1
|
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: 2] [Impact Index Per Article: 2.0] [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.
Collapse
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
| |
Collapse
|
2
|
Labbaf Z, Petratou K, Ermlich L, Backer W, Tarbashevich K, Reichman-Fried M, Luschnig S, Schulte-Merker S, Raz E. A robust and tunable system for targeted cell ablation in developing embryos. Dev Cell 2022; 57:2026-2040.e5. [PMID: 35914525 DOI: 10.1016/j.devcel.2022.07.008] [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: 02/01/2022] [Revised: 05/10/2022] [Accepted: 07/07/2022] [Indexed: 11/03/2022]
Abstract
Cell ablation is a key method in the research fields of developmental biology, tissue regeneration, and tissue homeostasis. Eliminating specific cell populations allows for characterizing interactions that control cell differentiation, death, behavior, and spatial organization of cells. Current methodologies for inducing cell death suffer from relatively slow kinetics, making them unsuitable for analyzing rapid events and following primary and immediate consequences of the ablation. To address this, we developed a cell-ablation system that is based on bacterial toxin/anti-toxin proteins and enables rapid and cell-autonomous elimination of specific cell types and organs in zebrafish embryos. A unique feature of this system is that it uses an anti-toxin, which allows for controlling the degree and timing of ablation and the resulting phenotypes. The transgenic zebrafish generated in this work represent a highly efficient tool for cell ablation, and this approach is applicable to other model organisms as demonstrated here for Drosophila.
Collapse
Affiliation(s)
- Zahra Labbaf
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Kleio Petratou
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Laura Ermlich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Wilko Backer
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Katsiaryna Tarbashevich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Michal Reichman-Fried
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Stefan Luschnig
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Stefan Schulte-Merker
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Erez Raz
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany.
| |
Collapse
|
3
|
Srivastava A, Pati S, Kaushik H, Singh S, Garg LC. Toxin-antitoxin systems and their medical applications: current status and future perspective. Appl Microbiol Biotechnol 2021; 105:1803-1821. [PMID: 33582835 DOI: 10.1007/s00253-021-11134-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 01/13/2021] [Accepted: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Almost all bacteria synthesize two types of toxins-one for its survival by regulating different cellular processes and another as a strategy to interact with host cells for pathogenesis. Usually, "bacterial toxins" are contemplated as virulence factors that harm the host organism. However, toxins produced by bacteria, as a survival strategy against the host, also hamper its cellular processes. To overcome this, the bacteria have evolved with the production of a molecule, referred to as antitoxin, to negate the deleterious effect of the toxin against itself. The toxin and antitoxins are encoded by a two-component toxin-antitoxin (TA) system. The antitoxin, a protein or RNA, sequesters the toxins of the TA system for neutralization within the bacterial cell. In this review, we have described different TA systems of bacteria and their potential medical and biotechnological applications. It is of interest to note that while bacterial toxin-antitoxin systems have been well studied, the TA system in unicellular eukaryotes, though predicted by the investigators, have never been paid the desired attention. In the present review, we have also touched upon the TA system of eukaryotes identified to date. KEY POINTS: Bacterial toxins harm the host and also affect the bacterial cellular processes. The antitoxin produced by bacteria protect it from the toxin's harmful effects. The toxin-antitoxin systems can be targeted for various medical applications.
Collapse
Affiliation(s)
- Akriti Srivastava
- Department of Life Sciences, Shiv Nadar University, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh, 201314, India
| | - Soumya Pati
- Department of Life Sciences, Shiv Nadar University, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh, 201314, India
| | - Himani Kaushik
- Gene Regulation Laboratory, National Institute of Immunology, New Delhi, 110067, India
| | - Shailja Singh
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Lalit C Garg
- Gene Regulation Laboratory, National Institute of Immunology, New Delhi, 110067, India.
| |
Collapse
|
4
|
Zhang W, Wu Q. Applications of phage-derived RNA-based technologies in synthetic biology. Synth Syst Biotechnol 2020; 5:343-360. [PMID: 33083579 PMCID: PMC7564126 DOI: 10.1016/j.synbio.2020.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/22/2020] [Accepted: 09/27/2020] [Indexed: 12/20/2022] Open
Abstract
As the most abundant biological entities with incredible diversity, bacteriophages (also known as phages) have been recognized as an important source of molecular machines for the development of genetic-engineering tools. At the same time, phages are crucial for establishing and improving basic theories of molecular biology. Studies on phages provide rich sources of essential elements for synthetic circuit design as well as powerful support for the improvement of directed evolution platforms. Therefore, phages play a vital role in the development of new technologies and central scientific concepts. After the RNA world hypothesis was proposed and developed, novel biological functions of RNA continue to be discovered. RNA and its related elements are widely used in many fields such as metabolic engineering and medical diagnosis, and their versatility led to a major role of RNA in synthetic biology. Further development of RNA-based technologies will advance synthetic biological tools as well as provide verification of the RNA world hypothesis. Most synthetic biology efforts are based on reconstructing existing biological systems, understanding fundamental biological processes, and developing new technologies. RNA-based technologies derived from phages will offer abundant sources for synthetic biological components. Moreover, phages as well as RNA have high impact on biological evolution, which is pivotal for understanding the origin of life, building artificial life-forms, and precisely reprogramming biological systems. This review discusses phage-derived RNA-based technologies terms of phage components, the phage lifecycle, and interactions between phages and bacteria. The significance of RNA-based technology derived from phages for synthetic biology and for understanding the earliest stages of biological evolution will be highlighted.
