Toxin–antitoxin systems are widespread in bacterial genomes. They are usually composed of two elements: a toxin that inhibits an essential cellular process and an antitoxin that counteracts its cognate toxin. In the past decade, a number of new toxin–antitoxin systems have been described, bringing new growth inhibition mechanisms to light as well as novel modes of antitoxicity. However, recent advances in the field profoundly questioned the role of these systems in bacterial physiology, stress response and antimicrobial persistence. This shifted the paradigm of the functions of toxin–antitoxin systems to roles related to interactions between hosts and their mobile genetic elements, such as viral defence or plasmid stability. In this Review, we summarize the recent progress in understanding the biology and evolution of these small genetic elements, and discuss how genomic conflicts could shape the diversification of toxin–antitoxin systems.
This is a preview of subscription content
Subscribe to Journal
Get full journal access for 1 year
only 7,71 € per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Ogura, T. & Hiraga, S. Mini-F plasmid genes that couple host cell division to plasmid proliferation. Proc. Natl Acad. Sci. USA 80, 4784–4788 (1983).
Gerdes, K., Rasmussen, P. B. & Molin, S. Unique type of plasmid maintenance function: postsegregational killing of plasmid-free cells. Proc. Natl Acad. Sci. USA 83, 3116–3120 (1986).
Yarmolinsky, M. B. Programmed cell death in bacterial populations. Science 267, 836–837 (1995).
Karoui, H., Bex, F., Drèze, P. & Couturier, M. Ham22, a mini-F mutation which is lethal to host cell and promotes recA-dependent induction of lambdoid prophage. EMBO J. 2, 1863–1868 (1983).
Jaffé, A., Ogura, T. & Hiraga, S. Effects of the ccd function of the F plasmid on bacterial growth. J. Bacteriol. 163, 841–849 (1985).
Hiraga, S., Jaffé, A., Ogura, T., Mori, H. & Takahashi, H. F plasmid ccd mechanism in Escherichia coli. J. Bacteriol. 166, 100–104 (1986).
Tam, J. E. & Kline, B. C. The F plasmid ccd autorepressor is a complex of CcdA and CcdB proteins. Mol. Gen. Genet. 219, 26–32 (1989).
Gerdes, K. et al. Mechanism of postsegregational killing by the hok gene product of the parB system of plasmid R1 and its homology with the relF gene product of the E. coli relB operon. EMBO J. 5, 2023–2029 (1986).
Gerdes, K., Helin, K., Christensen, O. W. & Løbner-Olesen, A. Translational control and differential RNA decay are key elements regulating postsegregational expression of the killer protein encoded by the parB locus of plasmid R1. J. Mol. Biol. 203, 119–129 (1988).
Van Melderen, L., Bernard, P. & Couturier, M. Lon-dependent proteolysis of CcdA is the key control for activation of CcdB in plasmid-free segregant bacteria. Mol. Microbiol. 11, 1151–1157 (1994).
Tsuchimoto, S., Nishimura, Y. & Ohtsubo, E. The stable maintenance system pem of plasmid R100: degradation of PemI protein may allow PemK protein to inhibit cell growth. J. Bacteriol. 174, 4205–4211 (1992).
Masuda, Y., Miyakawa, K., Nishimura, Y. & Ohtsubo, E. chpA and chpB, Escherichia coli chromosomal homologs of the pem locus responsible for stable maintenance of plasmid R100. J. Bacteriol. 175, 6850–6856 (1993).
Christensen, S. K., Pedersen, K., Hansen, F. G. & Gerdes, K. Toxin-antitoxin loci as stress-response-elements: ChpAK/MazF and ChpBK cleave translated RNAs and are counteracted by tmRNA. J. Mol. Biol. 332, 809–819 (2003).
Wilbaux, M., Mine, N., Guérout, A.-M., Mazel, D. & Van Melderen, L. Functional interactions between coexisting toxin-antitoxin systems of the ccd family in Escherichia coli O157:H7. J. Bacteriol. 189, 2712–2719 (2007).
Pandey, D. P. & Gerdes, K. Toxin-antitoxin loci are highly abundant in free-living but lost from host-associated prokaryotes. Nucleic Acids Res. 33, 966–976 (2005).
Leplae, R. et al. Diversity of bacterial type II toxin-antitoxin systems: a comprehensive search and functional analysis of novel families. Nucleic Acids Res. 39, 5513–5525 (2011).
Ramisetty, B. C. M. & Santhosh, R. S. Horizontal gene transfer of chromosomal Type II toxin-antitoxin systems of Escherichia coli. FEMS Microbiol. Lett. 363, fnv238 (2016).
Makarova, K. S., Wolf, Y. I. & Koonin, E. V. Comprehensive comparative-genomic analysis of type 2 toxin-antitoxin systems and related mobile stress response systems in prokaryotes. Biol. Direct 4, 19 (2009).
Hayes, F. & Van Melderen, L. Toxins-antitoxins: diversity, evolution and function. Crit. Rev. Biochem. Mol. Biol. 46, 386–408 (2011).
Fiedoruk, K., Daniluk, T., Swiecicka, I., Sciepuk, M. & Leszczynska, K. Type II toxin-antitoxin systems are unevenly distributed among Escherichia coli phylogroups. Microbiology (Reading) 161, 158–167 (2015).
Fineran, P. C. et al. The phage abortive infection system, ToxIN, functions as a protein-RNA toxin-antitoxin pair. Proc. Natl Acad. Sci. USA 106, 894–899 (2009).
Wang, X. et al. A new type V toxin-antitoxin system where mRNA for toxin GhoT is cleaved by antitoxin GhoS. Nat. Chem. Biol. 8, 855–861 (2012).
Aakre, C. D., Phung, T. N., Huang, D. & Laub, M. T. A bacterial toxin inhibits DNA replication elongation through a direct interaction with the β sliding clamp. Mol. Cell 52, 617–628 (2013).
Freire, D. M. et al. An NAD+ phosphorylase toxin triggers Mycobacterium tuberculosis cell death. Mol. Cell 73, 1282–1291.e8 (2019).
Cai, Y. et al. A nucleotidyltransferase toxin inhibits growth of Mycobacterium tuberculosis through inactivation of tRNA acceptor stems. Sci. Adv. 6, eabb6651 (2020).
Jimmy, S. et al. A widespread toxin-antitoxin system exploiting growth control via alarmone signaling. Proc. Natl Acad. Sci. USA 117, 10500–10510 (2020).
