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Antimicrob Agents Chemother. 1987 November; 31(11): 1734-1738

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

L L Nolan and T F Fehr

Division of Public Health, Morrill Science Center, University of Massachusetts, Amherst 01003-0081.

ABSTRACT

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.

Antimicrob Agents Chemother. 1987 November; 31(11): 1734-1738






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