Cloning and Expression of Human Serum Albumin (HSA) in Escherichia coli

Background and Aim: Human serum albumin (HSA) is the most abundant protein in human blood plasma. It has multiple important physiological functions such as stabilizing plasma oncotic pressure, carrying a wide variety of compounds, and provisioning the bulk of plasma antioxidant activity. Like other pharmaceutical proteins, HSA is initially attained by fractionation of collected human blood plasma. However, blood is a finite and insecure source for the generation of human therapeutic drugs. Moreover, extracted proteins can be contaminated with various blood-derived pathogens such as human immunodeficiency virus (HIV) and hepatitis. Thereby, it is necessary to achieve simple and efficient approach for production of pharmaceuticals.Methods: In this study, cloning of HSA gene into the pET-۲۸a(+) expression plasmid under control of a bacteriophage T۷ RNA polymerase promoter system allowed IPTG-inducible production of recombinant HSA protein in Escherichia coli strain BL۲۱. In this direction, transformed bacteria were cultured in liquid LB medium supplemented with ۱ mM IPTG. To measure expression level of recombinant protein, the culture was inoculated on rotary shaker (۱۵۰ rpm) at ۳۷ °C for different duration time (۰, ۴, ۸, ۱۲ and ۱۶ h). Recombinant HSA protein was purified from the transformed bacterial cell extract by Immobilized Metal Affinity Chromatography using a Ni-NTA column. The amount of the purified rHSA was determined by the Bradford total protein assay kit.Results: The results indicated that IPTG has a key role in expression of rHSA gene in the host cells. The production of rHSA protein was not observed in bacterial cells during ۰ h of IPTG-treatment. The maximum expression of recombinant protein occurred when ۱ mM IPTG was used for ۱۲ h.Conclusion: Today, recombinant human proteins make up a considerable part of FDA-approved biotechnological drugs. Microbial expression platforms are the most commonly used systems among the expression hosts. E. coli system is widely used for the production of heterologous recombinant proteins due to its easier culture, short life cycle, well-known genetics, and easy genetic manipulation. In this experiment recombinant HSA was successfully expression in E. coli.

Keywords:

Recombinant protein , Human Albumin , E. coli , Expression vector