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Khan S, Ahmad F, Ansari MI, Ashfaque M, Islam MH, Khubaib M. Toxin-Antitoxin system of Mycobacterium tuberculosis: Roles beyond stress sensor and growth regulator. Tuberculosis (Edinb) 2023; 143:102395. [PMID: 37722233 DOI: 10.1016/j.tube.2023.102395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/15/2023] [Accepted: 08/10/2023] [Indexed: 09/20/2023]
Abstract
The advent of effective drug regimen and BCG vaccine has significantly decreased the rate of morbidity and mortality of TB. However, lengthy treatment and slower recovery rate, as well as reactivation of the disease with the emergence of multi-drug, extensively-drug, and totally-drug resistance strains, pose a serious concern. The complexities associated are due to the highly evolved and complex nature of the bacterium itself. One of the unique features of Mycobacterium tuberculosis [M.tb] is that it has undergone reductive evolution while maintaining and amplified a few gene families. One of the critical gene family involved in the virulence and pathogenesis is the Toxin-Antitoxin system. These families are believed to harbor virulence signature and are strongly associated with various stress adaptations and pathogenesis. The M.tb TA systems are linked with growth regulation machinery during various environmental stresses. The genes of TA systems are differentially expressed in the host during an active infection, oxidative stress, low pH stress, and starvation, which essentially indicate their role beyond growth regulators. Here in this review, we have discussed different roles of TA gene families in various stresses and their prospective role at the host-pathogen interface, which could be exploited to understand the M.tb associated pathomechanisms better and further designing the new strategies against the pathogen.
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Affiliation(s)
- Saima Khan
- Department of Biosciences, Integral University, Lucknow, India
| | - Firoz Ahmad
- Department of Biosciences, Integral University, Lucknow, India
| | | | | | | | - Mohd Khubaib
- Department of Biosciences, Integral University, Lucknow, India.
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2
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Zeng X, Hu L, Ai Q, Liu CJ, Xiong LX, Yang WW, Zhang X, Liu L, Li GQ. Helicobacter macacae MazF interplays with Escherichia coli homologs and enhances antibiotic tolerance. Helicobacter 2023; 28:e13014. [PMID: 37559199 DOI: 10.1111/hel.13014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/17/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND Toxin-antitoxin systems are highly variable, even among strains of the same bacterial species. The MazEF toxin-antitoxin system is found in many bacteria and plays important roles in various biological processes such as antibiotic tolerance and phage defense. However, no interplay of MazEF systems between different species was reported. MATERIALS AND METHODS MazEF toxin-antitoxin system of Helicobacter macacae was examined in three Escherichia coli strains with and without endogenous MazEF knockout. In vivo toxicity, antibiotic tolerance, and live/dead staining followed by flowcytometry analysis were performed to evaluate the functionality and interplay of the toxin-antitoxin system between the two species. RESULTS Controlled ectopic expression of MazF of H. macacae (MazFhm) in E. coli did not affect its growth. However, in endogenous MazEF knockout E. coli strains, MazFhm expression caused a sharp growth arrest. The toxicity of MazFhm could be neutralized by both the antitoxin of MazE homolog of H.macacae and the antitoxin of MazE of E. coli, indicating interplay of MazEF toxin-antitoxin systems between the two species. Induced expression of MazFhm enhanced tolerance to a lethal dose of levofloxacin, suggesting enhanced persister formation, which was further confirmed by live/dead cell staining. CONCLUSIONS The MazEF toxin-antitoxin system of H. macace enhances persister formation and thus antibiotic tolerance in E. coli. Our findings reveal an interplay between the MazEF systems of H. macacae and E. coli, emphasizing the need to consider this interaction while evaluating the toxicity and functionality of MazF homologs from different species in future studies.
