Isolation and characterization of DNA-dependent RNA polymerase III from Leishmania mexicana and inhibition by purine analogs

Autor: Nolan, L L, Fehr, T F
Zdroj: Antimicrobial Agents and Chemotherapy; November 1987, Vol. 31 Issue: 11 p1734-1738, 5p
Abstrakt: A DNA-dependent RNA polymerase has been isolated and characterized from the parasitic flagellated protozoan Leishmania mexicana. The initial stages of purification utilized high-ionic-strength extraction and protamine sulfate treatment. The enzyme was further purified by differential elution by heparin-Sepharose, DEAE-Sephadex, and carboxymethyl-Sephadex chromatography. Analysis of the chromatographically purified RNA polymerase on nondenaturing gels revealed two electrophoretic forms. The enzyme isolated had characteristics of true DNA-dependent RNA polymerase since it required DNA and all four nucleoside triphosphates for synthesis of RNase-sensitive products. Analysis of ammonium sulfate and metal ion optima, as well as relative activities of the enzyme with Mn2+ versus Mg2+, gave results similar to those reported for other RNA polymerase IIIs in eucaryotes. Formycin A triphosphate was found to be a noncompetitive inhibitor of RNA polymerase III, and cordycepin triphosphate was found to be inhibitory, although the exact mode of inhibition was not determined.
Databáze: Supplemental Index