Songailiene, I. et al. HEPN-MNT toxin-antitoxin system: the HEPN ribonuclease is neutralized by oligoAMPylation. Mol. Cell 80, 955–970.e7 (2020).
Kurata, T. et al. RelA-SpoT homolog toxins pyrophosphorylate the CCA end of tRNA to inhibit protein synthesis. Mol. Cell 81, 3160–3170.e9 (2021).
Li, M. et al. Toxin-antitoxin RNA pairs safeguard CRISPR-Cas systems. Science 372, eabe5601 (2021).
Hargreaves, D. et al. Structural and functional analysis of the Kid toxin protein from E. coli plasmid R1. Structure 10, 1425–1433 (2002).
Sterckx, Y. G.-J. et al. A unique hetero-hexadecameric architecture displayed by the Escherichia coli O157 PaaA2-ParE2 antitoxin-toxin complex. J. Mol. Biol. 428, 1589–1603 (2016).
Castro-Roa, D. et al. The Fic protein Doc uses an inverted substrate to phosphorylate and inactivate EF-Tu. Nat. Chem. Biol. 9, 811–817 (2013).
Harms, A. et al. Adenylylation of gyrase and Topo IV by FicT toxins disrupts bacterial DNA topology. Cell Rep. 12, 1497–1507 (2015).
Dalton, K. M. & Crosson, S. A conserved mode of protein recognition and binding in a ParD-ParE toxin-antitoxin complex. Biochemistry 49, 2205–2215 (2010).
Kumar, P., Issac, B., Dodson, E. J., Turkenburg, J. P. & Mande, S. C. Crystal structure of Mycobacterium tuberculosis YefM antitoxin reveals that it is not an intrinsically unstructured protein. J. Mol. Biol. 383, 482–493 (2008).
Brown, B. L., Lord, D. M., Grigoriu, S., Peti, W. & Page, R. The Escherichia coli toxin MqsR destabilizes the transcriptional repression complex formed between the antitoxin MqsA and the mqsRA operon promoter. J. Biol. Chem. 288, 1286–1294 (2013).
Zhang, D., de Souza, R. F., Anantharaman, V., Iyer, L. M. & Aravind, L. Polymorphic toxin systems: comprehensive characterization of trafficking modes, processing, mechanisms of action, immunity and ecology using comparative genomics. Biol. Direct 7, 18 (2012).
Harms, A. et al. A bacterial toxin-antitoxin module is the origin of inter-bacterial and inter-kingdom effectors of Bartonella. PLoS Genet. 13, e1007077 (2017).
Kawano, M., Oshima, T., Kasai, H. & Mori, H. Molecular characterization of long direct repeat (LDR) sequences expressing a stable mRNA encoding for a 35-amino-acid cell-killing peptide and a cis-encoded small antisense RNA in Escherichia coli. Mol. Microbiol. 45, 333–349 (2002).
Darfeuille, F., Unoson, C., Vogel, J. & Wagner, E. G. H. An antisense RNA inhibits translation by competing with standby ribosomes. Mol. Cell 26, 381–392 (2007).
Kawano, M., Aravind, L. & Storz, G. An antisense RNA controls synthesis of an SOS-induced toxin evolved from an antitoxin. Mol. Microbiol. 64, 738–754 (2007).
Fozo, E. M. et al. Repression of small toxic protein synthesis by the Sib and OhsC small RNAs. Mol. Microbiol. 70, 1076–1093 (2008).
Lehnherr, H., Maguin, E., Jafri, S. & Yarmolinsky, M. B. Plasmid addiction genes of bacteriophage P1: doc, which causes cell death on curing of prophage, and phd, which prevents host death when prophage is retained. J. Mol. Biol. 233, 414–428 (1993).
Li, G.-Y., Zhang, Y., Inouye, M. & Ikura, M. Inhibitory mechanism of Escherichia coli RelE-RelB toxin-antitoxin module involves a helix displacement near an mRNA interferase active site. J. Biol. Chem. 284, 14628–14636 (2009).
Jurėnas, D., Van Melderen, L. & Garcia-Pino, A. Mechanism of regulation and neutralization of the AtaR-AtaT toxin-antitoxin system. Nat. Chem. Biol. 15, 285–294 (2019).
Samson, J. E., Spinelli, S., Cambillau, C. & Moineau, S. Structure and activity of AbiQ, a lactococcal endoribonuclease belonging to the type III toxin-antitoxin system. Mol. Microbiol. 87, 756–768 (2013).
Short, F. L. et al. Selectivity and self-assembly in the control of a bacterial toxin by an antitoxic noncoding RNA pseudoknot. Proc. Natl Acad. Sci. USA 110, E241–E249 (2013).
Masuda, H., Tan, Q., Awano, N., Wu, K.-P. & Inouye, M. YeeU enhances the bundling of cytoskeletal polymers of MreB and FtsZ, antagonizing the CbtA (YeeV) toxicity in Escherichia coli. Mol. Microbiol. 84, 979–989 (2012).
Jankevicius, G., Ariza, A., Ahel, M. & Ahel, I. The toxin-antitoxin system DarTG catalyzes reversible ADP-ribosylation of DNA. Mol. Cell 64, 1109–1116 (2016).
Marimon, O. et al. An oxygen-sensitive toxin-antitoxin system. Nat. Commun. 7, 13634 (2016).
Yu, X. et al. Characterization of a toxin-antitoxin system in Mycobacterium tuberculosis suggests neutralization by phosphorylation as the antitoxicity mechanism. Commun. Biol. 3, 216 (2020).
Choi, J. S. et al. The small RNA, SdsR, acts as a novel type of toxin in Escherichia coli. RNA Biol. 15, 1319–1335 (2018).
Shao, Y. et al. TADB: a web-based resource for type 2 toxin-antitoxin loci in bacteria and archaea. Nucleic Acids Res. 39, D606–D611 (2011).
Wen, J. & Fozo, E. M. sRNA antitoxins: more than one way to repress a toxin. Toxins 6, 2310–2335 (2014).
Blower, T. R. et al. Identification and classification of bacterial type III toxin-antitoxin systems encoded in chromosomal and plasmid genomes. Nucleic Acids Res. 40, 6158–6173 (2012).
