(392c) Enhancing Protein Secretion In E. Coli by Codon Engineering

Secretion of recombinant proteins to the extracellular media has the potential to reduce protein aggregation and to simplify downstream purification. Here we have studied the effect of synonymous codon changes on recombinant protein secretion via Type-I pathway in E. coli, based on our hypothesis that translation rate of heterologous protein may be related to the ability to secrete higher levels of product via this pathway. We observed that certain synonymous changes in codon usage in specific parts of the gene of interest can result in nearly 10 fold increase in secretion of active protein via Type-I pathway. We also investigated the effects of both the position of synonymous codon clusters as well as the types of codon changes on the intracellular and extracellular expression. The effect of synonymous codon changes on the folding of the polypeptide destined for secretion, and its intracellular fate was explored. We also tested the strategy to improve secretion via multiple secretion pathways and observed similar useful effects of codon engineering.