Design and Production of a Chimeric Enzyme with Efficient Antibacterial Properties on Staphylococcus aureus

Abstract

Improper use of antibiotics has alarmingly led to the emergence of antibiotic resistance. Hence, this necessitated an urgent need 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 2 (LYZ2) is a modular region of the gene 61 (gp61) of phage φMR11 with lytic activity against S. aureus. However, it does not possess a cell wall recognition domain, which is usually found in lysins acting against gram-positive bacteria. Therefore, in this study, we engineered the LYZ2 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 (CST_Enz)) into the pET28a vector, and expressed the enzyme in E. coli BL21 (DE3) cell. The 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 0.5 µg/ml. Besides, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of CST_Enz were both approximately 64 times lower than those of LYZ2, indicating the increased bacteriolytic activity of the engineered version of the enzyme. In conclusion, the chimeric enzybiotic can be used as a potential antibacterial agent to limit infections caused by methicillin-resistant Staphylococcus aureus (MRSA).