Effect of protein fusion on the stability of proteolytically sensitive sites in recombinant DNA proteins

Abstract

Different recombinant fusion proteins expressed intracellularly in E. coli were studied with respect to their stability against proteolytic degradation. The fusion proteins have a common N-terminal derived from the IgG-binding domains of staphylococcal protein A, but differ in size, structure and function of their C-terminal parts. The constructions include fusion to the IgG-binding domains of streptococcal protein G and/or E. coli β-galactosidase. All fusion proteins were soluble and had IgG binding and, if furnished with β-galactosidase, also enzymatic activity. It was found that the C-terminal region of protein A was susceptible to degradation by cytoplasmic proteases. Fusion of protein G and/or β-galactosidase to the C-terminal of the sensitive proteins protected them from proteolysis.