Mutant/mutation
The mutant expresses a C-terminal HA-tagged version of S54

Protein (function)
The encoded protein contains eight predicted transmembrane regions and two low complexity regions

Phenotype
Analysis of a mutant expressing a C-terminal HA-tagged version of S54 showed the following: Western blot analysis of samples of schizonts, gametocytes, zygotes and ookinetes of the S54-HA parasites with anti-HA mAb, protein bands of approximately 54 kDa were detected in zygotes and ookinetes. Using IFA with the anti-HA mAb, fluorescent signals were detected in gametes and ookinetes, but not schizonts or gametocytes. Pbs54 was detected in both male and female gametes. Without permeabilization, Pbs54 fluorescence was only associated with the flagella, whereas the permeabilized male gametes displayed fluorescence on both the flagella and residual body. Regardless of membrane permeabilization, Pbs54 was associated with the plasma membrane (PM) of the female gametes. Pbs54 was localized at the periphery of ookinetes and co-localized with the ookinete surface protein PSOP25.

Analysis of a mutant lacking expression of S54 (RMgm-5406) showed the following: Normal gametocyte production, sex ratio, male gamete formation (exflagellation). However, reduced (59%) interactions between male and female gametes (as shown by microscopic analysis). Reduced (64%) formation of mature ookinetes. Mosquitoes feeding on mice infected with Δpbs54 parasites displayed a 60.7–72.4% infection prevalence, a 24.3–36.0% reduction compared with wild type (WT) parasites. Moreover, the mean number of oocysts per midgut in mosquitoes feeding on Δpbs54-infected mice was 72.7–76.7% lower than those feeding on WT parasite-infected mice.

Additional information

Other mutants