Detection and characterization of DNA polymerase activity in Entamoeba histolytica

DNA polymerase activity was detected and characterized in nuclear extracts from trophozoites of Entamoeba histolytica. The activity was high at pH 2 to pH 6, but at pH 8 and 10 the activity was very low. The presence of K⁺ was inhibitory for the activity and a higher concentration of K⁺ markedly inhibited the activity. Magnesium ions (Mg²⁺) were absolutely required for activity and its optimal concentration was 6 to 8 mM. The activity was markedly inhibited by aphidicolin which is an inhibitor of mammalian DNA polymerases α, δ, and ε and also by N-ethylmaleimide which is an inhibitor of DNA polymerases, α, γ, δ and ε. However, inhibition of the activity by 2',3'-dideoxythymidine-5'-triphosphate which is an inhibitor of DNA polymerases β and γ was relatively weak. Thus sensitivity of the E. histolytica enzyme to these inhibitors was similar to that of mammalian DNA polymerases (α, δ and ε) of the α family. Monoclonal antibodies against human DNA polymerase α did not bind to DNA polymerase of E. histolytica.