New tools for new antibiotic targets – The development of novel probes for mechanistic studies on bacterial glycolipid-processing enzymes

In 2019 antimicrobial resistance (AMR) killed more people than breast cancer, HIV and malaria. Addressing AMR is a real-world need (QUB Strategy 2030). Bacteria produce many different glycopolymers that are vital to their survival, including peptidoglycan, which is a key component of the bacterial cell wall required for structural integrity, and lipopolysaccharide (LPS), which protects Gram-negative bacteria from bile salts and lipophilic antibiotics. The bacterial cell wall is targeted by many clinically used antibiotics, including penicillin, vancomycin and fosfomycin. Peptidoglycan and LPS biosynthesis involve several key glycolipid intermediates, all of which are linked to the cell membrane by the universal lipid carrier, undecaprenyl phosphate. The enzymes that process undecaprenyl-containing biomolecules are hot antibiotic targets, as they are unique to bacteria and absolutely essential to their growth. In particular, a class of enzymes called flippases, which transport some undecaprenyl-linked biomolecules across cell membranes, may be the Achilles heel of bacteria as they are a bottleneck in glycopolymer syntheses. However, detailed studies on these enzymes have been limited due to a lack of suitable probes to interrogate their mechanism of action. An understanding of enzyme mechanism is a vital pre-requisite to the rationale design of inhibitors.

This project has two main objectives: 1) to develop novel high-throughput assays for flippases that allow mechanistic studies and inhibitor screens to be performed; and 2) to develop substrate mimics that can be co-crystallized with flippases. This is a highly interdisciplinary project. Natural product isolation, the chemical synthesis of glycolipid probes and enzymatic assays will be performed in the Cochrane Lab. Protein expression and the growth of protein crystals and protein/glycolipid co-crystals will be performed along with collaborators in the Caffrey Lab at Trinity College Dublin. The student will also complete a 3 month internship at the Swiss Lightsource in the Paul Scherrer Institut (Switzerland) macromolecular X-ray crystallography.

For more information please contact: Dr Stephen Cochrane (s.cochrane@qub.ac.uk) 

Applications must be submitted online, by the deadline, using the QUB Direct Application Portal https://dap.qub.ac.uk/portal/user/u_login.php