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Reassessing the role of type II toxin-antitoxin systems in formation of escherichia coli type II persister cells

Goormaghtigh, Frédéric ; Fraikin, Nathan ; Putrinš, Marta ; Hallaert, Thibaut ; Hauryliuk, Vasili LU orcid ; Garcia-Pino, Abel ; Sjödin, Andreas ; Kasvandik, Sergo ; Udekwu, Klas and Tenson, Tanel , et al. (2018) In mBio 9(3).
Abstract

Persistence is a reversible and low-frequency phenomenon allowing a subpopulation of a clonal bacterial population to survive antibiotic treatments. Upon removal of the antibiotic, persister cells resume growth and give rise to viable progeny. Type II toxin-antitoxin (TA) systems were assumed to play a key role in the formation of persister cells in Escherichia coli based on the observation that successive deletions of TA systems decreased persistence frequency. In addition, the model proposed that stochastic fluctuations of (p)ppGpp levels are the basis for triggering activation of TA systems. Cells in which TA systems are activated are thought to enter a dormancy state and therefore survive the antibiotic treatment. Using... (More)

Persistence is a reversible and low-frequency phenomenon allowing a subpopulation of a clonal bacterial population to survive antibiotic treatments. Upon removal of the antibiotic, persister cells resume growth and give rise to viable progeny. Type II toxin-antitoxin (TA) systems were assumed to play a key role in the formation of persister cells in Escherichia coli based on the observation that successive deletions of TA systems decreased persistence frequency. In addition, the model proposed that stochastic fluctuations of (p)ppGpp levels are the basis for triggering activation of TA systems. Cells in which TA systems are activated are thought to enter a dormancy state and therefore survive the antibiotic treatment. Using independently constructed strains and newly designed fluorescent reporters, we reassessed the roles of TA modules in persistence both at the population and single-cell levels. Our data confirm that the deletion of 10 TA systems does not affect persistence to ofloxacin or ampicillin. Moreover, microfluidic experiments performed with a strain reporting the induction of the yefM-yoeB TA system allowed the observation of a small number of type II persister cells that resume growth after removal of ampicillin. However, we were unable to establish a correlation between high fluorescence and persistence, since the fluorescence of persister cells was comparable to that of the bulk of the population and none of the cells showing high fluorescence were able to resume growth upon removal of the antibiotic. Altogether, these data show that there is no direct link between induction of TA systems and persistence to antibiotics. IMPORTANCE Within a growing bacterial population, a small subpopulation of cells is able to survive antibiotic treatment by entering a transient state of dormancy referred to as persistence. Persistence is thought to be the cause of relapsing bacterial infections and is a major public health concern. Type II toxin-antitoxin systems are small modules composed of a toxic protein and an antitoxin protein counteracting the toxin activity. These systems were thought to be pivotal players in persistence until recent developments in the field. Our results demonstrate that previous influential reports had technical flaws and that there is no direct link between induction of TA systems and persistence to antibiotics.

