Function and diversification of ESCRT proteins in plant endosomal sorting

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This project will analyze how cells degrade proteins anchored in membranes and how this process affects plant development. The activities associated with this project will provide training opportunities for undergraduates, a graduate student, and a postdoctoral researcher in cell biology, biochemistry, light and electron microscopy, and computational biology. It will also provide the scientific community with tools and data to understand basic principles of plant biology and the function of structures within cells called organelles. In collaboration with the Medical Engineering Group and the Fabrication Laboratory for 3D printing at the Wisconsin Discovery Center in Madison, three-dimensional prints representing different organelles will be produced for outreach activities with K-12 students in the Madison area. The ability of cells to perform basic cellular functions and to interact with each other and with their environment relies on controlling the composition of their plasma membrane, that is, the number and kind of receptors, transporters, enzymes that are exposed to the cell surface. Plasma membrane proteins that need to be degraded are first delivered to endosomes where are sorted into endosomal lumenal vesicles for their degradation in lytic organelles, such as lysosomes and vacuoles. Although essential for the life of all eukaryotic cells, how endosomal vesicles form and how they sequester plasma membrane proteins is not fully understood. This proposal aims to 1) analyze previously uncharacterized features of the membrane geometry in plant endosomes by electron tomography and computational simulations; 2) characterize a novel protein complex that could mediate local modifications of membrane lipids to contribute to endosomal maturation; 3) analyze the role of a novel connection between endosomal proteins and the machinery that regulates the delivery of vesicles to the plasma membrane.