Prokaryotic Expression of Antimicrobial Peptide CATH PR1-2 from the Skin of Paa robertingeri in Escherichia coli

The aim of this study was to investigate the prokaryotic expression of antimicrobial peptide cathelicidin (CATH) PR1 and PR2 from the skin of Paa robertingeri in Escherichia coli. Two active peptides, CATH PR1 and CATH PR2, belong to the CATH family in the skin of P. robertingeri. CATH PR1 has a relatively high antimicrobial activity, especially for the drug-resistant strains found in clinical practice; however, no antimicrobial activity has been found in CATH PR2. The molecular weights of both CATH PR1 and CATH PR2 are relatively low (3195.88 and 2838.34 Da, respectively). Thus, the genetic processes, as well as the expression and purification of these proteins, are difficult to perform. Therefore, in this study, CATH PR1 and CATH PR2 genes were tandem ligated and then connected to the plasmid pET-32a. This reconstructed plasmid was then transfected into the expression vector E. coli BL21 to construct the recombinant expression system. The fusion expression of peptide PR was stable in E. coli after induction with 1.0 mol/L isopropyl beta-D-1-thiogalactopyranoside at 37 degrees C for 4 h. The antimicrobial activity assay using Staphylococcus aureus (Song) and Candida albicans 08030102 showed that the antimicrobial activity of PR was similar to the antimicrobial activity of CATH PR1. This study showed that artificial modification of the amino acid sequences of PR1 and PR2 could result in better protein expression in prokaryotes, and the fusion protein expressed had relatively high antimicrobial and other biological activities. In conclusion, the findings suggest future prospects of the commercialization of this method.