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Affiliation(s)
- Xi Zeng
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
- Department of Gastroenterology, The First Affiliated Hospital of Shaoyang University, Shaoyang, China
| | - Limiao Hu
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Qi Ai
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Cai-Juan Liu
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Lu-Xi Xiong
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Wei-Wei Yang
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Xiaotuan Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Logen Liu
- Clinical Research Center, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
- Hunan Provincial Key Laboratory of Basic and Clinical Pharmacological Research on Gastrointestinal Tumors, University of South China, Hengyang, China
| | - Guo-Qing Li
- Department of Gastroenterology, The Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
- Hunan Provincial Key Laboratory of Basic and Clinical Pharmacological Research on Gastrointestinal Tumors, University of South China, Hengyang, China
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3
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Sundaram K, Vajravelu LK, Paul AJ. Functional characterization of toxin-antitoxin system in Mycobacterium tuberculosis. Indian J Tuberc 2023; 70:149-157. [PMID: 37100570 DOI: 10.1016/j.ijtb.2022.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 05/06/2022] [Accepted: 05/20/2022] [Indexed: 04/28/2023]
Abstract
Toxin-Antitoxin (TA) system is abundant in the microbial genome, especially in bacteria and archaea. Its genetic elements and addiction modules with the role of bacterial persistence and virulence. The TA system consists of a toxin and most unstable antitoxin that could be a protein or non-encoded RNA, TA loci are chromosomally determined and their cellular functions are mostly unknown. Approximately 93 TA systems were demonstrated and more functionally available in M. tuberculosis (Mtb), the organism responsible for tuberculosis (TB). It is an airborne disease, which is causing ill-health to humans. M. tuberculosis possesses higher TA loci than other microbes and non-tubercle bacilli, the following TA types have been identified such as VapBC, MazEF, HigBA, RelBE, ParDE, DarTG, PemIK, MbcTA, and one tripartite type II TAC-Chaperone system. Toxin-antitoxin Database (TADB) brings a detailed update on Toxin-Antitoxin classification in the different pathogens such as staphylococcus aureus, streptococcus pneumonia, Vibrio cholerae, Salmonella typhimurium, Shigella flexneri, and helicobacter pylori, etc. So, this Toxin-Antitoxin system is a master regulator for bacterial growth, and an essential factor in analyzing the properties and function of disease persistence, biofilm formation, and pathogenicity. The TA system is an advanced tool to develop a new therapeutic agent against M. tuberculosis.
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Affiliation(s)
- Karthikeyan Sundaram
- Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattangulathur, Chennai, 603203, Tamilnadu, India.
| | - Leela Kagithakara Vajravelu
- Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattangulathur, Chennai, 603203, Tamilnadu, India
| | - Alamu Juliana Paul
- Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattangulathur, Chennai, 603203, Tamilnadu, India
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4
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Bacteriophages benefit from mobilizing pathogenicity islands encoding immune systems against competitors. Cell 2022; 185:3248-3262.e20. [PMID: 35985290 DOI: 10.1016/j.cell.2022.07.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 04/08/2022] [Accepted: 07/18/2022] [Indexed: 01/26/2023]
Abstract
Bacteria encode sophisticated anti-phage systems that are diverse and versatile and display high genetic mobility. How this variability and mobility occurs remains largely unknown. Here, we demonstrate that a widespread family of pathogenicity islands, the phage-inducible chromosomal islands (PICIs), carry an impressive arsenal of defense mechanisms, which can be disseminated intra- and inter-generically by helper phages. These defense systems provide broad immunity, blocking not only phage reproduction, but also plasmid and non-cognate PICI transfer. Our results demonstrate that phages can mobilize PICI-encoded immunity systems to use them against other mobile genetic elements, which compete with the phages for the same bacterial hosts. Therefore, despite the cost, mobilization of PICIs may be beneficial for phages, PICIs, and bacteria in nature. Our results suggest that PICIs are important players controlling horizontal gene transfer and that PICIs and phages establish mutualistic interactions that drive bacterial ecology and evolution.
