FLAG tagging by CuAAC and nanogram-scale purification of the target protein for a bioactive metabolite involved in circadian rhythmic leaf movement in Leguminosae

We report a stepwise FLAG-tagging strategy for the purification of target proteins for bioactive metabolites. This method realizes the microscale purification and identification of target protein from as few as 1 x 10(5) differentiated cells. Using this method, we isolated and identified MetE as a cytosolic target protein of potassium isolespedezate, a metabolite controlling plant nyctinasty.