Mutant/mutation
The mutant lacks expression of prefoldin subunit 5, putative and expresses mCherry and luciferase under control of constitutive promoters

Protein (function)
Prefoldin is a heterohexameric chaperone complex known to be involved in the assembly and maintenance of actin as well as α- and β-tubulins in a wide range of eukaryotes. P. berghei possesses 6 prefoldin subunits and since the function of prefoldin is conserved among many eukaryotic species, it may also be involved in the cytoskeletal assembly in Plasmodium, which is essential for sporozoite formation. Here, we investigated the function of subunit 5 of P. berghei prefoldin complex during Plasmodium mosquito stage development

Phenotype
Slightly fewer oocysts compared to wild type. No decrease in oocyst numbers between day 14 and 21, indicating a defect in oocyst rupture and sporozoite egress. Oocyst size at day 7 and 10 smaller compared to wild type (and larger at day 14 and 21 compared to wild type). Inside oocysts PbPCS5-KO parasites form thinner and elongated sporozoites with fewer microtubules. No midgut and salivary gland sporozoites could be detected.

Additional information
Evidence is presented that:
- PbPCS5 is dispensable for DNA replication but seems to be important at a later stage of sporogony.
- The microtubular organization is disturbed in PbPCS5-KO oocysts
- PbPCS5-KO parasites form thinner and elongated sporozoites with fewer microtubules
- PbPCS5-KO microtubules extend into the sporoblast during sporogony
- Subpellicular microtubules contact nuclei within sporoblast
From the paper: ' PbPCS5 has at least two functions during parasite development in mosquitoes: i) it is needed for the correct polymerization of subpellicular microtubules. In the absence of PbPCS5, fewer subpellicular microtubules are assembled that then reach into the sporoblast where they can contact and deform nuclei, and ii), PbPCS5 appears also to be required for achieving the correct organization of nuclei. Nuclei are seemingly unable to enter the forming sporozoites resulting in many anucleated sporozoites. This might be due to an effect on nucleus orientation or rootlet fibre assembly. Alternatively, the forming sporozoite buds might be too narrow for nuclei to be pulled in. PbPCS5-deficient sporozoites were unable to egress from oocysts and only mechanical disruption could release them from oocysts'.

Other mutants