Mutant/mutation
The mutant lacks expression of Concavin (PIMS22). In addition, it does not contain a (positive) drug selectable marker. The selectable marker has been removed by negative selection.

Protein (function)
See mutant RMgm-4999 for previous analyses of this protein (PIMMS22; Concavin):
PfPIMMS22 encodes a 393 amino acid (45 kDa) protein and PbPIMMS22 encodes a 393 aa (44 kDa) protein, both with no predicted signal peptide or transmembrane domain. The protein is highly conserved amongst Plasmodium orthologues. PyPIMMS22 (PY17X_1424900) was previously identified in salivary gland sporozoites through a  subtractive hybridization (SSH) profiling and termed sporozoite protein S15. The same protein was also identified in midgut oocyst sporozoites as an interacting partner to the apicomplexan specific RNA-binding protein, ALBA4, which is involved in mRNA regulation in gametocyte and midgut oocyst sporozoite development. PIMMS22 homologues are found in other apicomplexan parasites including Toxoplasma gondii, Neospora caninum and Eimeria with sequence identities to PIMMS22 ranging from 36% to 42%. InterPro domain analysis revealed no recognizable domain in PIMMS22. Evidence is presented for ookinete defects in invasion and traversal of the midgut epithelium (although this cannot completely explain the strongly reduced oocysts numbers, indicating reduced ookinete to oocyst transition after midgut traversal). Strongly reduced oocyst numbers. Strongly reduced sporozoite numbers. No infection of mice by the bite of infected mosquitoes.

From this study: Due to its impact on the convex-concave polarity of sporozoites we named the protein Concavin

Phenotype
We regularly found large numbers of concavin(-) sporozoites within the salivary glands, however, a large proportion of sporozoites showed an abnormal shape. While wild type sporozoites usually keep the typical curved and slender shape at any time post salivary gland entry, concavin(-) sporozoites rounded up over time. Rounding up of concavin(-) sporozoites was initiated at the posterior end of the cell and hence appeared different to the  rounding observed after liver cell entry. 
Over 90% of oocyst-derived concavin(-) sporozoites were normally formed. Yet with prolonged residency in salivary glands more sporozoites became deformed or rounded up completely. In contrast, we never observed deformed wild type sporozoites, neither in the midgut nor in the salivary gland. Curiously, both deformed and normally shaped sporozoites were still able to move. While normally shaped concavin(-) sporozoites displayed circular movement in a wild type manner with nearly wild type speed, deformed sporozoites progressed with significantly slower speed. Deformed sporozoites also moved on less curved paths as did wild type or normally formed concavin(-) parasites.
8 of 12 mice that were bitten by concavin(-) infected mosquitoes became infected. In these 8 mice the development of the blood stage infection was delayed by over one day compared to the wild type controls (a loss of 90% infectivity).

Additional information
Analysis of a mutant expressing GF_tagged concavin showed: 
Concavin-GFP could be detected in gametocytes, ookinetes, sporozoites and liver stages and was absent in blood stage parasites. In gametocytes the protein localized diffusely while in ookinetes and salivary gland derived sporozoites concavin-GFP localized at the periphery suggesting an association with the plasma membrane. To specify concavin-GFP localization we next fixed concavin-GFP expressing sporozoites and labelled them with anti-GFP antibodies with or without membrane permeabilization. Antibodies only detected concavin-GFP after permeabilization suggesting an internal localization of the protein.

Evidence is prsented that: 
- Concavin-GFP is highly mobile and does not localize to the cytoskeleton
- Disintegration of sporozoites migrating in the skin
- Complementation with a palmitoylation site mutant partially restores sporozoite form.
We next complemented concavin(-) parasites with a concavin version that expresses an alanine instead of the cysteine of the likely palmitoylation site fused to GFP. This concavin^C7A-GFP parasite readily yielded sporozoites in oocysts and salivary glands. Quantitation of sporozoite shape from both locations showed that at any time point assessed, over 80% of sporozoites showed a normal shape, even as late as 22 days after infection, when the vast majority of concavin(-) sporozoites showed aberrant shapes. This suggests that palmitoylation alone is not essential for concavin function

Other mutants