Study reveals murepavadin acts as broad-spectrum outer membrane permeabilizer in Gram-negative bacteria
Researchers have discovered that murepavadin, previously considered a Pseudomonas-specific antibiotic, acts as a broad-spectrum outer membrane permeabiliser by binding to lipid A and disrupting bacterial membranes across many Gram-negative species. The drug was originally known to target LptD, an LPS transport protein in Pseudomonas aeruginosa, but its mechanism of entry into the periplasm had remained unclear. This finding suggests murepavadin could enhance susceptibility to other antibiotics and host immune defences in a much wider range of bacterial pathogens than previously recognised.
A study posted to bioRxiv reveals that murepavadin, a Pseudomonas-specific antibiotic targeting the LPS transport protein LptD, employs a self-directed uptake mechanism in which binding to lipid A induces disruption of the bacterial outer membrane (OM), allowing the drug to access the periplasm and reach its target. Critically, this lipid A interaction was not limited to Pseudomonas aeruginosa: the researchers found that murepavadin caused OM disruption across a wide range of Gram-negative bacteria, increasing their susceptibility to other antibiotics. The study also demonstrated that murepavadin-mediated membrane disruption sensitised Escherichia coli to the membrane attack complex of the complement system, a key component of innate immune defence. These findings reframe murepavadin not merely as a species-specific antibiotic but as a broad-spectrum membrane permeabiliser with potential utility in combination therapies. The results could have significant implications for addressing antibiotic resistance, as potentiating existing antibiotics and host defences against a wider bacterial range may reduce the need for novel drug development.
What's missing
As a preprint, this study has not yet undergone peer review, and the findings should be interpreted with caution. The study does not address potential toxicity or selectivity concerns of murepavadin's broad-spectrum membrane activity toward host cells, nor does it clarify whether the observed sensitisation effects translate to in vivo models. The clinical relevance of complement sensitisation in the context of immunocompromised patients, who are most at risk from Pseudomonas infections, is also not discussed.
What different sources said
- bioRxivCenter
Murepavadin is a broad-spectrum outer membrane permeabiliser
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.