Polycistronic expression of CGA-N46 gene in Bacillus subtilis DB1342

CGA-N46 is a small antifungal derived peptide and consists of the 31st to 76th amino acids of the N-terminus of human Chromogranin A. Polycistronic expression of CGA-N46 gene in Bacillus subtilis DB1342 was used to improve its production. Single, double and three copies of exogenous gene fragment which contained ribosome binding site (RBS),sacB signal peptide nucleotide sequence (sacB s), CGA-N46 encoding sequence (cga-N46) and stop codon were tandem constructed into the muticloning sites of pSBPTQ. The engineered expression plasmids which bore monocistronic, bicistronic and tricistronic expression cassettes of the CGA-N46 gene were transformed into the competent B. subtilis strain DB1342. The expression results of the engineered strains DB1342(p-N46), DB1342(p-2N46) and DB1342(p-3N46) demonstrated that monocistronic and bicistronic expression systems produced low amounts of CGA-N46 while the tricistronic expression system improved the production of the peptide. Our results are helpful for improving the production of small peptides by engineered strains.   Key words: Antifungal peptide, CGA-N46, Polycistronic expression, Secreted expression.