Project Summary Plasmodium falciparum is a unicellular eukaryote that causes the most severe form of human malaria. In the human blood stage of malaria infection, P. falciparum undergoes asexual replication to propagate itself exponentially, resulting in the classic symptoms of malaria. This is a critical stage of the parasite’s life cycle and a compelling process to target for new therapeutics. Plasmodium utilizes a divergent form of cell division with a unique method of cytokinesis called segmentation, wherein genetic material and organelles are simultaneously partitioned into 20-36 daughter cells. This is a high-fidelity process that is largely driven by the basal complex, the putative contractile ring of the parasite. Despite its pivotal role for parasite survival and proliferation, our mechanistic understanding of the basal complex is limited. To address this knowledge gap, our lab and others have identified a dozen proteins that comprise the basal complex. Of these, three proteins emerged as a subgroup, each of which contain transmembrane domains. Previous studies demonstrate that they localize to the basal complex and my preliminary data suggests that at least one of these is important for parasite replication. It remains unclear, however, whether these proteins are associated with a membrane and what specific function they serve during segmentation. In this study, I will integrate biochemical and super-resolution microscopy approaches to decipher the precise location of the transmembrane proteins. This will provide direct evidence of a link between the basal complex and parasite membrane. I will also use direct and inducible knockout systems together with cell viability assays and live-cell microscopy to thoroughly interrogate the function of the transmembrane proteins. This will reveal how transmembrane domains contribute to the broader cytokinetic function of the basal complex. Collectively, the findings from this study will represent the first step towards a mechanistic understanding of the basal complex in Plasmodium. Further, insights from this study will enable future comparative analyses between parasites and model eukaryotes, revealing parasite-specific adaptations that can be leveraged for novel therapeutics. The proposed research will thoroughly develop my conceptual and technical expertise in Plasmodium biology. Specifically, this proposal will expand my current skills in biochemical, microscopy, and genetic techniques, honing my technical expertise and establishing a research niche. Moreover, I aim to leverage both our understanding of eukaryotic cell division and my experience in the related parasite Toxoplasma, to achieve these goals. Training at Boston Children’s Hospital and within the larger Harvard community offers a rich and stimulating environment to support this proposal and my development as a scientist and mentor. Here, I will build strong scientific relationships with leaders in microbiology and molecular biology through local meetings and international conferences and commit to training the next generation of scientists. Overall, I am well positioned to carry out this research and propel my career towards an independent investigator position.

PROJECT NARRATIVE The malaria parasite causes a staggering global health burden, yet its key biological structures and processes remain understudied. To better understand parasite cell division, this proposal focuses on the proteins that comprise the cytokinesis-driving contractile ring. By investigating the role of three transmembrane proteins, the goal is to reveal novel insights into parasite-specific mechanisms of cytokinesis that can inform the next generation of antimalarial drugs.