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

David A. Elliott, Michael T. McIntosh, H. Dean Hosgood, Shuo Chen, Gina Zhang, Pavlina Baevova, Keith A. Joiner

Research output: Contribution to journalArticle

105 Scopus citations

Abstract

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, whichweterm 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 (<0.004 fl) vesicles that are marked by the early endosomal regulatory protein Rab5a. A third process, also arising from cytostomes, creates long thin tubes previously termed cytostomal tubes in an actin-dependent manner. The fourth pathway, which we term phagotrophy, is similar to the Big Gulp in that it more closely resembles phagocytosis, except that phagotrophy does not require actin polymerization. Each of these four processes has aspects that are unique to Plasmodium, thus opening avenues to antimalarial therapy.

Original languageEnglish (US)
Pages (from-to)2463-2468
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number7
DOIs
StatePublished - Feb 19 2008
Externally publishedYes

Keywords

  • Actin
  • Cytosome
  • Endocytosis
  • Food vacuole
  • Transport

ASJC Scopus subject areas

  • General

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