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Septin assembly and organization from yeast to mammals

Cytoskeletal polymer systems assemble into diverse and dynamic arrays for proper cell structure and function. The septins are a highly conserved component of the cytoskeleton that are important for processes such as cytokinesis, membrane compartmentalization, and exocytosis. These filament-forming, GTP-binding proteins are widely expressed from fungi to mammals, where they are especially enriched in the mammalian brain. Septins come together in cells to build higher-order structures such as rings, bars, and fibers. Despite the ubiquity and central role of septins in fundamental cell processes and disease, there are substantial gaps in our understanding of the mechanisms driving septin polymer assembly, dynamics and function in vivo. We have applied and developed novel imaging approaches to analyze septin organization in cells with diverse septin assemblies, functions and shapes. 

Our work on this problem has led to the development of new polarized fluorescence microscopy approaches with collaborator Rudolf Oldenbourg at the Marine Biological Laboratory in Woods Hole, MA.  In the movie below you can see septins at the budding yeast neck going through a splitting transition for cytokinesis.  The lines on the left of the image and the colors on the right represent the orientation of the dipole moments of the population of GFPs.  We analyzed the orientation of the GFP fused to septins through this transition and found septins dramatically change organization in this transition in a matter of minutes.  We are now looking at individual septin molecules during this transition to understand the basis of this swift reorientation.

 

Last Updated: 5/28/14