Collapse
Affiliation(s)
- Wenhui Zhang
- MOE Key Lab. Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qiong Wu
- MOE Key Lab. Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China
- Corresponding author. MOE Key Lab. Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
5
|
Zhang SP, Wang Q, Quan SW, Yu XQ, Wang Y, Guo DD, Peng L, Feng HY, He YX. Type II toxin–antitoxin system in bacteria: activation, function, and mode of action. BIOPHYSICS REPORTS 2020. [DOI: 10.1007/s41048-020-00109-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|
6
|
Kim DH, Kang SM, Park SJ, Jin C, Yoon HJ, Lee BJ. Functional insights into the Streptococcus pneumoniae HicBA toxin-antitoxin system based on a structural study. Nucleic Acids Res 2019; 46:6371-6386. [PMID: 29878152 PMCID: PMC6159526 DOI: 10.1093/nar/gky469] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/15/2018] [Indexed: 12/12/2022] Open
Abstract
Streptococcus pneumonia has attracted increasing attention due to its resistance to existing antibiotics. TA systems are essential for bacterial persistence under stressful conditions such as nutrient deprivation, antibiotic treatment, and immune system attacks. In particular, S. pneumoniae expresses the HicBA TA gene, which encodes the stable HicA toxin and the labile HicB antitoxin. These proteins interact to form a non-toxic TA complex under normal conditions, but the toxin is activated by release from the antitoxin in response to unfavorable growth conditions. Here, we present the first crystal structure showing the complete conformation of the HicBA complex from S. pneumonia. The structure reveals that the HicA toxin contains a double-stranded RNA-binding domain that is essential for RNA recognition and that the C-terminus of the HicB antitoxin folds into a ribbon-helix-helix DNA-binding motif. The active site of HicA is sterically blocked by the N-terminal region of HicB. RNase activity assays show that His36 is essential for the ribonuclease activity of HicA, and nuclear magnetic resonance (NMR) spectra show that several residues of HicB participate in binding to the promoter DNA of the HicBA operon. A toxin-mimicking peptide that inhibits TA complex formation and thereby increases toxin activity was designed, providing a novel approach to the development of new antibiotics.
Collapse
Affiliation(s)
- Do-Hee Kim
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Sung-Min Kang
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Sung Jean Park
- College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, 534-2 Yeonsu-dong, Yeonsu-gu, Incheon 13120, Republic of Korea
| | - Chenglong Jin
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hye-Jin Yoon
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, 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
| |
Collapse
|
7
|
Cox KEL, Schildbach JF. Sequence of the R1 plasmid and comparison to F and R100. Plasmid 2017; 91:53-60. [PMID: 28359666 DOI: 10.1016/j.plasmid.2017.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/13/2017] [Accepted: 03/26/2017] [Indexed: 12/29/2022]
Abstract
The R1 antibiotic resistance plasmid, originally discovered in a clinical Salmonella isolate in London, 1963, has served for decades as a key model for understanding conjugative plasmids. Despite its scientific importance, a complete sequence of this plasmid has never been reported. We present the complete genome sequence of R1 along with a brief review of the current knowledge concerning its various genetic systems and a comparison to the F and R100 plasmids. R1 is 97,566 nucleotides long and contains 120 genes. The plasmid consists of a backbone largely similar to that of F and R100, a Tn21-like transposon that is nearly identical to that of R100, and a unique 9-kb sequence that bears some resemblance to sequences found in certain Klebsiella oxytoca strains. These three regions of R1 are separated by copies of the insertion sequence IS1. Overall, the structure of R1 and comparison to F and R100 suggest a fairly stable shared conjugative plasmid backbone into which a variety of mobile elements have inserted to form an "accessory" genome, containing multiple antibiotic resistance genes, transposons, remnants of phage genes, and genes whose functions remain unknown.
Collapse
Affiliation(s)
- Katherine E L Cox
- Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA.
| | - Joel F Schildbach
- Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA.
| |
Collapse
|
8
|
Chan WT, Espinosa M, Yeo CC. Keeping the Wolves at Bay: Antitoxins of Prokaryotic Type II Toxin-Antitoxin Systems. Front Mol Biosci 2016; 3:9. [PMID: 27047942 PMCID: PMC4803016 DOI: 10.3389/fmolb.2016.00009] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/04/2016] [Indexed: 12/21/2022] Open
Abstract
In their initial stages of discovery, prokaryotic toxin-antitoxin (TA) systems were confined to bacterial plasmids where they function to mediate the maintenance and stability of usually low- to medium-copy number plasmids through the post-segregational killing of any plasmid-free daughter cells that developed. Their eventual discovery as nearly ubiquitous and repetitive elements in bacterial chromosomes led to a wealth of knowledge and scientific debate as to their diversity and functionality in the prokaryotic lifestyle. Currently categorized into six different types designated types I–VI, type II TA systems are the best characterized. These generally comprised of two genes encoding a proteic toxin and its corresponding proteic antitoxin, respectively. Under normal growth conditions, the stable toxin is prevented from exerting its lethal effect through tight binding with the less stable antitoxin partner, forming a non-lethal TA protein complex. Besides binding with its cognate toxin, the antitoxin also plays a role in regulating the expression of the type II TA operon by binding to the operator site, thereby repressing transcription from the TA promoter. In most cases, full repression is observed in the presence of the TA complex as binding of the toxin enhances the DNA binding capability of the antitoxin. TA systems have been implicated in a gamut of prokaryotic cellular functions such as being mediators of programmed cell death as well as persistence or dormancy, biofilm formation, as defensive weapons against bacteriophage infections and as virulence factors in pathogenic bacteria. It is thus apparent that these antitoxins, as DNA-binding proteins, play an essential role in modulating the prokaryotic lifestyle whilst at the same time preventing the lethal action of the toxins under normal growth conditions, i.e., keeping the proverbial wolves at bay. In this review, we will cover the diversity and characteristics of various type II TA antitoxins. We shall also look into some interesting deviations from the canonical type II TA systems such as tripartite TA systems where the regulatory role is played by a third party protein and not the antitoxin, and a unique TA system encoding a single protein with both toxin as well as antitoxin domains.
