Recombinant expression and refolding of the c-type lysozyme from Spodoptera litura in E. coli

The chicken-type lysozyme of the insect Spodoptera litura (SLLyz) is a polypeptide of 121 amino acids containing four disulfide bridges and 17 rare codons and participates in innate defense as an anti-bacterial enzyme. The recombinant S. litura lysozyme (rSLLyz) expressed as a C-terminal fusion protein with glutathione S-transferase (GST) in Rosetta(DE3) Singles. The protein was produced as an inclusion body which was solubilized in 8 M urea, renatured by on-column refolding, and purified by reversed-phase chromatography to 95% purity. The purified rSLLyz demonstrated antibacterial activity against B. megateriumI confirmed by inhibition zone assay. The overexpression and refolding strategy described in this study will provide a reliable technique for maximizing production and purification of proteins expressed as inclusion bodies in E. coli.

Keywords
antibacterial activity, inclusion body, lysozyme, on-column refolding, recombinant expression, Spodoptera litura