Atmospheric carbon dioxide levels are higher today than at any point in the past 800,000 years, therefore, understanding carbon fixation mechanisms has become very important. Almost half of global carbon remediation is performed by bacteria that package the machinery required to fix carbon dioxide into organelles made entirely of protein called carboxysomes. Despite their importance to the global carbon cycle, how a carboxysome is organized in the cell is unclear. This research will elucidate the mechanisms of carboxysome organization to understand how this vital organelle is maintained in a cell population. An understanding of the basic biological mechanisms by which carboxysomes are organized will provide a means to utilize them for synthetic biology applications. This project will further NSF’s mission of expanding science and engineering research potential by improving natural carbon fixation and has broad impacts on education, engaging the public, and increasing scientific literacy by giving the public an appreciation for how bacterial function can have global implications.

Organelles are traditionally thought of as lipid bound and restricted to eukaryotic cells. It is now appreciated that membraneless organelles are present in all cell types. A recently identified way to form a membraneless organelle is by Liquid-Liquid Phase Separation, where proteins condense into droplets. Little is known about how membraneless organelles are organized in a cell. Several recent studies suggest the carboxysome has liquid-like properties - a paradigm shift in our understanding of these carbon-fixing organelles. In the cyanobacterium Synechococcus elongatus, carboxysomes are evenly spaced along the cell length. The project team recently identified the system responsible for the maintenance of carboxysome distribution, but the mechanism remains unknown. This research will contribute the first mechanistic understanding of how liquid-like organelles are spatially organized in bacteria.

This project is jointly funded by the Cellular Dynamics and Function and Molecular Biophysics Clusters, Division of Molecular and Cellular Biosciences, Directorate for Biological Sciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

National Science Foundation (NSF)
Division of Molecular and Cellular Biosciences (MCB)
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Charles Cunningham
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Regents of the University of Michigan - Ann Arbor
Ann Arbor
United States
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