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Çöl B, Kürkçü MS, Di Bek E. Genome-Wide Screens Identify Genes Responsible for Intrinsic Boric Acid Resistance in Escherichia coli. Biol Trace Elem Res 2024:10.1007/s12011-024-04129-0. [PMID: 38466471 DOI: 10.1007/s12011-024-04129-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/24/2024] [Indexed: 03/13/2024]
Abstract
Boric acid (BA) has antimicrobial properties and is used to combat bacterial infections, including Enterobacteria. However, the molecular mechanisms and cellular responses to BA are still unknown. This genomics study aims to provide new information on the genes and molecular mechanisms related to the antimicrobial effect of BA in Escherichia coli. The Keio collection of E. coli was used to screen 3985 single-gene knockout strains in order to identify mutant strains that were sensitive or hypersensitive to BA at certain concentrations. The mutant strains were exposed to different concentrations of BA ranging from 0 to 120 mM in LB media. Through genome-wide screens, 92 mutants were identified that were relatively sensitive to BA at least at one concentration tested. The related biological processes in the particular cellular system were listed. This study demonstrates that intrinsic BA resistance is the result of various mechanisms acting together. Additionally, we identified eighteen out of ninety-two mutant strains (Delta_aceF, aroK, cheZ, dinJ, galS, garP, glxK, nohA, talB, torR, trmU, trpR, yddE, yfeS, ygaV, ylaC, yoaC, yohN) that exhibited sensitivity using other methods. To increase sensitivity to BA, we constructed double and triple knockout mutants of the selected sensitive mutants. In certain instances, engineered double and triple mutants exhibited significantly amplified effects. Overall, our analysis of these findings offers further understanding of the mechanisms behind BA toxicity and intrinsic resistance in E. coli.
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Affiliation(s)
- Bekir Çöl
- Faculty of Science, Department of Biology, Mugla Sitki Kocman University, Mugla, Turkey.
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey.
| | - Merve Sezer Kürkçü
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey
- Research and Application Center For Research Laboratories, Mugla Sitki Kocman University, Mugla, Turkey
| | - Esra Di Bek
- Research Laboratories Center, Biotechnology Research Center, Mugla Sitki Kocman University, Mugla, Turkey
- Köyceğiz Vocational School of Health Services, Department of Pharmacy Services, Mugla Sitki Kocman University, Mugla, Turkey
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Hyun JS, Pun R, Park SJ, Lee BJ. Effect of Divalent Metal Ions on the Ribonuclease Activity of the Toxin Molecule HP0894 from Helicobacter pylori. Life (Basel) 2024; 14:225. [PMID: 38398734 PMCID: PMC10890551 DOI: 10.3390/life14020225] [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: 12/27/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
Bacteria and archaea respond and adapt to environmental stress conditions by modulating the toxin-antitoxin (TA) system for survival. Within the bacterium Helicobacter pylori, the protein HP0894 is a key player in the HP0894-HP0895 TA system, in which HP0894 serves as a toxin and HP0895 as an antitoxin. HP0894 has intrinsic ribonuclease (RNase) activity that regulates gene expression and translation, significantly influencing bacterial physiology and survival. This activity is influenced by the presence of metal ions such as Mg2+. In this study, we explore the metal-dependent RNase activity of HP0894. Surprisingly, all tested metal ions lead to a reduction in RNase activity, with zinc ions (Zn2+) causing the most significant decrease. The secondary structure of HP0894 remained largely unaffected by Zn2+ binding, whereas structural rigidity was notably increased, as revealed using CD analysis. NMR characterized the Zn2+ binding, implicating numerous His, Asp, and Glu residues in HP0894. In summary, these results suggest that metal ions play a regulatory role in the RNase activity of HP0894, contributing to maintaining the toxin molecule in an inactive state under normal conditions.
