LytU-SH3b fusion protein as a novel and efficient enzybiotic against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a challenging infectious agent worldwide. The ever growing antibiotic resistance has made the researchers to look for new anti-staphylococcal agents. Autolysins are staphylococcal enzymes that lyse bacterial cell wall for cell division. Autolysins can be used as novel enzybiotics (enzymes have antibiotic effects) for staphylococcal infections. LytU is a newly explored autolysin. SH3b is a potent cell wall binding domain that can be fused to lytic enzymes to increase their activity. The aim of this study was to design a novel and efficient fusion enzybiotic that could lyse staphylococcal cell wall peptidoglycan by disrupting the bacteria. LytU-SH3b fusion construct was synthesized and LytU was amplified through the construct, using overhang PCR. The fusion and native forms that had his-tag were synthesized by recombinant technology in Escherichia coli BL21 (DE3) strain and purified utilizing Ni-NTA agarose beads. LytU and LytU-SH3b activity and potency were assessed using plate lysis assay, turbidity reduction assay and minimal inhibitory concentration (MIC) tests. All these tests showed that LytU-SH3b has more activity and potency than LytU. LytU-SH3b has MIC 421 fold lesser than LytU. Finally, LytU-SH3b is a novel and efficient recombinant enzybiotic that can lyse MRSA as an alternative to chemical small molecule antibiotics.