title: The circumsporozoite protein of Plasmodium falciparum is expressed and localized to the cell surface in the free-living ciliate Tetrahymena thermophila.
abstract: Heterologous expression is an important tool for characterization of protein function, structural studies, and production of antigen. While many different host systems have been utilized for the expression of Plasmodium falciparum proteins, the extreme AT-richness of its genome represents an obstacle to efficient expression. In addition, primary sequence motifs such as glycosyl phosphatidyl-inositol (GPI) cleavage/attachment sites of P. falciparum are not recognized in currently used expression hosts. Recently, DNA-mediated transformation has been used for expression of heterologous genes in the ciliated protozoan Tetrahymena thermophila. We report the stable expression of full-length P. falciparum circumsporozoite (CS) protein in T. thermophila. The expressed gene utilized the native CS protein N-terminal secretory signal sequence and the C-terminal GPI anchoring signal. Immunofluorescence imaging demonstrated that the CS protein was localized to the cell surface of Tetrahymena. Metabolic labeling with tritiated myristate resulted in incorporation of label into the recombinant CS protein, indicating that the protein was bound to the cell surface via a GPI anchor. This is the first report of the recognition of targeting and GPI anchoring signals of the P. falciparum CS protein in a heterologous expression host.
authors.affiliation: Department of Medical Microbiology and Parasitology, University of Georgia, Athens 30602, USA. peterson@vet.uga.edu
authors.forename: David S
authors.initials: DS
authors.lastname: Peterson
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Kokila
authors.initials: K
authors.lastname: Asokan
authors.forename: Jacek
authors.initials: J
authors.lastname: Gaertig
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D005822:Genetic Vectors; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016808:Tetrahymena thermophila / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic
chemical_list: D017261:Glycosylphosphatidylinositols; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C041595:circumsporozoite protein, Protozoan