Improving recombinant protein solubility in Escherichia coli: Identification of best chaperone combination which assists folding of human basic fibroblast growth factor

Manipulating the cytoplasmic folding environment by increasing the intracellular concentration of folding modulators, such as chaperone molecules, causes the convenient production of heterologous proteins. Wrong selection of chaperones will negatively affect the host cells physiology and the production of heterologous proteins. Due to this reason, type and combination of chaperone molecules are crucial to produce more soluble and active form of target protein. In the current study, the co-overproduction of five different combinations of 6 chaperones, comprising "DnaK/DnaJ/GrpE/GroES/GroEL", "GroES/GroEL", "DnaK/DnaJ/GrpE", "GroES/GroEL/TF" and "TF" along with recombinant human basic fibroblast growth factor (rhbFGF) were studied. As a result, we proved that none of these combinations was able to completely prevent the formation of inclusion bodies, but co-overexpression of the bacterial chaperone system TF along with rhbFGF could significantly enhance the yield of soluble protein. Recombinant soluble hbFGF that co-expressed with TF was then purified from the cells and was found to be identical to the active rhbFGF expressed alone with respect to size and spectral properties.