title: Cell cycle-dependent phosphorylation of Theileria annulata schizont surface proteins.
abstract: The invasion of Theileria sporozoites into bovine leukocytes is rapidly followed by the destruction of the surrounding host cell membrane, allowing the parasite to establish its niche within the host cell cytoplasm. Theileria infection induces host cell transformation, characterised by increased host cell proliferation and invasiveness, and the activation of anti-apoptotic genes. This process is strictly dependent on the presence of a viable parasite. Several host cell kinases, including PI3-K, JNK, CK2 and Src-family kinases, are constitutively activated in Theileria-infected cells and contribute to the transformed phenotype. Although a number of host cell molecules, including IkB kinase and polo-like kinase 1 (Plk1), are recruited to the schizont surface, very little is known about the schizont molecules involved in host-parasite interactions. In this study we used immunofluorescence to detect phosphorylated threonine (p-Thr), serine (p-Ser) and threonine-proline (p-Thr-Pro) epitopes on the schizont during host cell cycle progression, revealing extensive schizont phosphorylation during host cell interphase. Furthermore, we established a quick protocol to isolate schizonts from infected macrophages following synchronisation in S-phase or mitosis, and used mass spectrometry to detect phosphorylated schizont proteins. In total, 65 phosphorylated Theileria proteins were detected, 15 of which are potentially secreted or expressed on the surface of the schizont and thus may be targets for host cell kinases. In particular, we describe the cell cycle-dependent phosphorylation of two T. annulata surface proteins, TaSP and p104, both of which are highly phosphorylated during host cell S-phase. TaSP and p104 are involved in mediating interactions between the parasite and the host cell cytoskeleton, which is crucial for the persistence of the parasite within the dividing host cell and the maintenance of the transformed state.
authors: Division of Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors: Olga
authors: O
authors: Wiens
authors: Department of Infection Biology, Institute of Infection and Global Health & School of Veterinary Science, University of Liverpool, Liverpool, England.
authors: Dong
authors: D
authors: Xia
authors: Division of Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors: Conrad
authors: C
authors: von Schubert
authors: Department of Infection Biology, Institute of Infection and Global Health & School of Veterinary Science, University of Liverpool, Liverpool, England; The National Institute for Health Research Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, England.
authors: Jonathan M
authors: JM
authors: Wastling
authors: Division of Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors: Dirk A E
authors: DA
authors: Dobbelaere
authors: Institute of Cell Biology, University of Bern, Bern, Switzerland.
authors: Volker T
authors: VT
authors: Heussler
authors: Division of Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors: Kerry L
authors: KL
authors: Woods
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D048749:Cytokinesis; D006790:Host-Parasite Interactions; D007399:Interphase; D008565:Membrane Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000378:metabolism*; D052939:Schizonts / Q000378:metabolism*; D016796:Theileria annulata / Q000378:metabolism*
chemical_list: D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins