title: Trafficking determinants for PfEMP3 export and assembly under the Plasmodium falciparum-infected red blood cell membrane.
abstract: During the maturation of intracellular asexual stages of Plasmodium falciparum parasite-encoded proteins are exported into the erythrocyte cytosol. A number of these parasite proteins attach to the host cell cytoskeleton and facilitate transformation of a disk-shaped erythrocyte into a rounded and more rigid infected erythrocyte able to cytoadhere to the vasculature. Knob formation on the surface of infected erythrocytes is critical for this cytoadherence to the host endothelium. P. falciparum proteins have been identified that localize to the parasite-infected erythrocyte membrane: the variant cytoadherence ligand erythrocyte membrane protein 1 (PfEMP1), the knob-associated histidine-rich protein (KAHRP) and the erythrocyte membrane protein 3 (PfEMP3). In this study, we have generated parasites expressing PfEMP3-green fluorescent protein chimeras and identified domains involved in entry to the secretory pathway, export across the parasitophorous vacuolar membrane and attachment to Maurer's clefts and the erythrocyte membrane. Solubility assays, fluorescence photobleaching experiments and immunogold electron microscopy suggest that the exported chimeric proteins are trafficked in a complex rather than in vesicles. This study characterizes elements involved in the tight but transient binding of PfEMP3 to Maurer's clefts and shows that the same elements are necessary for correct assembly under the erythrocyte membrane.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, Vic. 3050, Australia.
authors.forename: Ellen
authors.initials: E
authors.lastname: Knuepfer
authors.forename: Melanie
authors.initials: M
authors.lastname: Rug
authors.forename: Nectarios
authors.initials: N
authors.lastname: Klonis
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
authors.forename: Alan F
authors.initials: AF
authors.lastname: Cowman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000469:parasitology; D004912:Erythrocytes / Q000469:parasitology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C411566:EMP3 protein, Plasmodium falciparum; D008565:Membrane Proteins; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins