The Role of Neddylation in Malaria Parasites.

Plasmodium parasites, the causative agents of malaria, rely on sophisticated cellular mechanisms to survive and proliferate within their hosts. Plasmodium complex life cycle requires posttranslational modifications (PTMs) to control cellular activities. Neddylation is a type of PTM in which NEDD8 is covalently attached to target proteins and plays an important role in cell cycle control and metabolism. Covalent attachment to its substrates requires the Nedd8-activating enzyme, E1; the NEDD8-conjugating enzyme, E2; and the ligase, E3. In Plasmodium, protein neddylation is essential for parasite development during the stage I-II transition from zygote to ookinete differentiation and malaria transmission. Here, we discuss the current understanding of protein neddylation in Plasmodium, which is involved in malaria transmission.

Neddylation is essential for malaria transmission in Plasmodium berghei.

Neddylation is a type of posttranslational modification known to regulate a wide range of cellular processes by covalently conjugating the ubiquitin-like protein Nedd8 to target proteins at lysine residues. However, the role of neddylation in malaria parasites has not been determined. Here, for the first time, we showed that neddylation plays an essential role in malaria transmission in Plasmodium berghei. We found that disruption of Nedd8 did not affect blood-stage propagation, gametocyte development, gamete formation, or zygote formation while abolishing the formation of ookinetes and further transmission of the parasites in mosquitoes. These phenotypic defects in Nedd8 knockout parasites were complemented by reintroducing the gene that restored mosquito transmission to wild-type levels. Our data establish the role of P. berghei Nedd8 in malaria parasite transmission.IMPORTANCENeddylation is a process by which Nedd8 is covalently attached to target proteins through three-step enzymatic cascades. The attachment of Nedd8 residues results in a range of diverse functions, such as cell cycle regulation, metabolism, immunity, and tumorigenesis. The potential neddylation substrates are cullin (CUL) family members, which are implicated in controlling the cell cycle. Cullin neddylation leads to the activation of cullin-RING ubiquitin ligases, which regulate a myriad of biological processes through target-specific ubiquitylation. Neddylation possibly regulates meiosis in zygotes, which subsequently develop into ookinetes. Our findings point to an essential function of this neddylation pathway and highlight its possible importance in designing novel intervention strategies.

Protein O-Fucosyltransferase Is Required for the Efficient Invasion of Hepatocytes by Plasmodium berghei Sporozoites.

The O-fucosylation of the thrombospondin type I repeat (TSR) domain is important for TSR-containing proteins' optimal folding and stability. However, the importance of Plasmodium O-fucosyltransferase 2 (POFut2) remains unclear due to two different reports. Here, we disrupted the POFut2 gene in Plasmodium berghei and demonstrated that POFut2 KO parasites develop normally in blood and mosquito stages but show reduced infectivity in mice. We found that the reduced infectivity of POFut2 KO sporozoites was due to a diminished level of TRAP that affected the parasite gliding motility and hepatocyte infectivity. Using all-atom MD simulation, we also hypothesize that O-fucosylation impacts the TSR domain's stability more than its heparin binding capacity.