Plasmodium falciparum CRK4 links early mitotic events to the onset of S-phase during schizogony

Imaging malaria parasites across scales and time

The idea that disease is caused at the cellular level is so fundamental to us that we might forget the critical role microscopy played in generating and developing this insight. Visually identifying diseased or infected cells lays the foundation for any effort to curb human pathology. Since the discovery of the Plasmodium-infected red blood cells, which cause malaria, microscopy has undergone an impressive development now literally resolving individual molecules. This review explores the expansive field of light microscopy, focusing on its application to malaria research. Imaging technologies have transformed our understanding of biological systems, yet navigating the complex and ever-growing landscape of techniques can be daunting. This review offers a guide for researchers, especially those working on malaria, by providing historical context as well as practical advice on selecting the right imaging approach. The review advocates an integrated methodology that prioritises the research question while considering key factors like sample preparation, fluorophore choice, imaging modality, and data analysis. In addition to presenting seminal studies and innovative applications of microscopy, the review highlights a broad range of topics, from traditional techniques like white light microscopy to advanced methods such as superresolution microscopy and time-lapse imaging. It addresses the emerging challenges of microscopy, including phototoxicity and trade-offs in resolution and speed, and offers insights into future technologies that might impact malaria research. This review offers a mix of historical perspective, technological progress, and practical guidance that appeal to novice and advanced microscopists alike. It aims to inspire malaria researchers to explore imaging techniques that could enrich their studies, thus advancing the field through enhanced visual exploration of the parasite across scales and time.

APEX-based proximity labeling in Plasmodium identifies a membrane protein with dual functions during mosquito infection

Transmission of the malaria parasite Plasmodium to mosquitoes necessitates gamete egress from red blood cells to allow zygote formation and ookinete motility to enable penetration of the midgut epithelium. Both processes are dependent on the secretion of proteins from distinct sets of specialized vesicles. Inhibiting some of these proteins has shown potential for blocking parasite transmission to the mosquito. To identify new transmission blocking vaccine candidates, we aimed to define the microneme content from ookinetes of the rodent model organism Plasmodium berghei using APEX2-mediated rapid proximity-dependent biotinylation. Besides known proteins of ookinete micronemes, this identified over 50 novel candidates and sharpened the list of a previous survey based on subcellular fractionation. Functional analysis of a first candidate uncovered a dual role for this membrane protein in male gametogenesis and ookinete midgut traversal. Mutation of a putative trafficking motif in the C-terminus affected ookinete to oocyst transition but not gamete formation. This suggests the existence of distinct functional and transport requirements for Plasmodium proteins in different parasite stages.

Post-Translational Modifications of Proteins of Malaria Parasites during the Life Cycle

Post-translational modifications (PTMs) are essential for regulating protein functions, influencing various fundamental processes in eukaryotes. These include, but are not limited to, cell signaling, protein trafficking, the epigenetic control of gene expression, and control of the cell cycle, as well as cell proliferation, differentiation, and interactions between cells. In this review, we discuss protein PTMs that play a key role in the malaria parasite biology and its pathogenesis. Phosphorylation, acetylation, methylation, lipidation and lipoxidation, glycosylation, ubiquitination and sumoylation, nitrosylation and glutathionylation, all of which occur in malarial parasites, are reviewed. We provide information regarding the biological significance of these modifications along all phases of the complex life cycle of Plasmodium spp. Importantly, not only the parasite, but also the host and vector protein PTMs are often crucial for parasite growth and development. In addition to metabolic regulations, protein PTMs can result in epitopes that are able to elicit both innate and adaptive immune responses of the host or vector. We discuss some existing and prospective results from antimalarial drug discovery trials that target various PTM-related processes in the parasite or host.

The molecular mechanisms driving Plasmodium cell division

Malaria, a vector borne disease, is a major global health and socioeconomic problem caused by the apicomplexan protozoan parasite Plasmodium. The parasite alternates between mosquito vector and vertebrate host, with meiosis in the mosquito and proliferative mitotic cell division in both hosts. In the canonical eukaryotic model, cell division is either by open or closed mitosis and karyokinesis is followed by cytokinesis; whereas in Plasmodium closed mitosis is not directly accompanied by concomitant cell division. Key molecular players and regulatory mechanisms of this process have been identified, but the pivotal role of certain protein complexes and the post-translational modifications that modulate their actions are still to be deciphered. Here, we discuss recent evidence for the function of known proteins in Plasmodium cell division and processes that are potential novel targets for therapeutic intervention. We also identify key questions to open new and exciting research to understand divergent Plasmodium cell division.