Purification and Immunity Analysis of Recombinant 6His- HPT Protein Expressed in E.coli

Key words: 
• HPT /
• Expression and purification /
• E. coli /
• Immunity activity

Abstract: Objective To obtain HPT protein (Hygromycin B Phosphotransferase), a kind of plantselective maker gene product expressed from E. coli and to prepare the polyclonal antibody (pAbs)against it. Methods HPT cDNA fragment was obtained by PCR and was inserted into theprokaryotic expressing vector pBV222. Then the constructed recombinant plasmid pBV222-HPT wastransfered into E. coli DH5α for HPT expression. The recombinant expressing system was confirmedby restriction endonuclease digestion, DNA sequencing and protein expression. E. coli cells were lysedby sonication and detergent dissolution. After cell membrane was extracted, the inclusion bodies weredenatured by 8 mol/L Urea and purified with metal chelate affinity chromatography on Ni-NTAagarose under denaturing condition. The purified 6His-HPT was characterized by SDS-PAGE, andused to immunize rabbit. The titer and specificity of antisera were detected by ELISA and Westernblot respecitively. Results Analysis of DNA sequence and restricted enzymes showed that thesequence of PBV222-HPT plasmid was correct. The amount of recombinant HPT expressed in E. coliaccounted for 30% of total cellular proteins. From 1 liter of fermentative bacteria about 22 milligramsof pure recombinant HPT was isolated with purity above 95%. The recombinant HPT protein couldproduce high titer antiserum in rabbits and show good immunity activity. Western blot showedspecific binding reaction between the antiserum to the purified 6His-HPT protein and their expressedproducts (plants protein and bacterial protein). Conclusion HPT protein can be expressed andpurified from E. coli by a relatively simple method, which has high immunity activity.