Anantharaman, V., Makarova, K. S., Burroughs, A. M., Koonin, E. V. & Aravind, L. Comprehensive analysis of the HEPN superfamily: identification of novel roles in intra-genomic conflicts, defense, pathogenesis and RNA processing. Biol. Direct 8, 15 (2013).
Otsuka, Y. et al. IscR regulates RNase LS activity by repressing rnlA transcription. Genetics 185, 823–830 (2010).
Turnbull, K. J. & Gerdes, K. HicA toxin of Escherichia coli derepresses hicAB transcription to selectively produce HicB antitoxin. Mol. Microbiol. 104, 781–792 (2017).
Fraikin, N., Rousseau, C. J., Goeders, N. & Van Melderen, L. Reassessing the role of the type II MqsRA toxin-antitoxin system in stress response and biofilm formation: mqsA is transcriptionally uncoupled from mqsR. mBio 10, e02678-19 (2019).
Kamada, K., Hanaoka, F. & Burley, S. K. Crystal structure of the MazE/MazF complex: molecular bases of antidote-toxin recognition. Mol. Cell 11, 875–884 (2003).
Madl, T. et al. Structural basis for nucleic acid and toxin recognition of the bacterial antitoxin CcdA. J. Mol. Biol. 364, 170–185 (2006).
Garcia-Pino, A. et al. Doc of prophage P1 is inhibited by its antitoxin partner Phd through fold complementation. J. Biol. Chem. 283, 30821–30827 (2008).
Afif, H., Allali, N., Couturier, M. & Van Melderen, L. The ratio between CcdA and CcdB modulates the transcriptional repression of the ccd poison-antidote system. Mol. Microbiol. 41, 73–82 (2001).
Overgaard, M., Borch, J., Jørgensen, M. G. & Gerdes, K. Messenger RNA interferase RelE controls relBE transcription by conditional cooperativity. Mol. Microbiol. 69, 841–857 (2008).
Garcia-Pino, A. et al. Allostery and intrinsic disorder mediate transcription regulation by conditional cooperativity. Cell 142, 101–111 (2010).
Talavera, A. et al. A dual role in regulation and toxicity for the disordered N-terminus of the toxin GraT. Nat. Commun. 10, 972 (2019).
Hallez, R. et al. New toxins homologous to ParE belonging to three-component toxin-antitoxin systems in Escherichia coli O157:H7. Mol. Microbiol. 76, 719–732 (2010).
Zielenkiewicz, U. & Ceglowski, P. The toxin-antitoxin system of the streptococcal plasmid pSM19035. J. Bacteriol. 187, 6094–6105 (2005).
Fozo, E. M. et al. Abundance of type I toxin-antitoxin systems in bacteria: searches for new candidates and discovery of novel families. Nucleic Acids Res. 38, 3743–3759 (2010).
Masachis, S. & Darfeuille, F. Type I toxin-antitoxin systems: regulating toxin expression via Shine-Dalgarno sequence sequestration and small RNA binding. Microbiol. Spectr. https://doi.org/10.1128/microbiolspec.RWR-0030-2018 (2018).
Gerdes, K., Thisted, T. & Martinussen, J. Mechanism of post-segregational killing by the hok/sok system of plasmid R1: sok antisense RNA regulates formation of a hok mRNA species correlated with killing of plasmid-free cells. Mol. Microbiol. 4, 1807–1818 (1990).
Romilly, C., Deindl, S. & Wagner, E. G. H. The ribosomal protein S1-dependent standby site in tisB mRNA consists of a single-stranded region and a 5′ structure element. Proc. Natl Acad. Sci. USA 116, 15901–15906 (2019).
Romilly, C., Lippegaus, A. & Wagner, E. G. H. An RNA pseudoknot is essential for standby-mediated translation of the tisB toxin mRNA in Escherichia coli. Nucleic Acids Res. 48, 12336–12347 (2020).
Vogel, J., Argaman, L., Wagner, E. G. H. & Altuvia, S. The small RNA IstR inhibits synthesis of an SOS-induced toxic peptide. Curr. Biol. 14, 2271–2276 (2004).
Durand, S., Gilet, L. & Condon, C. The essential function of B. subtilis RNase III is to silence foreign toxin genes. PLoS Genet. 8, e1003181 (2012).
Li, G.-W., Burkhardt, D., Gross, C. & Weissman, J. S. Quantifying absolute protein synthesis rates reveals principles underlying allocation of cellular resources. Cell 157, 624–635 (2014).
Ruiz-Echevarría, M. J., de la Cueva, G. & Díaz-Orejas, R. Translational coupling and limited degradation of a polycistronic messenger modulate differential gene expression in the parD stability system of plasmid R1. Mol. Gen. Genet. 248, 599–609 (1995).
Blower, T. R. et al. A processed noncoding RNA regulates an altruistic bacterial antiviral system. Nat. Struct. Mol. Biol. 18, 185–190 (2011).
De Jonge, N. et al. Rejuvenation of CcdB-poisoned gyrase by an intrinsically disordered protein domain. Mol. Cell 35, 154–163 (2009).
Lehnherr, H. & Yarmolinsky, M. B. Addiction protein Phd of plasmid prophage P1 is a substrate of the ClpXP serine protease of Escherichia coli. Proc. Natl Acad. Sci. USA 92, 3274–3277 (1995).
Diago-Navarro, E., Hernández-Arriaga, A. M., Kubik, S., Konieczny, I. & Díaz-Orejas, R. Cleavage of the antitoxin of the parD toxin-antitoxin system is determined by the ClpAP protease and is modulated by the relative ratio of the toxin and the antitoxin. Plasmid 70, 78–85 (2013).
Van Melderen, L. et al. ATP-dependent degradation of CcdA by Lon protease. Effects of secondary structure and heterologous subunit interactions. J. Biol. Chem. 271, 27730–27738 (1996).
Dubiel, A., Wegrzyn, K., Kupinski, A. P. & Konieczny, I. ClpAP protease is a universal factor that activates the parDE toxin-antitoxin system from a broad host range RK2 plasmid. Sci. Rep. 8, 15287 (2018).
Ziemski, M., Leodolter, J., Taylor, G., Kerschenmeyer, A. & Weber-Ban, E. Genome-wide interaction screen for Mycobacterium tuberculosis ClpCP protease reveals toxin-antitoxin systems as a major substrate class. FEBS J. 288, 111–126 (2021).
