The signal sequence of exported protein-1 directs the green fluorescent protein to the parasitophorous vacuole of transfected malaria parasites.
The malaria parasite, Plasmodium falciparum, spends part of its life cycle inside the erythrocytes of its human host. In the mature stages of intraerythrocytic growth, the parasite undertakes extensive remodeling of its adopted cellular home by exporting proteins beyond the confines of its own plasma membrane. To examine the signals involved in export of parasite proteins, we have prepared transfected parasites expressing a chimeric protein comprising the N-terminal region of the Plasmodium falciparum exported protein-1 appended to green fluorescent protein. The majority of the population of the chimeric protein appears to be correctly processed and trafficked to the parasitophorous vacuole, indicating that this is the default destination for protein secretion. Some of the protein is redirected to the parasite food vacuole and further degraded. Photobleaching studies reveal that the parasitophorous vacuole contains subcompartments that are only partially interconnected. Dual labeling with the lipid probe, BODIPY-TR-ceramide, reveals the presence of membrane-bound extensions that can bleb from the parasitophorous vacuole to produce double membrane-bound compartments. We also observed regions and extensions of the parasitophorous vacuole, where there is segregation of the lumenal chimera from the lipid components. These regions may represent sites for the sorting of proteins destined for the trafficking to sites beyond the parasitophorous vacuole membrane.
Adisa
Akinola
A
Department of Biochemistry, La Trobe University, Bundoora, 3086, Victoria, Australia.
Rug
Melanie
M
Klonis
Nectarios
N
Foley
Michael
M
Cowman
Alan F
AF
Tilley
Leann
L
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D014162:Transfection; D014617:Vacuoles / Q000469:parasitology / Q000502:physiology* / Q000648:ultrastructure
D000953:Antigens, Protozoan; D017931:DNA Primers; D008164:Luminescent Proteins; D021382:Protein Sorting Signals; D015800:Protozoan Proteins; C063362:QF116 antigen, Plasmodium falciparum; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins