Permeation of tetracyclines through membranes of liposomes and <i>Escherichia coli</i>

Sigler, Albrecht; Schubert, Peter; Hillen, Wolfgang; Niederweis, Michael

doi:10.1046/j.1432-1327.2000.01026.x

Cited by 51 publications

(35 citation statements)

References 38 publications

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“…As stated in the introduction, the presence of TetR(B) is required for tetracyclineinduced fluorescence of liposomes (13). We found, however, that the planktonic cells of strains AMG1 and AMS6, which are devoid of TetR(B) (data not shown), exhibited a fluorescence pattern identical to that of AMG2 (Fig.…”

Section: Resultsmentioning

confidence: 54%

“…We have developed a method to directly visualize cells coming in contact with tetracycline, based on the report that in the presence of the TetR(B) protein in liposomes (see http:// biosafety.ihe.be/AR/Tetracycline/Menu_Tet for tetracycline resistance determinant nomenclature), this antibiotic fluoresces when activated by UV light (13). TetR(B) is constitutively synthesized in bacteria containing Tn10 and regulates the expression of the tetA(B) gene that encodes the tetracycline efflux pump (2).…”

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confidence: 99%

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Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms

Stone

Wood

Dixon

et al. 2002

Antimicrob Agents Chemother

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We have developed a method for visualizing Escherichia coli cells that are exposed to tetracycline in a biofilm, based on a previous report that liposomes containing the E. coli TetR(B) protein fluoresce when exposed to this antibiotic. By our method, cells devoid of TetR(B) also exhibited tetracycline-dependent fluorescence. At 50 g of tetracycline ml؊1 , planktonic cells of a uropathogenic E. coli (UPEC) strain developed maximal fluorescence after 7.5 to 10 min of exposure. A similar behavior was exhibited by cells in a 24-or 48-h UPEC biofilm, as examined by confocal laser microscopy, regardless of whether they lined empty spaces or occupied densely packed regions. Further, a comparison of phase-contrast and fluorescent images of corresponding biofilm zones showed that all the cells fluoresced. Thus, all the biofilm cells were exposed to tetracycline and there were no pockets within the biofilm where the antibiotic failed to reach. It also appeared unlikely that niches of reduced exposure to the antibiotic existed within the biofilms.Diseases involving bacterial biofilms are generally chronic and difficult to treat, because bacteria in biofilms are more resistant to antimicrobial agents than their planktonic (freeliving) counterparts. Biofilms contribute to several serious diseases, such as endocarditis, cystitis, cystic fibrosis, and infections of prosthetic devices (4-6a).It is not known why biofilms possess greater resistance. The possibility that this might be due to a lack of penetration of antibiotics has received considerable attention. Although several studies suggest that biofilms permit antibiotic penetration (1,6,8,9,10,12,14), it was not ascertained in these studies if this involved exposure of all constituent cells to the antibiotic.We have developed a method to directly visualize cells coming in contact with tetracycline, based on the report that in the presence of the TetR(B) protein in liposomes (see http:// biosafety.ihe.be/AR/Tetracycline/Menu_Tet for tetracycline resistance determinant nomenclature), this antibiotic fluoresces when activated by UV light (13). TetR(B) is constitutively synthesized in bacteria containing Tn10 and regulates the expression of the tetA(B) gene that encodes the tetracycline efflux pump (2). We report here that the biofilms of uropathogenic Escherichia coli (UPEC) and K-12 strains of E. coli (11) are readily permeable to tetracycline and permit exposure of all the constituent cells to this antibiotic. MATERIALS AND METHODSBacterial strains and plasmids. A clinical isolate of uropathogenic E. coli (AMG1), obtained from the Microbiology Section of the Infectious Diseases Department of the Stanford Medical Center, and our laboratory E. coli strain, AMS6 (11), were employed. A tetracycline-resistant strain of AMG1, referred to as AMG2, containing the TetR(B) protein was generated using the Tn10 transposon, and the " hop" technique; the latter employs a temperature-sensitive phage (561) as the Tn10 vehicle. Transposition was achieved as described previously (15), using...

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Section: Resultsmentioning

confidence: 54%

mentioning

confidence: 99%

Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms

Stone

Wood

Dixon

et al. 2002

Antimicrob Agents Chemother

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“…As tetracycline diffusion equilibrium (t 1/2 ¼ 35 ± 15 min) 60 is reached much faster than steady-state GFP expression (30 h, Supplementary Fig. 1b), the rate of tetracycline uptake was neglected.…”

Section: Article Nature Communications | Doi: 101038/ncomms4612mentioning

confidence: 99%

Sensitive detection of proteasomal activation using the Deg-On mammalian synthetic gene circuit

et al. 2014

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The ubiquitin proteasome system (UPS) has emerged as a drug target for diverse diseases characterized by altered proteostasis, but pharmacological agents that enhance UPS activity have been challenging to establish. Here we report the Deg-On system, a genetic inverter that translates proteasomal degradation of the transcriptional regulator TetR into a fluorescent signal, thereby linking UPS activity to an easily detectable output, which can be tuned using tetracycline. We demonstrate that this circuit responds to modulation of UPS activity in cell culture arising from the inhibitor MG-132 and activator PA28g. Guided by predictive modelling, we enhanced the circuit's signal sensitivity and dynamic range by introducing a feedback loop that enables self-amplification of TetR. By linking UPS activity to a simple and tunable fluorescence output, these genetic inverters will enable a variety of applications, including screening for UPS activating molecules and selecting for mammalian cells with different levels of proteasome activity.

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“…The passage across the Gram-negative outer membrane occurs through porin channels, which are more permeant to hydrophilic molecules. The uptake of tetracycline through the bacterial cytoplasmic membrane seems to occur by passive diffusion, where the drug is accumulated in response to a pH gradient [9,10].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a tetracycline–platinum (II) complex active against resistant bacteria

Chartone-Souza

Loyola

Bucciarelli-Rodriguez

et al. 2005

Journal of Inorganic Biochemistry

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Permeation of tetracyclines through membranes of liposomes and Escherichia coli

Cited by 51 publications

References 38 publications

Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms

Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms

Sensitive detection of proteasomal activation using the Deg-On mammalian synthetic gene circuit

Synthesis and characterization of a tetracycline–platinum (II) complex active against resistant bacteria

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