LeRoux, M., Culviner, P. H., Liu, Y. J., Littlehale, M. L. & Laub, M. T. Stress can induce transcription of toxin-antitoxin systems without activating toxin. Mol. Cell 79, 280–292.e8 (2020).
Bordes, P. et al. SecB-like chaperone controls a toxin-antitoxin stress-responsive system in Mycobacterium tuberculosis. Proc. Natl Acad. Sci. USA 108, 8438–8443 (2011).
Bordes, P. et al. Chaperone addiction of toxin-antitoxin systems. Nat. Commun. 7, 13339 (2016).
Texier, P. et al. ClpXP-mediated degradation of the TAC antitoxin is neutralized by the SecB-like chaperone in Mycobacterium tuberculosis. J. Mol. Biol. 433, 166815 (2021).
Schumacher, M. A. et al. Role of unusual P loop ejection and autophosphorylation in HipA-mediated persistence and multidrug tolerance. Cell Rep. 2, 518–525 (2012).
Piscotta, F. J., Jeffrey, P. D. & Link, A. J. ParST is a widespread toxin-antitoxin module that targets nucleotide metabolism. Proc. Natl Acad. Sci. USA 116, 826–834 (2019).
Critchlow, S. E. et al. The interaction of the F plasmid killer protein, CcdB, with DNA gyrase: induction of DNA cleavage and blocking of transcription. J. Mol. Biol. 273, 826–839 (1997).
Bernard, P. & Couturier, M. Cell killing by the F plasmid CcdB protein involves poisoning of DNA-topoisomerase II complexes. J. Mol. Biol. 226, 735–745 (1992).
Dao-Thi, M.-H. et al. Molecular basis of gyrase poisoning by the addiction toxin CcdB. J. Mol. Biol. 348, 1091–1102 (2005).
Jiang, Y., Pogliano, J., Helinski, D. R. & Konieczny, I. ParE toxin encoded by the broad-host-range plasmid RK2 is an inhibitor of Escherichia coli gyrase. Mol. Microbiol. 44, 971–979 (2002).
Ames, J. R., Muthuramalingam, M., Murphy, T., Najar, F. Z. & Bourne, C. R. Expression of different ParE toxins results in conserved phenotypes with distinguishable classes of toxicity. Microbiologyopen 8, e902 (2019).
Roberts, R. C., Ström, A. R. & Helinski, D. R. The parDE operon of the broad-host-range plasmid RK2 specifies growth inhibition associated with plasmid loss. J. Mol. Biol. 237, 35–51 (1994).
Guo, Y. et al. RalR (a DNase) and RalA (a small RNA) form a type I toxin-antitoxin system in Escherichia coli. Nucleic Acids Res. 42, 6448–6462 (2014).
Jurėnas, D. & Van Melderen, L. The variety in the common theme of translation inhibition by type II toxin-antitoxin systems. Front. Genet. 11, 262 (2020).
Culviner, P. H. & Laub, M. T. Global analysis of the E. coli toxin MazF reveals widespread cleavage of mRNA and the inhibition of rRNA maturation and ribosome biogenesis. Mol. Cell 70, 868–880.e10 (2018).
Mets, T. et al. Toxins MazF and MqsR cleave Escherichia coli rRNA precursors at multiple sites. RNA Biol. 14, 124–135 (2017).
Mets, T. et al. Fragmentation of Escherichia coli mRNA by MazF and MqsR. Biochimie 156, 79–91 (2019).
Barth, V. C. & Woychik, N. A. The sole Mycobacterium smegmatis MazF toxin targets tRNALys to impart highly selective, codon-dependent proteome reprogramming. Front. Genet. 10, 1356 (2019).
Winther, K. S. & Gerdes, K. Enteric virulence associated protein VapC inhibits translation by cleavage of initiator tRNA. Proc. Natl Acad. Sci. USA 108, 7403–7407 (2011).
Cruz, J. W. et al. Growth-regulating Mycobacterium tuberculosis VapC-mt4 toxin is an isoacceptor-specific tRNase. Nat. Commun. 6, 7480 (2015).
Winther, K., Tree, J. J., Tollervey, D. & Gerdes, K. VapCs of Mycobacterium tuberculosis cleave RNAs essential for translation. Nucleic Acids Res. 44, 9860–9871 (2016).
Cintrón, M. et al. Accurate target identification for Mycobacterium tuberculosis endoribonuclease toxins requires expression in their native host. Sci. Rep. 9, 5949 (2019).
Winther, K. S., Brodersen, D. E., Brown, A. K. & Gerdes, K. VapC20 of Mycobacterium tuberculosis cleaves the sarcin-ricin loop of 23S rRNA. Nat. Commun. 4, 2796 (2013).
Pedersen, K. et al. The bacterial toxin RelE displays codon-specific cleavage of mRNAs in the ribosomal A site. Cell 112, 131–140 (2003).
Goeders, N., Drèze, P.-L. & Van Melderen, L. Relaxed cleavage specificity within the RelE toxin family. J. Bacteriol. 195, 2541–2549 (2013).
Schureck, M. A., Repack, A., Miles, S. J., Marquez, J. & Dunham, C. M. Mechanism of endonuclease cleavage by the HigB toxin. Nucleic Acids Res. 44, 7944–7953 (2016).
Jørgensen, M. G., Pandey, D. P., Jaskolska, M. & Gerdes, K. HicA of Escherichia coli defines a novel family of translation-independent mRNA interferases in bacteria and archaea. J. Bacteriol. 191, 1191–1199 (2009).
Kaspy, I. et al. HipA-mediated antibiotic persistence via phosphorylation of the glutamyl-tRNA-synthetase. Nat. Commun. 4, 3001 (2013).
Vang Nielsen, S. et al. Serine-threonine kinases encoded by split hipA homologs inhibit tryptophanyl-tRNA synthetase. mBio 10, e01138-19 (2019).
Jurėnas, D. et al. AtaT blocks translation initiation by N-acetylation of the initiator tRNAfMet. Nat. Chem. Biol. 13, 640–646 (2017).
Rycroft, J. A. et al. Activity of acetyltransferase toxins involved in Salmonella persister formation during macrophage infection. Nat. Commun. 9, 1993 (2018).
Wilcox, B. et al. Escherichia coli ItaT is a type II toxin that inhibits translation by acetylating isoleucyl-tRNAIle. Nucleic Acids Res. 46, 7873–7885 (2018).