Collapse
Affiliation(s)
- Wai Ting Chan
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Manuel Espinosa
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Chew Chieng Yeo
- Faculty of Medicine, Biomedical Research Centre, Universiti Sultan Zainal Abidin Kuala Terengganu, Malaysia
| |
Collapse
|
9
|
Chan WT, Balsa D, Espinosa M. One cannot rule them all: Are bacterial toxins-antitoxins druggable? FEMS Microbiol Rev 2015; 39:522-40. [PMID: 25796610 PMCID: PMC4487406 DOI: 10.1093/femsre/fuv002] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2015] [Indexed: 01/31/2023] Open
Abstract
Type II (proteic) toxin–antitoxin (TA) operons are widely spread in bacteria and archaea. They are organized as operons in which, usually, the antitoxin gene precedes the cognate toxin gene. The antitoxin generally acts as a transcriptional self-repressor, whereas the toxin acts as a co-repressor, both proteins constituting a harmless complex. When bacteria encounter a stressful environment, TAs are triggered. The antitoxin protein is unstable and will be degraded by host proteases, releasing the free toxin to halt essential processes. The result is a cessation of cell growth or even death. Because of their ubiquity and the essential processes targeted, TAs have been proposed as good candidates for development of novel antimicrobials. We discuss here the possible druggability of TAs as antivirals and antibacterials, with focus on the potentials and the challenges that their use may find in the ‘real’ world. We present strategies to develop TAs as antibacterials in view of novel technologies, such as the use of very small molecules (fragments) as inhibitors of protein–protein interactions. Appropriate fragments could disrupt the T:A interfaces leading to the release of the targeted TA pair. Possible ways of delivery and formulation of Tas are also discussed. We consider various approaches to develop the toxins of the type II family as possible candidates to drug discovery; druggability of toxins-antitoxins could be possible as antivirals. As antibacterials, they might be considered as druggable but delivery and formulation may not be simple so far.
Collapse
Affiliation(s)
- Wai Ting Chan
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28006-Madrid, Spain
| | - Dolors Balsa
- Immunology & Vaccines, Laboratorios LETI, Gran Via de les Corts Catalanes 184. 08034-Barcelona, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28006-Madrid, Spain
| |
Collapse
|
10
|
Bertelli C, Aeby S, Chassot B, Clulow J, Hilfiker O, Rappo S, Ritzmann S, Schumacher P, Terrettaz C, Benaglio P, Falquet L, Farinelli L, Gharib WH, Goesmann A, Harshman K, Linke B, Miyazaki R, Rivolta C, Robinson-Rechavi M, van der Meer JR, Greub G. Sequencing and characterizing the genome of Estrella lausannensis as an undergraduate project: training students and biological insights. Front Microbiol 2015; 6:101. [PMID: 25745418 PMCID: PMC4333871 DOI: 10.3389/fmicb.2015.00101] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/26/2015] [Indexed: 12/25/2022] Open
Abstract
With the widespread availability of high-throughput sequencing technologies, sequencing projects have become pervasive in the molecular life sciences. The huge bulk of data generated daily must be analyzed further by biologists with skills in bioinformatics and by "embedded bioinformaticians," i.e., bioinformaticians integrated in wet lab research groups. Thus, students interested in molecular life sciences must be trained in the main steps of genomics: sequencing, assembly, annotation and analysis. To reach that goal, a practical course has been set up for master students at the University of Lausanne: the "Sequence a genome" class. At the beginning of the academic year, a few bacterial species whose genome is unknown are provided to the students, who sequence and assemble the genome(s) and perform manual annotation. Here, we report the progress of the first class from September 2010 to June 2011 and the results obtained by seven master students who specifically assembled and annotated the genome of Estrella lausannensis, an obligate intracellular bacterium related to Chlamydia. The draft genome of Estrella is composed of 29 scaffolds encompassing 2,819,825 bp that encode for 2233 putative proteins. Estrella also possesses a 9136 bp plasmid that encodes for 14 genes, among which we found an integrase and a toxin/antitoxin module. Like all other members of the Chlamydiales order, Estrella possesses a highly conserved type III secretion system, considered as a key virulence factor. The annotation of the Estrella genome also allowed the characterization of the metabolic abilities of this strictly intracellular bacterium. Altogether, the students provided the scientific community with the Estrella genome sequence and a preliminary understanding of the biology of this recently-discovered bacterial genus, while learning to use cutting-edge technologies for sequencing and to perform bioinformatics analyses.
