A Novel RNA Scaffold System for the Enhancement of the in vivo Solubilization of Recombinant Proteins in Escherichia coli

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Almando Geraldi, Le Minh Bui, Sun Chang Kim

Korea Advanced institute of Science and Technology, South Korea

Inclusion bodies formation of recombinant proteins is one of the major obstacles for their industrial applications. Several approaches such as the use of solubility-enhancing tags, the overexpression of folding modulators, and the modification of physicochemical conditions, have been explored to minimize the formation of inclusion bodies. To further minimize the formation of inclusion bodies while increasing the solubility of recombinant proteins, we designed a novel RNA scaffold system in which a molecular chaperone DnaJ was fused with an RNA binding domain that specifically binds a unique RNA sequence in an engineered RNA hairpin loop structure on the 3’-UTR of the recombinant protein-encoding mRNA. Arranging molecular chaperones in proximity with the translational machinery of recombinant proteins can promote the rapid interaction between molecular chaperones and newly synthesized recombinant proteins to prevent the formation of inclusion bodies. As expected, our RNA scaffold system successfully increased the solubility of selected aggregation-prone proteins overproduced in Escherichia coli (UDP-6-glucose-dehydrogenase, anti p21-Ras ScFv, and anti p21-Ras ScFv fused with a cell penetrating peptide). Our RNA scaffold system would provide a valuable tool for the production of recombinant proteins in soluble and active forms in E. coli as well as for the improvement of the yields of metabolically engineered pathways.