Distinct trafficking and localization of STEVOR proteins in three stages of the Plasmodium falciparum life cycle.
The genome of Plasmodium falciparum harbors three extensive multigene families, var, rif, and stevor (for subtelomeric variable open reading frame), located mainly in the subtelomeric regions of the parasite's 14 chromosomes. STEVOR variants are known to be expressed in asexual parasites, but no function has as yet been ascribed to this protein family. We have examined the expression of STEVOR proteins in intraerythrocytic sexual stages, gametocytes, and extracellular sporozoites isolated from infected Anopheles mosquitoes. In gametocytes, stevor transcripts appear transiently early in development but STEVOR proteins persist for several days and are transported out of the parasite, travel through the host cell cytoplasm, and localize to the erythrocyte plasma membrane. In contrast to asexual parasites, gametocytes move STEVOR to the periphery via a trafficking pathway independent of Maurer's clefts. In sporozoites, STEVOR appear dispersed throughout the cytoplasm in vesicle-like structures. The pattern of STEVOR localization we have observed in gametocytes and sporozoites differs significantly from that in asexual parasite stages. STEVOR variants are therefore likely to perform different functions in each stage of the parasites life cycle in which they occur.
McRobert
Louisa
L
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St, WC1E 7HT, UK.
Preiser
Peter
P
Sharp
Sarah
S
Jarra
William
W
Kaviratne
Mallika
M
Taylor
Martin C
MC
Renia
Laurent
L
Sutherland
Colin J
CJ
D000818:Animals; D000852:Anopheles / Q000469:parasitology; D000953:Antigens, Protozoan / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D004912:Erythrocytes / Q000469:parasitology; D005455:Fluorescent Antibody Technique; D006801:Humans; D008018:Life Cycle Stages; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012469:Salivary Glands / Q000469:parasitology
D000953:Antigens, Protozoan; D015800:Protozoan Proteins; C474556:STEVOR antigen, Plasmodium falciparum