Project description:Efflux pumps are a significant challenge for the development of new antibacterial agents. Overcoming efflux requires an in-depth understanding of efflux pump functions, substrate specificities, and the development of inhibitors. However, the complexities of drug efflux networks have limited such studies. To address these challenges, we report the generation of Efflux KnockOut-35 (EKO-35), a highly susceptible Escherichia coli strain lacking 35 efflux pumps. We demonstrate the utility of this strain by constructing an efflux platform consisting of strains individually expressing genes encoding efflux pumps forming tripartite complexes with the outer membrane channel TolC. This platform was profiled against a curated diverse compound collection, which enabled us to define physicochemical properties that contribute to transport. We also show the E. coli drug efflux network is conditionally essential for growth, and that the platform can be used to investigate efflux pump inhibitor specificities and also efflux pump interplay. We believe EKO-35 and the efflux platform will have widespread application for the study of drug efflux.
2022-08-31 | PXD033975 | Pride
Project description:EKO-35: A genetic platform to investigate the functions of bacterial drug efflux pumps
Project description:The number and overlapping substrate repertoire of multidrug efflux pumps in the E. coli genome suggest a physiological role apart from multidrug resistance. This role was investigated using transcriptomic analyses of cDNAs labeled from E. coli AG102 mRNA (hyper drug resistant, marR1) and its isogenic major efflux pump mutants. Keywords: Mutation Analysis
Project description:Expression of efflux pumps is a key feature of most cells which are resistant to multiple antibiotics. This study used TraDIS-Xpress, a genome wide transposon mutagenesis technology to identify genes in Escherichia coli and Salmonella Typhimurium involved in drug efflux and its regulation. We exposed mutant libraries to the canonical efflux substrate acriflavine in the presence and absence of the efflux inhibitor phenylalanine-arginine β-naphthylamide. Comparisons between conditions identified efflux specific and drug specific responses. Known efflux associated genes were easily identified including: AcrAB-TolC, MarA, RamA and SoxS confirming specificity of the response. Further genes encoding cell envelope maintenance enzymes and products involved with stringent response activation, DNA housekeeping, respiration and glutathione biosynthesis were also identified as affecting efflux activity in both species. We identified a conserved set of pathways crucial for efflux activity in these experimental conditions which expands the list of genes known to impact efflux efficacy.
Project description:Drug efflux is a common resistance mechanism found in bacteria and cancer cells. Although several structures of drug efflux pumps are available, they provide only limited functional information on the phenomenon of drug efflux. Here, we performed deep mutational scanning (DMS) on the bacterial ATP binding cassette (ABC) transporter EfrCD from Enterococcus faecalis to determine the drug efflux activity profile of more than 1400 single variants
Project description:The identification of multidrug resistant (MDR), extensively and totally drug resistant Mycobacterium tuberculosis (Mtb), in vulnerable sites such as Mumbai, is a grave threat to the control of tuberculosis. The current study aimed at explaining the rapid expression of MDR in Directly Observed Treatment Short Course (DOTS) compliant patients, represents the first study comparing global transcriptional profiles of 3 pairs of clinical Mtb isolates, collected longitudinally at initiation and completion of DOTS. While the isolates were drug susceptible (DS) at onset and MDR at completion of DOTS, they exhibited identical DNA fingerprints at both points of collection. The whole genome transcriptional analysis was performed using total RNA from H37Rv and 3 locally predominant spoligotypes viz. MANU1, CAS and Beijing, hybridized on MTBv3 (BuG@S) microarray, and yielded 36, 98 and 45 differentially expressed genes respectively. Genes encoding transcription factors (sig, rpoB), cell wall biosynthesis (emb genes), protein synthesis (rpl) and additional central metabolic pathways (ppdK, pknH, pfkB) were found to be down regulated in the MDR isolates as compared to the DS isolate of the same genotype. Up regulation of drug efflux pumps, ABC transporters, trans-membrane proteins and stress response transcriptional factors (whiB) in the MDR isolates was observed. The data indicated that Mtb, without specific mutations in drug target genes may persist in the host due to additional mechanisms like drug efflux pumps and lowered rate of metabolism. Furthermore this population of Mtb, which also showed reduced DNA repair activity, would result in selection and stabilization of spontaneous mutations in drug target genes, causing selection of a MDR strain in the presence of drug pressures. Efflux pump such as drrA may play a significant role in increasing fitness of low level drug resistant cells and assist in survival of Mtb till acquisition of drug resistant mutations with least fitness cost. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-134]
Project description:Membrane efflux pumps play a major role in bacterial multidrug resistance. The tripartite multidrug efflux pump system from Escherichia coli, AcrAB-TolC, is a target for inhibition to lessen resistance development and restore antibiotic efficacy, with homologs in other ESKAPE pathogens. Here, we rationalize a mechanism of inhibition against the periplasmic adaptor protein, AcrA, using a combination of hydrogen/deuterium exchange mass spectrometry, cellular efflux assays, and molecular dynamics simulations. We define the structural dynamics of AcrA and find that an inhibitor can inflict long-range stabilisation across all four of its domains, whereas an interacting efflux substrate has minimal effect. Our results support a model where an inhibitor forms a molecular wedge within a cleft between the lipoyl and αβ domains of AcrA, diminishing its conformational transmission of drug-evoked signals from AcrB to TolC. This work provides molecular insights into multidrug adaptor protein function which could be valuable for developing antimicrobial therapeutics.
Project description:The alarming rise of antimicrobial resistance in Mycobacterium tuberculosis coupled with the shortage of new antibiotics has made tuberculosis (TB) control a global health priority. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the growth of multi-drug resistant isolates of M. tuberculosis. Repurposing NSAIDs, with known clinical properties and safety records, offers a direct route to clinical trials. Therefore we investigated the novel mechanisms of anti-mycobacterial action of the NSAID, carprofen. Integrative molecular and microbiological approaches revealed that carprofen, a bactericidal drug, inhibited bacterial drug efflux mechanisms. In addition, carprofen restricted mycobacterial biofilm-like growth, highlighting the requirement of efflux-mediated communicative systems for the formation of biofilms. Transcriptome profiling revealed that carprofen likely acts by inhibiting respiration through the disruption of membrane potential, which may explain why spontaneous drug-resistant mutants could not be raised due to the pleiotropic nature of carprofen’s anti-tubercular action. This immunomodulatory drug has the potential to reverse TB antimicrobial resistance by inhibiting drug efflux pumps and biofilm formation, and paves a new chemotherapeutic path for tackling tuberculosis.
Project description:Through chemical contamination of natural environments, microbial communities are exposed to many different types of chemical stressors; however, research on whole genome responses to this contaminant stress is limited. This study examined the transcriptome response of a common soil bacterium, Pseudomonas aeruginosa, to the common environmental contaminant pentachlorophenol (PCP). Cells were grown in chemostats at a low growth rate to obtain substrate-limited, steady-state, balanced-growth conditions. The PCP stress was administered as a continuous increase in concentration, and samples taken over time were examined for physiological function changes with whole cell acetate uptake rates (WAUR) and cell viability, and for gene expression changes using Affymetrix GeneChip technology and RT-PCR. Cell viability, measured by heterotrophic plate counts, showed a moderately steady decrease after exposure to the stressor, but WAURs did not change in response to PCP. In contrast to the physiological data, the microarray data showed significant changes in the expression of several genes. In particular, genes coding for multi-drug efflux pumps, including MexAB-OprM, were strongly upregulated. The upregulation of these efflux pumps protected the cells from the potentially toxic effects of PCP, allowing the physiological whole-cell function to remain constant. Keywords: stress response to pentachlorophenol