title: Plasmodium knowlesi thioredoxin peroxidase 1 binds to nucleic acids and has RNA chaperone activity.
abstract: Malaria parasites are under oxidative attack throughout their life cycle in human body and mosquito vector. Therefore, Plasmodium antioxidant defenses are crucial for its survival and being considered as interesting target for antimalarial drug design. Plasmodium knowlesi has emerged recently from its simian host to human in Southeast Asia and has been recognized as the fifth Plasmodium species that can cause human malaria. In this study, we cloned and characterized thioredoxin peroxidase 1 from P. knowlesi (PkTPx-1). PkTPx-1 gene was cloned, and recombinant protein was produced by heterologous overexpression in Escherichia coli. The recombinant protein was used for evaluation of enzymatic activity and polyclonal antibody production. Using the recombinant PkTPx-1 protein, its antioxidant activity was confirmed in a mixed-function oxidation assay where PkTPx-1 prevented nicking of DNA by hydroxyl radicals. PkTPx-1 was able to bind to double-strand DNA and RNA and had RNA chaperone activity in a nucleic acid melting assay indicating new function of PkTPx-1 other than antioxidant activity. Using specific polyclonal antibodies, it was indicated that PkTPx-1 is expressed in the cytoplasm of the parasite. Altogether, these results suggest that PkTPx-1 not only protects the parasite from the adverse effects of reactive oxygen species but also has RNA chaperone activity.
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, 080-8555, Obihiro, Hokkaido, Japan.
authors.forename: Hassan
authors.initials: H
authors.lastname: Hakimi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Suganuma
authors.forename: Miho
authors.initials: M
authors.lastname: Usui
authors.forename: Hirono
authors.initials: H
authors.lastname: Masuda-Suganuma
authors.forename: Jose Ma M
authors.initials: JM
authors.lastname: Angeles
authors.forename: Masahito
authors.initials: M
authors.lastname: Asada
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawai
authors.forename: Noboru
authors.initials: N
authors.lastname: Inoue
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kawazu
mesh_terms: D000595:Amino Acid Sequence; D000975:Antioxidants / Q000378:metabolism; D001210:Asia, Southeastern; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D054464:Peroxiredoxins / Q000378:metabolism*; D016790:Plasmodium knowlesi / Q000201:enzymology* / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics
chemical_list: D000975:Antioxidants; D018832:Molecular Chaperones; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA; D004247:DNA; D054464:Peroxiredoxins
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