Unoson, C. & Wagner, E. G. H. A small SOS-induced toxin is targeted against the inner membrane in Escherichia coli. Mol. Microbiol. 70, 258–270 (2008).
Weel-Sneve, R. et al. Single transmembrane peptide DinQ modulates membrane-dependent activities. PLoS Genet. 9, e1003260 (2013).
Patel, S. & Weaver, K. E. Addiction toxin Fst has unique effects on chromosome segregation and cell division in Enterococcus faecalis and Bacillus subtilis. J. Bacteriol. 188, 5374–5384 (2006).
Mutschler, H., Gebhardt, M., Shoeman, R. L. & Meinhart, A. A novel mechanism of programmed cell death in bacteria by toxin-antitoxin systems corrupts peptidoglycan synthesis. PLoS Biol. 9, e1001033 (2011).
Rocker, A. et al. The ng_ζ1 toxin of the gonococcal epsilon/zeta toxin/antitoxin system drains precursors for cell wall synthesis. Nat. Commun. 9, 1686 (2018).
Tan, Q., Awano, N. & Inouye, M. YeeV is an Escherichia coli toxin that inhibits cell division by targeting the cytoskeleton proteins, FtsZ and MreB. Mol. Microbiol. 79, 109–118 (2011).
Engelberg-Kulka, H., Amitai, S., Kolodkin-Gal, I. & Hazan, R. Bacterial programmed cell death and multicellular behavior in bacteria. PLoS Genet. 2, e135 (2006).
Engelberg-Kulka, H., Hazan, R. & Amitai, S. mazEF: a chromosomal toxin-antitoxin module that triggers programmed cell death in bacteria. J. Cell Sci. 118, 4327–4332 (2005).
Helaine, S. et al. Internalization of Salmonella by macrophages induces formation of nonreplicating persisters. Science 343, 204–208 (2014).
Maisonneuve, E. & Gerdes, K. Molecular mechanisms underlying bacterial persisters. Cell 157, 539–548 (2014).
Wang, X. et al. Antitoxin MqsA helps mediate the bacterial general stress response. Nat. Chem. Biol. 7, 359–366 (2011).
Kolodkin-Gal, I., Hazan, R., Gaathon, A., Carmeli, S. & Engelberg-Kulka, H. A linear pentapeptide is a quorum-sensing factor required for mazEF-mediated cell death in Escherichia coli. Science 318, 652–655 (2007).
Belitsky, M. et al. The Escherichia coli extracellular death factor EDF induces the endoribonucleolytic activities of the toxins MazF and ChpBK. Mol. Cell 41, 625–635 (2011).
Aizenman, E., Engelberg-Kulka, H. & Glaser, G. An Escherichia coli chromosomal ‘addiction module’ regulated by guanosine [corrected] 3′,5′-bispyrophosphate: a model for programmed bacterial cell death. Proc. Natl Acad. Sci. USA 93, 6059–6063 (1996).
Vesper, O. et al. Selective translation of leaderless mRNAs by specialized ribosomes generated by MazF in Escherichia coli. Cell 147, 147–157 (2011).
Pedersen, K., Christensen, S. K. & Gerdes, K. Rapid induction and reversal of a bacteriostatic condition by controlled expression of toxins and antitoxins. Mol. Microbiol. 45, 501–510 (2002).
Tsilibaris, V., Maenhaut-Michel, G., Mine, N. & Van Melderen, L. What is the benefit to Escherichia coli of having multiple toxin-antitoxin systems in its genome? J. Bacteriol. 189, 6101–6108 (2007).
Ramisetty, B. C. M., Raj, S. & Ghosh, D. Escherichia coli MazEF toxin-antitoxin system does not mediate programmed cell death. J. Basic. Microbiol. 56, 1398–1402 (2016).
Kaldalu, N., Maiväli, Ü., Hauryliuk, V. & Tenson, T. Reanalysis of proteomics results fails to detect MazF-mediated stress proteins. mBio 10, e00949-19 (2019).
Christensen, S. K. & Gerdes, K. RelE toxins from bacteria and archaea cleave mRNAs on translating ribosomes, which are rescued by tmRNA. Mol. Microbiol. 48, 1389–1400 (2003).
Christensen, S. K., Mikkelsen, M., Pedersen, K. & Gerdes, K. RelE, a global inhibitor of translation, is activated during nutritional stress. Proc. Natl Acad. Sci. USA 98, 14328–14333 (2001).
González Barrios, A. F. et al. Autoinducer 2 controls biofilm formation in Escherichia coli through a novel motility quorum-sensing regulator (MqsR, B3022). J. Bacteriol. 188, 305–316 (2006).
Kwan, B. W. et al. The MqsR/MqsA toxin/antitoxin system protects Escherichia coli during bile acid stress. Environ. Microbiol. 17, 3168–3181 (2015).
Soo, V. W. C. & Wood, T. K. Antitoxin MqsA represses curli formation through the master biofilm regulator CsgD. Sci. Rep. 3, 3186 (2013).
Dörr, T., Vulić, M. & Lewis, K. Ciprofloxacin causes persister formation by inducing the TisB toxin in Escherichia coli. PLoS Biol. 8, e1000317 (2010).
Verstraeten, N. et al. Obg and membrane depolarization are part of a microbial Bet-Hedging strategy that leads to antibiotic tolerance. Mol. Cell 59, 9–21 (2015).
Berghoff, B. A., Hoekzema, M., Aulbach, L. & Wagner, E. G. H. Two regulatory RNA elements affect TisB-dependent depolarization and persister formation. Mol. Microbiol. 103, 1020–1033 (2017).
Ramisetty, B. C. M., Ghosh, D., Roy Chowdhury, M. & Santhosh, R. S. What is the link between stringent response, endoribonuclease encoding type II toxin-antitoxin systems and persistence? Front. Microbiol. 7, 1882 (2016).
Maisonneuve, E., Castro-Camargo, M. & Gerdes, K. Retraction notice to: (p)ppGpp controls bacterial persistence by stochastic induction of toxin-antitoxin activity. Cell 172, 1135 (2018).
Retraction for Maisonneuve. et al. Bacterial persistence by RNA endonucleases. Proc. Natl Acad. Sci. USA 115, E2901 (2018).
Harms, A., Fino, C., Sørensen, M. A., Semsey, S. & Gerdes, K. Prophages and growth dynamics confound experimental results with antibiotic-tolerant persister cells. mBio 8, e01964–17 (2017).