Collapse
Affiliation(s)
- Claire Bertelli
- Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne Lausanne, Switzerland ; SIB Swiss Institute of Bioinformatics Lausanne, Switzerland
| | - Sébastien Aeby
- Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne Lausanne, Switzerland
| | | | - James Clulow
- School of Biology, University of Lausanne Lausanne, Switzerland
| | | | - Samuel Rappo
- School of Biology, University of Lausanne Lausanne, Switzerland
| | | | | | | | - Paola Benaglio
- Department of Medical Genetics, University of Lausanne Lausanne, Switzerland
| | - Laurent Falquet
- Division of Biochemistry, Department of Biology, University of Fribourg Fribourg, Switzerland ; SIB Swiss Institute of Bioinformatics Lausanne, Switzerland
| | | | - Walid H Gharib
- Department of Ecology and Evolution, University of Lausanne Lausanne, Switzerland ; SIB Swiss Institute of Bioinformatics Lausanne, Switzerland
| | - Alexander Goesmann
- Department of Bioinformatics and Systems Biology, Justus-Liebig-University Giessen Gießen, Germany
| | - Keith Harshman
- Lausanne Genomic Technologies Facility, Center for Integrative Genomics, University of Lausanne Lausanne, Switzerland
| | - Burkhard Linke
- Department of Bioinformatics and Systems Biology, Justus-Liebig-University Giessen Gießen, Germany
| | - Ryo Miyazaki
- Department of Fundamental Microbiology, University of Lausanne Lausanne, Switzerland
| | - Carlo Rivolta
- Department of Medical Genetics, University of Lausanne Lausanne, Switzerland
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne Lausanne, Switzerland ; SIB Swiss Institute of Bioinformatics Lausanne, Switzerland
| | | | - Gilbert Greub
- Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne Lausanne, Switzerland
| |
Collapse
|
11
|
Wang J, Xu R, Liu A. IRDL cloning: a one-tube, zero-background, easy-to-use, directional cloning method improves throughput in recombinant DNA preparation. PLoS One 2014; 9:e107907. [PMID: 25243603 PMCID: PMC4171505 DOI: 10.1371/journal.pone.0107907] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 08/20/2014] [Indexed: 11/19/2022] Open
Abstract
Rapid and efficient construction of expression vectors and subsequent transformation are basic recombinant methods for the investigation of gene functionality. Although novel cloning methods have recently been developed, many laboratories worldwide continue to use traditional restriction digestion-ligation methods to construct expression vectors owing to financial constraints and the unavailability of appropriate vectors. We describe an improved restriction digestion-ligation (IRDL) cloning method that combines the advantage of directional cloning from double digestion-ligation with that of a low background observed by using a positive selection marker gene ccdB to facilitate digestion and ligation in a single tube. The IRDL cloning overcomes the time-consuming and laborious limits of traditional methods, thereby providing an easy-to-use, low-cost, and one-step strategy for directional cloning of target DNA fragments into an expression vector. As a proof-of-concept example, we developed two yeast vectors to demonstrate the feasibility and the flexibility of the IRDL cloning method. This method would provide an effective and easy-to-use system for gene cloning and functional genomics studies.
Collapse
Affiliation(s)
- Jiancai Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of China
- Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Ronghua Xu
- Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Aizhong Liu
- Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, People's Republic of China
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Kunming, People's Republic of China
| |
Collapse
|
12
|
Chopra N, Saumitra, Pathak A, Bhatnagar R, Bhatnagar S. Linkage, mobility, and selfishness in the MazF family of bacterial toxins: a snapshot of bacterial evolution. Genome Biol Evol 2014; 5:2268-84. [PMID: 24265503 PMCID: PMC3879964 DOI: 10.1093/gbe/evt175] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Prokaryotic MazF family toxins cooccur with cognate antitoxins having divergent
DNA-binding folds and can be of chromosomal or plasmid origin. Sequence similarity search
was carried out to identify the Toxin–Antitoxin (TA) operons of MazF family followed
by sequence analysis and phylogenetic studies. The genomic DNA upstream of the TA operons
was searched for the presence of regulatory motifs. The MazF family toxins showed a
conserved hydrophobic pocket in a multibinding site and are present in pathogenic
bacteria. The toxins of the MazF family are associated with four main types of cognate
antitoxin partners and cluster as a subfamily on the branches of the phylogenetic tree.
This indicates that transmission of the entire operon is the dominant mode of inheritance.
The plasmid borne TA modules were interspersed between the chromosomal TA modules of the
same subfamily, compatible with a frequent interchange of TA genes between the chromosome
and the plasmid akin to that observed for antibiotic resistance gens. The split network of
the MazF family toxins showed the AbrB-linked toxins as a hub of horizontal gene transfer.
Distinct motifs are present in the upstream region of each subfamily. The presence of MazF
family TA modules in pathogenic bacteria and identification of a conserved binding pocket
are significant for the development of novel antibacterials to disrupt the TA interaction.
However, the role of TAs in stress resistance needs to be established. Phylogenetic
studies provide insight into the evolution of MazF family TAs and effect on the bacterial
genome.
