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Luo G, Ming T, Yang L, He L, Tao T, Wang Y. Modulators targeting protein-protein interactions in Mycobacterium tuberculosis. Microbiol Res 2024; 284:127675. [PMID: 38636239 DOI: 10.1016/j.micres.2024.127675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 04/20/2024]
Abstract
Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis), mainly transmitted through droplets to infect the lungs, and seriously affecting patients' health and quality of life. Clinically, anti-TB drugs often entail side effects and lack efficacy against resistant strains. Thus, the exploration and development of novel targeted anti-TB medications are imperative. Currently, protein-protein interactions (PPIs) offer novel avenues for anti-TB drug development, and the study of targeted modulators of PPIs in M. tuberculosis has become a prominent research focus. Furthermore, a comprehensive PPI network has been constructed using computational methods and bioinformatics tools. This network allows for a more in-depth analysis of the structural biology of PPIs and furnishes essential insights for the development of targeted small-molecule modulators. Furthermore, this article provides a detailed overview of the research progress and regulatory mechanisms of PPI modulators in M. tuberculosis, the causative agent of TB. Additionally, it summarizes potential targets for anti-TB drugs and discusses the prospects of existing PPI modulators.
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Affiliation(s)
- Guofeng Luo
- School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Tianqi Ming
- State Key Laboratory of Southwestern Chinese Medicine Resources, Department of Pharmacology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Luchuan Yang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Lei He
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Tao Tao
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Yanmei Wang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China.
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2
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Sinha PR, Balasubramanian R, Hegde SR. Integrated sequence and -omic features reveal novel small proteome of Mycobacterium tuberculosis. Front Microbiol 2024; 15:1335310. [PMID: 38812687 PMCID: PMC11133741 DOI: 10.3389/fmicb.2024.1335310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 04/15/2024] [Indexed: 05/31/2024] Open
Abstract
Bioinformatic studies on small proteins are under-represented due to difficulties in annotation posed by their small size. However, recent discoveries emphasize the functional significance of small proteins in cellular processes including cell signaling, metabolism, and adaptation to stress. In this study, we utilized a Random Forest classifier trained on sequence features, RNA-Seq, and Ribo-Seq data to uncover small proteins (smORFs) in M. tuberculosis. Independent predictions for the exponential and starvation conditions resulted in 695 potential smORFs. We examined the functional implications of these smORFs using homology searches, LC-MS/MS, and ChIP-seq data, testing their expression in diverse growth conditions, and identifying protein domains. We provide evidence that some of these smORFs could be part of operons, or exist as upstream ORFs. This expanded data resource for the proteins of M. tuberculosis would aid in fine-tuning the existing protein and gene regulatory networks, thereby improving system-wide studies. The primary goal of this study was to uncover and characterize smORFs in M. tuberculosis through bioinformatic analysis, shedding light on their functional roles and genomic organization. Further investigation of these potential smORFs would provide valuable insights into the genome organization and functional diversity of the M. tuberculosis proteome.
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Affiliation(s)
| | | | - Shubhada R. Hegde
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, India
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3
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Bonabal S, Darfeuille F. Preventing toxicity in toxin-antitoxin systems: An overview of regulatory mechanisms. Biochimie 2024; 217:95-105. [PMID: 37473832 DOI: 10.1016/j.biochi.2023.07.013] [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: 05/12/2023] [Revised: 07/13/2023] [Accepted: 07/17/2023] [Indexed: 07/22/2023]
Abstract
Toxin-antitoxin systems (TAs) are generally two-component genetic modules present in almost every prokaryotic genome. The production of the free and active toxin is able to disrupt key cellular processes leading to the growth inhibition or death of its host organism in absence of its cognate antitoxin. The functions attributed to TAs rely on this lethal phenotype ranging from mobile genetic elements stabilization to phage defense. Their abundance in prokaryotic genomes as well as their lethal potential make them attractive targets for new antibacterial strategies. The hijacking of TAs requires a deep understanding of their regulation to be able to design such approach. In this review, we summarize the accumulated knowledge on how bacteria cope with these toxic genes in their genome. The characterized TAs can be grouped based on the way they prevent toxicity. Some systems rely on a tight control of the expression to prevent the production of the toxin while others control the activity of the toxin at the post-translational level.
