title: A membrane-anchored Theileria parva cyclophilin with a non-cleaved amino-terminal signal peptide for entry into the endoplasmic reticulum.
abstract: Recent studies suggest that peptidyl-prolyl isomerases of the cyclophilin family, that access the secretory pathway, can be involved in the interaction of parasitic protozoa with mammalian host cells. The amino acid sequence of a cDNA encoding a cyclophilin family member of the intracellular protozoan parasite of cattle Theileria parva contains a conserved C-terminal domain that exhibits 70% amino acid identity to cyclophilin proteins from other organisms, and a unique 60 amino acid novel N-terminal extension. Cell-free expression of the cDNA revealed a 26kDa amino translation product, indicating expression of the N-terminal domain. The protein-coding region contains three short introns, less than 100 base pairs in length and Northern blot analysis demonstrates expression of a single 0.9 kb transcript in the piroplasm and schizont stages. The transcript is present in high abundance in the intra-lymphocytic schizont stage. The recombinant protein binds to immobilized cyclosporin A, a finding consistent with peptidyl-prolyl cis-trans isomerase function in vivo. A predicted N-terminal signal peptide was functional for entry into the eukaryotic secretory transport pathway in a cell-free in vitro transcription/translation system. The C-terminal cyclophilin domain was translocated across the membrane of the endoplasmic reticulum and the uncleaved signal peptide functioned as a membrane anchor.
authors.affiliation: Institute for Vascular Biology and Thrombosis Research, University of Vienna, Brunner Str. 59, A1235 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ebel
authors.forename: Roger
authors.initials: R
authors.lastname: Pellé
authors.forename: Rozmin
authors.initials: R
authors.lastname: Janoo
authors.forename: Joachim
authors.initials: J
authors.lastname: Lipp
authors.forename: Richard
authors.initials: R
authors.lastname: Bishop
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D021983:Cyclophilins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D016572:Cyclosporine / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics* / Q000502:physiology; D012313:RNA / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D016797:Theileria parva / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
chemical_list: D021382:Protein Sorting Signals; D012313:RNA; D016572:Cyclosporine; D004247:DNA; D021983:Cyclophilins