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5
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Tamiya-Ishitsuka H, Tsuruga M, Noda N, Yokota A. Conserved Amino Acid Moieties of Candidatus Desulforudis audaxviator MazF Determine Ribonuclease Activity and Specificity. Front Microbiol 2021; 12:748619. [PMID: 34867867 PMCID: PMC8634880 DOI: 10.3389/fmicb.2021.748619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/21/2021] [Indexed: 11/17/2022] Open
Abstract
The toxin-antitoxin (TA) system, inherent to various prokaryotes, plays a critical role in survival and adaptation to diverse environmental stresses. The toxin MazF, belonging to the type II TA system, functions as a sequence-specific ribonuclease that recognizes 3 to 7 bases. In recent studies, crystallographic analysis of MazFs from several species have suggested the presence of amino acid sites important for MazF substrate RNA binding and for its catalytic activity. Herein, we characterized MazF obtained from Candidatus Desulforudis audaxviator (MazF-Da) and identified the amino acid residues necessary for its catalytic function. MazF-Da, expressed using a cell-free protein synthesis system, is a six-base-recognition-specific ribonuclease that preferentially cleaves UACAAA sequences and weakly cleaves UACGAA and UACUAA sequences. We found that MazF-Da exhibited the highest activity at around 60°C. Analysis using mutants with a single mutation at an amino acid residue site that is well conserved across various MazF toxins showed that G18, E20, R25, and P26 were important for the ribonuclease activity of MazF-Da. The recognition sequence of the N36A mutant differed from that of the wild type. This mutant cleaved UACAAG sequences in addition to UACAAA sequences, but did not cleave UACGAA or UACUAA sequences, suggesting that Asn36 affects the loosening and narrowing of MazF-Da cleavage sequence recognition. Our study posits UACAAA as the recognition sequence of MazF-Da and provides insight into the amino acid sites that are key to its unique enzymatic properties.
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Affiliation(s)
- Hiroko Tamiya-Ishitsuka
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Masako Tsuruga
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Naohiro Noda
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Akiko Yokota
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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6
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Kumar N, Sharma S, Kaushal PS. Protein synthesis in Mycobacterium tuberculosis as a potential target for therapeutic interventions. Mol Aspects Med 2021; 81:101002. [PMID: 34344520 DOI: 10.1016/j.mam.2021.101002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 07/11/2021] [Accepted: 07/16/2021] [Indexed: 12/18/2022]
Abstract
Mycobacterium tuberculosis (Mtb) causes one of humankind's deadliest diseases, tuberculosis. Mtb protein synthesis machinery possesses several unique species-specific features, including its ribosome that carries two mycobacterial specific ribosomal proteins, bL37 and bS22, and ribosomal RNA segments. Since the protein synthesis is a vital cellular process that occurs on the ribosome, a detailed knowledge of the structure and function of mycobacterial ribosomes is essential to understand the cell's proteome by translation regulation. Like in many bacterial species such as Bacillus subtilis and Streptomyces coelicolor, two distinct populations of ribosomes have been identified in Mtb. Under low-zinc conditions, Mtb ribosomal proteins S14, S18, L28, and L33 are replaced with their non-zinc binding paralogues. Depending upon the nature of physiological stress, species-specific modulation of translation by stress factors and toxins that interact with the ribosome have been reported. In addition, about one-fourth of messenger RNAs in mycobacteria have been reported to be leaderless, i.e., without 5' UTR regions. However, the mechanism by which they are recruited to the Mtb ribosome is not understood. In this review, we highlight the mycobacteria-specific features of the translation apparatus and propose exploiting these features to improve the efficacy and specificity of existing antibiotics used to treat tuberculosis.
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Affiliation(s)
- Niraj Kumar
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India
| | - Shivani Sharma
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India
| | - Prem S Kaushal
- Structural Biology & Translation Regulation Laboratory, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, 121 001, India.
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7
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Jin C, Kang SM, Kim DH, Lee BJ. Structural and functional analysis of the Klebsiella pneumoniae MazEF toxin-antitoxin system. IUCRJ 2021; 8:362-371. [PMID: 33953923 PMCID: PMC8086154 DOI: 10.1107/s2052252521000452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Bacterial toxin-antitoxin (TA) systems correlate strongly with physiological processes in bacteria, such as growth arrest, survival and apoptosis. Here, the first crystal structure of a type II TA complex structure of Klebsiella pneumoniae at 2.3 Å resolution is presented. The K. pneumoniae MazEF complex consists of two MazEs and four MazFs in a heterohexameric assembly. It was estimated that MazEF forms a dodecamer with two heterohexameric MazEF complexes in solution, and a truncated complex exists in heterohexameric form. The MazE antitoxin interacts with the MazF toxin via two binding modes, namely, hydro-phobic and hydro-philic interactions. Compared with structural homologs, K. pneumoniae MazF shows distinct features in loops β1-β2, β3-β4 and β4-β5. It can be inferred that these three loops have the potential to represent the unique characteristics of MazF, especially various substrate recognition sites. In addition, K. pneumoniae MazF shows ribonuclease activity and the catalytic core of MazF lies in an RNA-binding pocket. Mutation experiments and cell-growth assays confirm Arg28 and Thr51 as critical residues for MazF ribonuclease activity. The findings shown here may contribute to the understanding of the bacterial MazEF TA system and the exploration of antimicrobial candidates to treat drug-resistant K. pneumoniae.
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Affiliation(s)
- Chenglong Jin
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Sung-Min Kang
- College of Pharmacy, Duksung Women’s University, Seoul, 01369, Republic of Korea
| | - Do-Hee Kim
- College of Pharmacy, Jeju National University, Jeju, 63243, Republic of Korea
- Interdisciplinary Graduate Program in Advanced Convergence Technology & Science, Jeju National University, Jeju, 63243, Republic of Korea
| | - Bong-Jin Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul, 08826, Republic of Korea
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8
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Tandon H, Melarkode Vattekatte A, Srinivasan N, Sandhya S. Molecular and Structural Basis of Cross-Reactivity in M. tuberculosis Toxin-Antitoxin Systems. Toxins (Basel) 2020; 12:E481. [PMID: 32751054 PMCID: PMC7472061 DOI: 10.3390/toxins12080481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/21/2020] [Accepted: 06/23/2020] [Indexed: 01/12/2023] Open
Abstract
Mycobacterium tuberculosis genome encodes over 80 toxin-antitoxin (TA) systems. While each toxin interacts with its cognate antitoxin, the abundance of TA systems presents an opportunity for potential non-cognate interactions. TA systems mediate manifold interactions to manage pathogenicity and stress response network of the cell and non-cognate interactions may play vital roles as well. To address if non-cognate and heterologous interactions are feasible and to understand the structural basis of their interactions, we have performed comprehensive computational analyses on the available 3D structures and generated structural models of paralogous M. tuberculosis VapBC and MazEF TA systems. For a majority of the TA systems, we show that non-cognate toxin-antitoxin interactions are structurally incompatible except for complexes like VapBC15 and VapBC11, which show similar interfaces and potential for cross-reactivity. For TA systems which have been experimentally shown earlier to disfavor non-cognate interactions, we demonstrate that they are structurally and stereo-chemically incompatible. For selected TA systems, our detailed structural analysis identifies specificity conferring residues. Thus, our work improves the current understanding of TA interfaces and generates a hypothesis based on congenial binding site, geometric complementarity, and chemical nature of interfaces. Overall, our work offers a structure-based explanation for non-cognate toxin-antitoxin interactions in M. tuberculosis.
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Affiliation(s)
- Himani Tandon
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
| | - Akhila Melarkode Vattekatte
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
- Biologie Intégrée du Globule Rouge UMR_S1134, INSERM, Université Paris, Université de la Réunion, Université des Antilles, F-75739 Paris, France
- Laboratoire d’Excellence GR-Ex, F-75739 Paris, France
- Faculté des Sciences et Technologies, Saint Denis Messag, F-97715 La Réunion, France
- Institut National de la Transfusion Sanguine (INTS), F-75739 Paris, France
| | - Narayanaswamy Srinivasan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
| | - Sankaran Sandhya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
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9
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Chen R, Zhou J, Sun R, Du C, Xie W. Conserved Conformational Changes in the Regulation of Mycobacterium tuberculosis MazEF-mt1. ACS Infect Dis 2020; 6:1783-1795. [PMID: 32485099 DOI: 10.1021/acsinfecdis.0c00048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Toxin-antitoxin (TA) systems, which regulate many important cellular processes, are abundantly present in prokaryotic organisms. MazEF is a common type of TA system implicated in the formation of "persisters cells" of the pathogen Mycobacterium tuberculosis, which contains 10 such systems. However, the exact function and inhibition mode of each MazF protein are not quite understood. Here, we report four high-resolution crystal structures of MazF-mt1 in various forms, including one in complex with MazE-mt1. The toxin displayed two unique interlocked loops that allow the formation of a tight dimer. These loops would open upon interacting with the MazE-mt1 antitoxin mediated by the last two helices of MazE-mt1. With our structure-based design, a mutant that could bind to the antitoxin with an enhanced affinity was produced. Combined crystallographic and biochemical studies further revealed that the binding affinity of MazE-mt1 to MazF-mt1 was mainly attributed to its α3 helical region, while the terminal helix η1 contributes very little or even negatively to the association of the pair, in stark contrast to the MazEF-mt9 system. This study provides structural insight into the binding mode and the inhibition mechanism of the MazE/F-mt1 TA pair, which may reflect the functional differences between different TA systems.
