Mechanisms Governing Translational Regulation During Plasmodium Transmission

Project Summary New malarial infections start with a bite of a female Anopheles mosquito, which introduces the sporozoite form of the Plasmodium parasite into the skin of that individual. To get to this point, the parasite must have successfully infected and developed within the mosquito over the course of two weeks or more, using active responses to overcome the mosquito’s defenses. Having accomplished this, the sporozoite must now switch into a mode of preparation and become poised for a moment of opportunity to transmit from the mosquito back to its mammalian host. In this proposed work, we will identify key mechanisms by which the sporozoite can prepare itself through the translational regulation of selected mRNAs. Recently, it was discovered that sporozoites use two overlapping and orthogonal programs of translational repression (Programs 1 and 2) to allow translation of specific mRNAs to occur only at key moments in their development. However, while we now know many specific mRNAs that are regulated by these programs, we do not know what proteins act upon them to cause them to be silenced/repressed (trans factors). Moreover, while we know when these programs are turned off during development and transmission of the parasite, we do not know what environmental cues initiate this transition in translational regulation. Therefore, in this proposed work we will investigate the protein trans factors that allow for selective regulation of mRNAs that are known to be critical to sporozoite development and transmission. Through this work, we will identify the consequences of interfering with these regulatory programs, the environmental stimuli that are sensed to trigger the release of translational repression, and the central role that the specialized ribosome plays in these processes. These experimental questions will be addressed through reverse genetics, protein biochemistry, imaging flow cytometry, transcriptomics, proteomics, and cryogenic electron microscopy (cryo EM). In accomplishing this, we aim to identify crucial regulatory features of the malaria parasite that control sporozoite development and transmission to a new mammalian host.