Collapse
Affiliation(s)
- Nikita Chopra
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology, Dwarka, New Delhi, India
| | | | | | | | | |
Collapse
|
13
|
Functional and structural analysis of HicA3-HicB3, a novel toxin-antitoxin system of Yersinia pestis. J Bacteriol 2014; 196:3712-23. [PMID: 25112480 DOI: 10.1128/jb.01932-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The mechanisms involved in the virulence of Yersinia pestis, the plague pathogen, are not fully understood. In previous research, we found that a Y. pestis mutant lacking the HicB3 (YPO3369) putative orphan antitoxin was attenuated for virulence in a murine model of bubonic plague. Toxin-antitoxin systems (TASs) are widespread in prokaryotes. Most bacterial species possess many TASs of several types. In type II TASs, the toxin protein is bound and neutralized by its cognate antitoxin protein in the cytoplasm. Here we identify the hicA3 gene encoding the toxin neutralized by HicB3 and show that HicA3-HicB3 constitutes a new functional type II TAS in Y. pestis. Using biochemical and mutagenesis-based approaches, we demonstrate that the HicA3 toxin is an RNase with a catalytic histidine residue. HicB3 has two functions: it sequesters and neutralizes HicA3 by blocking its active site, and it represses transcription of the hicA3B3 operon. Gel shift assays and reporter fusion experiments indicate that the HicB3 antitoxin binds to two operators in the hicA3B3 promoter region. We solved the X-ray structures of HicB3 and the HicA3-HicB3 complex; thus, we present the first crystal structure of a TA complex from the HicAB family. HicB3 forms a tetramer that can bind two HicA3 toxin molecules. HicA3 is monomeric and folds as a double-stranded-RNA-binding domain. The HicB3 N-terminal domain occludes the HicA3 active site, whereas its C-terminal domain folds as a ribbon-helix-helix DNA-binding motif.
Collapse
|
14
|
Structural basis of mRNA recognition and cleavage by toxin MazF and its regulation by antitoxin MazE in Bacillus subtilis. Mol Cell 2013; 52:447-58. [PMID: 24120662 DOI: 10.1016/j.molcel.2013.09.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/30/2013] [Accepted: 09/05/2013] [Indexed: 11/21/2022]
Abstract
MazF is an mRNA interferase, which, upon activation during stress conditions, cleaves mRNAs in a sequence-specific manner, resulting in cellular growth arrest. During normal growth conditions, the MazF toxin is inactivated through binding to its cognate antitoxin, MazE. How MazF specifically recognizes its mRNA target and carries out cleavage and how the formation of the MazE-MazF complex inactivates MazF remain unclear. We present crystal structures of MazF in complex with mRNA substrate and antitoxin MazE in Bacillus subtilis. The structure of MazF in complex with uncleavable UUdUACAUAA RNA substrate defines the molecular basis underlying the sequence-specific recognition of UACAU and the role of residues involved in the cleavage through site-specific mutational studies. The structure of the heterohexameric (MazF)2-(MazE)2-(MazF)2 complex in Bacillus subtilis, supplemented by mutational data, demonstrates that the positioning of the C-terminal helical segment of MazE within the RNA-binding channel of the MazF dimer prevents mRNA binding and cleavage by MazF.
Collapse
|
15
|
Unterholzner SJ, Hailer B, Poppenberger B, Rozhon W. Characterisation of the stbD/E toxin-antitoxin system of pEP36, a plasmid of the plant pathogen Erwinia pyrifoliae. Plasmid 2013; 70:216-25. [PMID: 23632277 DOI: 10.1016/j.plasmid.2013.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 04/15/2013] [Accepted: 04/17/2013] [Indexed: 11/29/2022]
Abstract
pEP36 is a plasmid ubiquitously present in Erwinia pyrifoliae, a pathogen which causes black stem blight of Asian pear. pEP36 is highly stable in its host, even in the absence of selective pressure. The plasmid is closely related to pEA29, which is widespread in E. amylovora, the causative agent of fire blight of apple and pear trees. Here we report that pEP36 possesses a functional hybrid toxin-antitoxin module, stbD/E(pEP36), with the toxin showing homology to the RelE/ParE proteins and the antidote belonging to the Phd/YefM antitoxin family. Bacteria expressing the StbE(pEP36) toxin arrest cell growth and enter a viable but non-culturable stage. However, they maintain their typical cell length and do not show filamentation. Pulse-chase experiments revealed that StbE(pEP36) acts as a global inhibitor of protein synthesis while it does not interfere with DNA and RNA synthesis. The StbD(pEP36) antitoxin is capable of neutralising StbE(pEP36) toxicity. Additional experiments show that the stbD/E(pEP36) module can stabilise plasmids at least 20-fold. Thus the toxin-antitoxin system may contribute to the remarkable stability of pEP36.
