Stuck in Transit: a High-Res ssNMR Study on the Antibiotic Murepavadin that Targets the Essential Outer Membrane Protein LptD and Disrupts LPS Transport in Gram-Negative Bacteria

Abstract

Antibiotics are extremely important in this day and age for the general health of the populace. There is sadly a major problem with the widespread (over)use of these drugs: cases of multi-drug resistant bacteria, especially Gram-negative bacteria are becoming more prevalent. These Gram-negative superbugs have an additional impregnable membrane that greatly increases their resistance towards their environment and antimicrobial compounds. We will need novel antibiotics to combat these pathogens, however only very few novel antibiotics have been approved for clinical use in the last decades. Murepavadin is a β-hairpin peptidomimetic antibiotic that is active against ESKAPE pathogen Pseudomonas aeruginosa (Pa). Pa is a major cause of death in patients suffering from cystic fibrosis, a genetic disorder that leads to abnormally viscous mucus in the lungs. This altered environment is perfect for opportunistic bacterial infections, which develops into a chronic infection as the Pa is impossible to get rid of without the use of antibiotics. Murepavadin targets the lipopolysaccharide (LPS) transport protein LptD that is essential in Pa and many more Gram-negative bacteria. Inhibition of the LptD prevents LPS insertion into the outer membrane and will lead to cell death. Thus far, there is no structural information on Murepavadin’s mode of action and interaction with Pa LptD available. Here, we propose an approach for elucidating Murepavadin’s interaction with Pa LptD at high-resolution and in physiologically relevant conditions using solid-state NMR. This project will provide not only novel insight about Murepavadin and LptD, but will also provide a basis for improvement of existing and development of novel antibiotics targeting the essential OMP LptD.