Mutant/mutation
In the promoter swap' mutant: the promoter of the endogenous cdpk1 gene is replaced by the promoter of clag9 (PBANKA_140060). In addition, cdpk1 is C-terminally tagged with GFP.

Protein (function)
In malaria parasites, intracellular Ca²⁺ signals are translated into stage-specific cellular responses by members of a family of Ca2+-dependent protein kinases (CDPKs), which combine an N-terminal kinase domain with a C-terminal, calmodulin-like regulatory domain in the same polypeptide.

Phenotype

CDPK1 is considered vital for blood stage development/multiplication. See also RMgm-518 for unsuccessful attempts to knock-out CDPK1.
In the 'promoter-swap' mutant the promoter of cdpk1 is replaced by an 'asexual blood stage’ promoter that is silent (or has a strongly reduced activity) in ookinetes (the promoter of clag9 (PBANKA_140060). Expression of CDPK1 was absent in mutant ookinetes whereas wild type ookinetes express CDPK1.

See also the phenotype of gametocytes/gametes. Zygotes are formed but are arrested during development into mature ookinetes at the 'retort' stage. These retort forms are immotile.

Additional information
Transmission electron micrographs of CDPK1-deficient retort-like ookinetes revealed no gross abnormalities that could account for the morphology defect of the mutant, which had a completely assembled apical complex with collar, apical rings and micronemes (Figure 2E), and a typical pellicle, consisting of the plasma membrane, the inner membrane complex and regularly spaced subpellicular microtubules.

Evidence is presented that arrest of ookinete development is not the result of the previously proposed function for CDPK1 in regulating parasite motility. It is proposed that CDPK1 translationally activates mRNA species in the developing zygote that in macrogametes remain repressed via their 3' and 5'UTRs.

The Pclag-cdpk1-gfp mutant was generated in the cdpk1-gfp background (RMgm-772) by inserting the hdhfr-clag promoter cassette upstream of the cdpk1-gfp fusion gene.

As a control, the stage-specific expression line Pclag-cdpk1-gfp was complemented in trans by inserting a Pcdpk1-cdpk1-gfp expression cassette into the nonessential cssu locus of a wild-type P. berghei strain, then crossing this line with the Pclag-cdpk1-gfp mutant by feeding mosquitoes on a mouse infected with both transgenic parasites. Sporozoites originating from the cross were used to infect another mouse and parasites were cloned by limiting dilution. PCR genotyping of progeny clones identified a recombinant carrying both the Pclag-cdpk1-gfp allele in the cdpk1 locus and the complementing Pcdpk1-cdpk1-gfp allele in the cssu locus. Complementation in trans completely restored CDPK1-GFP expression levels in schizonts and gametocytes.

Other mutants
RMgm-518: unsuccessful attempts to disrupt cdpk1
RMgm-772: A mutant expressing CDPK1-GFP from the endogenous cdpk1 promoter
RMgm-966: A mutant lacking expression of CDPK! (successful disruption of cdpk1!)
RMgm-967: A mutant containing a FRTed ORF of the cdpk1 locus. Analyses of this mutant indicates the lack of an essential role of CDPK1 for liver stage development