A New Bacterial Co-expression System for Over-expressing Soluble Protein and Validating ProteinProtein Interaction

Toxic, membrane, and hydrophobic proteins are usually difficult to individually over-express in Escherichia coli because they require a binding-partner protein for folding and stability. To obtain these types of soluble proteins or protein complexes, protein co-expression is used. Such co-expression systems are extremely suitable for the high-throughput validation of protein–protein interactions. In a previous study, we developed a novel co-expression vector, pHEX, which is compatible, and thus can be partnered, with many commercially available E. coli vectors, such as pGEX and pMAL. Either of the vectors allows proteins to be expressed individually as a tagged fusion protein and can be used directly for protein co-purification. This protocol presents the experimental procedure for the co-expression method.