The catalytic subunit of Plasmodium falciparum casein kinase 2 is essential for gametocytogenesis

Abstract

Casein kinase 2 (CK2) is a pleiotropic kinase phosphorylating substrates in different cellular compartments in eukaryotes. In the malaria parasite Plasmodium falciparum, PfCK2 is vital for asexual proliferation of blood-stage parasites. Here, we applied CRISPR/Cas9-based gene editing to investigate the function of the PfCK2α catalytic subunit in gametocytes, the sexual forms of the parasite that are essential for malaria transmission. We show that PfCK2α localizes to the nucleus and cytoplasm in asexual and sexual parasites alike. Conditional knockdown of PfCK2α expression prevented the transition of stage IV into transmission-competent stage V gametocytes, whereas the conditional knockout of pfck2a completely blocked gametocyte maturation already at an earlier stage of sexual differentiation. In summary, our results demonstrate that PfCK2α is not only essential for asexual but also sexual development of P. falciparum blood-stage parasites and encourage studies exploring PfCK2α as a potential target for dual-active antimalarial drugs.

Plasmodium falciparum CRK4 links early mitotic events to the onset of S-phase during schizogony

“…Based on the presence of a conserved amino acid motif in Pf CRK4, the pleiotropic kinase Pf CK2 was previously predicted to phosphorylate Pf CRK4 at serine 977 (Pease et al, 2013). Pf CK2 is essential for parasite proliferation in the blood stage (Hitz et al, 2021) and we found the catalytic alpha subunit of Pf CK2 (PF3D7_1108400) in the proximity of Pf CRK4 (Fig. S3, Tab.…”

Functional inactivation of Plasmodium falciparum glycogen synthase kinase GSK3 modulates erythrocyte invasion and blocks gametocyte maturation

“…The P. falciparum genome encodes for 65 eukaryotic protein kinases ( 22 ), of which various members have already been described to be involved in essential processes, including egress, host cell invasion, or gametocytogenesis ( 17 , 19 , 38 , 53 ). Nevertheless, to date, only one malaria targeting kinase inhibitor has reached the phase of clinical trials: the PI4K-inhibitor MMV390048 was shown to be safe and well tolerated with high antimalarial activity against all stages of the parasitic life cycle except hypnozoites.…”

“…A substantial body of work highlights the role of this enzyme class in the regulation of host cell invasion ( 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ). For instance, the physiological role of protein kinase A, casein kinase 2 (CK2) as well as glycogen synthase kinase 3 (GSK3) during the host cell invasion has been demonstrated ( 6 , 7 , 8 , 9 , 10 , 16 , 17 , 18 , 19 ). These invasion-related kinases target the cytoplasmic domains of so-called invasins ( 6 , 8 , 9 , 10 , 16 )—proteins that are secreted during the invasion process and mediate binding to surface receptors on the host cell.…”

“…Recent studies provided evidence that protein kinases play an important role in gametocytogenesis and the subsequent formation of gametes ( 17 , 19 , 37 , 38 ). Gametocytes are sexually committed parasite stages that are able to leave the intraerythrocytic proliferation cycle and are transmissible to the mosquito vector ( 39 , 40 ).…”

The 3-phosphoinositide–dependent protein kinase 1 is an essential upstream activator of protein kinase A in malaria parasites

“…For this purpose, the SLI_PKAc_cKD transfection construct was PLOS BIOLOGY generated in 3 successive cloning steps using Gibson assembly reactions. First, the SLI_cKD precursor plasmid was generated by joining 4 fragments in a Gibson assembly reaction: (1) the plasmid backbone amplified from pUC19 (primers PCRA_F and PCRA_R) as previously described [53]; (2) the SpeI/BamHI cloning site followed by the gfp-dd sequence amplified from pD_ck2α-gfpdd [82] using primers gfp_F and dd_R; (3) the 2a-bsd sequence amplified from pSLI-BSD [35] (primers 2A_F and bsd_R); and (4) the glmS-hrp2 3 0 sequence amplified from pD_cOE (described below) (primers glmS1_F and term_R). Second, a 4-fragment Gibson assembly reaction was performed using (1) the SalI-and EcoRI-digested SLI_cKD precursor plasmid; (2) the calmodulin (PF3D7_1434200) promoter amplified from pHcamGFP-DD [53] (primers cam1_F and cam1_R); (3) the yeast dihydroorotate dehydrogenase (ydhodh) resistance gene (conferring resistance to DSM1) amplified from the pUF1-Cas-9 plasmid [83] (primers ydhodh_F and ydhodh_R); and (4) the pbdt 3 0 terminator amplified from pUF1-Cas-9 [83] (primers pbdt3_F and pbdt3_R).…”