Multiple DNA-dependent RNA polymerases in Trypanosoma cruzi

Area of Science:

• Molecular Biology
• Parasitology
• Biochemistry

Background:

• Trypanosoma cruzi is the causative agent of Chagas disease.
• Understanding its molecular machinery, including RNA polymerase, is crucial for therapeutic development.
• Previous characterization of RNA polymerases in T. cruzi is limited.

Purpose of the Study:

• To isolate and characterize DNA-dependent RNA polymerase from Trypanosoma cruzi epimastigotes.
• To investigate the properties and potential differences between distinct RNA polymerase activities.

Main Methods:

• Solubilization and chromatographic purification of RNA polymerase from T. cruzi epimastigotes.
• Enzyme activity assays using DNA templates.
• Sensitivity testing against inhibitors like alpha-amanitin, actinomycin D, and rifampicin.

Main Results:

• A single peak of RNA polymerase activity was observed after A-25 Sephadex chromatography.
• Phosphocellulose chromatography resolved two distinct peaks of RNA polymerase activity.
• The two peaks exhibited differential sensitivity to alpha-amanitin, with IC50 values of 17.8 µg/mL and 44.6 µg/mL.
• Both activities were inhibited by actinomycin D and stimulated by Mn2+, utilizing single-stranded DNA optimally.

Conclusions:

• Trypanosoma cruzi epimastigotes possess at least two distinct DNA-dependent RNA polymerase forms.
• These enzymes differ in their susceptibility to alpha-amanitin, indicating potential functional divergence.
• Further research into these polymerases could reveal novel drug targets for Chagas disease.