Biology subjects

Cote, J.-P.

Publications and source records attributed to Cote, J.-P..

3 recordsLinked to original sources

bioRxiv2023

Metabolic connections between folate and peptidoglycan pathways in Pseudomonas aeruginosa inform rational design of a dual-action inhibitor

Peptidoglycan is an important bacterial macromolecule that confers cell shape and structural integrity, and a key antibiotic target. The synthesis and turnover of peptidoglycan are carefully coordinated with other cellular processes and pathways. Although there are established connections between peptidoglycan and DNA replication or outer membrane biosynthesis, connections between peptidoglycan and folate metabolism are comparatively unexplored. Folate is an essential cofactor for bacterial growth and required for the synthesis of many important metabolites. Here we show that inhibition of folate synthesis in the important Gram-negative pathogen Pseudomonas aeruginosa has downstream effects on peptidoglycan metabolism and integrity. Folate inhibitors reduced expression of the AmpC {beta}-lactamase through perturbation of peptidoglycan recycling, potentiating the activity of {beta}-lactams normally cleaved by that resistance enzyme. Folate inhibitors also synergized with fosfomycin, which inhibits MurA - the first committed step in peptidoglycan synthesis - resulting in dose-dependent formation of round cells that underwent explosive lysis.The insights from this work were used to design a dual-active inhibitor that overcomes NDM-1-mediated meropenem resistance and synergizes with the folate inhibitor, trimethoprim. This work shows that folate and peptidoglycan metabolism are intimately connected and offers new opportunities to exploit this relationship in strategies to overcome antibiotic resistance in Gram-negative pathogens.

microbiology↗

bioRxiv2023

Probiotic Lactobacillus strains decrease the susceptibility of Salmonella Typhimurium to the last resort antibiotic azithromycin.

Bacteria are involved in numerous interactions during infection and among host-associated microbial populations. Salmonella enterica serovar Typhimurium is a foodborne pathogen of great importance as well as a model organism to study interactions within a microbial community. In this study, we found that S. Typhimurium becomes tolerant to azithromycin when co-cultured with strains of Lactobacillus. Similarly, acidified media, from cell-free supernatant of Lactobacillus cultures for instance, also induced the tolerance of S. Typhimurium to azithromycin. The addition of membrane disruptors restored the normal sensitivity to azithromycin in acidified media, but not when Lactobacillus was present. These results suggested that the acidification of the media led to modification in envelope homeostasis, but that a different mechanism promoted the tolerance to azithromycin in the presence of Lactobacillus strains. To further understand how Lactobacillus strains modify the sensitivity of S. Typhimurium to azithromycin, a high-throughput assay was carried using the single gene deletion collection of the S. Typhimurium (1) in coculture with L. rhamnosus and (2) in sterile acidic conditions (pH 5.5 media only). As expected, both screens identified genes involved in envelope homeostasis and membrane permeability. Our results also suggest that changes in the metabolism of S. Typhimurium induce the tolerance observed in the presence of L. rhamnosus. Our results thus highlight two different mechanisms by which Lactobacillus strains induce tolerance of S. Typhimurium to antibiotics. ImportanceThis study provides valuable insights into the intricate interactions between bacteria during infections and within host-associated microbial communities. Specifically, it sheds light on the significant role of Lactobacillus strains in inducing antibiotic tolerance in Salmonella enterica serovar Typhimurium, a critical foodborne pathogen and model organism for microbial community studies. The findings not only uncover the mechanisms underlying this antibiotic tolerance but also reveal two distinct pathways through which Lactobacillus strains might influence Salmonellas response to antibiotics. Understanding these mechanisms has the potential to enhance our knowledge of bacterial infections and may have implications for the development of strategies to combat antibiotic resistance in pathogens like Salmonella. Furthermore, our results underscore the necessity to explore beyond the direct antimicrobial effects of antibiotics, emphasizing the broader microbial community context.

microbiology↗

bioRxiv2022

Central metabolism is a key player in E. coli biofilm stimulation by sub-MIC antibiotics

Exposure of Escherichia coli to sub-inhibitory antibiotics stimulates biofilm formation through poorly characterized mechanisms. Using a high-throughput Congo Red binding assay to report on biofilm matrix production, we screened [~]4000 E. coli K12 deletion mutants for deficiencies in this biofilm stimulation response. Mutants lacking acnA, nuoE, or lpdA failed to respond to sub-MIC novobiocin, implicating central metabolism and aerobic respiration in biofilm stimulation. These genes are members of the ArcA/B regulon - controlled by a respiration-sensitive two-component system. Mutants of arcA and arcB had a pre-activated phenotype, where biofilm formation was already high relative to wild type in vehicle control conditions and failed to increase further with the addition of sub-MIC antibiotics. Supporting a role for respiratory stress, the biofilm stimulation response was inhibited when nitrate was provided as an alternative electron acceptor. Deletion of genes encoding the nitrate respiratory machinery abolished its effects, and nitrate respiration increased during growth with sub-MIC antibiotics. In probing the generalizability of biofilm stimulation, we found that the stimulation response to translation inhibitors was minimally affected by nitrate supplementation. Finally, using a metabolism-sensitive dye, we showed spatial co-localization of increased respiration with sub-MIC bactericidal antibiotics. By characterizing the biofilm stimulation response to sub-MIC antibiotics at a systems level, we identified multiple avenues for design of therapeutics that impair bacterial stress management.

microbiology↗