Characterization and functional recovery of a novel antimicrobial peptide (CECdir-CECret) from inclusion bodies after expression in Escherichia coli.

CECdir-CECret is a novel non-toxic doublet 8.5 kDa peptide representing the natural coding sequence of the antimicrobial peptide Cecropin A from Drosophila melanogaster fused in-frame to its own inverted version. Expression of this cloned doublet peptide in Escherichia coli, yielded peptides that were mostly packaged into inclusion bodies. The new molecule was purified, solubilized and refolded, through a standard guanidine-based procedure. The recovered refolded peptides were then characterized by HPLC chromatography, MALDI-TOF-mass spectrometry and peptide sequencing, and finally evaluated for their antimicrobial potential. The novel doublet peptide CECdir-CECret, displays an enhanced in vitro antimicrobial activity and action spectrum in comparison to the monomer Cecropin A.