Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>

ABSTRACT Bacterial toxin-antitoxin (TA) systems encode a toxin and an antitoxin that counteracts the toxin. Such TA systems are found abundantly on bacterial chromosomes and on extrachromosomal genetic elements. The toxin is always a protein. Based on the nature of the antitoxin (protein or RNA) and...

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Autores principales:	Alexander Mager, Tommy Safran, Hanna Engelberg-Kulka
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2021
Materias:	E. coli toxin-antitoxin protein localization Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/bbcff92448f54265bb90d74ba1fa6cd0
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spelling	oai:doaj.org-article:bbcff92448f54265bb90d74ba1fa6cd02021-11-10T18:37:51ZIntracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>10.1128/mBio.01417-212150-7511https://doaj.org/article/bbcff92448f54265bb90d74ba1fa6cd02021-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01417-21https://doaj.org/toc/2150-7511ABSTRACT Bacterial toxin-antitoxin (TA) systems encode a toxin and an antitoxin that counteracts the toxin. Such TA systems are found abundantly on bacterial chromosomes and on extrachromosomal genetic elements. The toxin is always a protein. Based on the nature of the antitoxin (protein or RNA) and on their mode of regulation, they are classified into six groups (I to VI). In the group II TA systems, both the toxin and the antitoxin are proteins, and the gene specifying the antitoxin precedes the gene specifying for the toxin. Here, we studied the intracellular localization in Escherichia coli cells of the proteins specified by the following type II TA modules: mazEF, chpBIK, mqsRA, and rnlAB. We visualized the localization of these proteins by fusing them with the fluorescent protein mCherry using recombinant DNA technology. We used fluorescence microscopy and image analysis software to obtain and quantify protein distribution data. With the exception of the chpBIK TA module, we found that the localization of each toxin-antitoxin complex was different from the localization of the toxin itself. Our results demonstrate clearly that the presence of the antitoxin shifts the localization of its respective toxin toward the middle of the cell, which could contribute to the reduction of cellular toxicity. IMPORTANCE Bacterial toxin-antitoxin (TA) systems, which were discovered in 1985, have since been studied extensively. These studies have focused particularly on the distribution of these bacterial TA systems on either plasmids or on bacterial chromosomes, their functionality, their targets, their relation to virulence, and their mechanisms of action. Our study, reported here, is the first to clarify the intracellular localization of the proteins specified for some type II TA systems. We have shown that, with the exception of the chpBIK module, each toxin-antitoxin complex was localized in a different part of the cell than the toxin itself. Our results revealed clearly that the presence of the antitoxin changes the localization of the toxin by moving the toxin toward the middle of the cell. Until now, the general view has been that the antagonistic effect of the antitoxins over their cognate toxins is based only on their direct structural interactions. Here, we show that this antagonistic effect is also a function of a specific change in the intracellular localization of the toxin.Alexander MagerTommy SafranHanna Engelberg-KulkaAmerican Society for MicrobiologyarticleE. colitoxin-antitoxinprotein localizationMicrobiologyQR1-502ENmBio, Vol 12, Iss 4 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	E. coli toxin-antitoxin protein localization Microbiology QR1-502
spellingShingle	E. coli toxin-antitoxin protein localization Microbiology QR1-502 Alexander Mager Tommy Safran Hanna Engelberg-Kulka Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
description	ABSTRACT Bacterial toxin-antitoxin (TA) systems encode a toxin and an antitoxin that counteracts the toxin. Such TA systems are found abundantly on bacterial chromosomes and on extrachromosomal genetic elements. The toxin is always a protein. Based on the nature of the antitoxin (protein or RNA) and on their mode of regulation, they are classified into six groups (I to VI). In the group II TA systems, both the toxin and the antitoxin are proteins, and the gene specifying the antitoxin precedes the gene specifying for the toxin. Here, we studied the intracellular localization in Escherichia coli cells of the proteins specified by the following type II TA modules: mazEF, chpBIK, mqsRA, and rnlAB. We visualized the localization of these proteins by fusing them with the fluorescent protein mCherry using recombinant DNA technology. We used fluorescence microscopy and image analysis software to obtain and quantify protein distribution data. With the exception of the chpBIK TA module, we found that the localization of each toxin-antitoxin complex was different from the localization of the toxin itself. Our results demonstrate clearly that the presence of the antitoxin shifts the localization of its respective toxin toward the middle of the cell, which could contribute to the reduction of cellular toxicity. IMPORTANCE Bacterial toxin-antitoxin (TA) systems, which were discovered in 1985, have since been studied extensively. These studies have focused particularly on the distribution of these bacterial TA systems on either plasmids or on bacterial chromosomes, their functionality, their targets, their relation to virulence, and their mechanisms of action. Our study, reported here, is the first to clarify the intracellular localization of the proteins specified for some type II TA systems. We have shown that, with the exception of the chpBIK module, each toxin-antitoxin complex was localized in a different part of the cell than the toxin itself. Our results revealed clearly that the presence of the antitoxin changes the localization of the toxin by moving the toxin toward the middle of the cell. Until now, the general view has been that the antagonistic effect of the antitoxins over their cognate toxins is based only on their direct structural interactions. Here, we show that this antagonistic effect is also a function of a specific change in the intracellular localization of the toxin.
format	article
author	Alexander Mager Tommy Safran Hanna Engelberg-Kulka
author_facet	Alexander Mager Tommy Safran Hanna Engelberg-Kulka
author_sort	Alexander Mager
title	Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
title_short	Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
title_full	Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
title_fullStr	Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
title_full_unstemmed	Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>
title_sort	intracellular localization of the proteins encoded by some type ii toxin-antitoxin systems in <named-content content-type="genus-species">escherichia coli</named-content>
publisher	American Society for Microbiology
publishDate	2021
url	https://doaj.org/article/bbcff92448f54265bb90d74ba1fa6cd0
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Intracellular Localization of the Proteins Encoded by Some Type II Toxin-Antitoxin Systems in <named-content content-type="genus-species">Escherichia coli</named-content>

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