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Affiliation(s)
- Ja-Shil Hyun
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Rabin Pun
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Sung Jean Park
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Bong-Jin Lee
- College of Pharmacy, Ajou University, 206 World Cup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
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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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4
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Chaudhary S, Yadav M, Mathpal S, Chandra S, Rathore JS. Genomic assortment and interactive insights of the chromosomal encoded control of cell death ( ccd) toxin-antitoxin (TA) module in Xenorhabdus nematophila. J Biomol Struct Dyn 2023; 41:7032-7044. [PMID: 36002267 DOI: 10.1080/07391102.2022.2114940] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 08/14/2022] [Indexed: 10/15/2022]
Abstract
In the present circumstances, toxin-antitoxin (TA) modules have a great consideration due to their elusive role in bacterial physiology. TA modules consist of a toxic part and a counteracting antitoxin part and these are abundant genetic loci harbored on bacterial plasmids and chromosomes. The control of cell death (ccd) TA locus was the first identified TA module and its unitary function (such as plasmid maintenance) has been described, however, the function of its chromosomal counterparts is still ambiguous. Here, we are exploring the genomic assortment, structural and functional association of chromosomally encoded ccdAB TA homolog (ccdABXn1) in the genome of an entomopathogenic bacterium Xenorhabdus nematophila. This bacterium is a symbiotic model with the nematode Steinernema carpocapsae that infects and kills the host insect. By genomic assortment analysis, our observations suggested that CcdA antitoxin homologs are not more closely related than CcdB toxin homologs. Further results suggest that the ccdABXn1 TA homolog has sulphonamide (such as 4C6, for CcdA homolog) and peptide (such as gyrase, for CcdB homolog) ligand partners with a typical TA interaction network that may affect essential cellular metabolism of the X. nematophila. Collectively, our results improve the knowledge and conception of the metabolic interactive role of ccdAB TA homologs in X. nematophila physiology.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Shobhi Chaudhary
- Gautam Buddha University, School of Biotechnology, Greater Noida, Uttar Pradesh, India
| | - Mohit Yadav
- Gautam Buddha University, School of Biotechnology, Greater Noida, Uttar Pradesh, India
| | - Shalini Mathpal
- Department of Biotechnology, Kumaun University Uttarakhand, Bhimtal, India
| | - Subhash Chandra
- Department of Botany, Computational Biology & Biotechnology Laboratory, Soban Singh Jeena University, Almora, Uttarakhand, India
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Coşkun USŞ, Dagcioglu Y. Evaluation of toxin-antitoxin genes, antibiotic resistance, and virulence genes in Pseudomonas aeruginosa isolates. REVISTA DA ASSOCIACAO MEDICA BRASILEIRA (1992) 2023; 69:51-55. [PMID: 36820713 PMCID: PMC9937597 DOI: 10.1590/1806-9282.20220493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/05/2022] [Indexed: 02/19/2023]
Abstract
OBJECTIVE Toxin-antitoxin genes RelBE and HigBA are known to be involved in the formation of biofilm, which is an important virulence factor for Pseudomonas aeruginosa. The purpose of this study was to determine the presence of toxin-antitoxin genes and exoenzyme S and exotoxin A virulence genes in P. aeruginosa isolates and whether there is a relationship between toxin-antitoxin genes and virulence genes as well as antibiotic resistance. METHODS Identification of the isolates and antibiotic susceptibilities was determined by a VITEK 2 (bioMérieux, France) automated system. The presence of toxin-antitoxin genes, virulence genes, and transcription levels were detected by real-time polymerase chain reaction. RESULTS RelBE and HigBA genes were detected in 94.3% (82/87) of P. aeruginosa isolates, and exoenzyme S and exotoxin A genes were detected in all of the isolates (n=87). All of the isolates that harbor the toxin-antitoxin and virulence genes were transcribed. There was a significant increase in the RelBE gene transcription level in imipenem- and meropenem-sensitive isolates and in the HigBA gene transcription level in amikacin-sensitive isolates (p<0.05). There was a significant correlation between RelBE and exoenzyme S (p=0.001). CONCLUSION The findings suggest that antibiotic resistance may be linked to toxin-antitoxin genes. Furthermore, the relationship between RelBE and exoenzyme S indicates that toxin-antitoxin genes in P. aeruginosa isolates are not only related to antibiotic resistance but also play an influential role in bacterial virulence. Larger collections of comprehensive studies on this subject are required. These studies should contribute significantly to the solution of the antibiotic resistance problem.
