DNA‐dependent RNA polymerase from the chlorotetracycline producing strain of Streptomyces aureofaciens

Abstract
RNA polymerase from Streptomyces aureofaciens has been purified by polyethyleneimine precipitation followed by chromatography first on DEAE‐cellulose, then heparin‐Sepharose and finally on an aminooxybutylcellulose matrix containing immobilised S. aureofaciens DNA. The enzyme is composed of three subunits of ∼ 145, 136 and 44 kDa that are in a ratio of approx. 1:1:2. In many isolations two additional subunits of ∼ 68 and 39 kDa and some minor protein bands of ∼ 110 85 and 61 kDa are also present. Thus, the structure of this enzyme is very similar to other bacterial RNA polymerases, exhibiting an α2ββ′ core and the additional proteins θ and σ.