A comparative study of nuclear and chloroplast DNA dependent RNA polymerases from wheat leaves

Abstract

1. 1. Three DNA dependent RNA polymerases have been purified from chromatin and chloroplast fractions of wheat leaves. 2. 2. The purified enzymes were completely dependent on exogenous DNA after purification by glycerol gradient, DEAE-Sephadex and phosphocellulose chromatography. 3. 3. The nuclear enzymes, I and II, showed a strong preference for denatured nuclear DNA, whereas the chloroplast enzyme preferred denatured chloroplast DNA. 4. 4. The three enzymes require either Mg 2+ or Mn 2+ for activity. 5. 5. α-amanitin specifically inhibited RNA polymerase II but has no effect on polymerase I and chloroplast polymerase. 6. 6. Enzyme I is most active at very low ionic strength (0.10 mM KC1), whereas enzyme II and chloroplast enzyme show maximum activity at 150mM and 50 mM KC1 respectively.