The conserved apicomplexan Aurora kinase TgArk3 is involved in endodyogeny, duplication rate and parasite virulence

Abstract

Aurora kinases are eukaryotic serine/threonine protein kinases that regulate key events associated with chromatin condensation, centrosome and spindle function, and cytokinesis. Elucidating the roles of Aurora kinases in apicomplexan parasites is crucial to understand the cell cycle control during Plasmodium schizogony or Toxoplasma endodyogeny. Here, we report on the localization of two previously uncharacterized Toxoplasma Aurora-related kinases (Ark2 and Ark3) in tachyzoites and of the uncharacterized Ark3 orthologue in Plasmodium falciparum erythrocytic stages. In T. gondii, we show that TgArk2 and TgArk3 concentrate at specific sub-cellular structures linked to parasite division: the mitotic spindle and intranuclear mitotic structures (TgArk2), and the outer core of the centrosome and the budding daughter cells cytoskeleton (TgArk3). By tagging the endogenous PfArk3 gene with the green fluorescent protein (GFP) in live parasites, we show that PfArk3 protein expression peaks late in schizogony and localizes at the periphery of budding schizonts. Disruption of the TgArk2 gene reveals no essential function for tachyzoite propagation in vitro, which is surprising giving that the P. falciparum and P. berghei orthologues are essential for erythrocyte schizogony. In contrast, knock-down of TgArk3 protein results in pronounced defects in parasite division and a major growth deficiency. TgArk3-depleted parasites display several defects, such as reduced parasite growth rate, delayed egress and parasite duplication, defect in rosette formation, reduced parasite size and invasion efficiency and lack of virulence in mice. Our study provides new insights into cell cycle control in Toxoplasma and malaria parasites, and highlights Aurora kinase 3 as potential drug target.

A coiled-coil protein is required for coordination of karyokinesis and cytokinesis in Toxoplasma gondii

“…Moreover, the function of cyclin and Cdk‐related kinases have been recently deciphered in T. gondii , adding another layer of regulation in cell cycle control (Alvarez & Suvorova, ). In T. gondii , kinases were shown to regulate the centrosome function during the cell cycle: TgMAPK‐L1 restricts the duplication of the outer core (Suvorova et al, ), TgNek‐1 is involved in centrosome splitting (Chen & Gubbels, :1), TgCDPK7 is involved in centrosome positioning (Morlon‐Guyot et al, ), and TgArk3 plays a role in parasite division (Berry et al, ). Moreover, an arginine methyltransferase (TgPRMT1) may have a non‐essential role in centrosome dynamics (El Bissati et al, ).…”

Genome-Wide Identification and Evolutionary Analysis of Sarcocystis neurona Protein Kinases

“…NEKs are involved in cell cycle regulation, while Aurora kinases play pivotal roles in endodyogeny, duplication rate and parasite virulence [33]. Taken together, the presence of a variety of ROPKs in S. neurona is interesting given the fact that in T. gondii , ROPKs are key virulence factors [63].…”

“…It should however be noted that the activation of Plasmodium MAPK via Pfnek-1/3-mediated phosphorylation has only been demonstrated in vitro; there is no sufficient evidence of MAPK signaling in vivo in the parasite. Finally, some of the notable OPKs include aurora kinases, rhoptry kinases (ROPKs) and parasite-specific eukaryotic initiation factor-2 (elF2) kinases (elF2K), which are important in parasite virulence and differentiation [23,33,34]. …”

Towards a molecular architecture of the centrosome in Toxoplasma gondii

“…Ark2 is dispensable and associates with the mitotic spindle. Ark3 is associated with the centrosome outer core and daughter cell cytoskeleton and is required for endodyogeny and duplication (Figure B) (Berry et al, ). In contrast to Ark2, Toxoplasma Ark1 is present in the nucleus and is essential for mitosis (Figure B, our unpublished data).…”