Partial purification and characterization of DNA polymerase β-like enzyme from Plasmodium falciparum

Abstract

DNA polymerases play crucial roles, not only in DNA replication, transcription and recombination, but also in DNA repair to maintain the integrity of the cell's genome. In Plasmodium falciparum, only three types of DNA polymerases-α, γ, and δ have previously been characterized, whereas DNA polymerase β, the major enzyme operating during base excision repair in eukaryotes, has yet to be isolated and characterized. In this study, DNA polymerase β-like activity was detected in crude extract of P. falciparum trophozoites. P. falciparum DNA polymerase β-like enzyme was partially purified using fast protein liquid chromatography, with a yield of 2.8% and 825-fold purification. The partially purified enzyme was highly resistant to aphidicolin and N-ethylmaleimide, as in other eukaryotic enzymes, but was also resistant to 2′,3′-dideoxythymidine-5′-triphosphate and to other synthetic nucleoside analogs. The parasite enzyme showed low processivity. Using UG mismatch substrate to investigate base excision repair, the P. falciparum DNA polymerase β-like enzyme could repair a patch size of 3-5 nucleotides, indicative of involvement in a long patch repair pathway, the first evidence of such a property in the DNA polymerase of a malaria parasite. © 2007 Elsevier B.V. All rights reserved.