The plastidic DNA replication enzyme complex of Plasmodium falciparum

Mol Biochem Parasitol. 2005 Jun;141(2):145-153. doi: 10.1016/j.molbiopara.2005.02.002.


The replication and repair of organellar genomes in the malaria parasite Plasmodium falciparum is poorly understood. We have assessed the properties of an open reading frame Pfprex (formerly known as pom1) and confirm that it specifies a multi-domain polypeptide with DNA primase, DNA helicase, DNA polymerase and 3'-5' exonuclease activities. The sequence of the primase/helicase domain is phylogenetically related to the T7-bacteriophage gene 4 product and mammalian mitochondrial helicase, Twinkle. Despite that, the N-terminal sequence of this multi-domain polypeptide directs a green fluorescent protein reporter specifically to the P. falciparum apicoplast and not to the mitochondrion. Phylogenetic analysis placed the DNA polymerase sequence with the family A bacterial polymerases, most closely to those of the thermophilic Aquifex species. Notably, the malarial enzyme was optimally active at 75 degrees C. Pfprex is the first example of a gene encoding contiguous DNA polymerase, DNA primase and DNA helicase components. We propose it has a key role in replication of the malarial plastid genome, a validated drug target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA Helicases / chemistry
  • DNA Helicases / genetics
  • DNA Helicases / metabolism
  • DNA Polymerase III / chemistry
  • DNA Polymerase III / genetics
  • DNA Polymerase III / metabolism
  • DNA Primase / chemistry
  • DNA Primase / genetics
  • DNA Primase / metabolism
  • DNA Replication*
  • Exonucleases / chemistry
  • Exonucleases / genetics
  • Exonucleases / metabolism
  • Genes, Protozoan
  • Genes, Reporter
  • Green Fluorescent Proteins / analysis
  • Green Fluorescent Proteins / genetics
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / genetics*
  • Multienzyme Complexes / metabolism
  • Organelles / genetics
  • Organelles / metabolism*
  • Phylogeny
  • Plasmodium falciparum / enzymology*
  • Plasmodium falciparum / genetics
  • Protein Structure, Tertiary
  • Protein Transport
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / metabolism
  • Sequence Homology


  • Multienzyme Complexes
  • Protozoan Proteins
  • prex protein, Plasmodium falciparum
  • Green Fluorescent Proteins
  • DNA Polymerase III
  • DNA Primase
  • DNA polymerase A
  • Exonucleases
  • DNA Helicases