Summary: | <p>Abstract</p> <p>Background</p> <p>The overproduction of recombinant proteins in host cells often leads to their misfolding and aggregation. Previous attempts to increase the solubility of recombinant proteins by co-overproduction of individual chaperones were only partially successful. We now assessed the effects of combined overproduction of the functionally cooperating chaperone network of the <it>E. coli </it>cytosol on the solubility of recombinant proteins.</p> <p>Results</p> <p>A two-step procedure was found to show the strongest enhancement of solubility. In a first step, the four chaperone systems GroEL/GroES, DnaK/DnaJ/GrpE, ClpB and the small HSPs IbpA/IbpB, were coordinately co-overproduced with recombinant proteins to optimize <it>de novo </it>folding. In a second step, protein biosynthesis was inhibited to permit chaperone mediated refolding of misfolded and aggregated proteins <it>in vivo</it>. This novel strategy increased the solubility of 70% of 64 different heterologous proteins tested up to 42-fold.</p> <p>Conclusion</p> <p>The engineered <it>E. coli </it>strains and the two-step procedure presented here led to a remarkable increase in the solubility of a various recombinant proteins and should be applicable to a wide range of target proteins produced in biotechnology.</p>
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