Collapse
Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural Crops, Technische Universität München, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
| | | | | | | |
Collapse
|
16
|
Wright O, Stan GB, Ellis T. Building-in biosafety for synthetic biology. Microbiology (Reading) 2013; 159:1221-1235. [DOI: 10.1099/mic.0.066308-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Oliver Wright
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
| | - Guy-Bart Stan
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
| | - Tom Ellis
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
17
|
Williams JJ, Hergenrother PJ. Artificial activation of toxin-antitoxin systems as an antibacterial strategy. Trends Microbiol 2012; 20:291-8. [PMID: 22445361 DOI: 10.1016/j.tim.2012.02.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 01/31/2012] [Accepted: 02/13/2012] [Indexed: 11/18/2022]
Abstract
Toxin-antitoxin (TA) systems are unique modules that effect plasmid stabilization via post-segregational killing of the bacterial host. The genes encoding TA systems also exist on bacterial chromosomes, and it has been speculated that these are involved in a variety of cellular processes. Interest in TA systems has increased dramatically over the past 5 years as the ubiquitous nature of TA genes on bacterial genomes has been revealed. The exploitation of TA systems as an antibacterial strategy via artificial activation of the toxin has been proposed and has considerable potential; however, efforts in this area remain in the early stages and several major questions remain. This review investigates the tractability of targeting TA systems to kill bacteria, including fundamental requirements for success, recent advances, and challenges associated with artificial toxin activation.
Collapse
Affiliation(s)
- Julia J Williams
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | |
Collapse
|
18
|
The ζ toxin induces a set of protective responses and dormancy. PLoS One 2012; 7:e30282. [PMID: 22295078 PMCID: PMC3266247 DOI: 10.1371/journal.pone.0030282] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 12/13/2011] [Indexed: 11/19/2022] Open
Abstract
The ζε module consists of a labile antitoxin protein, ε, which in dimer form (ε2) interferes with the action of the long-living monomeric ζ phosphotransferase toxin through protein complex formation. Toxin ζ, which inhibits cell wall biosynthesis and may be bactericide in nature, at or near physiological concentrations induces reversible cessation of Bacillus subtilis proliferation (protective dormancy) by targeting essential metabolic functions followed by propidium iodide (PI) staining in a fraction (20–30%) of the population and selects a subpopulation of cells that exhibit non-inheritable tolerance (1–5×10−5). Early after induction ζ toxin alters the expression of ∼78 genes, with the up-regulation of relA among them. RelA contributes to enforce toxin-induced dormancy. At later times, free active ζ decreases synthesis of macromolecules and releases intracellular K+. We propose that ζ toxin induces reversible protective dormancy and permeation to PI, and expression of ε2 antitoxin reverses these effects. At later times, toxin expression is followed by death of a small fraction (∼10%) of PI stained cells that exited earlier or did not enter into the dormant state. Recovery from stress leads to de novo synthesis of ε2 antitoxin, which blocks ATP binding by ζ toxin, thereby inhibiting its phosphotransferase activity.
Collapse
|
19
|
Chen CF, Chu CY, Chen TH, Lee SJ, Shen CN, Hsiao CD. Establishment of a transgenic zebrafish line for superficial skin ablation and functional validation of apoptosis modulators in vivo. PLoS One 2011; 6:e20654. [PMID: 21655190 PMCID: PMC3105106 DOI: 10.1371/journal.pone.0020654] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 05/09/2011] [Indexed: 01/31/2023] Open
Abstract
Background Zebrafish skin is composed of enveloping and basal layers which form a first-line defense system against pathogens. Zebrafish epidermis contains ionocytes and mucous cells that aid secretion of acid/ions or mucous through skin. Previous studies demonstrated that fish skin is extremely sensitive to external stimuli. However, little is known about the molecular mechanisms that modulate skin cell apoptosis in zebrafish. Methodology/Principal Findings This study aimed to create a platform to conduct conditional skin ablation and determine if it is possible to attenuate apoptotic stimuli by overexpressing potential apoptosis modulating genes in the skin of live animals. A transgenic zebrafish line of Tg(krt4:NTR-hKikGR)cy17 (killer line), which can conditionally trigger apoptosis in superficial skin cells, was first established. When the killer line was incubated with the prodrug metrodinazole, the superficial skin displayed extensive apoptosis as judged by detection of massive TUNEL- and active caspase 3-positive signals. Great reductions in NTR-hKikGR+ fluorescent signals accompanied epidermal cell apoptosis. This indicated that NTR-hKikGR+ signal fluorescence can be utilized to evaluate apoptotic events in vivo. After removal of metrodinazole, the skin integrity progressively recovered and NTR-hKikGR+ fluorescent signals gradually restored. In contrast, either crossing the killer line with testing lines or transiently injecting the killer line with testing vectors that expressed human constitutive active Akt1, mouse constitutive active Stat3, or HPV16 E6 element displayed apoptosis-resistant phenotypes to cytotoxic metrodinazole as judged by the loss of reduction in NTR-hKikGR+ fluorescent signaling. Conclusion/Significance The killer/testing line binary system established in the current study demonstrates a nitroreductase/metrodinazole system that can be utilized to conditionally perform skin ablation in a real-time manner, and provides a valuable tool to visualize and quantify the anti-apoptotic potential of interesting target genes in vivo. The current work identifies a potential use for transgenic zebrafish as a high-throughput platform to validate potential apoptosis modulators in vivo.
