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.
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