Abstract: Series 114, Lecture 4

The Harvey Lectures Series 114 (2018—2019)

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Lecture #4: Thursday, February 21, 2019 — Time and Location

Of Gels and Liquids: Organizing the Cytoplasm of Eukaryotic Cells

Geraldine Seydoux, PhD

Geraldine Seydoux, PhD

Huntington Sheldon Professor in Medical Discovery
Professor of Molecular Biology and Genetics

Howard Hughes Medical Institute, Johns Hopkins University School of Medicine

Baltimore, Maryland

Dr Seydoux's Website

Eukaryotic cells use microcompartments (“organelles”) to segregate proteins with different functions. Some organelles lack enveloping membranes and appear as protein-rich condensates or “granules” suspended in the cytoplasm. In his classic study (1899), E. B. Wilson described the cytoplasm of starfish eggs as “a mixture of liquids in the form of a fine emulsion”. The idea that granules are in fact liquid is enjoying a revival today, as certain granule proteins have been shown to condense into liquid droplets in vitro. My laboratory is using genetics to study the P granules of the small worm C. elegans. I will discuss our finding that P granules are not entirely liquid, but also contain a gel-like coat that stabilizes the liquid core of P granules. The coat is made up of unusual, intrinsically-disordered proteins that can be stimulated by RNA to form gels in vitro. Similar proteins have been noticed across eukarya, raising the possibility that gel-like polymers may be a common strategy to create microcompartments in eukaryotic cells.