Functional characterization of the endolysin gene encoded by Pseudomonas aeruginosa bacteriophage PaP1

An endolysin gene was identified in PaP1, a novel virulent bacteriophage of Pseudomonas aeruginosa. The PaP1 endolysin gene encodes a 186 amino acid protein, containing a peptidoglycan binding domain at its C-terminus. Bioinformatic analysis revealed that PaP1 Endolysin possesses high sequence similarity with many bacteriophage endolysins or endolysin like genes at peptide level. The endolysin gene was cloned and expressed in Escherichia coli M15 (pREP4). Assays of the enzymatic activity of the purified recombinant protein indicated that PaP1 endolysin can hydrolyze the cell wall of P. aeruginosa and can inhibit the growth of Staphylococcus aureus. This protein is proposed to degrade the peptidoglycan of the host from within the cell at the terminal stage of the phage reproduction cycle. Biochemical analyses of the properties of this novel P. aeruginosa bacteriophage endolysin indicate that it has potential enzybiotic applications.