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Affiliation(s)
- Ran Chen
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Jie Zhou
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Runlin Sun
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Chaochao Du
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, 651 E. Dongfeng Road, Guangzhou, Guangdong 510060, People’s Republic of China
| | - Wei Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou, Guangdong 510006, People’s Republic of China
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10
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Kang SM, Koo JS, Kim CM, Kim DH, Lee BJ. mRNA Interferase Bacillus cereus BC0266 Shows MazF-Like Characteristics Through Structural and Functional Study. Toxins (Basel) 2020; 12:toxins12060380. [PMID: 32521689 PMCID: PMC7354611 DOI: 10.3390/toxins12060380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/05/2020] [Accepted: 06/06/2020] [Indexed: 11/16/2022] Open
Abstract
Toxin–antitoxin (TA) systems are prevalent in bacteria and are known to regulate cellular growth in response to stress. As various functions related to TA systems have been revealed, the importance of TA systems are rapidly emerging. Here, we present the crystal structure of putative mRNA interferase BC0266 and report it as a type II toxin MazF. The MazF toxin is a ribonuclease activated upon and during stressful conditions, in which it cleaves mRNA in a sequence-specific, ribosome-independent manner. Its prolonged activity causes toxic consequences to the bacteria which, in turn, may lead to bacterial death. In this study, we conducted structural and functional investigations of Bacillus cereus MazF and present the first toxin structure in the TA system of B. cereus. Specifically, B. cereus MazF adopts a PemK-like fold and also has an RNA substrate-recognizing loop, which is clearly observed in the high-resolution structure. Key residues of B. cereus MazF involved in the catalytic activity are also proposed, and in vitro assay together with mutational studies affirm the ribonucleic activity and the active sites essential for its cellular toxicity.
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Affiliation(s)
- Sung-Min Kang
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanakgu, Seoul 08826, Korea; (S.-M.K.); (J.S.K.); (C.-M.K.)
| | - Ji Sung Koo
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanakgu, Seoul 08826, Korea; (S.-M.K.); (J.S.K.); (C.-M.K.)
| | - Chang-Min Kim
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanakgu, Seoul 08826, Korea; (S.-M.K.); (J.S.K.); (C.-M.K.)
| | - Do-Hee Kim
- College of Pharmacy, Jeju National University, Jeju 63243, Korea;
| | - Bong-Jin Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanakgu, Seoul 08826, Korea; (S.-M.K.); (J.S.K.); (C.-M.K.)
