KARBOXYSOMEN - STRUKTUR AV EN CELLORGANELL
Tidsperiod: 2012-01-01 till 2014-12-31
Projektledare: Inger Andersson
Budget: 1 900 000 SEK
The aim is to study the structure and function of the CO2-concentration machinery in phytoplankton. Competition between O2 and CO2 at the active site of the CO2-fixing enzyme, Rubisco, reduces the efficiency of carbon fixation, and poses a general problem for all photosynthetic organisms. The conditions are particularly severe in the oceans, because CO2 supplies are restricted by slow diffusion rates and high pH values. To boost the CO2-concentration to a level that sustains growth, phytoplankton have evolved CO2-concentrating mechanisms (CCMs), using transporters and specialised organelles named carboxysomes. As a result, marine CO2-fixation is extremely efficient with a significant environmental impact. Little is known about the composition, organisation, and 3D structure of carboxysomes. They are believed to contain Rubisco and carbonic anhydrase enzymes enclosed in a protein shell and possibly additional components. Carboxysomes are believed to change their structures depending on illumination and CO2-concentration. We study the structural systems biology of photosynthetic carbon fixation in picoplankton, containing CCMs with the aim to describe the interactions of the individual components. Biochemical and structural studies on cells and on isolated organelles/components are underway. Our goal is to obtain a 3D structure for the intact carboxysome by ultrafast coherent diffraction. Our recent results on cells and viruses show this to be feasible.