Cloning, purification, and antibacterial activity of the pneumococcal bacteriophage lytic enzyme CPL-1

Objective: To produce phage lytic enzyme CPL-1 by gene engineering. Methods: According to the bias of codon utilization of Escherichia coli, the cpl-1 gene was synthesized and inserted into the vector pET28a to construct the recombinant expression plasmid (pET28a-cpl-1) and then transformed into BL21 (DE3). Results: Recombinant CPL-1 was expressed and resulted in soluble form that amounted to 30% (w/w) of total cellular proteins, and then purified by affinity chromatography on DEAE-sepharose. The final recovery of recombinant CPL-1 was 70% and >97% in purity. In vitro susceptibility testing showed that purified CPL-1 had significant antimicrobial activity. Conclusions: Development of CPL-1 may provide a new method to prevent and treat S. pneumoniae infection.