- Correspondence: ; Tel.: +82-2-880-7869
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11
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Jurėnas D, Van Melderen L. The Variety in the Common Theme of Translation Inhibition by Type II Toxin-Antitoxin Systems. Front Genet 2020; 11:262. [PMID: 32362907 PMCID: PMC7180214 DOI: 10.3389/fgene.2020.00262] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
Type II Toxin–antitoxin (TA) modules are bacterial operons that encode a toxic protein and its antidote, which form a self-regulating genetic system. Antitoxins put a halter on toxins in many ways that distinguish different types of TA modules. In type II TA modules, toxin and antitoxin are proteins that form a complex which physically sequesters the toxin, thereby preventing its toxic activity. Type II toxins inhibit various cellular processes, however, the translation process appears to be their favorite target and nearly every step of this complex process is inhibited by type II toxins. The structural features, enzymatic activities and target specificities of the different toxin families are discussed. Finally, this review emphasizes that the structural folds presented by these toxins are not restricted to type II TA toxins or to one particular cellular target, and discusses why so many of them evolved to target translation as well as the recent developments regarding the role(s) of these systems in bacterial physiology and evolution.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille Université, Marseille, France
| | - Laurence Van Melderen
- Cellular and Molecular Microbiology, Faculté des Sciences, Université libre de Bruxelles, Gosselies, Belgium
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12
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Pavelich IJ, Maehigashi T, Hoffer ED, Ruangprasert A, Miles SJ, Dunham CM. Monomeric YoeB toxin retains RNase activity but adopts an obligate dimeric form for thermal stability. Nucleic Acids Res 2019; 47:10400-10413. [PMID: 31501867 PMCID: PMC6821326 DOI: 10.1093/nar/gkz760] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/13/2019] [Accepted: 08/21/2019] [Indexed: 11/30/2022] Open
Abstract
Chromosomally-encoded toxin-antitoxin complexes are ubiquitous in bacteria and regulate growth through the release of the toxin component typically in a stress-dependent manner. Type II ribosome-dependent toxins adopt a RelE-family RNase fold and inhibit translation by degrading mRNAs while bound to the ribosome. Here, we present biochemical and structural studies of the Escherichia coli YoeB toxin interacting with both a UAA stop and an AAU sense codon in pre- and post-mRNA cleavage states to provide insights into possible mRNA substrate selection. Both mRNAs undergo minimal changes during the cleavage event in contrast to type II ribosome-dependent RelE toxin. Further, the 16S rRNA decoding site nucleotides that monitor the mRNA in the aminoacyl(A) site adopt different orientations depending upon which toxin is present. Although YoeB is a RelE family member, it is the sole ribosome-dependent toxin that is dimeric. We show that engineered monomeric YoeB is active against mRNAs bound to both the small and large subunit. However, the stability of monomeric YoeB is reduced ∼20°C, consistent with potential YoeB activation during heat shock in E. coli as previously demonstrated. These data provide a molecular basis for the ability of YoeB to function in response to thermal stress.
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Affiliation(s)
- Ian J Pavelich
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.,Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Tatsuya Maehigashi
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Eric D Hoffer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | - Stacey J Miles
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Christine M Dunham
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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Chen R, Tu J, Tan Y, Cai X, Yang C, Deng X, Su B, Ma S, Liu X, Ma P, Du C, Xie W. Structural and Biochemical Characterization of the Cognate and Heterologous Interactions of the MazEF-mt9 TA System. ACS Infect Dis 2019; 5:1306-1316. [PMID: 31267737 DOI: 10.1021/acsinfecdis.9b00001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Toxin-antitoxin (TA) modules widely exist in bacteria, and their activities are associated with the persister phenotype of the pathogen Mycobacterium tuberculosis (M. tb). M. tb causes tuberculosis, a contagious and severe airborne disease. There are 10 MazEF TA systems in M. tb that play important roles in stress adaptation. How the antitoxins antagonize toxins in M. tb or how the 10 TA systems crosstalk to each other are of interest, but the detailed molecular mechanisms are largely unclear. MazEF-mt9 is a unique member among the MazEF family due to its tRNase activity, which is usually carried out by the VapC toxins. Here, we present the cocrystal structure of the MazEF-mt9 complex at 2.7 Å. By characterizing the association mode between the TA pairs through various techniques, we found that MazF-mt9 bound not only its cognate antitoxin but also the noncognate antitoxin MazE-mt1, a phenomenon that could be also observed in vivo. Based on our structural and biochemical work, we propose that the cognate and heterologous interactions among different TA systems work together in vivo to relieve the toxicity of MazF-mt9 toward M. tb cells.