Collapse
Affiliation(s)
- Chi-Fang Chen
- Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
| | - Che-Yu Chu
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
| | - Te-Hao Chen
- National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
| | - Shyh-Jye Lee
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Chia-Ning Shen
- Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
- Genome Research Center, Academia Sinica, NanKang, Taipei, Taiwan
- * E-mail: (C-NS); (C-DH)
| | - Chung-Der Hsiao
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
- Center for Nanotechnology, Chung Yuan Christian University, Chung-Li, Taiwan
- * E-mail: (C-NS); (C-DH)
| |
Collapse
|
20
|
Chopra N, Agarwal S, Verma S, Bhatnagar S, Bhatnagar R. Modeling of the structure and interactions of the B. anthracis antitoxin, MoxX: deletion mutant studies highlight its modular structure and repressor function. J Comput Aided Mol Des 2011; 25:275-91. [PMID: 21336656 DOI: 10.1007/s10822-011-9419-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 02/07/2011] [Indexed: 02/07/2023]
Abstract
Our previous report on Bacillus anthracis toxin-antitoxin module (MoxXT) identified it to be a two component system wherein, PemK-like toxin (MoxT) functions as a ribonuclease (Agarwal S et al. JBC 285:7254-7270, 2010). The labile antitoxin (MoxX) can bind to/neutralize the action of the toxin and is also a DNA-binding protein mediating autoregulation. In this study, molecular modeling of MoxX in its biologically active dimeric form was done. It was found that it contains a conserved Ribbon-Helix-Helix (RHH) motif, consistent with its DNA-binding function. The modeled MoxX monomers dimerize to form a two-stranded antiparallel ribbon, while the C-terminal region adopts an extended conformation. Knowledge guided protein-protein docking, molecular dynamics simulation, and energy minimization was performed to obtain the structure of the MoxXT complex, which was exploited for the de novo design of a peptide capable of binding to MoxT. It was found that the designed peptide caused a decrease in MoxX binding to MoxT by 42% at a concentration of 2 μM in vitro. We also show that MoxX mediates negative transcriptional autoregulation by binding to its own upstream DNA. The interacting regions of both MoxX and DNA were identified in order to model their complex. The repressor activity of MoxX was found to be mediated by the 16 N-terminal residues that contains the ribbon of the RHH motif. Based on homology with other RHH proteins and deletion mutant studies, we propose a model of the MoxX-DNA interaction, with the antiparallel β-sheet of the MoxX dimer inserted into the major groove of its cognate DNA. The structure of the complex of MoxX with MoxT and its own upstream regulatory region will facilitate design of molecules that can disrupt these interactions, a strategy for development of novel antibacterials.
Collapse
Affiliation(s)
- Nikita Chopra
- Division of Biotechnology, Netaji Subhas Institute of Technology, Dwarka, New Delhi 110078, India
| | | | | | | | | |
Collapse
|
21
|
|
22
|
Diago-Navarro E, Hernandez-Arriaga AM, López-Villarejo J, Muñoz-Gómez AJ, Kamphuis MB, Boelens R, Lemonnier M, Díaz-Orejas R. parD toxin-antitoxin system of plasmid R1 - basic contributions, biotechnological applications and relationships with closely-related toxin-antitoxin systems. FEBS J 2010; 277:3097-117. [DOI: 10.1111/j.1742-4658.2010.07722.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
23
|
Plasmid pSM19035, a model to study stable maintenance in Firmicutes. Plasmid 2010; 64:1-17. [PMID: 20403380 DOI: 10.1016/j.plasmid.2010.04.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/09/2010] [Accepted: 04/13/2010] [Indexed: 12/15/2022]
Abstract
pSM19035 is a low-copy-number theta-replicating plasmid, which belongs to the Inc18 family. Plasmids of this family, which show a modular organization, are functional in evolutionarily diverse bacterial species of the Firmicutes Phylum. This review summarizes our understanding, accumulated during the last 20 years, on the genetics, biochemistry, cytology and physiology of the five pSM19035 segregation (seg) loci, which map outside of the minimal replicon. The segA locus plays a role both in maximizing plasmid random segregation, and in avoiding replication fork collapses in those plasmids with long inverted repeated regions. The segB1 locus, which acts as the ultimate determinant of plasmid maintenance, encodes a short-lived epsilon(2) antitoxin protein and a long-lived zeta toxin protein, which form a complex that neutralizes zeta toxicity. The cells that do not receive a copy of the plasmid halt their proliferation upon decay of the epsilon(2) antitoxin. The segB2 locus, which encodes two trans-acting, ParA- and ParB-like proteins and six cis-acting parS centromeres, actively ensures equal or roughly equal distribution of plasmid copies to daughter cells. The segC locus includes functions that promote the shift from the use of DNA polymerase I to the replicase (PolC-PolE DNA polymerases). The segD locus, which encodes a trans-acting transcriptional repressor, omega(2), and six cis-acting cognate sites, coordinates the expression of genes that control copy number, better-than-random segregation and partition, and assures the proper balance of these different functions. Working in concert the five different loci achieve almost absolute plasmid maintenance with a minimal growth penalty.