Goormaghtigh, F. et al. Reassessing the role of type II Toxin-antitoxin systems in formation of Escherichia coli type II persister cells. mBio 9, e00640-18 (2018).
Pontes, M. H. & Groisman, E. A. Slow growth determines nonheritable antibiotic resistance in Salmonella enterica. Sci. Signal. 12, eaax3938 (2019).
Rosendahl, S., Tamman, H., Brauer, A., Remm, M. & Hõrak, R. Chromosomal toxin-antitoxin systems in Pseudomonas putida are rather selfish than beneficial. Sci. Rep. 10, 9230 (2020).
Christensen, S. K. et al. Overproduction of the Lon protease triggers inhibition of translation in Escherichia coli: involvement of the yefM-yoeB toxin-antitoxin system. Mol. Microbiol. 51, 1705–1717 (2004).
Völzing, K. G. & Brynildsen, M. P. Stationary-phase persisters to ofloxacin sustain DNA damage and require repair systems only during recovery. mBio 6, e00731-15 (2015).
Goormaghtigh, F. & Van Melderen, L. Single-cell imaging and characterization of Escherichia coli persister cells to ofloxacin in exponential cultures. Sci. Adv. 5, eaav9462 (2019).
Korch, S. B., Henderson, T. A. & Hill, T. M. Characterization of the hipA7 allele of Escherichia coli and evidence that high persistence is governed by (p)ppGpp synthesis. Mol. Microbiol. 50, 1199–1213 (2003).
Levin-Reisman, I. et al. Antibiotic tolerance facilitates the evolution of resistance. Science 355, 826–830 (2017).
Santi, I., Manfredi, P., Maffei, E., Egli, A. & Jenal, U. Evolution of antibiotic tolerance shapes resistance development in chronic Pseudomonas aeruginosa infections. mBio 12, e03482-20 (2021).
Rotem, E. et al. Regulation of phenotypic variability by a threshold-based mechanism underlies bacterial persistence. Proc. Natl Acad. Sci. USA 107, 12541–12546 (2010).
Guegler, C. K. & Laub, M. T. Shutoff of host transcription triggers a toxin-antitoxin system to cleave phage RNA and abort infection. Mol. Cell 81, 2361–2373.e9 (2021).
Cooper, T. F. & Heinemann, J. A. Postsegregational killing does not increase plasmid stability but acts to mediate the exclusion of competing plasmids. Proc. Natl Acad. Sci. USA 97, 12643–12648 (2000).
Saavedra De Bast, M., Mine, N. & Van Melderen, L. Chromosomal toxin-antitoxin systems may act as antiaddiction modules. J. Bacteriol. 190, 4603–4609 (2008).
Cegłowski, P., Boitsov, A., Chai, S. & Alonso, J. C. Analysis of the stabilization system of pSM19035-derived plasmid pBT233 in Bacillus subtilis. Gene 136, 1–12 (1993).
Bravo, A., Ortega, S., de Torrontegui, G. & Díaz, R. Killing of Escherichia coli cells modulated by components of the stability system ParD of plasmid R1. Mol. Gen. Genet. 215, 146–151 (1988).
Dy, R. L., Przybilski, R., Semeijn, K., Salmond, G. P. C. & Fineran, P. C. A widespread bacteriophage abortive infection system functions through a Type IV toxin-antitoxin mechanism. Nucleic Acids Res. 42, 4590–4605 (2014).
de la Hoz, A. B. et al. Plasmid copy-number control and better-than-random segregation genes of pSM19035 share a common regulator. Proc. Natl Acad. Sci. USA 97, 728–733 (2000).
Ni, S. et al. Conjugative plasmid-encoded toxin-antitoxin system PrpT/PrpA directly controls plasmid copy number. Proc. Natl Acad. Sci. USA 118, e2011577118 (2021).
Wozniak, R. A. F. & Waldor, M. K. A toxin-antitoxin system promotes the maintenance of an integrative conjugative element. PLoS Genet. 5, e1000439 (2009).
Escudero, J. A., Loot, C., Nivina, A. & Mazel, D. The integron: adaptation on demand. Microbiol. Spectr. 3, 3.2.10 (2015).
Iqbal, N., Guérout, A.-M., Krin, E., Le Roux, F. & Mazel, D. Comprehensive functional analysis of the 18 Vibrio cholerae N16961 toxin-antitoxin systems substantiates their role in stabilizing the superintegron. J. Bacteriol. 197, 2150–2159 (2015).
Szekeres, S., Dauti, M., Wilde, C., Mazel, D. & Rowe-Magnus, D. A. Chromosomal toxin-antitoxin loci can diminish large-scale genome reductions in the absence of selection. Mol. Microbiol. 63, 1588–1605 (2007).
Yuan, J., Yamaichi, Y. & Waldor, M. K. The three vibrio cholerae chromosome II-encoded ParE toxins degrade chromosome I following loss of chromosome II. J. Bacteriol. 193, 611–619 (2011).
Cooper, T. F. & Heinemann, J. A. Selection for plasmid post-segregational killing depends on multiple infection: evidence for the selection of more virulent parasites through parasite-level competition. Proc. Biol. Sci. 272, 403–410 (2005).
Cooper, T. F., Paixão, T. & Heinemann, J. A. Within-host competition selects for plasmid-encoded toxin-antitoxin systems. Proc. Biol. Sci. 277, 3149–3155 (2010).
Santos-Sierra, S., Giraldo, R. & Díaz-Orejas, R. Functional interactions between homologous conditional killer systems of plasmid and chromosomal origin. FEMS Microbiol. Lett. 152, 51–56 (1997).
Santos Sierra, S., Giraldo, R. & Díaz Orejas, R. Functional interactions between chpB and parD, two homologous conditional killer systems found in the Escherichia coli chromosome and in plasmid R1. FEMS Microbiol. Lett. 168, 51–58 (1998).
Garvey, P., Fitzgerald, G. F. & Hill, C. Cloning and DNA sequence analysis of two abortive infection phage resistance determinants from the lactococcal plasmid pNP40. Appl. Environ. Microbiol. 61, 4321–4328 (1995).
Pecota, D. C. & Wood, T. K. Exclusion of T4 phage by the hok/sok killer locus from plasmid R1. J. Bacteriol. 178, 2044–2050 (1996).
Otsuka, Y. & Yonesaki, T. A novel endoribonuclease, RNase LS, in Escherichia coli. Genetics 169, 13–20 (2005).
