Divergent Plasmodium kinases drive MTOC, kinetochore and axoneme organisation in male gametogenesis.

Sexual development and male gamete formation of the malaria parasite in the mosquito midgut are initiated by rapid endomitosis in the activated male gametocyte. This process is highly regulated by protein phosphorylation, specifically by three divergent male-specific protein kinases (PKs): CDPK4, SRPK1, and MAP2. Here, we localise each PK during male gamete formation using live-cell imaging, identify their putative interacting partners by immunoprecipitation, and determine the morphological consequences of their absence using ultrastructure expansion and transmission electron microscopy. Each PK has a distinct location in either the nuclear or the cytoplasmic compartment. Protein interaction studies revealed that CDPK4 and MAP2 interact with key drivers of rapid DNA replication, whereas SRPK1 is involved in RNA translation. The absence of each PK results in severe defects in either microtubule-organising centre organisation, kinetochore segregation, or axoneme formation. This study reveals the crucial role of these PKs during endomitosis in formation of the flagellated male gamete and uncovers some of their interacting partners that may drive this process.