The Evolutionary Conservation of <i>Escherichia coli</i> Drug Efflux Pumps Supports Physiological Functions

Teelucksingh, Tanisha; Thompson, Laura K.; Cox, Georgina

doi:10.1128/jb.00367-20

Cited by 59 publications

(62 citation statements)

References 161 publications

(255 reference statements)

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“…Drug efflux pumps are bacterial transmembrane protein complexes [ 90 ]. If the efflux pump system achieves the timely exclusion of membrane-permeable antibacterial agents, the pathogenic bacterial cell avoids contact with the antibacterial agent in the membrane, which reduces the bactericidal effect of the agent and enhances the resistance of the pathogen via the membrane [ 91 ].…”

Section: Antibacterial Mechanisms Of Natural Alkaloidsmentioning

confidence: 99%

Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

et al. 2021

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Alkaloids are nitrogen-containing heterocyclic compounds typically isolated from plants. They represent one of the most important types of natural products because of their large number and structural diversity and complexity. Based on their chemical core structures, alkaloids are classified as isoquinolines, quinolines, indoles, piperidine alkaloids, etc. In-depth analyses of alkaloids have revealed their antibacterial activities. To date, due to the widespread use of antibiotics, the problem of drug-resistant bacterial infections has been gradually increasing, which severely affects the clinical efficacy of antibacterial therapies and patient safety. Therefore, significant research efforts are focused on alkaloids because they represent a potentially new type of natural antibiotic with a wide antibacterial spectrum, rare adverse reactions, and a low tendency to produce drug resistance. Their main antibacterial mechanisms include inhibition of bacterial cell wall synthesis, change in cell membrane permeability, inhibition of bacterial metabolism, and inhibition of nucleic acid and protein synthesis. This article reviews recent reports about the chemical structures and the antibacterial activities and mechanisms of alkaloids. The purpose is to solve the problem of bacterial resistance and to provide a certain theoretical basis and research ideas for the development of new antibacterial drugs.

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Section: Antibacterial Mechanisms Of Natural Alkaloidsmentioning

confidence: 99%

Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

et al. 2021

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“…Efflux systems are categorized into families by sequence similarity, structure–including protein fold, conserved domains, and number of transmembrane spanning regions–as well as by their energy source and substrates [ 65 ]. It is not known whether the Bucl8-associated pump relies on ATP hydrolysis to transport FA, but the associated FusC IMP transporter does not contain an ATP-binding domain, therefore, it is an unlikely an ABC-type transporter.…”

Section: Discussionmentioning

confidence: 99%

“…Efflux pumps support physiological functions [ 65 ]. The decrease in bacterial growth of the Bp82 Δbucl8-fusE mutant suggests that the Bucl8-associated pump may be involved in modulating essential cellular stresses, both in the environment and in infected human host [ 14 ].…”

Section: Discussionmentioning

confidence: 99%

Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a putative tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei

et al. 2020

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Bacterial efflux pumps are an important pathogenicity trait because they extrude a variety of xenobiotics. Our laboratory previously identified in silico Burkholderia collagen-like protein 8 (Bucl8) in the hazardous pathogens Burkholderia pseudomallei and Burkholderia mallei. We hypothesize that Bucl8, which contains two predicted tandem outer membrane efflux pump domains, is a component of a putative efflux pump. Unique to Bucl8, as compared to other outer membrane proteins, is the presence of an extended extracellular region containing a collagen-like (CL) domain and a non-collagenous C-terminus (Ct). Molecular modeling and circular dichroism spectroscopy with a recombinant protein, corresponding to this extracellular CL-Ct portion of Bucl8, demonstrated that it adopts a collagen triple helix, whereas functional assays screening for Bucl8 ligands identified binding to fibrinogen. Bioinformatic analysis of the bucl8 gene locus revealed it resembles a classical efflux-pump operon. The bucl8 gene is co-localized with downstream fusCDE genes encoding fusaric acid (FA) resistance, and with an upstream gene, designated as fusR, encoding a LysR-type transcriptional regulator. Using reverse transcriptase (RT)-qPCR, we defined the boundaries and transcriptional organization of the fusR-bucl8-fusCDE operon. We found exogenous FA induced bucl8 transcription over 80-fold in B. pseudomallei, while deletion of the entire bucl8 locus decreased the minimum inhibitory concentration of FA 4-fold in its isogenic mutant. We furthermore showed that the putative Bucl8-associated pump expressed in the heterologous Escherichia coli host confers FA resistance. On the contrary, the Bucl8-associated pump did not confer resistance to a panel of clinically-relevant antimicrobials in Burkholderia and E. coli. We finally demonstrated that deletion of the bucl8-locus drastically affects the growth of the mutant in L-broth. We determined that Bucl8 is a component of a novel tetrapartite efflux pump, which confers FA resistance, fibrinogen binding, and optimal growth.

