Substrate Specificity within a Family of Outer Membrane Carboxylate Channels

Eren, Elif; Vijayaraghavan, Jagamya; Liu, Jiaming; Cheneke, Belete R.; Touw, Debra S.; Lepore, B.W.; Indic, Mridhu; Movileanu, Liviu; Berg, Bert van den

doi:10.1371/journal.pbio.1001242

Cited by 110 publications

(236 citation statements)

References 49 publications

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“…Notably, some oprD mutations occur in isolates with MICs to imipenem or meropenem of 0.06-4 μg/mL, considered to be within the susceptible range (25), suggesting that increased fitness and full carbapenem resistance may be separable properties of the OprD protein. This might be explained by the findings of Eren et al (29) who reported that multiple Fig. 2A) or the level of oprD mRNA transcription (strains CS1-S23; Dataset S1).…”

Section: Resultsmentioning

confidence: 90%

Enhanced in vivo fitness of carbapenem-resistant oprD mutants of Pseudomonas aeruginosa revealed through high-throughput sequencing

Skurnik

Roux

Cattoir

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

120

110

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An important question regarding the biologic implications of antibiotic-resistant microbes is how resistance impacts the organism's overall fitness and virulence. Currently it is generally thought that antibiotic resistance carries a fitness cost and reduces virulence. For the human pathogen Pseudomonas aeruginosa, treatment with carbapenem antibiotics is a mainstay of therapy that can lead to the emergence of resistance, often through the loss of the carbapenem entry channel OprD. Transposon insertion-site sequencing was used to analyze the fitness of 300,000 mutants of P. aeruginosa strain PA14 in a mouse model for gut colonization and systemic dissemination after induction of neutropenia. Transposon insertions in the oprD gene led not only to carbapenem resistance but also to a dramatic increase in mucosal colonization and dissemination to the spleen. These findings were confirmed in vivo with different oprD mutants of PA14 as well as with related pairs of carbapenem-susceptible and -resistant clinical isolates. Compared with OprD + strains, those lacking OprD were more resistant to killing by acidic pH or normal human serum and had increased cytotoxicity against murine macrophages. RNA-sequencing analysis revealed that an oprD mutant showed dramatic changes in the transcription of genes that may contribute to the various phenotypic changes observed. The association between carbapenem resistance and enhanced survival of P. aeruginosa in infected murine hosts suggests that either drug resistance or host colonization can cause the emergence of more pathogenic, drug-resistant P. aeruginosa clones in a single genetic event.

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Section: Resultsmentioning

confidence: 90%

Enhanced in vivo fitness of carbapenem-resistant oprD mutants of Pseudomonas aeruginosa revealed through high-throughput sequencing

Skurnik

Roux

Cattoir

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

120

110

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“…Carbapenem ␤-lactams and basic amino acids share structural resemblances in parts of their molecules, which explains their common recognition by the specific site in the well-characterized P. aeruginosa OprD/OccD1 channel (6,7,10,37,45) (Fig. S2).…”

Section: Resultsmentioning

confidence: 99%

The Acinetobacter Outer Membrane Contains Multiple Specific Channels for Carbapenem β-Lactams as Revealed by Kinetic Characterization Analyses of Imipenem Permeation into Acinetobacter baylyi Cells

Morán-Barrio

Cameranesi

Relling

et al. 2017

Antimicrob Agents Chemother

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The number and type of outer membrane (OM) channels responsible for carbapenem uptake in Acinetobacter are still not well defined. Here, we addressed these questions by using Acinetobacter baylyi as a model species and a combination of methodologies aimed to characterize OM channels in their original membrane environment. Kinetic and competition analyses of imipenem (IPM) uptake by A. baylyi whole cells allowed us to identify different carbapenem-specific OM uptake sites. Comparative analyses of IPM uptake by A. baylyi wild-type (WT) cells and ΔcarO mutants lacking CarO indicated that this OM protein provided a carbapenem uptake site displaying saturable kinetics and common binding sites for basic amino acids compatible with a specific channel. The kinetic analysis uncovered another carbapenem-specific channel displaying a somewhat lower affinity for IPM than that of CarO and, in addition, common binding sites for basic amino acids as determined by competition studies. The use of A. baylyi gene deletion mutants lacking OM proteins proposed to function in carbapenem uptake in Acinetobacter baumannii indicated that CarO and OprD/OccAB1 mutants displayed low but consistent reductions in susceptibility to different carbapenems, including IPM, meropenem, and ertapenem. These two mutants also showed impaired growth on L-Arg but not on other carbon sources, further supporting a role of CarO and OprD/OccAB1 in basic amino acid and carbapenem uptake. A multiple-carbapenem-channel scenario may provide clues to our understanding of the contribution of OM channel loss or mutation to the carbapenem-resistant phenotype evolved by pathogenic members of the Acinetobacter genus.KEYWORDS Acinetobacter, antibiotic resistance, basic amino acid channels, carbapenem outer membrane channels, carbapenem resistance, Gram-negative bacteria, outer membrane proteins T he genus Acinetobacter (family Moraxellaceae, order Pseudomonadales, class Gammaproteobacteria) is composed of Gram-negative aerobic bacteria ubiquitously found in the environment and endowed with a large spectrum of metabolic capabilities (1-5). Some Acinetobacter members, such as those composing the A. calcoaceticus/A. baumannii (Acb) complex, are frequently associated with opportunistic nosocomial infections, with the responsible lineages generally displaying multidrug-resistant (MDR) phenotypes (3, 4). Infectious Acinetobacter lineages have shown an outstanding ability to rapidly evolve resistance when subjected to new antimicrobial challenges, and a

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“…Lastly, we note the fact that D13-9001 was effective in inhibiting efflux in intact cells of P. aeruginosa (983), although it is essentially a neutral compound and is unlikely to perturb the OM. However, the two P. aeruginosa-active EPIs, PA␤N and D13-9001, contain multiple charged groups and may thus traverse the OM through one of the specific channels, allowing the influx of basic amino acids, peptides, and even some acidic compounds (984).…”

Section: D13-9001mentioning

confidence: 99%

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

2015

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SUMMARY The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.

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Substrate Specificity within a Family of Outer Membrane Carboxylate Channels

Abstract: Characterization of a large family of outer membrane channels from gram-negative bacteria suggest how they can thrive in nutrient-poor environments and how channel inactivation can contribute to antibiotic resistance.

Cited by 110 publications

References 49 publications

Enhanced in vivo fitness of carbapenem-resistant oprD mutants of Pseudomonas aeruginosa revealed through high-throughput sequencing

Enhanced in vivo fitness of carbapenem-resistant oprD mutants of Pseudomonas aeruginosa revealed through high-throughput sequencing

The Acinetobacter Outer Membrane Contains Multiple Specific Channels for Carbapenem β-Lactams as Revealed by Kinetic Characterization Analyses of Imipenem Permeation into Acinetobacter baylyi Cells

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

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