Improving soluble expression of a single-chain antibody fragment against human epidermal growth factor receptor 2 (her2) by co-expression of chaperones

Amir Mirzapour estabragh,1,* Vajihe akbari,2 Hamid mir mohammad sadeghiˡ,3

1. Department of Pharmaceutical Biotechnology, Isfahan University of Medical sciences
2. Department of Pharmaceutical Biotechnology, Isfahan University of Medical sciences
3. Department of Pharmaceutical Biotechnology, Isfahan University of Medical sciences

Abstract


Introduction

The human epidermal growth factor receptor (her) family plays an important role in cell growth and signaling, and its expression is altered in many kinds of cancer cells. antibody fragments can be substitutes for complete antibodies in many of their therapeutic and diagnostic applications. in previous studies, the therapeutic potential of an antibody fragments for treating her2-related cancers has also been reported. however, the majority of anti-her2his-scfv protein was expressed as inclusion bodies by escherichia coli. various methods have been proposed to stop or reduce the formation of inclusion bodies during the production of recombinant proteins. one of them is the co-expression of molecular chaperones with these proteins.

Methods

The mixture of plasmids pkje7 and pet22b-scfv was transformed by the electroporation method to the cells of the e. coli strain bl21(de3). bacteria harboring chaperone and scfv gene were cultured and when the culture reached to od600 of 0.5, arabinose was added to induce expression chaperone and iptg (1mm) was used to express the scfv protein. then, bacterial cells were harvested and dispersed in a suitable buffer, and the cells were lysed by sonication. the soluble and insoluble fractions of cell lysate were separated by centrifugation and each part was purified using a ni-nta affinity column. to compare the expression level antibodies were used in each system of expression by sds-page and western blotting assay, as well as the method of bradford to determine protein concentration.

Results

Our results showed that the majority (80-90 %) of anti-her2his-scfv” was expressed as inclusion bodies and insoluble protein. however, co-expression of chaperones and anti-her2his-scfv significantly increase soluble expression of anti-her2his-scfv.

Conclusion

The results obtained in the present study indicate that co-expression of molecular chaperones pkje7 will enhance solubility and as result the biological function of anti-her2his-scfv expressed by e. coli.

Keywords

Her2; single-chain variable fragment; molecular chaperone; inclusion bodies; protein folding