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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ampicillin, RelE, Single cell, YoeB
in
mBio
volume
9
issue
3
article number
e00640-18
pages
14 pages
publisher
American Society for Microbiology
external identifiers
  • scopus:85048558212
  • pmid:29895634
ISSN
2161-2129
DOI
10.1128/mBio.00640-18
language
English
LU publication?
no
additional info
Funding Information: This work is supported by the Fonds National de la Recherche Scientifique (FNRS) (T.0147.15F PDR and J.0061.16F CDR to L.V.M.) and FRFS-WELBIO grant (CR-2017S-03, T.0066.18 PDR and F.4505.16 MIS to A.G.-P.), the Fonds d’Encouragement à la Recherche ULB (FER-ULB) (to A.G.-P. and L.V.M.), the Interuniversity Attraction Poles Program initiated by the Belgian Science Policy Office (MICRODEV to L.V.M.), the Fonds Jean Brachet and Fondation Van Buuren (to L.V.M. and A.G.-P.), the Estonian Research Council (IUT2-22 to T.T., M.P., and N.K.), the European Regional Development Fund through the Centre of Excellence in Molecular Cell Engineering (to V.H., M.P., N.K., and T.T.), the Swedish Research Council (Vetenskapsrådet) (2013-4680 to V.H.) and the Ragnar Söderberg Foundation (Ragnar Söderberg Fellow in Medicine 2014 to V.H.). N.F. is a Ph.D. fellow at FNRS-FRS (Fonds de la Recherche Scientifique). Funding Information: We are grateful to Natacha Mine, Mariliis Hinnu, Spyridon Gkotzis, and Bertrand Delahaye for technical support and Philippe Goffin for providing plasmids. We thank Etienne Maisonneuve and Kenn Gerdes for donating strains. We thank the reviewers for their constructive comments. This work is supported by the Fonds National de la Recherche Scientifique (FNRS) (T.0147.15F PDR and J.0061.16F CDR to L.V.M.) and FRFS-WELBIO grant (CR-2017S-03, T.0066.18 PDR and F.4505.16 MIS to A.G.-P.), the Fonds d’Encouragement à la Recherche ULB (FER-ULB) (to A.G.-P. and L.V.M.), the Interuniversity Attraction Poles Program initiated by the Belgian Science Policy Office (MICRODEV to L.V.M.), the Fonds Jean Brachet and Fondation Van Buuren (to L.V.M. and A.G.-P.), the Estonian Research Council (IUT2-22 to T.T., M.P., and N.K.), the European Regional Development Fund through the Centre of Excellence in Molecular Cell Engineering (to V.H., M.P., N.K., and T.T.), the Swedish Research Council (Vetenskapsrådet) (2013-4680 to V.H.) and the Ragnar Söderberg Foundation (Ragnar Söderberg Fellow in Medicine 2014 to V.H.). N.F. is a Ph.D. fellow at FNRS-FRS (Fonds de la Recherche Scientifique). Publisher Copyright: © 2018 Goormaghtigh et al. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.
id
e5adcf64-02f6-43b9-bd56-2bb7dac27745
date added to LUP
2021-09-24 20:36:50
date last changed
2024-06-15 16:57:30
@article{e5adcf64-02f6-43b9-bd56-2bb7dac27745,
  abstract     = {{<p>Persistence is a reversible and low-frequency phenomenon allowing a subpopulation of a clonal bacterial population to survive antibiotic treatments. Upon removal of the antibiotic, persister cells resume growth and give rise to viable progeny. Type II toxin-antitoxin (TA) systems were assumed to play a key role in the formation of persister cells in Escherichia coli based on the observation that successive deletions of TA systems decreased persistence frequency. In addition, the model proposed that stochastic fluctuations of (p)ppGpp levels are the basis for triggering activation of TA systems. Cells in which TA systems are activated are thought to enter a dormancy state and therefore survive the antibiotic treatment. Using independently constructed strains and newly designed fluorescent reporters, we reassessed the roles of TA modules in persistence both at the population and single-cell levels. Our data confirm that the deletion of 10 TA systems does not affect persistence to ofloxacin or ampicillin. Moreover, microfluidic experiments performed with a strain reporting the induction of the yefM-yoeB TA system allowed the observation of a small number of type II persister cells that resume growth after removal of ampicillin. However, we were unable to establish a correlation between high fluorescence and persistence, since the fluorescence of persister cells was comparable to that of the bulk of the population and none of the cells showing high fluorescence were able to resume growth upon removal of the antibiotic. Altogether, these data show that there is no direct link between induction of TA systems and persistence to antibiotics. IMPORTANCE Within a growing bacterial population, a small subpopulation of cells is able to survive antibiotic treatment by entering a transient state of dormancy referred to as persistence. Persistence is thought to be the cause of relapsing bacterial infections and is a major public health concern. Type II toxin-antitoxin systems are small modules composed of a toxic protein and an antitoxin protein counteracting the toxin activity. These systems were thought to be pivotal players in persistence until recent developments in the field. Our results demonstrate that previous influential reports had technical flaws and that there is no direct link between induction of TA systems and persistence to antibiotics.</p>}},
  author       = {{Goormaghtigh, Frédéric and Fraikin, Nathan and Putrinš, Marta and Hallaert, Thibaut and Hauryliuk, Vasili and Garcia-Pino, Abel and Sjödin, Andreas and Kasvandik, Sergo and Udekwu, Klas and Tenson, Tanel and Kaldalu, Niilo and Van Melderen, Laurence}},
  issn         = {{2161-2129}},
  keywords     = {{Ampicillin; RelE; Single cell; YoeB}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{3}},
  publisher    = {{American Society for Microbiology}},
  series       = {{mBio}},
  title        = {{Reassessing the role of type II toxin-antitoxin systems in formation of escherichia coli type II persister cells}},
  url          = {{http://dx.doi.org/10.1128/mBio.00640-18}},
  doi          = {{10.1128/mBio.00640-18}},
  volume       = {{9}},
  year         = {{2018}},
}