An IRP-like protein from Plasmodium falciparum binds to a mammalian iron-responsive element.
This study cloned and sequenced the complementary DNA (cDNA) encoding of a putative malarial iron responsive element-binding protein (PfIRPa) and confirmed its identity to the previously identified iron-regulatory protein (IRP)-like cDNA from Plasmodium falciparum. Sequence alignment showed that the plasmodial sequence has 47% identity with human IRP1. Hemoglobin-free lysates obtained from erythrocyte-stage P falciparum contain a protein that binds a consensus mammalian iron-responsive element (IRE), indicating that a protein(s) with iron-regulatory activity was present in the lysates. IRE-binding activity was found to be iron regulated in the electrophoretic mobility shift assays. Western blot analysis showed a 2-fold increase in the level of PfIRPa in the desferrioxamine-treated cultures versus control or iron-supplemented cells. Malarial IRP was detected by anti-PfIRPa antibody in the IRE-protein complex from P falciparum lysates. Immunofluorescence studies confirmed the presence of PfIRPa in the infected red blood cells. These findings demonstrate that erythrocyte P falciparum contains an iron-regulated IRP that binds a mammalian consensus IRE sequence, raising the possibility that the malaria parasite expresses transcripts that contain IREs and are iron-dependently regulated.
Loyevsky
M
M
Howard University, Washington, DC, USA. mloyevsky@howard.edu
LaVaute
T
T
Allerson
C R
CR
Stearman
R
R
Kassim
O O
OO
Cooperman
S
S
Gordeuk
V R
VR
Rouault
T A
TA
D000154:Aconitate Hydratase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017931:DNA Primers; D003676:Deferoxamine / Q000494:pharmacology; D004912:Erythrocytes / Q000469:parasitology*; D019084:Fluorescent Antibody Technique, Indirect; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism; D035941:Iron Regulatory Protein 1; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D008322:Mammals; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000187:drug effects / Q000502:physiology*; D015800:Protozoan Proteins / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D017931:DNA Primers; D006454:Hemoglobins; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D007501:Iron; D000154:Aconitate Hydratase; D035941:Iron Regulatory Protein 1; D003676:Deferoxamine