acids or neurochemicals. To improve the sensors’ selectivity and sensitivity, we applied rational protein engineering by identifying and mutagenizing amino acid residues and successfully demonstrated the first ligand-specific biosensors for phenylalanine, tyrosine, phenylethylamine, and tyramine. Additionally, our approach revealed insights into the uncharacterized structure of the FeaR regulator, including critical residues in ligand binding. These results lay the groundwork for developing kinetically-adaptive microbes for diverse applications (3). In this talk, we will discuss our recent efforts to develop other structurally similar compounds.

1. Amrofell, Rottinghaus, and Moon, Curr Opin Biotechnol, 2020. 66: p. 11-17.
2. Rottinghaus, Amrofell, and Moon, Biotechnology Journal, 2020. 15: p. 1900319.
3. Rottinghaus, Xi et al. Cell Systems, 2022. 13: p204-214.e4.