Protein Inclusion Bodies in Recombinant Bacteria

Abstract

Fast and high-level expression of heterologous proteins in bacterial hosts often results in the accumulation of almost pure aggregates (inclusion bodies, IBs) of the target protein. Although knowledge of the pathways and influential factors of protein folding in vivo has increased for many years, the complexity of the cellular networks does not allow easily the prediction of favourable conditions for production of correctly folded proteins. Therefore, IB-based production is still a potential and straightforward strategy for the production of complex recombinant proteins. IB-based processes combine the advantages of a high concentration of the target protein produced in well-characterized bacteria such as Escherichia coli, efficient protocols for IB isolation, purification and in vitro protein refolding without the need of elaborate coexpression systems and time-consuming trial-and-error expression optimization. Recent advances in understanding the molecular physiology of IB formation and in resolubilization enable a streamlined development of fermentation processes to obtain a high-quality product. In addition, simple strategies have been established to improve the purification and renaturation of disulfide bond containing proteins allowing for a fast transfer of those processes to industrial production scale.