Four distinct pathways of hemoglobin uptake in the malaria parasite Plasmodium falciparum

• Published in: Proceedings of the National Academy of Sciences - PNAS 2008-02, Vol.105 (7), p.2463-2468
• Main Authors: Elliott, David A, McIntosh, Michael T, Hosgood, H. Dean III, Chen, Shuo, Zhang, Gina, Baevova, Pavlina, Joiner, Keith A
• Format: Article
• Language: English
• Subjects: Actins; Actins - metabolism; Animals; Bacterial proteins; Biological Sciences; Cells; Cytosol; Drug therapy; Endocytosis; Erythrocytes; Hemoglobin; Hemoglobins; Hemoglobins - metabolism; Hemoglobins - ultrastructure; Malaria; Malaria - parasitology; Microscopy, Immunoelectron; Parasites; Parasitic protozoa; Parasitism; Plasmodium falciparum; Plasmodium falciparum - metabolism; Plasmodium falciparum - ultrastructure; rab5 GTP-Binding Proteins - metabolism; Schizonts; Schizonts - ultrastructure; Trophozoites; Trophozoites - ultrastructure; Vacuoles; Vacuoles - ultrastructure; Vector-borne diseases
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0711067105

During the bloodstage of malaria infection, the parasite internalizes and degrades massive amounts of hemoglobin from the host red blood cell. Using serial thin-section electron microscopy and three-dimensional reconstruction, we demonstrate four independent, but partially overlapping, hemoglobin-uptake processes distinguishable temporally, morphologically, and pharmacologically. Early ring-stage parasites undergo a profound morphological transformation in which they fold, like a cup, onto themselves and in so doing take a large first gulp of host cell cytoplasm. This event, which we term the "Big Gulp," appears to be independent of actin polymerization and marks the first step in biogenesis of the parasite's lysosomal compartment--the food vacuole. A second, previously identified uptake process, uses the cytostome, a well characterized and morphologically distinct structure at the surface of the parasite. This process is more akin to classical endocytosis, giving rise to small (