RNA-POLYMERASE ACTIVITY OF THE DNA-PROTEIN COMPLEX FROM CHLOROPLASTS OF THE FERN AZOLLA-PINNATA

We studied biochemical properties of RNA polymerase associated with th e DNA-protein complex isolated from chloroplasts of the fern Azolla pi nnata R.Br. It is demonstrated that the reaction catalyzed by bound RN A polymerase depends on the presence of all four nucleoside triphospha tes and is suppressed by RNase added to the reagent mixture. The prese nce of Mg2+ ions is absolutely necessary for manifestation of RNA-poly merase activity. Endogenous chloroplast DNA was found to serve as temp late for RNA polymerase of the DNA-protein complex. Activity of the en zyme is not suppressed by rifampicin (100 mug/ml) or alpha-amanitin (1 00 mug/ml). It is also resistant to heparin (2-20 mug/ml). Under condi tions in vitro, initiation and elongation of RNA chains is observed fo r a period of at least 60 min of incubation. The temperature optimum o f the RNA synthesis reaction is 30-degrees-C, the pH optimum 7.5. It i s demonstrated that RNA polymerase of the DNA-protein complex from chl oroplasts of A. pinnata reads rRNA genes.