Engineered Regulon to Enable Autonomous Azide Ion Biosensing, Recombinant Protein Production, and <i>in Vivo</i> Glycoengineering

Detection of azide-tagged biomolecules (e.g., azido sugars) inside living cells using “click” chemistry has been revolutionary to the field chemical biology. However, we currently still lack suitable synthetic biology tools autonomously and rapidly detect azide ions. Here, have developed an engineered promoter system called cyn regulon, complementary Escherichia coli strains, selectively ions induce downstream expression reporter genes. The operon allowed highly tunable green fluorescent protein (GFP) over three orders inducer ion concentrations (0.01–5 mM) induced GFP by 600-fold compared uninduced control. Next, showcase superior performance this cyn-operon classical lac-operon for recombinant production. Finally, highlight how toolkit can enable glycoengineering-based applications facilitating in vivo activity screening mutant carbohydrate-active enzymes (CAZymes), glycosynthases, sugars as donor substrates.