title: The Toxoplasma gondii calcium-dependent protein kinase 7 is involved in early steps of parasite division and is crucial for parasite survival.
abstract: Apicomplexan parasites express various calcium-dependent protein kinases (CDPKs), and some of them play essential roles in invasion and egress. Five of the six CDPKs conserved in most Apicomplexa have been studied at the molecular and cellular levels in Plasmodium species and/or in Toxoplasma gondii parasites, but the function of CDPK7 was so far uncharacterized. In T. gondii, during intracellular replication, two parasites are formed within a mother cell through a unique process called endodyogeny. Here we demonstrate that the knock-down of CDPK7 protein in T. gondii results in pronounced defects in parasite division and a major growth deficiency, while it is dispensable for motility, egress and microneme exocytosis. In cdpk7-depleted parasites, the overall DNA content was not impaired, but the polarity of daughter cells budding and the fate of several subcellular structures or proteins involved in cell division were affected, such as the centrosomes and the kinetochore. Overall, our data suggest that CDPK7 is crucial for proper maintenance of centrosome integrity required for the initiation of endodyogeny. Our findings provide a first insight into the probable role of calcium-dependent signalling in parasite multiplication, in addition to its more widely explored role in invasion and egress.
authors.affiliation: Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université de Montpellier I et II, Montpellier, France.
authors.forename: Juliette
authors.initials: J
authors.lastname: Morlon-Guyot
authors.forename: Laurence
authors.initials: L
authors.lastname: Berry
authors.forename: Chun-Ti
authors.initials: CT
authors.lastname: Chen
authors.forename: Marc-Jan
authors.initials: MJ
authors.lastname: Gubbels
authors.forename: Maryse
authors.initials: M
authors.lastname: Lebrun
authors.forename: Wassim
authors.initials: W
authors.lastname: Daher
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002470:Cell Survival; D018385:Centrosome / Q000378:metabolism; D055785:Gene Knockdown Techniques; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D014122:Toxoplasma / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D018797:Cell Cycle Proteins; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases