Composition and stage dynamics of mitochondrial complexes inPlasmodium falciparum

Abstract

Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The unusual mitochondrion of malaria parasites is a validated drug target but remains poorly understood. Here, we apply complexome profiling to map the inventory of protein complexes across the pathogenic asexual blood stages and the transmissible gametocyte stages of Plasmodium falciparum. We identify remarkably divergent composition and clade-specific additions of all respiratory chain complexes. Furthermore, we show that respiratory chain complex components and linked metabolic pathways are up to 40-fold more prevalent in gametocytes, while glycolytic enzymes are substantially reduced. Underlining this functional switch, we find that cristae are exclusively present in gametocytes. Leveraging these divergent properties and stage dynamics for drug development presents an attractive opportunity to discover novel classes of antimalarials and increase our repertoire of gametocytocidal drugs.

A prioritized and validated resource of mitochondrial proteins in Plasmodium identifies leads to unique biology

“…For 14 of the 76 conserved proteins with an unknown function, we found a mitochondrial ortholog using the sensitive homology detection tool HHpred (37) that can improve their annotation (Supplemental Table 2). For example, the human and yeast orthologs of PF3D7_0306000 (Bayesian rank 41) are both cytochrome b-cl complex subunit 8, making it very likely that the Plasmodium protein is also cytochrome b-cl complex subunit 8, as confirmed by recent complexome profiling (12). Other similar examples include PF3D7_1357600 (rank 283) that is likely a mitochondrial member of the 39S ribosomal protein family L53, and PF3D7_1309900 (rank 78) that is likely succinate dehydrogenase assembly factor 2.…”

“…Known proteins with a CHCH domain are localized to the mitochondrial intermembrane space where they can participate in disulfide bond formation, suggesting that PF3D7_1417900, PF3D7_1142800, and PF3D7_0927100 might also be in the intermembrane space. Complexome profiling revealed that the first two are part of the ATP synthase complex (12). We tested PF3D7_1417900 and PF3D7_0927100 experimentally and confirmed them to be mitochondrial (PBANKA_ 1024800 and PBANKA_0827900 in Fig 3B respectively).…”

“…Although we rejected BCL2 homology for both proteins after a detailed examination of the residues conserved in the BCL2 family, we confirmed the mitochondrial localization of PF3D7_0213200 (PBANKA_0310100 in Fig 3A) and PF3D7_0611300 (PBANKA_0l 09600 in Fig 3B). Indeed, complexome profiling revealed that the latter is part of the ATP synthase complex (12).…”

“…In general, most members of the protein complexes (described in (12)) were retrieved by our mitochondrial score (Supplementary Tables 2 and 5). Of the 24 electron transport chain members that were newly discovered by complexome profiling (12), 19 were in our top 295 (Supplemental Tables 2 and 5). The results outlined above reinforce the robustness of the predictions and that the ranked list of the complete nuclear encoded P. falciparum proteome, which we name PlasmoMitoCarta, is a useful resource for Plasmodium researchers.…”

“…This is further highlighted by the observation that in asexual blood-stage parasites no cristae are detectable in the mitochondrial membrane, while in gametocyte mitochondria cristae-like structures that typically accumulate respiratory chain complexes are observed (10). A recent complexome profiling study demonstrated that the level of complex V components in asexual blood stage parasites was only 3% of the level in gametocytes (12). Another intriguing aspect of mitochondria in Plasmodium and closely related species is that they are the only mitochondria that have no detectable homolog of the FeS cluster assembly protein frataxin (13), a protein that occurs even in mitosomes (14).…”