Cloning and Characterization of an Endolysin LysSA120 as a Potential Staphylococcus Biofilm-Removing Agent

Staphylococcus aureus, including methicillin- and vancomycin-resistant variants (MRSA, VRSA), causes infections that are increasingly difficult to treat with conventional antibiotics. One of the approaches to developing new therapeutics to treat staphylococcal infections is the use of bacteriophages specific to these bacteria or the lytic enzymes of such bacteriophages, which are capable of hydrolyzing the cell walls of these bacteria. Phage-encoded endolysins offer an alternative promising class of antimicrobial agents. In this study, LysSA120, a 250-amino-acid endolysin encoded by the S. aureus podophage vB_SauP_120, was cloned, expressed in Escherichia coli, and characterized. The domain organization and tertiary structure of LysSA120 were predicted. Recombinant LysSA120 hydrolyzed cell walls were obtained from S. aureus, S. epidermidis, S. haemolyticus, S. warneri, S. auricularis and S. saprophyticus. It was shown that treatment of S. aureus planktonic cells with endolysin LysSA120 led to reduced viability. Furthermore, LysSA120 could hydrolyze mature biofilm formed by VRSA. The lytic spectrum and antibiofilm activity of LysSA120 warrant its further evaluation as an enzybiotic against drug-resistant staphylococcal infections.