MAHRP-1, a novel Plasmodium falciparum histidine-rich protein,binds ferriprotoporphyrin IX and localizes to the Maurer's clefts |
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Authors: | Spycher Cornelia Klonis Nectarios Spielmann Tobias Kump Erwin Steiger Sylvia Tilley Leann Beck Hans-Peter |
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Institution: | Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, Socinstrasse 51, CH-4051 Basel, Switzerland. |
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Abstract: | Using a stage-specific cDNA library from Plasmodium falciparum we have identified a gene coding for a novel histidine-rich protein (MAHRP-1). The gene is exclusively transcribed during early erythrocyte stages and codes for a small transmembrane protein. The C-terminal region contains a polymorphic stretch of histidine-rich repeats. Fluorescence microscopy studies using polyclonal mouse sera revealed that MAHRP-1 is located at the Maurer's clefts, which represent parasite-induced structures within the cytosol of infected erythrocytes. Biochemical studies showed that recombinant MAHRP-1 binds the toxic hemoglobin degradation product, ferriprotoporphyrin (FP) with a submicromolar dissociation constant and a stoichiometry determined by the number of DHGH motifs. The bound FP has increased peroxidase-like activity and is 10-fold more susceptible to H2O2-induced degradation compared with unbound FP. These properties of MAHRP-1 suggest it may play a protective role against oxidative stress, and its location at the Maurer's clefts suggests a function in promoting the correct trafficking of exported proteins, such as P. falciparum erythrocyte membrane protein-1. |
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