A genetically encoded fluorescent biosensor for visualization of acetyl-CoA in live cells

Acetyl-coenzyme A is a central metabolite that participates in many cellular pathways. Evidence suggests that acetyl-CoA metabolism is highly compartmentalized in mammalian cells. Yet methods to measure acetyl-CoA in living cells are lacking. Herein, we engineered an acetyl-CoA biosensor from the bacterial protein PanZ and circularly permuted green fluorescent protein (cpGFP). The sensor, "PancACe," has a maximum change of ∼2-fold and a response range of ∼10 μM-2 mM acetyl-CoA. We demonstrated that the sensor has a greater than 7-fold selectivity over coenzyme A, butyryl-CoA, malonyl-CoA, and succinyl-CoA, and a 2.3-fold selectivity over propionyl-CoA. We expressed the sensor in E. coli and showed that it enables detection of rapid changes in acetyl-CoA levels. By localizing the sensor to either the cytoplasm, nucleus, or mitochondria in human cells, we showed that it enables subcellular detection of changes in acetyl-CoA levels, the magnitudes of which agreed with an orthogonal PicoProbe assay.