title: Re-assessing the locations of components of the classical vesicle-mediated trafficking machinery in transfected Plasmodium falciparum.
abstract: The malaria parasite, Plasmodium falciparum, exports proteins beyond the confines of its own plasma membrane, however there is debate regarding the machinery used for these trafficking events. We have generated transgenic parasites expressing chimeric proteins and used immunofluorescence studies to determine the locations of plasmodial homologues of the COPII component, Sar1p, and the Golgi-docking protein, Bet3p. The P. falciparum Sar1p (PfSar1p) chimeras bind to the endoplasmic reticulum surface and define a network of membranes wrapped around parasite nuclei. As the parasite matures, the endomembrane systems of individual merozoites remain interconnected until very late in schizogony. Antibodies raised against plasmodial Bet3p recognise two foci of reactivity in early parasite stages that increase in number as the parasite matures. Some of the P. falciparum Bet3p (PfBet3p) compartments are juxtaposed to compartments defined by the cis Golgi marker, PfGRASP, while others are distributed through the cytoplasm. The compartments defined by the trans Golgi marker, PfRab6, are separate, suggesting that the Golgi is dispersed. Bet3p-green fluorescent protein (GFP) is partly associated with punctate structures but a substantial population diffuses freely in the parasite cytoplasm. By contrast, yeast Bet3p is very tightly associated with immobile structures. This study challenges the view that the COPII complex and the Golgi apparatus are exported into the infected erythrocyte cytoplasm.
authors.affiliation: Department of Biochemistry, La Trobe University, Melbourne 3086, Vic., Australia.
authors.forename: Akinola
authors.initials: A
authors.lastname: Adisa
authors.forename: Sarah
authors.initials: S
authors.lastname: Frankland
authors.forename: Melanie
authors.initials: M
authors.lastname: Rug
authors.forename: Katherine
authors.initials: K
authors.lastname: Jackson
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Maier
authors.forename: Peter
authors.initials: P
authors.lastname: Walsh
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
authors.forename: Nectarios
authors.initials: N
authors.lastname: Klonis
authors.forename: Paul R
authors.initials: PR
authors.lastname: Gilson
authors.forename: Alan F
authors.initials: AF
authors.lastname: Cowman
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D010963:Plasmodium falciparum / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D019076:Transgenes; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins