Tuning different expression parameters to achieve soluble recombinant proteins in E. coli: advantages of high-throughput screening

Proteins are the main reagents for structural, biomedical, and biotechnological studies; however, some important challenges remain concerning protein solubility and stability. Numerous strategies have been developed, with some success, to mitigate these challenges, but a universal strategy is still elusive. Currently, researchers face a plethora of alternatives for the expression of the target protein, which generates a great diversity of conditions to be evaluated. Among these, different promoter strength, diverse expression host and constructs, or special culture conditions have an important role in protein solubility. With the arrival of automated high-throughput screening (HTS) systems, the evaluation of hundreds of different conditions within reasonable cost and time limits is possible. This technology increases the chances to obtain the target protein in a pure, soluble, and stable state. This review focuses on some of the most commonly used strategies for the expression of recombinant proteins in the enterobacterium Escherichia coli, including the use of HTS for the production of soluble proteins.