Expression of Melittin in Fusion with GST in Escherichia coli and Its Purification as a Pure Peptide with Good Bacteriostatic Efficacy

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Abstract
The expression and purification of melittin (MET) in microbials are difficult because of its antibacterial activities. In this work, MET was fused with a glutathione-S-transferase (GST) tag and expressed in Escherichia coli to overcome its lethality to host cells. The fusion protein GST-MET was highly expressed and then purified by glutathione sepharose high-performance affinity chromatography, digested with prescission protease, and further purified by Superdex Peptide 10/300 GL chromatography. Finally, 3.5 mg/L recombinant melittin (rMET) with a purity of >90% was obtained; its antibacterial activities against Gram-positive Bacillus pumilus and Staphylococcus pasteuri were similar to those of commercial MET. A circular dichroism spectroscopic assay showed that the rMET peptide secondary structure was similar to those of the commercial form. To our knowledge, this is the report of the preparation of active pure rMET with no tags. The successful expression and purification of rMET will enable large-scale, industrial biosynthesis of MET.
Funding Information
  • State Administration of Foreign Experts Affairs (111-2-06)
  • Ministry of Education of the People's Republic of China (111-2-06, LITE2018-12)
  • Ministry of Science and Technology of the People's Republic of China (2018YFA0900302)
  • Government of Jiangsu Province (2015-SWYY-010)
  • Ministry of Finance (LITE2018-12)
  • National Natural Science Foundation of China (31970045)
  • National Development and Reform Commission of the People's Republic of China (LITE2018-12)

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