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Saha R, Bhattacharje G, De S, Das AK. Deciphering the conformational stability of MazE7 antitoxin in Mycobacterium tuberculosis from molecular dynamics simulation study. J Biomol Struct Dyn 2023:1-17. [PMID: 37965715 DOI: 10.1080/07391102.2023.2280675] [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: 07/24/2023] [Accepted: 11/01/2023] [Indexed: 11/16/2023]
Abstract
MazEF Toxin-antitoxin (TA) systems are associated with the persistent phenotype of the pathogen, Mycobacterium tuberculosis (Mtb), aiding their survival. Though extensively studied, the mode of action between the antitoxin-toxin and DNA of this family remains largely unclear. Here, the important interactions between MazF7 toxin and MazE7 antitoxin, and how MazE7 binds its promoter/operator region have been studied. To elucidate this, molecular dynamics (MD) simulation has been performed on MazE7, MazF7, MazEF7, MazEF7-DNA, and MazE7-DNA complexes to investigate how MazF7 and DNA affect the conformational change and dynamics of MazE7 antitoxin. This study demonstrated that the MazE7 dimer is disordered and one monomer (Chain C) attains stability after binding to the MazF7 toxin. Both the monomers (Chain C and Chain D) however are stabilized when MazE7 binds to DNA. MazE7 is also observed to sterically inhibit tRNA from binding to MazF7, thus suppressing its toxic activity. Comparative structural analysis performed on all the available antitoxins/antitoxin-toxin-DNA structures revealed MazEF7-DNA mechanism was similar to another TA system, AtaRT_E.coli. Simulation performed on the crystal structures of AtaR, AtaT, AtaRT, AtaRT-DNA, and AtaR-DNA showed that the disordered AtaR antitoxin attains stability by AtaT and DNA binding similar to MazE7. Based on these analyses it can thus be hypothesized that the disordered antitoxins enable tighter toxin and DNA binding thus preventing accidental toxin activation. Overall, this study provides crucial structural and dynamic insights into the MazEF7 toxin-antitoxin system and should provide a basis for targeting this TA system in combating Mycobacterium tuberculosis.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Rituparna Saha
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Gourab Bhattacharje
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Soumya De
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
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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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Chen R, Zhou J, Xie W. Mechanistic Insight into the Peptide Binding Modes to Two M. tb MazF Toxins. Toxins (Basel) 2021; 13:toxins13050319. [PMID: 33925254 PMCID: PMC8145246 DOI: 10.3390/toxins13050319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 04/26/2021] [Accepted: 04/26/2021] [Indexed: 11/30/2022] Open
Abstract
Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis (M. tb). It is regarded as a major health threat all over the world, mainly because of its high mortality and drug-resistant nature. Toxin-antitoxin (TA) systems are modules ubiquitously found in prokaryotic organisms, and the well-studied MazEF systems (MazE means “what is it?” in Hebrew) are implicated in the formation of “persister cells” in the M. tb pathogen. Here, we report cocrystal structures of M. tb MazF-mt1 and -mt9, two important MazF members responsible for specific mRNA and tRNA cleavages, respectively, in complexes with truncated forms of their cognate antitoxin peptides. These peptides bind to the toxins with comparable affinities to their full-length antitoxins, which would reduce the RNA-cleavage capacities of the toxins in vitro. After structural analysis of the binding modes, we systemically tested the influence of the substitutions of individual residues in the truncated MazE-mt9 peptide on its affinity. This study provides structural insight into the binding modes and the inhibition mechanisms between the MazE/F-mt TA pairs. More importantly, it contributes to the future design of peptide-based antimicrobial agents against TB and potentially relieves the drug-resistance problems by targeting novel M. tb proteins.
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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 510006, China; (R.C.); (J.Z.)
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No.1119, Haibin Road, Nansha District, Guangzhou 511458, 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 510006, China; (R.C.); (J.Z.)
| | - 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 510006, China; (R.C.); (J.Z.)
- Correspondence:
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4
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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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5
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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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6
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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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7
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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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8
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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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9
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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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10
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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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11
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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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