Expression of a modified antimicrobial peptide BhSGAMP-1-S (Bradysia hygida) in Escherichia coli and characterization of its activity.

OBJECTIVE

Bradysia hygida salivary glands antimicrobial peptide 1 (BhSGAMP-1) is one of the antimicrobial peptides involved in a preventive mechanism of defense of the fly Bradysia hygida. To know better about the molecular characterization of this antimicrobial peptide, we expressed and purified the modified BhSGAMP-1-S and investigated its antimicrobial activity.

METHODS

We synthesized the gene of BhSGAMP-1-S designed with preferred codons of Escherichia coli and expressed it as a fusion protein in E. coli TB1 by using pMAL-c2X as vector. We purified the fusion protein using amylase resin affinity chromatography. In addition, we cleaved the fusion protein by enterokinase and the released recombinant BhSGAMP-1-S was separated by size exclusion chromatography, then followed by reversed-phase high performance liquid chromatography. We analyzed the antimicrobial activities of the purified recombinant BhSGAMP-1-S by bioassays.

RESULTS

The fusion protein was mostly expressed in soluble form under the optimized conditions. The recombinant BhSGAMP-1-S was produced with a pure yield of 0.38 mg/100 mL culture medium. Antimicrobial assays demonstrated that the recombinant BhSGAMP-1-S was active against several Gram-positive and Gram-negative bacteria and fungi.

CONCLUSION

It appears to be the first successful production of the recombinant BhSGAMP-1-S from fly Bradysia hygida. Data presented here confirm that the recombinant BhSGAMP-1-S is now ready for further studying and characterizing their antimicrobial properties.