Bacillus subtilis core RNA polymerase, containing a His(6)-fusion to the C-
terminus of the beta' subunit, was isolated by Ni-NTA, Superdex 200 gel fil
tration, and Mono Q anion-exchange chromatography. The purified core enzyme
was shown to be free of the major sigma factor sigma(A) and the transcript
ion factors NusA and GreA. The purification procedure can be completed with
in 1 working day, is scalable, and yields highly purified and active core R
NA polymerase. (C) 2000 Academic Press.