Recent developments in difficult protein expression: a guide to E. coli strains, promoters, and relevant host mutations.

Escherichia coli is a versatile and popular tool for heterologous protein production. Some of the reasons for its popularity include rapid growth, a variety of portable vectors, relatively simple genetics, and the potential for high-density cultivation. In addition, the extensive laboratory use of E. coli has resulted in technologies to target protein overexpression to various intracellular compartments. This is advantageous because these compartments have different environments that may facilitate folding of particular proteins of interest. This chapter discusses the properties of many of the E. coli strains available for protein expression in order to facilitate the choice of the best expression host for a particular protein of interest.