The biochemistry and fidelity of synthesis by the apicoplast genome replication DNA polymerase Pfprex from the malaria parasite Plasmodium falciparum.

ABSTRACT: Plasmodium falciparum, the major causative agent of human malaria, contains three separate genomes. The apicoplast (an intracellular organelle) contains an ?35-kb circular DNA genome of unusually high A/T content (>86%) that is replicated by the nuclear-encoded replication complex Pfprex. Herein, we have expressed and purified the DNA polymerase domain of Pfprex [KPom1 (Klenow-like polymerase of malaria 1)] and measured its fidelity using a LacZ-based forward mutation assay. In addition, we analyzed the kinetic parameters for the incorporation of both complementary and noncomplementary nucleotides using Kpom1 lacking 3'?5' exonucleolytic activity. KPom1 exhibits a strongly biased mutational spectrum in which T?C is the most frequent single-base substitution and differs significantly from the closely related Escherichia coli DNA polymerase I. Using E. coli harboring a temperature-sensitive polymerase I allele, we established that KPom1 can complement the growth-defective phenotype at an elevated temperature. We propose that the error bias of KPom1 may be exploited in the complementation assay to identify nucleoside analogs that mimic this base-mispairing and preferentially inhibit apicoplast DNA replication.

SUBMITTER: Kennedy SR 

PROVIDER: S-EPMC3117635 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature