Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 106, Issue 32, Pages 13323-13328Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0905387106
Keywords
antioxidant defense; protein import; redox metabolism; thioredoxin; Maurer's clefts
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Funding
- Deutsche Forschungsgemeinschaft [SFB 535, TP A12, BE1540/4-5]
- National Institutes of Health [NIH 1 R21 AI072615-01]
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Coevolution of the malarial parasite and its human host has resulted in a complex network of interactions contributing to the homeodynamics of the host-parasite unit. As a rapidly growing and multiplying organism, Plasmodium falciparum depends on an adequate antioxidant defense system that is efficient despite the absence of genuine catalase and glutathione peroxidase. Using different experimental approaches, we demonstrate that P. falciparum imports the human redox-active protein peroxiredoxin 2 (hPrx-2, hTPx1) into its cytosol. As shown by confocal microscopy and immunogold electron microscopy, hPrx-2 is also present in the Maurer's clefts, organelles that are described as being involved in parasite protein export. Enzyme kinetic analyses prove that hPrx-2 accepts Plasmodium cytosolic thioredoxin 1 as a reducing substrate. hPrx-2 accounts for roughly 50% of thioredoxin peroxidase activity in parasite extracts, thus indicating a functional role of hPrx-2 as an enzymatic scavenger of peroxides in the parasite. Under chloroquine treatment, a drug promoting oxidative stress, the abundance of hPrx-2 in the parasite increases significantly. P. falciparum has adapted to adopt the hPrx-2, thereby using the host protein for its own purposes.
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