Additional remarks phenotype | Mutant/mutation
The mutant lacks expression of AP2-L and expresses GFP-luciferase under control of the constitutive eef1a promoter
Protein (function)
Most sequence-specific transcription factor families found in other eukaryotes seem to be absent from Plasmodium. Instead, an expansion of a protein family containing one or more apetala2 (AP2) DNA-binding domains was observed across the phylum apicomplexa. In total, 27 members of this family have been found in the human malaria parasite Plasmodium falciparum (although a possible 28th member of the family may be present. In total, 26 of these have syntenic orthologs in rodent malaria species, each with its unique stage-specific expression profile.
The paper presents a systematic knockout (KO) screen targeting the ApiAP2 family in the rodent malaria parasite P. berghei. Phenotyping of eleven viable ApiAP2 KO mutants reveals ten critical gene functions at different points in the life cycle.
From the paper: To target P. berghei ApiAP2 genes systematically, we succeeded in producing deletion vectors for all but one member of the family (PBANKA_1313200) and transfected each of them into a reporter line constitutively expressing GFP to facilitate phenotyping. Fourteen ApiAP2 genes resisted at least four disruption attempts with up to two different vector designs, providing tentative evidence that more than half of the genes in this family are potentially essential for asexual blood stage growth in vivo. For the remaining eleven, a KO line could be generated. These included six genes that had not previously been studied in Plasmodium.
Phenotype
Normal sporozoite formation. Sporozoites fail to infect mice (parasites arrest during liver stage development; see 'Additional remarks phenotypes').
See mutant RMgm-792 for a more detailed description of the phenotype in the absence of AP2-L: 'Normal sporozoite production. Gliding motility, cell traversal and hepatocyte invasion of sporozoites is normal. Infectivity of sporozoites in vivo is 10.000 lower compared to wild type sporozoites (as measured by prepatent period). Development of liver stages is affected. At 24 hpi, the difference in size between the wild-type and AP2-L(2) liver stages was still subtle, but it became clear at 36 hpi. After 36 hpi, the sizes of the AP2-L(2) LS parasites scarcely increased, whereas the wild-type parasites continued to grow until 48 hpi. In accordance with the growth of the LS parasites, arrest of nuclear division became clear at 36 hpi in the AP2-L(2) parasites. The appearance of the nuclei remained the same, and no AP2-L(2) LS parasites in the cytomere stage were formed in the later stage. These observations indicate that the development of AP2-L(2) parasites almost completely arrested at about 36 hpi, i.e., in the middle of the schizont stage, which caused a severe decrease in their ability to infect the liver'
Additional information
From the paper:
Other mutants
See ApiAP2 |