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Affiliation(s)
- Simon Bonabal
- University of Bordeaux, INSERM U1212, CNRS UMR 5320, ARNA Laboratory, F-33000, Bordeaux, France
| | - Fabien Darfeuille
- University of Bordeaux, INSERM U1212, CNRS UMR 5320, ARNA Laboratory, F-33000, Bordeaux, France.
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4
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Syska C, Kiers A, Rancurel C, Bailly-Bechet M, Lipuma J, Alloing G, Garcia I, Dupont L. VapC10 toxin of the legume symbiont Sinorhizobium meliloti targets tRNASer and controls intracellular lifestyle. THE ISME JOURNAL 2024; 18:wrae015. [PMID: 38365913 PMCID: PMC10945364 DOI: 10.1093/ismejo/wrae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/05/2024] [Accepted: 01/25/2024] [Indexed: 02/18/2024]
Abstract
The soil bacterium Sinorhizobium meliloti can establish a nitrogen-fixing symbiosis with the model legume Medicago truncatula. The rhizobia induce the formation of a specialized root organ called nodule, where they differentiate into bacteroids and reduce atmospheric nitrogen into ammonia. Little is known on the mechanisms involved in nodule senescence onset and in bacteroid survival inside the infected plant cells. Although toxin-antitoxin (TA) systems have been shown to promote intracellular survival within host cells in human pathogenic bacteria, their role in symbiotic bacteria was rarely investigated. S. meliloti encodes several TA systems, mainly of the VapBC family. Here we present the functional characterization, through a multidisciplinary approach, of the VapBC10 TA system of S. meliloti. Following a mapping by overexpression of an RNase in Escherichia coli (MORE) RNA-seq analysis, we demonstrated that the VapC10 toxin is an RNase that cleaves the anticodon loop of two tRNASer. Thereafter, a bioinformatics approach was used to predict VapC10 targets in bacteroids. This analysis suggests that toxin activation triggers a specific proteome reprogramming that could limit nitrogen fixation capability and viability of bacteroids. Accordingly, a vapC10 mutant induces a delayed senescence in nodules, associated to an enhanced bacteroid survival. VapBC10 TA system could contribute to S. meliloti adaptation to symbiotic lifestyle, in response to plant nitrogen status.
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Affiliation(s)
- Camille Syska
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | - Aurélie Kiers
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | - Corinne Rancurel
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | - Marc Bailly-Bechet
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | | | - Geneviève Alloing
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | - Isabelle Garcia
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
| | - Laurence Dupont
- Université Côte d'Azur, INRAE, CNRS, Institut Sophia Agrobiotech (ISA), Sophia Antipolis 06903, France
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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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6
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Matern WM, Harris HT, Danchik C, McDonald M, Patel G, Srivastava A, Ioerger TR, Bader JS, Karakousis PC. Functional Whole Genome Screen of Nutrient-Starved Mycobacterium tuberculosis Identifies Genes Involved in Rifampin Tolerance. Microorganisms 2023; 11:2269. [PMID: 37764112 PMCID: PMC10534295 DOI: 10.3390/microorganisms11092269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), poses a global health challenge and is responsible for over a million deaths each year. Current treatment is lengthy and complex, and new, abbreviated regimens are urgently needed. Mtb adapts to nutrient starvation, a condition experienced during host infection, by shifting its metabolism and becoming tolerant to the killing activity of bactericidal antibiotics. An improved understanding of the mechanisms mediating antibiotic tolerance in Mtb can serve as the basis for developing more effective therapies. We performed a forward genetic screen to identify candidate Mtb genes involved in tolerance to the two key first-line antibiotics, rifampin and isoniazid, under nutrient-rich and nutrient-starved conditions. In nutrient-rich conditions, we found 220 mutants with differential antibiotic susceptibility (218 in the rifampin screen and 2 in the isoniazid screen). Following Mtb adaptation to nutrient starvation, 82 mutants showed differential antibiotic susceptibility (80 in the rifampin screen and 2 in the isoniazid screen). Using targeted mutagenesis, we validated the rifampin-hypersusceptible phenotype under nutrient starvation in Mtb mutants lacking the following genes: ercc3, moeA1, rv0049, and rv2179c. These findings shed light on potential therapeutic targets, which could help shorten the duration and complexity of antitubercular regimens.
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Affiliation(s)
- William M. Matern
- Department of Biomedical Engineering, Institute for Computational Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (W.M.M.)
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Harley T. Harris
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Carina Danchik
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Marissa McDonald
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Gopi Patel
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Aashish Srivastava
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA;
| | - Thomas R. Ioerger
- Department of Computer Science and Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Joel S. Bader
- Department of Biomedical Engineering, Institute for Computational Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (W.M.M.)
