The Gram-negative bacterium Escherichia coli is one of the most attractive host employed in the heterologous production of proteins. However, these target proteins are deposited as insoluble aggregates known as inclusion bodies (IBs) and hence are biologically inactive. The ubiquitous molecular chaperones, a group of unrelated classes of polypeptides help in the mediation of proper folding of the target protein. However, the choice of chaperone(s) is still based on a trial-and-error procedure. Wrong choice of chaperone(s) will affect both the host micro-organism and product stability, negatively. Recent advances in the mechanisms and substrate specificities of the major chaperones and their roles in the chaperone-network now gives some ideas for more rational choice of the chaperone(s) for co-expression. Here, the functions and mechanisms of interactions between the major molecular chaperones are presented.
Key words: molecular chaperones, inclusion bodies, heterologous, aggregates, protein folding