Component E of the DNA-dependent RNA polymerase of the archaebacterium Thermoplasma acidophilum is required for the transcription of native DNA.

Abstract

The role of component E of the DNA-dependent RNA polymerase of the archaebacterium Thermoplasma acidophilum in the transcription of Thermoplasma DNA has been analyzed. Component E (Mr 22000) is released upon formation of the binary complex of the polymerase with the DNA. Enzyme not containing component E is inactive on DNA but active on poly[d(A-T) X d(A-T)]. The activity on DNA can be restored by addition of component E. Two states of the binding complex between RNA polymerase and DNA, differing in their ionic strength stabilities, have been distinguished both in the presence and absence of component E. The transition temperature between the two states is 43 degrees C. Component E appears to open productive binding sites in native DNA in addition to the non-productive strong binding sites available for component-E-deficient enzyme.