DnaK/DnaJ-assisted recombinant protein production in Trichoplusia ni larvae.

The DnaK/DnaJ Escherichia coli chaperone pair, co-produced along with recombinant proteins, has been widely used to assist protein folding in bacterial cells, although with poor consensus about the ultimate effect on protein quality and its general applicability. Here, we have evaluated for the first time these bacterial proteins as folding modulators in a highly promising recombinant protein platform based on insect larvae. Intriguingly, the bacterial chaperones enhanced the solubility of a reporter, misfolding-prone GFP, doubling the yield of recombinant protein that can be recovered from the larvae extracts in a production process. This occurs without negative effects on the yield of total protein (extractable plus insoluble), indicative of a proteolytic stability of the chaperone substrate. It is in contrast with what has been observed in bacteria for the same reporter protein, which is dramatically degraded in a DnaK-dependent manner. The reported data are discussed in the context of the biotechnological potential and applicability of prokaryotic chaperones in complex, eukaryotic factories for recombinant protein production.