The Bacterial Translocase MraY: A Potential Antibiotic Target

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Antibiotic resistance is a huge problem facing the modern world. With only 1 new class of antibiotics approved in the last 30 years, the UK's chief medical officer Dame Sally Davies has described antibiotic resistance as a threat equivalent in severity to bioterrorism. Consequently there is an urgent need for novel antibiotic targets and the drugs themselves. MraY is a translocase enzyme that has a role in the synthesis of the peptidoglycan cell wall of bacteria by transferring the peptidoglycan subunits across the cell membrane. These are then crosslinked to form the 'chain-link'-like mesh of the cell wall by other enzymes that have commonly been the target of existing antibiotics such as vancomycin and the beta-lactams, including penicillin. Existing work has identified an antibacterial E-protein from a bacteriophage that targets MraY via protein-protein interactions which has a specific residue pattern on either side of the interaction. Analogues to this site have been synthesised, and with the recent publication of the MraY crystal structure in Science the hope is that this motif may be exploitable.

This research project will attempt to create a site directed MraY mutant against which existing antimicrobial peptides can be tested and quantified by fluorescence assay. It is hypothesised that aromatic pi-bond interactions may dictate the strength of MraY-E protein binding and so this area was targeted for mutagenesis. Additionally, a G4 bacteriophage peptide has been shown to inhibit with a different sequence and these interactions will be probed. IC50 levels were elucidated for pairwise combinations of E-proteins and synthetic inhibitors against the mutant enzymes generated during the project.

This project, while limited by time and materials, showed some promising preliminary results that can be explore further.