Recombinant expression of sericin-cecropin fusion protein and its functional activity

Objective Silk sericin is a natural polymer with potential utility in biomedical and biotechnological applications. Recombinantly expressed sericin ensures a source of pure protein with no contamination and with multiple properties when expressed as a fusion protein. Hence, the present paper aims to recombinantly express a functional silk sericin fusion protein. Results In order to develop a more effective sericin protein, we have attempted to recombinantly express a part of sericin sequence, which represents a highly conserved and internally repetitive unit of the sericin1 protein, and its fusion with cecropin B, a potent antimicrobial peptide. Both difficult-to-express proteins were expressed in Escherichia coli and purified by nickel-charged affinity resin. Further, functional assay demonstrated that both proteins were individually active against Gram-positive and negative bacteria, with enhanced bactericidal activity observed in sericin-cecropin B fusion protein. Conclusions To our knowledge, this is the first report not only on the recombinant expression of sericin as a fusion protein but also the bactericidal possibility of the 38-amino acid serine-rich motif of sericin protein. We also discuss the potential biomedical and biotechnological applications of this sericin hybrid protein.