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Affiliation(s)
- Ran Chen
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, 135 W. Xingang Road, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Jie Tu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, 135 W. Xingang Road, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Yaoju Tan
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Xingshan Cai
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Chengwen Yang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, 135 W. Xingang Road, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Xiangyu Deng
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, 135 W. Xingang Road, Guangzhou, Guangdong 510006, People’s Republic of China
| | - Biyi Su
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Shangming Ma
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Xin Liu
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Pinyun Ma
- Guangzhou Chest Hospital, 62 HengzhiGang Road, Guangzhou, Guangdong 510095, People’s Republic of China
| | - Chaochao Du
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, 651 E. Dongfeng Road, Guangzhou, Guangdong 510060, People’s Republic of China
| | - Wei Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, 135 W. Xingang Road, Guangzhou, Guangdong 510006, People’s Republic of China
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14
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A Systematic Overview of Type II and III Toxin-Antitoxin Systems with a Focus on Druggability. Toxins (Basel) 2018; 10:toxins10120515. [PMID: 30518070 PMCID: PMC6315513 DOI: 10.3390/toxins10120515] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 11/29/2018] [Accepted: 11/30/2018] [Indexed: 02/07/2023] Open
Abstract
Toxin-antitoxin (TA) systems are known to play various roles in physiological processes, such as gene regulation, growth arrest and survival, in bacteria exposed to environmental stress. Type II TA systems comprise natural complexes consisting of protein toxins and antitoxins. Each toxin and antitoxin participates in distinct regulatory mechanisms depending on the type of TA system. Recently, peptides designed by mimicking the interfaces between TA complexes showed its potential to activate the activity of toxin by competing its binding counterparts. Type II TA systems occur more often in pathogenic bacteria than in their nonpathogenic kin. Therefore, they can be possible drug targets, because of their high abundance in some pathogenic bacteria, such as Mycobacterium tuberculosis. In addition, recent bioinformatic analyses have shown that type III TA systems are highly abundant in the intestinal microbiota, and recent clinical studies have shown that the intestinal microbiota is linked to inflammatory diseases, obesity and even several types of cancer. We therefore focused on exploring the putative relationship between intestinal microbiota-related human diseases and type III TA systems. In this paper, we review and discuss the development of possible druggable materials based on the mechanism of type II and type III TA system.
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Slayden RA, Dawson CC, Cummings JE. Toxin-antitoxin systems and regulatory mechanisms in Mycobacterium tuberculosis. Pathog Dis 2018; 76:4969681. [PMID: 29788125 DOI: 10.1093/femspd/fty039] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/01/2018] [Indexed: 11/14/2022] Open
Abstract
There has been a significant reduction in annual tuberculosis incidence since the World Health Organization declared tuberculosis a global health threat. However, treatment of M. tuberculosis infections requires lengthy multidrug therapeutic regimens to achieve a durable cure. The development of new drugs that are active against resistant strains and phenotypically diverse organisms continues to present the greatest challenge in the future. Numerous phylogenomic analyses have revealed that the Mtb genome encodes a significantly expanded repertoire of toxin-antitoxin (TA) loci that makes up the Mtb TA system. A TA loci is a two-gene operon encoding a 'toxin' protein that inhibits bacterial growth and an interacting 'antitoxin' partner that neutralizes the inhibitory activity of the toxin. The presence of multiple chromosomally encoded TA loci in Mtb raises important questions in regard to expansion, regulation and function. Thus, the functional roles of TA loci in Mtb pathogenesis have received considerable attention over the last decade. The cumulative results indicate that they are involved in regulating adaptive responses to stresses associated with the host environment and drug treatment. Here we review the TA families encoded in Mtb, discuss the duplication of TA loci in Mtb, regulatory mechanism of TA loci, and phenotypic heterogeneity and pathogenesis.