Otsuka, Y. & Yonesaki, T. Dmd of bacteriophage T4 functions as an antitoxin against Escherichia coli LsoA and RnlA toxins. Mol. Microbiol. 83, 669–681 (2012).
Blower, T. R., Evans, T. J., Przybilski, R., Fineran, P. C. & Salmond, G. P. C. Viral evasion of a bacterial suicide system by RNA-based molecular mimicry enables infectious altruism. PLoS Genet. 8, e1003023 (2012).
Blower, T. R. et al. Evolution of Pectobacterium bacteriophage ΦM1 to escape two bifunctional type III toxin-antitoxin and abortive infection systems through mutations in a single viral gene. Appl. Environ. Microbiol. 83, e03229-16 (2017).
Chen, B., Akusobi, C., Fang, X. & Salmond, G. P. C. Environmental T4-family bacteriophages evolve to escape abortive infection via multiple routes in a bacterial host employing ‘altruistic suicide’ through type III toxin-antitoxin systems. Front. Microbiol. 8, 1006 (2017).
Hilliard, J. J., Maurizi, M. R. & Simon, L. D. Isolation and characterization of the phage T4 PinA protein, an inhibitor of the ATP-dependent Lon protease of Escherichia coli. J. Biol. Chem. 273, 518–523 (1998).
Sberro, H. et al. Discovery of functional toxin/antitoxin systems in bacteria by shotgun cloning. Mol. Cell 50, 136–148 (2013).
Lima-Mendez, G. et al. Toxin-antitoxin gene pairs found in Tn3 family transposons appear to be an integral part of the transposition module. mBio 11, e00452-20 (2020).
Loftie-Eaton, W. et al. Evolutionary paths that expand plasmid host-range: implications for spread of antibiotic resistance. Mol. Biol. Evol. 33, 885–897 (2016).
Lite, T.-L. V. et al. Uncovering the basis of protein-protein interaction specificity with a combinatorially complete library. eLife 9, e60924 (2020).
Aakre, C. D. et al. Evolving new protein-protein interaction specificity through promiscuous intermediates. Cell 163, 594–606 (2015).
Fiebig, A., Castro Rojas, C. M., Siegal-Gaskins, D. & Crosson, S. Interaction specificity, toxicity and regulation of a paralogous set of ParE/RelE-family toxin-antitoxin systems. Mol. Microbiol. 77, 236–251 (2010).
Mine, N., Guglielmini, J., Wilbaux, M. & Van Melderen, L. The decay of the chromosomally encoded ccdO157 toxin-antitoxin system in the Escherichia coli species. Genetics 181, 1557–1566 (2009).
Pedersen, K. & Gerdes, K. Multiple hok genes on the chromosome of Escherichia coli. Mol. Microbiol. 32, 1090–1102 (1999).
Goeders, N. & Van Melderen, L. Toxin-antitoxin systems as multilevel interaction systems. Toxins 6, 304–324 (2014).
Moran, N. A. & Bennett, G. M. The tiniest tiny genomes. Annu. Rev. Microbiol. 68, 195–215 (2014).
Anantharaman, V. & Aravind, L. New connections in the prokaryotic toxin-antitoxin network: relationship with the eukaryotic nonsense-mediated RNA decay system. Genome Biol. 4, R81 (2003).
Loris, R. et al. Crystal structure of CcdB, a topoisomerase poison from E. coli. J. Mol. Biol. 285, 1667–1677 (1999).
Arbing, M. A. et al. Crystal structures of Phd-Doc, HigA, and YeeU establish multiple evolutionary links between microbial growth-regulating toxin-antitoxin systems. Structure 18, 996–1010 (2010).
Coles, M. et al. AbrB-like transcription factors assume a swapped hairpin fold that is evolutionarily related to double-psi beta barrels. Structure 13, 919–928 (2005).
Gucinski, G. C. et al. Convergent evolution of the barnase/EndoU/Ccolicin/RelE (BECR) fold in antibacterial tRNase toxins. Structure 27, 1660–1674.e5 (2019).
Whitney, J. C. et al. An interbacterial NAD(P)+ glycohydrolase toxin requires elongation factor Tu for delivery to target cells. Cell 163, 607–619 (2015).
Ahmad, S. et al. An interbacterial toxin inhibits target cell growth by synthesizing (p)ppApp. Nature 575, 674–678 (2019).
Schirmer, T. et al. Evolutionary diversification of host-targeted bartonella effectors proteins derived from a conserved FicTA toxin-antitoxin module. Microorganisms 9, 1645 (2021).
Han, Q. et al. Crystal structure of Xanthomonas AvrRxo1-ORF1, a type III effector with a polynucleotide kinase domain, and its interactor AvrRxo1-ORF2. Structure 23, 1900–1909 (2015).
Triplett, L. R. et al. AvrRxo1 is a bifunctional type III secreted effector and toxin-antitoxin system component with homologs in diverse environmental contexts. PLoS ONE 11, e0158856 (2016).
Yadav, S. K. et al. Immunity proteins of dual nuclease T6SS effectors function as transcriptional repressors. EMBO Rep. 22, e53112 (2021).
Bertelsen, M. B. et al. Structural basis for toxin inhibition in the VapXD toxin-antitoxin system. Structure 29, 139–150.e3 (2021).
Matelska, D., Steczkiewicz, K. & Ginalski, K. Comprehensive classification of the PIN domain-like superfamily. Nucleic Acids Res. 45, 6995–7020 (2017).
Dziewit, L., Jazurek, M., Drewniak, L., Baj, J. & Bartosik, D. The SXT conjugative element and linear prophage N15 encode toxin-antitoxin-stabilizing systems homologous to the tad-ata module of the Paracoccus aminophilus plasmid pAMI2. J. Bacteriol. 189, 1983–1997 (2007).
Kang, S.-M. et al. Functional details of the Mycobacterium tuberculosis VapBC26 toxin-antitoxin system based on a structural study: insights into unique binding and antibiotic peptides. Nucleic Acids Res. 45, 8564–8580 (2017).
Sayed, N., Nonin-Lecomte, S., Réty, S. & Felden, B. Functional and structural insights of a Staphylococcus aureus apoptotic-like membrane peptide from a toxin-antitoxin module. J. Biol. Chem. 287, 43454–43463 (2012).