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
| | - Petros C. Karakousis
- Center for Systems Approaches to Infectious Diseases (C-SAID), School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; (H.T.H.)
- Tuberculosis Research Advancement Center, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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7
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Pagani TD, Corrêa PR, Lima C, Gomes LHF, Schwarz MGA, Galvão TC, Degrave WM, Valadares NF, Mendonça-Lima L. Impact of Genomic Deletion RD16 on the Expression of the Mycobacterium bovis BCG Moreau VapBC47 Toxin-Antitoxin System. Curr Issues Mol Biol 2023; 45:6538-6549. [PMID: 37623231 PMCID: PMC10453824 DOI: 10.3390/cimb45080412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/23/2023] [Accepted: 05/27/2023] [Indexed: 08/26/2023] Open
Abstract
Mycobacterium bovis BCG is the only vaccine against tuberculosis. The variable forms of cultivation throughout the years, before seed-lots were developed, allowed in vitro evolution of the original strain, generating a family of vaccines with different phenotypic and genotypic characteristics. Molecular studies revealed regions of difference (RDs) in the genomes of the various BCG strains. This work aims to characterize the gene pair rv3407-rv3408 (vapB47-vapC47), coding for a toxin-antitoxin system of the VapBC family, and to evaluate possible transcriptional effects due to the adjacent BCG Moreau-specific genomic deletion RD16. We show that these genes are co-transcribed in BCG strains Moreau and Pasteur, and that the inactivation of an upstream transcriptional repressor (Rv3405c) due to RD16 has a polar effect, leading to increased vapBC47 expression. Furthermore, we detect VapB47 DNA binding in vitro, dependent on a 5' vapB47 sequence that contributes to a palindrome, spanning the promoter and coding region. Our data shed light on the regulation of VapBC systems and on the impact of the BCG Moreau RD16 deletion in the expression of adjacent genes, contributing to a better understanding of BCG Moreau physiology.
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Affiliation(s)
- Talita Duarte Pagani
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | - Paloma Rezende Corrêa
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | - Cristiane Lima
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | - Leonardo Henrique Ferreira Gomes
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | - Marcos Gustavo Araujo Schwarz
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | - Teca Calcagno Galvão
- Laboratório de Bacteriologia, Centro de Referência Prof. Hélio Fraga, Escola Nacional de Saúde Pública Sergio Arouca, Fiocruz, Rio de Janeiro 21041-210, RJ, Brazil;
| | - Wim Maurits Degrave
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
| | | | - Leila Mendonça-Lima
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro 21040-360, RJ, Brazil; (T.D.P.); (P.R.C.); (C.L.); (L.H.F.G.); (M.G.A.S.); (W.M.D.)
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8
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Troian EA, Maldonado HM, Chauhan U, Barth VC, Woychik NA. Mycobacterium abscessus VapC5 toxin potentiates evasion of antibiotic killing by ribosome overproduction and activation of multiple resistance pathways. Nat Commun 2023; 14:3705. [PMID: 37349306 PMCID: PMC10287673 DOI: 10.1038/s41467-023-38844-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 05/18/2023] [Indexed: 06/24/2023] Open
Abstract
Mycobacterium abscessus (Mab) infections are inexplicably intractable to clearing after aggressive and lengthy treatment regimens. Here we discovered that acquisition of a single toxin-antitoxin system enables Mab to activate a phenotypic switch that enhances survival upon treatment with current first-line antibiotics. This switch is tripped when the VapC5 toxin inactivates tRNASerCGA by cleavage at only one site within its anticodon, leading to growth arrest. Concomitant tRNASerCGA depletion then reprograms the transcriptome to favor synthesis of proteins naturally low in the cognate Ser UCG codon including the transcription factor WhiB7 and members of its regulon as well as the ribosomal protein family. This programmed stockpiling of ribosomes is predicted to override the efficacy of ribosome-targeting antibiotics while the growth arrest phenotype attenuates antibiotics targeting cell wall synthesis. In agreement, VapC5 increases Mab persister formation upon exposure to amikacin and the next-generation oxazolidinone tedizolid (both target ribosomes) or cefoxitin (inhibits cell wall synthesis). These findings expand the repertoire of genetic adaptations harnessed by Mab to survive assaults intended to eradicate it, as well as provide a much-needed framework for selection of shorter and more efficacious alternate treatment options for Mab infections using currently available antimicrobials whose targets are not confounded by VapC5.
