Expression of Native-Sized Spider Silk Protein in Escherichia coli through Metabolic Engineering and Synthetic Biology Approach

Naturally found spider silk and elastin protein attract attention due to its outstanding physical properties coming from the highly repeated structure and size. However, the exceptional structure and size limits expression in heterologous hosts, where the repetitive sequences in mRNA create extensive secondary structures. And these structures decrease ribosome processivity and assist mRNA degradation. Using the naturally found protein as a model we present techniques to solve biological problems that occurred: using metabolic engineering to supply aminoacyl-tRNA pool as well as decreasing the RNase activity to assist higher production of the spider silk protein. The newly synthesized native-size spider dragline silk protein produced highest titer in Escherichia coli than those reported previously. The results provide insight into approaches to control expression of useful recombinant proteins containing high molecular weight and highly repetitive sequence. [This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation (NRF) of Korea (NRF-2012M1A2A2026556 and NRF-2012M1A2A2026557); the Intelligent Synthetic Biology Center through the Global Frontier Project (2011-0031963) of the Ministry of Education, Science and Technology (MEST) through the National Research Foundation of Korea]