Overproduction and purification of the recombinant, heterologous proteins from Escherichia coli cells

Production of sufficient amounts of chemically and conformationally homogenous proteins is a major requirement for basic research (functional and structural studies of proteins) as well as for application studies (immunoprophilaxis and therapy). Over the past twenty years, numerous expression systems (based on prokaryotic, yeast, insect, plant and mammalian cell cultures) have been described and tested for protein overproduction and purification. Here, we describe the major recent advances relevant to the successful overproduction and purification of heterologous proteins in the Escherichia coli system which is, thus far, the most commonly used organism for heterologous protein production. Issues addressed in this review include: vectors used for recombinant protein expression, cloning strategies and using different fusion tags that enhance protein solubility and facilitate protein purification. The influence of recombinant protein localization on enhancing the total protein yield and on retaining their native conformation is also discussed.