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The communication factor EDF and the toxin-antitoxin module mazEF determine the mode of action of antibiotics.

Kolodkin-Gal I, Sat B, Keshet A, Engelberg-Kulka H - PLoS Biol. (2008)

Bottom Line: We found that antibiotics of both groups caused: (i) mazEF-mediated cell death, and (ii) the production of ROS through MazF action.However, only antibiotics of the first group caused mazEF-mediated cell death that is ROS-dependent, whereas those of the second group caused mazEF-mediated cell death by an ROS-independent pathway.Furthermore, our results showed that the mode of action of antibiotics was determined by the ability of E. coli cells to communicate through the signaling molecule Extracellular Death Factor (EDF) participating in mazEF induction.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.

ABSTRACT
It was recently reported that the production of Reactive Oxygen Species (ROS) is a common mechanism of cell death induced by bactericidal antibiotics. Here we show that triggering the Escherichia coli chromosomal toxin-antitoxin system mazEF is an additional determinant in the mode of action of some antibiotics. We treated E. coli cultures by antibiotics belonging to one of two groups: (i) Inhibitors of transcription and/or translation, and (ii) DNA damaging. We found that antibiotics of both groups caused: (i) mazEF-mediated cell death, and (ii) the production of ROS through MazF action. However, only antibiotics of the first group caused mazEF-mediated cell death that is ROS-dependent, whereas those of the second group caused mazEF-mediated cell death by an ROS-independent pathway. Furthermore, our results showed that the mode of action of antibiotics was determined by the ability of E. coli cells to communicate through the signaling molecule Extracellular Death Factor (EDF) participating in mazEF induction.

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Completely Anaerobic Growth Conditions Prevented mazEF-Mediated Cell Death When mazEF Was Activated by Inhibiting Transcription and/or Translation but Not When Activated by DNA DamageE. coli MC4100relA+ (WT) and MC4100relA+ΔmazEF (ΔmazEF) were grown under either aerobic or anaerobic conditions. Cells were incubated either aerobically, without shaking, or in an anaerobic jar with: (A) rifampicin (10, 20, or 30 μg/ml) for 10 min or (B) nalidixic acid (2–3 mg/ml) for 10 min.
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pbio-0060319-g004: Completely Anaerobic Growth Conditions Prevented mazEF-Mediated Cell Death When mazEF Was Activated by Inhibiting Transcription and/or Translation but Not When Activated by DNA DamageE. coli MC4100relA+ (WT) and MC4100relA+ΔmazEF (ΔmazEF) were grown under either aerobic or anaerobic conditions. Cells were incubated either aerobically, without shaking, or in an anaerobic jar with: (A) rifampicin (10, 20, or 30 μg/ml) for 10 min or (B) nalidixic acid (2–3 mg/ml) for 10 min.

Mentions: To avoid the production of ROS, we studied mazEF-mediated cell death triggered by various antibiotics under completely anaerobic conditions, comparing those results to those of cultures grown aerobically. We activated mazEF by adding rifampicin to inhibit transcription (Figure 4A), by adding spectinomycin to inhibit translation (unpublished data), or by adding nalidixic acid to cause DNA damage (Figure 4B). Under conditions of aerobic growth, we observed mazEF-mediated cell death when the mazEF module was activated by rifampicin at concentrations between 10 and 30 μg/ml (Figure 4A). When we added the same (10–30 μg/ml, Figure 4A) or even higher concentrations (up to 60 μg/ml, unpublished data) of rifampicin to WT cells grown anaerobically, mazEF-mediated cell death was completely prevented. We observed similar results under anaerobic conditions when mazEF was activated by spectinomycin (unpublished data). However, when the mazEF module was activated by nalidicxic acid (2–3 mg/ml), we observed mazEF-mediated cell death even under anaerobic growth conditions (Figure 4B). Thus, in respect to cell death, inhibitors of transcription and/or translation behave differently than DNA damaging agents.