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“…Yet their evolution and persistence arise from their intrinsic contributions to bacterial survival that predate the antibiotic era. MDR pumps remove environmental or host-derived antimicrobials such as bile acids (8) as well as toxic products of the bacterium’s own metabolism (9,10).…”

Section: Introductionmentioning

confidence: 99%

“…The E. coli K-12 genome contains at least 36 multidrug efflux systems (9,11). The most active pump, AcrAB-TolC, exports antimicrobial drugs, antibiotics, dyes, organic solvents, essential oils, and hormones (12,13).…”

Section: Introductionmentioning

confidence: 99%

Salicylate, Bile Acids and Extreme Acid Cause Fitness Tradeoffs for Multidrug Pumps inEscherichia coliK-12

Lee

et al. 2020

Preprint

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The aspirin derivative salicylate selects against bacterial multidrug efflux pumps of Escherichia coli K-12 such as MdtEF-TolC and EmrAB-TolC, and acid stress regulators such as GadE. Salicylate uptake is driven by the transmembrane pH gradient (ΔpH) and the proton motive force (PMF) which drives many efflux pumps. We used flow cytometry to measure the fitness tradeoffs of salicylate, bile acids, and extreme low pH for E. coli cultured with pump deletants. The AcrAB-TolC efflux pump conferred a fitness advantage in the presence of bile acids, an efflux substrate. Without bile acids, AcrA incurred a small fitness cost. The fitness advantage with bile acids was eliminated by the PMF uncoupler CCCP. The Gad acid fitness island encodes components of MdtEF-TolC (an acid-adapted efflux pump) as well as acid regulator GadE. The fitness advantage of E. coli cocultured with a Gad deletant (Δslp-gadX) was lost in the presence of salicylate. Salicylate caused an even larger fitness cost for GadE. MdtE incurred negative or neutral fitness under all media conditions, as did EmrA. But when the competition cycle included two hours at pH 2, MdtE conferred a fitness advantage. The MdtE advantage required the presence of bile acids. Thus, the MdtEF-TolC pump is useful to E. coli for transient extreme acid exposure comparable to passage through the acidic stomach. Salicylate selects against some multidrug efflux pumps, whereas bile acids selects for them; and these fitness tradeoffs are amplified by extreme acid.IMPORTANCEControl of drug resistance in gut microbial communities is a compelling problem for human health. Growth of gut bacteria is limited by host-produced acids such as bile acids, and may be modulated by plant-derived acids such as salicylic acid. Membrane-soluble organic acids can control bacterial growth by disrupting membranes, decreasing cell pH, and depleting PMF. Our flow cytometry assay measures the fitness effects of exposure to membrane-soluble organic acids, with growth cycles that may include a period of extreme acid. We find that extreme-acid exposure leads to a fitness advantage for a multidrug pump, MdtEF-TolC, which otherwise incurs a large fitness cost. Thus, organic acids and stomach acid may play important roles in controlling multidrug resistance in the gut microbiome. Therapeutic acids might be developed to limit the prevalence of multidrug resistance pumps in environmental and host-associated communities.

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The Evolutionary Conservation of Escherichia coli Drug Efflux Pumps Supports Physiological Functions

Cited by 59 publications

References 161 publications

Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a putative tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei

Salicylate, Bile Acids and Extreme Acid Cause Fitness Tradeoffs for Multidrug Pumps inEscherichia coliK-12

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