title: Correct promoter control is needed for trafficking of the ring-infected erythrocyte surface antigen to the host cytosol in transfected malaria parasites.
abstract: Following invasion of human erythrocytes, the malaria parasite, Plasmodium falciparum, exports proteins beyond the confines of its own plasma membrane to modify the properties of the host red cell membrane. These modifications are critical to the pathogenesis of malaria. Analysis of the P. falciparum genome sequence has identified a large number of molecules with putative atypical signal sequences. The signals remain poorly characterized; however, a number of molecules with these motifs localize to the host erythrocyte. To examine the role of these atypical signal sequences in the export of parasite proteins, we have generated transfected parasites expressing a chimeric protein comprising the N-terminal region of the P. falciparum ring-infected erythrocyte surface antigen (RESA) appended to green fluorescent protein (GFP). This N-terminal region contains a hydrophobic stretch of amino acids that is presumed to act as a noncanonical secretory signal sequence. Modulation of the timing of transgene expression demonstrates that trafficking of malaria proteins into the host erythrocyte is dependent on both the presence of an appropriate transport signal and the timing of expression. Transgene expression under the control of a trophozoite-specific promoter mistargets the chimeric molecule to the parasitophorous vacuole surrounding the parasite. However, expression of RESA-GFP in schizont stages, under the control of the RESA promoter, enables correct trafficking of a population of the chimeric protein to the host erythrocyte.
authors.affiliation: Department of Biochemistry, La Trobe University, Melbourne, Victoria, Australia.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rug
authors.forename: Mark E
authors.initials: ME
authors.lastname: Wickham
authors.forename: Michael
authors.initials: M
authors.lastname: Foley
authors.forename: Alan F
authors.initials: AF
authors.lastname: Cowman
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003600:Cytosol / Q000378:metabolism*; D004912:Erythrocytes / Q000469:parasitology* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016778:Malaria, Falciparum / Q000469:parasitology; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D008164:Luminescent Proteins; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C050256:ring-infected erythrocyte surface antigen (RESA), Plasmodium falciparum; D049452:Green Fluorescent Proteins