PfSec13 is an unusual chromatin associated nucleoporin of Plasmodium falciparum, which is essential for parasite proliferation in human erythrocytes

Abstract

SummaryIn Plasmodium falciparum, the deadliest form of human malaria, the nuclear periphery has drawn much attention due to its role as a subnuclear compartment involved in virulence gene expression. Recent data have implicated components of the nuclear envelope in regulating gene expression in several eukaryotes. Special attention has been given to nucleoporins that compose the nuclear pore complex (NPC). However, very little is known about components of the nuclear envelope in Plasmodium parasites. Here we characterize PfSec13, an unusual nucleoporin of P. falciparum, which shows unique structural similarities suggesting that it is a fusion between Sec13 and Nup145C of yeast. Using super resolution fluorescence microscopy (3D-SIM) and in vivo imaging, we show that the dynamic localization of PfSec13 during parasites' intra-erythrocytic development corresponds with that of the NPCs and that these dynamics are associated with microtubules rather than with F-actin. In addition, PfSec13 does not co-localize with the heterochormatin markers HP1 and H3K9me3, suggesting euchromatic location of the NPCs. The proteins associated with PfSec13 indicate that this unusual Nup is involved in several cellular processes. Indeed, ultrastructural and chromatin immunoprecipitation analyses revealed that, in addition to the NPCs, PfSec13 is found in the nucleoplasm where it is associated with chromatin. Finally, we used peptide nucleic acids (PNA) to downregulate PfSec13 and show that it is essential for parasite proliferation in human erythrocytes.

Three-dimensional modeling of the P. falciparum genome during the erythrocytic cycle reveals a strong connection between genome architecture and gene expression

“…9A; Supplemental Table 6), providing independent support for the clustering of VRSM genes. Although previous FISH results indicated that var genes form two to five clusters in 3D per cell (Freitas-Junior et al 2000;Lopez-Rubio et al 2009), others recently showed single foci for the VRSM gene-associated repressive histone mark H3K9me3 and heterochromatin protein 1 (PfHP1) (Dahan-Pasternak et al 2013), as well as for H3K36me3 that marks both active and silenced var genes (Ukaegbu et al 2014). Because our experimental strategy (Hi-C) captures a population average, we are unable to distinguish between multiple VRSM gene clusters in 3D if the genes are randomly distributed among clusters from cell to cell.…”

Comparative interactomics provides evidence for functional specialization of the nuclear pore complex

“…The same catalytic activity is lacking in another flagellated excavate Giardia lamblia, 4 and autoproteolytic cleavage has been shown to be dispensable for cell growth in fission yeast. 26 Additionally, the Apicomplexan parasite Plasmodium falciparum has an unusual fusion of a portion of the a solenoid domain of this protein (ScNup145C) with PfSec 13 27 . Thus, trypanosomes do not represent the exception -instead, they are part of the rule that the outer ring complex (comprising one-third of the NPC's mass) can apparently vary considerably in form and function between different organisms.…”

Novel 2-Phenoxyanilide Congeners Derived from a Hit Structure of the TCAMS: Synthesis and Evaluation of Their in Vitro Activity against Plasmodium falciparum

“…The first group of ten compounds was substituted with chlorine in para position of the phenoxy residue, like in the scaffold of TCMDC-137332 (1-10). Another equivalent series was synthesized, in which the chlorine was replaced by a more polar methoxy group (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). …”

“…The derivatives 1-20 were examined in 3µM concentration performing viability assays measuring the bioluminescence in a luciferase assay system as described earlier [17][18][19][20]. A first screening, in which the cultures were incubated for 48 h, gave surprisingly low inhibition rates of the parasite growth (see Figure 3).…”