Mutant/mutation
The mutant expresses a C-terminal GFP-tagged version of  a mutated form of SEC13. In P. berghei SEC13 the polyproline motif is replaced by the polyproline motif of P. falciparum SEC13

Protein (function) and Phenotype
In P. berghei the ortholog of SEC13 contains a large C-terminal extension enriched in proline residues. This unordered domain is reminiscent of the C-terminal part in P. berghei SEC31, its binding partner in COPII vesicles. SEC31 also shows a similar, loosely conserved polyproline-rich stretch in P. falciparum and S. cerevisiae. The large, C-terminal extension of SEC13 is conserved in many Plasmodium species and is present in the related apicomplexans.

The number of proline residues in these SEC13 proteins ranges from 73 to 115. While individual proline residues within the SEC13 polyproline stretch of P. berghei are well conserved in the closely related P. yoelii parasite, another rodent malaria species, the amino acid sequence in P. falciparum is highly divergent and aligns poorly.

In order to address a possible function for this C-terminal extension we attempted the generation of a P. berghei mutant lacking this C-terminal polyproline motif. This was not possible indicating that this domain provides an essential role for this protein for parasite survival, either as part of COPII vesicles, or as a Nup, perhaps as an unusual SEC13-Nup145C fusion as suggested for P. falciparum.

Despite the large sequence divergence between P. berghei and P. falciparum, we were readily able to produce a mutant parasite line that expressed the polyproline motif of P. falciparum SEC13 in place of the P. berghei SEC13 polyproline motif. The staining pattern of this protein matched that of wildtype-like P. berghei SEC13-GFP.

Additional information

Other mutants
See FG-NUP