Fig. S1.

Development of the prpR-based 3HP biosensor. (A) Two helper enzymes, pcs from Chloroflexus aurantiacus and the endogenous prpC, convert 3HP into the prpR-binding compound 2-methylcitrate. (B) Exogenously supplied 3HP triggers a fluorescent response in cells containing the biosensor (green bars). Increasing the concentration of 3HP results in a higher fluorescent output. No biosensor activation is observed without the helper enzyme pcs (gray bars). (C) The fluorescent response of the biosensor to 6 mM 3HP begins after 1 h and achieves 90% saturation after 10 h (green line). Basal induction increases over time but remains low (gray line). Error bars and confidence bands represent the 95% confidence interval (n = 3).