Równicki, M. et al. Artificial activation of Escherichia coli mazEF and hipBA toxin-antitoxin systems by antisense peptide nucleic acids as an antibacterial strategy. Front. Microbiol. 9, 2870 (2018).
Kang, S.-M. et al. Structure-based de novo design of Mycobacterium tuberculosis VapC-activating stapled peptides. ACS Chem. Biol. 15, 2493–2498 (2020).
Kang, S.-M. et al. Structure-based design of peptides that trigger Streptococcus pneumoniae cell death. FEBS J. 288, 1546–1564 (2021).
Maleki, A., Ghafourian, S., Pakzad, I., Badakhsh, B. & Sadeghifard, N. mazE Antitoxin of toxin antitoxin system and fbpA as reliable targets to eradication of Neisseria meningitidis. Curr. Pharm. Des. 24, 1204–1210 (2018).
Trovatti, E., Cotrim, C. A., Garrido, S. S., Barros, R. S. & Marchetto, R. Peptides based on CcdB protein as novel inhibitors of bacterial topoisomerases. Bioorg. Med. Chem. Lett. 18, 6161–6164 (2008).
López-Igual, R., Bernal-Bayard, J., Rodríguez-Patón, A., Ghigo, J.-M. & Mazel, D. Engineered toxin-intein antimicrobials can selectively target and kill antibiotic-resistant bacteria in mixed populations. Nat. Biotechnol. 37, 755–760 (2019).
Park, J.-H., Yamaguchi, Y. & Inouye, M. Intramolecular regulation of the sequence-specific mRNA interferase activity of MazF fused to a MazE fragment with a linker cleavable by specific proteases. Appl. Environ. Microbiol. 78, 3794–3799 (2012).
Chono, H. et al. Acquisition of HIV-1 resistance in T lymphocytes using an ACA-specific E. coli mRNA interferase. Hum. Gene Ther. 22, 35–43 (2011).
de la Cueva-Méndez, G., Mills, A. D., Clay-Farrace, L., Díaz-Orejas, R. & Laskey, R. A. Regulatable killing of eukaryotic cells by the prokaryotic proteins Kid and Kis. EMBO J. 22, 246–251 (2003).
Shimazu, T., Mirochnitchenko, O., Phadtare, S. & Inouye, M. Regression of solid tumors by induction of MazF, a bacterial mRNA endoribonuclease. J. Mol. Microbiol. Biotechnol. 24, 228–233 (2014).
Stieber, D., Gabant, P. & Szpirer, C. The art of selective killing: plasmid toxin/antitoxin systems and their technological applications. Biotechniques 45, 344–346 (2008).
Bernard, P., Gabant, P., Bahassi, E. M. & Couturier, M. Positive-selection vectors using the F plasmid ccdB killer gene. Gene 148, 71–74 (1994).
Mok, W. W. K. & Li, Y. A highly efficient molecular cloning platform that utilises a small bacterial toxin gene. Chembiochem 14, 733–738 (2013).
Szpirer, C. Y. & Milinkovitch, M. C. Separate-component-stabilization system for protein and DNA production without the use of antibiotics. Biotechniques 38, 775–781 (2005).
Nehlsen, K., Herrmann, S., Zauers, J., Hauser, H. & Wirth, D. Toxin-antitoxin based transgene expression in mammalian cells. Nucleic Acids Res. 38, e32 (2010).
Suzuki, M., Zhang, J., Liu, M., Woychik, N. A. & Inouye, M. Single protein production in living cells facilitated by an mRNA interferase. Mol. Cell 18, 253–261 (2005).
Suzuki, M., Mao, L. & Inouye, M. Single protein production (SPP) system in Escherichia coli. Nat. Protoc. 2, 1802–1810 (2007).
Kristoffersen, P., Jensen, G. B., Gerdes, K. & Piskur, J. Bacterial toxin-antitoxin gene system as containment control in yeast cells. Appl. Environ. Microbiol. 66, 5524–5526 (2000).
Denkovskienė, E., Paškevičius, Š., Stankevičiūtė, J., Gleba, Y. & Ražanskienė, A. Control of T-DNA transfer from Agrobacterium tumefaciens to plants based on an inducible bacterial toxin-antitoxin system. Mol. Plant Microbe Interact. 33, 1142–1149 (2020).
Wright, O., Delmans, M., Stan, G.-B. & Ellis, T. GeneGuard: a modular plasmid system designed for biosafety. ACS Synth. Biol. 4, 307–316 (2015).
Baldacci-Cresp, F. et al. Escherichia colimazEF toxin-antitoxin system as a tool to target cell ablation in plants. J. Mol. Microbiol. Biotechnol. 26, 277–283 (2016).
Work in the L.V.M. laboratory is funded by the Wallonia Region (Algotech, grant 1510598), the ARC actions 2018–2023 and the FNRS-FRS (CDR ‘PERSIST’, grant J010818F). D.J. is supported by an FRM postdoctoral fellowship (SPF201809007142).
The authors declare no competing interests.
Peer review information
Nature Reviews Microbiology thanks Christina Bourne and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Internal segments of proteins that self-excise and ligate the remaining segments (exteins) during protein splicing.
- Chaperone-addiction motifs
Specific sequences that promote antitoxin destabilization unless recognized by the chaperone.
- DNA gyrase
Type II topoisomerase enzyme that relieves positive supercoiling in front of the replication forks.
Ligation of an amino acid to its cognate tRNA, also known as tRNA charging.
Enzyme that ligates AMP to an amino acid side chain of a target protein.
- Thymineless death
Rapid loss of viability occurring as a result of thymine deprivation.
- Anti-Shine–Dalgarno sequence
Sequence in the prokaryotic ribosome that helps to align the ribosome for translation initiation at the ATG start codon.
- Iteron sequences
DNA sequences recognized by replication initiation proteins that are involved in the control of the copy number of plasmids.
- Genetic drift
Stochastic fluctuations in the frequency of alleles that occur randomly and can eventually lead to the loss or fixation of these alleles.
Taxonomic groups of organisms related through their evolutionary history.
About this article
Cite this article
Jurėnas, D., Fraikin, N., Goormaghtigh, F. et al. Biology and evolution of bacterial toxin–antitoxin systems. Nat Rev Microbiol 20, 335–350 (2022). https://doi.org/10.1038/s41579-021-00661-1
Substrate recognition and cryo-EM structure of the ribosome-bound TAC toxin of Mycobacterium tuberculosis
Nature Communications (2022)