Reconstitution of Outer Membrane Protein Assembly from Purified Components

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Science  08 Apr 2010:
DOI: 10.1126/science.1188919


β-Barrel membrane proteins in Gram-negative bacteria, mitochondria, and chloroplasts are assembled by highly conserved multiprotein complexes. The mechanism by which these molecular machines fold and insert their substrates is poorly understood. It has not been possible to dissect the folding and insertion pathway because the process has not been reproduced in a biochemical system. We purified the components that fold and insert E. coli outer membrane proteins and reconstituted β-barrel protein assembly in proteoliposomes using the enzymatic activity of a protein substrate to report on its folding state. The assembly of this protein occurred without an energy source, but required a soluble chaperone in addition to the multiprotein assembly complex.