Expression and rapid one‐step purification of biologically active His‐tagged factor C by Ni2+affinity column chromatography

Factor C is an unusual extracellular protein capable of inducing cytodifferentiation in certain Streptomycesstrains. The protein is produced by Streptomyces griseus45H at such a low amount that the study of its mode of action was hindered by the shortage of purified protein. We report here the expression of C‐terminally hexa‐His‐tagged factor C in Streptomyces lividansand Escherichia coli. Expression in S. lividansis low while in E. coliit is relatively high, yielding about 5–10 mg of biologically fully active protein per liter culture.