IRG 1: Bacterial Nanoreactors

The nanometer scale polyhedral protein compartments (carboxysomes) found in many bacteria harbor an enzyme (RubisCO) that converts carbon dioxide to sugars, which in turn are used by the cell to synthesize other biomolecules. One of the carboxysome shell proteins (e-carbonic anhydrase) was found to catalyze the dehydration of bicarbonate and to direct the resulting CO 2 toward the inside of the carboxysome, where it is efficiently metabolized by RubisCO. It is currently thought that the orientation of the carbonic anhydrase in the protein shell constitutes a chemical diode that makes the carboxysome shell directionally permeable to CO 2 and allows it to function analogous to polymer film-immobilized catalysts. Work is currently underway to understand the self-assembly of carboxysome protein components, which ultimately may guide efforts to synthesize selectively permeable protein-based films for potential pharmaceutical or manufacturing applications.

So, A.-K., Espie, G.S., Williams, E.B., Shively , J.M., Heinhorst, S. and Cannon, G.C.: J. Bacteriol. 186: 623-630 (2004).