Overproduction and purification of sigma(s), the Escherichia coli stationary phase specific sigma transcription factor

This paper reports the overproduction and the details of a rapid method to purify active sigma(s) monomers from a T7 RNA polymerase-based protein expression system. This a-day procedure involves solubilizing inclusion bodies in sarkosyl detergent, removal of sarkosyl by dialysis, and a single gel filtration column chromatography step. The final yield of sigma(s) is about 9 mg of approximately 92% purity from 0.5 g of wet weight cells. Overproduced sigma(s) binds to core RNA polymerase and supports transcription from the bolAp1 promoter, a sigma(s)-dependent promoter. (C) 1996 Academic Press, Inc.