Collapse
|
24
|
Agarwal S, Mishra NK, Bhatnagar S, Bhatnagar R. PemK toxin of Bacillus anthracis is a ribonuclease: an insight into its active site, structure, and function. J Biol Chem 2009; 285:7254-70. [PMID: 20022964 DOI: 10.1074/jbc.m109.073387] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacillus anthracis genome harbors a toxin-antitoxin (TA) module encoding pemI (antitoxin) and pemK (toxin). This study describes the rPemK as a potent ribonuclease with a preference for pyrimidines (C/U), which is consistent with our previous study that demonstrated it as a translational attenuator. The in silico structural modeling of the PemK in conjunction with the site-directed mutagenesis confirmed the role of His-59 and Glu-78 as an acid-base couple in mediating the ribonuclease activity. The rPemK is shown to form a complex with the rPemI, which is in line with its function as a TA module. This rPemI-rPemK complex becomes catalytically inactive when both the proteins interact in a molar stoichiometry of 1. The rPemI displays vulnerability to proteolysis but attains conformational stability only upon rPemK interaction. The pemI-pemK transcript is shown to be up-regulated upon stress induction with a concomitant increase in the amount of PemK and a decline in the PemI levels, establishing the role of these modules in stress. The artificial perturbation of TA interaction could unleash the toxin, executing bacterial cell death. Toward this end, synthetic peptides are designed to disrupt the TA interaction. The peptides are shown to be effective in abrogating TA interaction in micromolar range in vitro. This approach can be harnessed as a potential antibacterial strategy against anthrax in the future.
Collapse
Affiliation(s)
- Shivangi Agarwal
- Laboratory of Molecular Biology and Genetic Engineering, , School of Biotechnology, Jawaharlal Nehru University, New Delhi-110067, India
| | | | | | | |
Collapse
|
25
|
Nehlsen K, Herrmann S, Zauers J, Hauser H, Wirth D. Toxin-antitoxin based transgene expression in mammalian cells. Nucleic Acids Res 2009; 38:e32. [PMID: 20007149 PMCID: PMC2836568 DOI: 10.1093/nar/gkp1140] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Long-term, recombinant gene expression in mammalian cells depends on the nature of the transgene integration site and its inherent properties to modulate transcription (epigenetic effects). Here we describe a method by which high transgene expression is achieved and stabilized in extensively proliferating cultures. The method is based on strict co-expression of the transgene with an antitoxin in cells that express the respective toxin. Since the strength of antitoxin expression correlates with an advantage for cell growth, the cells with strong antitoxin expression are enriched over time in cultures of heterogeneous cells. This principle was applied to CHO cell lines that conditionally express the toxin kid and that are transduced to co-express the antitoxin kis together with different transgenes of interest. Cultivation of pools of transfectants that express the toxin steadily increase their transgene expression within several weeks to reach a maximum that is up to 120-fold over the initial status. In contrast, average transgene expression drops in the absence of toxin expression. Together, we show that cells conditionally expressing kid can be employed to create overexpressing cells by a simple coupling of kis to the transgene of interest, without further manipulation and in absence of selectable drugs.
Collapse
Affiliation(s)
- K Nehlsen
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | | | | | | |
Collapse
|
26
|
Crystal Structure of the Antitoxin–Toxin Protein Complex RelB–RelE from Methanococcus jannaschii. J Mol Biol 2009; 393:898-908. [DOI: 10.1016/j.jmb.2009.08.048] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 08/04/2009] [Accepted: 08/18/2009] [Indexed: 12/15/2022]
|
27
|
Influence of operator site geometry on transcriptional control by the YefM-YoeB toxin-antitoxin complex. J Bacteriol 2008; 191:762-72. [PMID: 19028895 DOI: 10.1128/jb.01331-08] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
YefM-YoeB is among the most prevalent and well-characterized toxin-antitoxin complexes. YoeB toxin is an endoribonuclease whose activity is inhibited by YefM antitoxin. The regions 5' of yefM-yoeB in diverse bacteria possess conserved sequence motifs that mediate transcriptional autorepression. The yefM-yoeB operator site arrangement is exemplified in Escherichia coli: a pair of palindromes with core hexamer motifs and a center-to-center distance of 12 bp overlap the yefM-yoeB promoter. YefM is an autorepressor that initially recognizes a long palindrome containing the core hexamer, followed by binding to a short repeat. YoeB corepressor greatly enhances the YefM-operator interaction. Scanning mutagenesis demonstrated that the short repeat is crucial for correct interaction of YefM-YoeB with the operator site in vivo and in vitro. Moreover, altering the relative positions of the two palindromes on the DNA helix abrogated YefM-YoeB cooperative interactions with the repeats: complex binding to the long repeat was maintained but was perturbed to the short repeat. Although YefM lacks a canonical DNA binding motif, dual conserved arginine residues embedded in a basic patch of the protein are crucial for operator recognition. Deciphering the molecular basis of toxin-antitoxin transcriptional control will provide key insights into toxin-antitoxin activation and function.
Collapse
|
28
|
Makarov AA, Kolchinsky A, Ilinskaya ON. Binase and other microbial RNases as potential anticancer agents. Bioessays 2008; 30:781-90. [DOI: 10.1002/bies.20789] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
29
|
Abstract
The ribbon-helix-helix (RHH) superfamily of transcription factors uses a conserved three-dimensional structural motif to bind to DNA in a sequence-specific manner. This functionally diverse protein superfamily regulates the transcription of genes that are involved in the uptake of metals, amino-acid biosynthesis, cell division, the control of plasmid copy number, the lytic cycle of bacteriophages and, perhaps, many other cellular processes. In this Analysis, the structures of different RHH transcription factors are compared in order to evaluate the sequence motifs that are required for RHH-domain folding and DNA binding, as well as to identify conserved protein-DNA interactions in this superfamily.
Collapse
Affiliation(s)
- Eric R Schreiter
- Department of Chemistry and Protein Research Center, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931, Puerto Rico.
| | | |
Collapse
|