Reconstruction and optimized expression of a synthetic secretory leukocyte protease inhibitor (SLPI) gene in Escherichia coli BL21
An active substance that has the greatest effect on wound healing is Secretory Leukocyte ProteaseInhibitor (SLPI). It is known that the SLPI encoding genes can be isolated and expressed onamnion membrane. Previous studies, we isolated and optimized the SLPI gene throughEscherichia coli BL21 (DE3) mediated pET101/DTOPO, which expressed active recombinanthuman SLPI (rhSLPI ) stored in pET-ESLPI. However, the expression of the rhSLPI products hasnot yet been accomplished. In this study, we optimized SLPI expression by developing a syntheticSLPI gene based on amino acid sequences with codons and expressed in E. coli BL21 to give themaximum expression. We used pUC57 and pET-32a plasmids to promote the cloning of syntheticSLPI genes. A codon-optimized SLPI gene was successfully synthesized with codon adaptationindex value showing the distribution of codon usage frequency along the length of the genesequence. In addition, the pET-SLPIopt fusion protein was successfully optimized with band sizesof 5900bp (pET-32a) and 413bp (SLPI) by double-digestion of NcoI and EcoI restriction enzymes.After the pET-SLPIopt was induced with various IPTG concentrations (50, 100 and 500 uM) at30°C, both soluble and insoluble fractions were analyzed as a result of SDS-PAGE which showedthat the fusion protein, expressed predominantly in the supernatant, was 29.18 kDa. Our reportedfindings the recombinant protein of SLPI through pET-32a plasmid could be expressed indissolved form.