Design and Production of an Engineered Endolysin with Lytic Activity against Methicillin-Resistant Staphylococcus Aureus

BACKGROUND AND OBJECTIVESImproper use of antibiotics has alarmingly led to the emergence of antibiotic resistance. Hence, we urgently needed to find a suitable alternative to traditional antibiotics. Endolysins are enzymes produced at the end of the phage replication cycle and destroy the peptidoglycan of the bacterial cell wall leading to the lysis of the host bacterial cell. These enzymes are species-specific, exhibit high lytic activity, and it is almost impossible for bacteria to develop resistance against them. Lysozyme subfamily ۲ (LYZ۲) is a modular region of the gene ۶۱ (gp۶۱) of phage φMR۱۱ with lytic activity against S. aureus. However, it does not possess a cell wall recognition domain, usually found in lysins acting against gram-positive bacteria. Therefore, we aimed to design a chimeric endolysin capable of specifically targeting and eliminating methicillin-resistant Staphylococcus aureus (MRSA) bacteria.MATERIALS AND METHODSIn this study, we engineered the LYZ۲ by fusing a Staphylococcus aureus cell wall-binding domain (CBD) to its C-terminus and cloned the chimeric protein (named chimeric staphylococcus aureus–targeting enzybiotic (CSTEnz)) into the pET۲۸a vector, and expressed the enzyme in E. coli BL۲۱ (DE۳) cell. The antibacterial property of the enzyme was further evaluated by turbidity reduction assay, disk diffusion assay, and antimicrobial susceptibility testing.RESULTS AND DISCUSSIONThe engineered lysin displayed a rapid and specific lytic activity against susceptible and Methicillin-resistant staphylococcus aureus and inhibited the growth of the bacteria at concentrations higher than ۰.۵ μg/ml. Besides, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of CSTEnz were ۱۲۸ and ۶۴ times lower than those of LYZ۲, indicating the increased bacteriolytic activity of the engineered version of the enzyme.CONCLUSIONIn conclusion, the chimeric enzybiotic can be used as a potential antibacterial agent to limit infections caused by methicillin-resistant Staphylococcus aureus

کلیدواژه ها:

Endolysin ، Methicillin-Resistant Staphylococcus aureus ، Antibiotic Resistance ، Phage ، enzyme Engineering