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Affiliation(s)
- Richard A Slayden
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-0922, USA
| | - Clinton C Dawson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-0922, USA
| | - Jason E Cummings
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-0922, USA
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Quorum Sensing Extracellular Death Peptides Enhance the Endoribonucleolytic Activities of Mycobacterium tuberculosis MazF Toxins. mBio 2018; 9:mBio.00685-18. [PMID: 29717013 PMCID: PMC5930309 DOI: 10.1128/mbio.00685-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
mazEF is a toxin-antitoxin module located on chromosomes of most bacteria. MazF toxins are endoribonucleases antagonized by MazE antitoxins. Previously, we characterized several quorum sensing peptides called "extracellular death factors" (EDFs). When secreted from bacterial cultures, EDFs induce interspecies cell death. EDFs also enhance the endoribonucleolytic activity of Escherichia coli MazF. Mycobacterium tuberculosis carries several mazEF modules. Among them, the endoribonucleolytic activities of MazF proteins mt-1, mt-3, and mt-6 were identified. MazF-mt6 and MazF-mt-3 cleave M. tuberculosis rRNAs. Here we report the in vitro effects of EDFs on the endoribonucleolytic activities of M. tuberculosis MazFs. Escherichia coli EDF (EcEDF) and the three Pseudomonas aeruginosa EDFs (PaEDFs) individually enhance the endoribonucleolytic activities of MazF-mt6 and MazF-mt3 and overcome the inhibitory effect of MazE-mt3 or MazE-mt6 on the endoribonucleolytic activities of the respective toxins. We propose that these EDFs can serve as a basis for a novel class of antibiotics against M. tuberculosis. Mycobacterium tuberculosis is one of the leading causes of death from infectious disease. M. tuberculosis is highly drug resistant, and drug delivery to the infected site is very difficult. In previous studies, we showed that extracellular death factors (EDFs) can work as quorum sensing molecules which participate in interspecies bacterial cell death. In this study, we demonstrated the role of different EDFs in the endoribonucleolytic activities of M. tuberculosis MazFs. Escherichia coli EDF (EcEDF) and the three Pseudomonas aeruginosa EDFs (PaEDFs) individually enhance the endoribonucleolytic activities of MazF-mt6 and MazF-mt3. The current report provides a basis for the use of the EDF peptides EcEDF and PaEDF as novel antibiotics against M. tuberculosis.
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Ahn DH, Lee KY, Lee SJ, Park SJ, Yoon HJ, Kim SJ, Lee BJ. Structural analyses of the MazEF4 toxin-antitoxin pair in Mycobacterium tuberculosis provide evidence for a unique extracellular death factor. J Biol Chem 2017; 292:18832-18847. [PMID: 28972145 DOI: 10.1074/jbc.m117.807974] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/20/2017] [Indexed: 11/06/2022] Open
Abstract
The bacterial toxin-antitoxin MazEF system in the tuberculosis (TB)-causing bacterium Mycobacterium tuberculosis is activated under unfavorable conditions, including starvation, antibiotic exposure, and oxidative stress. This system contains the ribonucleolytic enzyme MazF and has emerged as a promising drug target for TB treatments targeting the latent stage of M. tuberculosis infection and reportedly mediates a cell death process via a peptide called extracellular death factor (EDF). Although it is well established that the increase in EDF-mediated toxicity of MazF drives a cell-killing phenomenon, the molecular details are poorly understood. Moreover, the divergence in sequences among reported EDFs suggests that each bacterial species has a unique EDF. To address these open questions, we report here the structures of MazF4 and MazEF4 complexes from M. tuberculosis, representing the first MazEF structures from this organism. We found that MazF4 possesses a negatively charged MazE4-binding pocket in contrast to the positively charged MazE-binding pockets in homologous MazEF complex structures from other bacteria. Moreover, using NMR spectroscopy and biochemical assays, we unraveled the molecular interactions of MazF4 with its RNA substrate and with a new EDF homolog originating from M. tuberculosis The EDF homolog discovered here possesses a positively charged residue at the C terminus, making this EDF distinct from previously reported EDFs. Overall, our results suggest that M. tuberculosis evolved a unique MazF and EDF and that the distinctive EDF sequence could serve as a starting point for designing new anti-tuberculosis drugs. We therefore conclude that this study might contribute to the development of a new line of anti-tuberculosis agents.
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Affiliation(s)
- Do-Hwan Ahn
- From the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742
| | - Ki-Young Lee
- From the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742
| | - Sang Jae Lee
- From the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742
| | - Sung Jean Park
- the College of Pharmacy, Gachon University, 534-2 Yeonsu-dong, Yeonsu-gu, Incheon
| | - Hye-Jin Yoon
- the Department of Biophysics and Chemical Biology, College of Natural Sciences, Seoul National University, Seoul 151-742, and
| | - Soon-Jong Kim
- the Department of Chemistry, Mokpo National University, Chonnam 534-729, Republic of Korea
| | - Bong-Jin Lee
- From the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742,
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