Mutant/mutation
The mutant lacks expression of  a transcription factor with AP2 domain(s) (AP2-Sp, AP2 in sporozoites)

Protein (function)
AP2-Sp belongs to the Apetala2 (AP2) family of genes which encode transcription factors (TFs). The AP2 family TFs were first identified in plants. Plant AP2 family TFs are named for their possession of at least one common DNA-binding domain of approximately 60 amino acids, the AP2 domain. Bioinformatic analyses have revealed the presence of 26 AP2-related genes in the Plasmodium genome. The predicted Plasmodium AP2-related genes encode proteins with one to four AP2 domains. AP2-Sp contains a single AP2 domain.

Phenotype
The phenotype analyses indicate an essential role of AP2-sp during sporozoite development. The phenotype analyses as described in 'Additional information' indicate that AP2-Sp is a transcription factor that binds to promoter regions of genes that are expressed during sporozoite formation and play a role in sporozoite infectivity and regulates expression of these genes.

Additional information
Nuclear staining of oocysts with Hoechst showed that the nucleus of each oocyst was divided into several small nuclei 10 days after the infective blood meal in mutant and in wild-type parasites. Semithin sections stained with Giemsa, however, revealed that the subsequent invagination of the plasma membrane, which is necessary for formation of sporoblasts, did not occur in mutant oocysts.

A transgenic P. berghei mutant was generated that expresses a GFP-tagged form of AP2-Sp (RMgm-398). Analyses of this mutant show expression of AP2-Sp in oocysts and sporozoites.

Evidence has been presented that the P. falciparum ortholog (PF14_0633) of P. berghei AP2-Sp is (also) transcribed in asexual blood stages (de Silva et al., PNAS, 2008, 105, 8393-8; Bozdech Z et al., 2003, PloS Biol. 1: E5).

Electrophoretic mobility-shift assay showed that the DNAbinding domain of AP2-Sp recognizes specific eight base sequences, beginning with TGCATG, which are present in the proximal promoter region of all known sporozoite-specific genes. Promoter assays demonstrated that these sequences act as cis-acting elements and are critical for the expression of sporozoite-specific genes with different expression profiles.

A transgenic parasite mutant was generated (RMgm-400) that express endogenous AP2-O (APETALA2 in ookinetes; PBANKA_090590; PF11_0442), but whose AP2 domain had been swapped with that of AP2-Sp. It is shown that in this mutant expression of several target genes of AP2-Sp were induced in the ookinete stage.

Other mutants
RMgm-398: a mutant expressing a GFP-tagged form of AP2-Sp (AP2 in sporozoites)
RMgm-400: a mutant expressing a mutated form of AP2-O (PBANKA_090590; PF11_0442)whose AP2 domain had been swapped with that of AP2-Sp
RMgm-207: a mutant lacking expression of AP2-O (AP2 in ookinetes: PBANKA_090590; PF11_0442)
RMgm-208: a mutant expressing a GFP-tagged form of AP2-O (AP2 in ookinetes; PBANKA_090590; PF11_0442)