The communication factor EDF and the toxin-antitoxin module mazEF determine the mode of action of antibiotics.

Kolodkin-Gal I, Sat B, Keshet A, Engelberg-Kulka H - PLoS Biol. (2008)

Completely Anaerobic Growth Conditions Prevented mazEF-Mediated Cell Death When mazEF Was Activated by Inhibiting Transcription and/or Translation but Not When Activated by DNA DamageE. coli MC4100relA+ (WT) and MC4100relA+ΔmazEF (ΔmazEF) were grown under either aerobic or anaerobic conditions. Cells were incubated either aerobically, without shaking, or in an anaerobic jar with: (A) rifampicin (10, 20, or 30 μg/ml) for 10 min or (B) nalidixic acid (2–3 mg/ml) for 10 min.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2602726&req=5

pbio-0060319-g004: Completely Anaerobic Growth Conditions Prevented mazEF-Mediated Cell Death When mazEF Was Activated by Inhibiting Transcription and/or Translation but Not When Activated by DNA DamageE. coli MC4100relA+ (WT) and MC4100relA+ΔmazEF (ΔmazEF) were grown under either aerobic or anaerobic conditions. Cells were incubated either aerobically, without shaking, or in an anaerobic jar with: (A) rifampicin (10, 20, or 30 μg/ml) for 10 min or (B) nalidixic acid (2–3 mg/ml) for 10 min.
Mentions: To avoid the production of ROS, we studied mazEF-mediated cell death triggered by various antibiotics under completely anaerobic conditions, comparing those results to those of cultures grown aerobically. We activated mazEF by adding rifampicin to inhibit transcription (Figure 4A), by adding spectinomycin to inhibit translation (unpublished data), or by adding nalidixic acid to cause DNA damage (Figure 4B). Under conditions of aerobic growth, we observed mazEF-mediated cell death when the mazEF module was activated by rifampicin at concentrations between 10 and 30 μg/ml (Figure 4A). When we added the same (10–30 μg/ml, Figure 4A) or even higher concentrations (up to 60 μg/ml, unpublished data) of rifampicin to WT cells grown anaerobically, mazEF-mediated cell death was completely prevented. We observed similar results under anaerobic conditions when mazEF was activated by spectinomycin (unpublished data). However, when the mazEF module was activated by nalidicxic acid (2–3 mg/ml), we observed mazEF-mediated cell death even under anaerobic growth conditions (Figure 4B). Thus, in respect to cell death, inhibitors of transcription and/or translation behave differently than DNA damaging agents.

Bottom Line: We found that antibiotics of both groups caused: (i) mazEF-mediated cell death, and (ii) the production of ROS through MazF action.However, only antibiotics of the first group caused mazEF-mediated cell death that is ROS-dependent, whereas those of the second group caused mazEF-mediated cell death by an ROS-independent pathway.Furthermore, our results showed that the mode of action of antibiotics was determined by the ability of E. coli cells to communicate through the signaling molecule Extracellular Death Factor (EDF) participating in mazEF induction.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.

ABSTRACT
It was recently reported that the production of Reactive Oxygen Species (ROS) is a common mechanism of cell death induced by bactericidal antibiotics. Here we show that triggering the Escherichia coli chromosomal toxin-antitoxin system mazEF is an additional determinant in the mode of action of some antibiotics. We treated E. coli cultures by antibiotics belonging to one of two groups: (i) Inhibitors of transcription and/or translation, and (ii) DNA damaging. We found that antibiotics of both groups caused: (i) mazEF-mediated cell death, and (ii) the production of ROS through MazF action. However, only antibiotics of the first group caused mazEF-mediated cell death that is ROS-dependent, whereas those of the second group caused mazEF-mediated cell death by an ROS-independent pathway. Furthermore, our results showed that the mode of action of antibiotics was determined by the ability of E. coli cells to communicate through the signaling molecule Extracellular Death Factor (EDF) participating in mazEF induction.

Show MeSH
Related in: MedlinePlus