The B1 domain of Streptococcal protein G serves as a multi-functional tag for recombinant protein production in plants

Abstract

Plants have long been considered as a cost-effective platform for recombinant production. Recently recognized additional advantage includes the low risk of contamination of human pathogens such as viruses and bacterial endotoxins. Indeed, a great advance has been made in developing plants as a “factory” to produce recombinant proteins to use for biopharmaceutical purposes. However, there is still a need to develop new tools for recombinant protein production in plants. In this study, we provide data showing that the B1 domain of Streptococcal protein G (GB1) can be a multi-functional domain of recombinant proteins in plants. N-terminal fusion of the GB1 domain increased the expression level of various target proteins ranging from 1.3 to 2.8 fold at the protein level depending on target proteins. The GB1 fusion led to the stabilization of the fusion proteins. Furthermore, the direct detection of GB1-fusion proteins by the secondary anti-IgG antibody eliminated the use of primary antibody for western blot analysis. Based on these data, we propose that the small GB1 domain can be used as a versatile tag for recombinant protein production in plants.