title: A 95 kDa protein of Plasmodium vivax and P. cynomolgi visualized by three-dimensional tomography in the caveola-vesicle complexes (Schüffner's dots) of infected erythrocytes is a member of the PHIST family.
abstract: Plasmodium vivax and P. cynomolgi produce numerous caveola-vesicle complex (CVC) structures within the surface of the infected erythrocyte membrane. These contrast with the electron-dense knob protrusions expressed at the surface of Plasmodium falciparum-infected erythrocytes. Here we investigate the three-dimensional (3-D) structure of the CVCs and the identity of a predominantly expressed 95 kDa CVC protein. Liquid chromatography - tandem mass spectrometry analysis of immunoprecipitates by monoclonal antibodies from P. cynomolgi extracts identified this protein as a member of the Plasmodium helical interspersed subtelomeric (PHIST) superfamily with a calculated mass of 81 kDa. We named the orthologous proteins PvPHIST/CVC-81(95) and PcyPHIST/CVC-81(95) , analysed their structural features, including a PEXEL motif, repeated sequences and a C-terminal PHIST domain, and show that PHIST/CVC-81(95) is most highly expressed in trophozoites. We generated images of CVCs in 3-D using electron tomography (ET), and used immuno-ET to show PHIST/CVC-81(95) localizes to the cytoplasmic side of the CVC tubular extensions. Targeted gene disruptions were attempted in vivo. The pcyphist/cvc-81(95) gene was not disrupted, but parasites containing episomes with the tgdhfr selection cassette were retrieved by selection with pyrimethamine. This suggests that PHIST/CVC-81(95) is essential for survival of these malaria parasites.
authors.affiliation: Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA.
authors.forename: Sheila
authors.initials: S
authors.lastname: Akinyi
authors.forename: Eric
authors.initials: E
authors.lastname: Hanssen
authors.forename: Esmeralda V S
authors.initials: EV
authors.lastname: Meyer
authors.forename: Jianlin
authors.initials: J
authors.lastname: Jiang
authors.forename: Cindy C
authors.initials: CC
authors.lastname: Korir
authors.forename: Balwan
authors.initials: B
authors.lastname: Singh
authors.forename: Stacey
authors.initials: S
authors.lastname: Lapp
authors.forename: John W
authors.initials: JW
authors.lastname: Barnwell
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
authors.forename: Mary R
authors.initials: MR
authors.lastname: Galinski
mesh_terms: D021941:Caveolae / Q000737:chemistry*; D002853:Chromatography, Liquid; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D055032:Electron Microscope Tomography; D004912:Erythrocytes / Q000469:parasitology*; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D020043:Genes, Essential; D006801:Humans; D021621:Imaging, Three-Dimensional; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016789:Plasmodium cynomolgi / Q000737:chemistry*; D010966:Plasmodium vivax / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000032:analysis* / Q000737:chemistry*; D017422:Sequence Analysis, DNA; D053719:Tandem Mass Spectrometry
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins