Expression System Evaluation and Optimization
Advances in E. coli expression of recombinant proteins are numerous and expanding. A major concern with this host is the production of insoluble protein (i.e. inclusion bodies). The Protein Expression Laboratory monitors developments in this field and is activity evaluating new E. coli strains and co-expression factors (particularly chaperones) in order to increase the yield of recombinant protein production. In a recent study, we have found an E. coli strain, BL21 (DE3) rnaseE pDsbC/Skp developed by Deb Chatterjee, to be quite effective at expressing higher levels of soluble protein than our previously used strain. In conjunction with Dom Esposito, we are planning to create a new strain that would allow the presence of two plasmids which currently are incompatible: a rare tRNA plasmid (present in our current strain and proven effective in overcoming the codon-bias of non-E. coli genes) and pDsbC/Skp. To help understand this result, and allow future analysis of new factors, new strains will be tested with a specific protein test panel containing “difficult proteins” to evaluate improvements to our current methods.