title: Molecular characterization of a 2-Cys peroxiredoxin from the human malaria parasite Plasmodium falciparum.
abstract: We have identified the 2-Cys peroxiredoxin (PfPrx-1) from the human malaria parasite Plasmodium falciparum. The PfPrx-1 showed the highest identity at amino acid level to the type II Prx among the currently known six subfamilies of mammalian Prx. The sequence identity between the PfPrx-1 and the previously reported 1-Cys Prx of P. falciparum (PfPrx-2), which corresponded to mammalian type VI Prx, was 25%. This suggests that the parasite possesses two Prx subfamilies. The PfPrx-1 showed significant sequence similarities with those of 2-Cys peroxiredoxins of plants in the BLASTX search. This may reflect the consequences of a genetic transfer from an algal endosymbiont to the parasite nucleus during evolution. The recombinant PfPrx-1 protein (rPfPrx-1) was expressed as a histidine fusion protein in Escherichia coli and purified with Ni chromatography. The rPfPrx-1 existed as dimers under non-reducing conditions and dissociated into monomers in the presence of dithiothreitol. The PfPrx-1 protein also exists as a dimer in the parasites themselves. The reduction of the oxidized enzyme by the donation of electrons from E. coli thioredoxin (Trx)/Trx reductase system was demonstrated in its reaction with H(2)O(2), using the rPfPrx-1 protein. These results suggested that the PfPrx-1 can act as a terminal peroxidase of the parasite Trx system. An elevated expression of the PfPrx-1 protein seen in the trophozoite, the stage with active metabolism, suggests an association of the parasite Trx system with its intracellular redox control.
authors.affiliation: Research Institute, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. skawazu@ri.imcj.go.jp
authors.forename: S
authors.initials: S
authors.lastname: Kawazu
authors.forename: K
authors.initials: K
authors.lastname: Komaki
authors.forename: N
authors.initials: N
authors.lastname: Tsuji
authors.forename: S
authors.initials: S
authors.lastname: Kawai
authors.forename: N
authors.initials: N
authors.lastname: Ikenoue
authors.forename: T
authors.initials: T
authors.lastname: Hatabu
authors.forename: H
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Himeno
authors.forename: S
authors.initials: S
authors.lastname: Kano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000235:genetics*; D054465:Peroxiredoxin VI; D054464:Peroxiredoxins; D010963:Plasmodium falciparum / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D015800:Protozoan Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D000975:Antioxidants; D015800:Protozoan Proteins; D010544:Peroxidases; D054465:Peroxiredoxin VI; D054464:Peroxiredoxins