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Affiliation(s)
- Eduardo A Troian
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Heather M Maldonado
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Unnati Chauhan
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Valdir C Barth
- Immunotherapy Laboratory, Basic Health Sciences Department, Federal University of Health Sciences of Porto Alegre (UFCSPA), R. Sarmento Leite, 245 - Centro Histórico, Porto Alegre, 90050-170, Brazil
| | - Nancy A Woychik
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA.
- Member, Rutgers Cancer Institute of New Jersey, Piscataway, NJ, USA.
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9
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Boss L, Kędzierska B. Bacterial Toxin-Antitoxin Systems' Cross-Interactions-Implications for Practical Use in Medicine and Biotechnology. Toxins (Basel) 2023; 15:380. [PMID: 37368681 DOI: 10.3390/toxins15060380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 05/30/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Toxin-antitoxin (TA) systems are widely present in bacterial genomes. They consist of stable toxins and unstable antitoxins that are classified into distinct groups based on their structure and biological activity. TA systems are mostly related to mobile genetic elements and can be easily acquired through horizontal gene transfer. The ubiquity of different homologous and non-homologous TA systems within a single bacterial genome raises questions about their potential cross-interactions. Unspecific cross-talk between toxins and antitoxins of non-cognate modules may unbalance the ratio of the interacting partners and cause an increase in the free toxin level, which can be deleterious to the cell. Moreover, TA systems can be involved in broadly understood molecular networks as transcriptional regulators of other genes' expression or modulators of cellular mRNA stability. In nature, multiple copies of highly similar or identical TA systems are rather infrequent and probably represent a transition stage during evolution to complete insulation or decay of one of them. Nevertheless, several types of cross-interactions have been described in the literature to date. This implies a question of the possibility and consequences of the TA system cross-interactions, especially in the context of the practical application of the TA-based biotechnological and medical strategies, in which such TAs will be used outside their natural context, will be artificially introduced and induced in the new hosts. Thus, in this review, we discuss the prospective challenges of system cross-talks in the safety and effectiveness of TA system usage.
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Affiliation(s)
- Lidia Boss
- Department of Bacterial Molecular Genetics, Faculty of Biology, University of Gdańsk, 80-309 Gdańsk, Poland
| | - Barbara Kędzierska
- Department of Bacterial Molecular Genetics, Faculty of Biology, University of Gdańsk, 80-309 Gdańsk, Poland
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10
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Kang SM. Mycobacterium tuberculosis Rv0229c Shows Ribonuclease Activity and Reveals Its Corresponding Role as Toxin VapC51. Antibiotics (Basel) 2023; 12:antibiotics12050840. [PMID: 37237743 DOI: 10.3390/antibiotics12050840] [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: 03/28/2023] [Revised: 04/24/2023] [Accepted: 04/27/2023] [Indexed: 05/28/2023] Open
Abstract
The VapBC system, which belongs to the type II toxin-antitoxin (TA) system, is the most abundant and widely studied system in Mycobacterium tuberculosis. The VapB antitoxin suppresses the activity of the VapC toxin through a stable protein-protein complex. However, under environmental stress, the balance between toxin and antitoxin is disrupted, leading to the release of free toxin and bacteriostatic state. This study introduces the Rv0229c, a putative VapC51 toxin, and aims to provide a better understanding of its discovered function. The structure of the Rv0229c shows a typical PIN-domain protein, exhibiting an β1-α1-α2-β2-α3-α4-β3-α5-α6-β4-α7-β5 topology. The structure-based sequence alignment showed four electronegative residues in the active site of Rv0229c, which is composed of Asp8, Glu42, Asp95, and Asp113. By comparing the active site with existing VapC proteins, we have demonstrated the justification for naming it VapC51 at the molecular level. In an in vitro ribonuclease activity assay, Rv0229c showed ribonuclease activity dependent on the concentration of metal ions such as Mg2+ and Mn2+. In addition, magnesium was found to have a greater effect on VapC51 activity than manganese. Through these structural and experimental studies, we provide evidence for the functional role of Rv0229c as a VapC51 toxin. Overall, this study aims to enhance our understanding of the VapBC system in M. tuberculosis.
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Affiliation(s)
- Sung-Min Kang
- College of Pharmacy, Duksung Women's University, Seoul 01369, Republic of Korea
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