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Affiliation(s)
- Umut Safiye Şay Coşkun
- Tokat Gaziosmanpaşa University, Faculty of Medicine, Department of Medical Microbiology – Tokat, Turkey.,Corresponding author:
| | - Yelda Dagcioglu
- Tokat Gaziosmanpaşa University, Training and Research Hospital, Genetic Laboratory – Tokat, Turkey
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Salman M, Sharma P, Kumar M, Ethayathulla AS, Kaur P. Targeting novel sites in DNA gyrase for development of anti-microbials. Brief Funct Genomics 2022; 22:180-194. [PMID: 36064602 DOI: 10.1093/bfgp/elac029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 07/28/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial resistance in bacteria poses major challenges in selection of the therapeutic regime for managing the infectious disease. There is currently an upsurge in the appearance of multiple drug resistance in bacterial pathogens and a decline in the discovery of novel antibiotics. DNA gyrase is an attractive target used for antibiotic discovery due to its vital role in bacterial DNA replication and segregation in addition to its absence in mammalian organisms. Despite the presence of successful antibiotics targeting this enzyme, there is a need to bypass the resistance against this validated drug target. Hence, drug development in DNA gyrase is a highly active research area. In addition to the conventional binding sites for the novobiocin and fluoroquinolone antibiotics, several novel sites are being exploited for drug discovery. The binding sites for novel bacterial type II topoisomerase inhibitor (NBTI), simocyclinone, YacG, Thiophene and CcdB are structurally and biochemically validated active sites, which inhibit the supercoiling activity of topoisomerases. The novel chemical moieties with varied scaffolds have been identified to target DNA gyrase. Amongst them, the NBTI constitutes the most advanced DNA gyrase inhibitor which are in phase III trial of drug development. The present review aims to classify the novel binding sites other than the conventional novobiocin and quinolone binding pocket to bypass the resistance due to mutations in the DNA gyrase enzyme. These sites can be exploited for the identification of new scaffolds for the development of novel antibacterial compounds.
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Affiliation(s)
- Mohd Salman
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Priyanka Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Mukesh Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - A S Ethayathulla
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
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Ethanol as additive enhances expression of Ranibizumab in Escherichia coli: Impact on cellular physiology and transcriptome. Process Biochem 2022. [DOI: 10.1016/j.procbio.2021.11.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Singh G, Yadav M, Ghosh C, Rathore JS. Bacterial toxin-antitoxin modules: classification, functions, and association with persistence. CURRENT RESEARCH IN MICROBIAL SCIENCES 2021; 2:100047. [PMID: 34841338 PMCID: PMC8610362 DOI: 10.1016/j.crmicr.2021.100047] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/04/2021] [Accepted: 07/05/2021] [Indexed: 11/24/2022] Open
Abstract
Ubiquitously present bacterial Toxin-Antitoxin (TA) modules consist of stable toxin associated with labile antitoxin. Classification of TAs modules based on inhibition of toxin through antitoxin in 8 different classes. Variety of specific toxin targets and the abundance of TA modules in various deadly pathogens. Specific role of TAs modules in conservation of the resistant genes, emergence of persistence & biofilm formation. Proposed antibacterial strategies involving TA modules for elimination of multi-drug resistance.
Toxin-antitoxin (TA) modules are ubiquitous gene loci among bacteria and are comprised of a toxin part and its cognate antitoxin part. Under normal physiological conditions, antitoxin counteracts the toxicity of the toxin whereas, during stress conditions, TA modules play a crucial role in bacterial physiology through involvement in the post-segregational killing, abortive infection, biofilms, and persister cell formation. Most of the toxins are proteinaceous that affect translation or DNA replication, although some other intracellular molecular targets have also been described. While antitoxins may be a protein or RNA, that generally neutralizes its cognate toxin by direct interaction or with the help of other signaling elements and thus helps in the TA module regulation. In this review, we have discussed the current state of the multifaceted TA (type I–VIII) modules by highlighting their classification and specific targets. We have also discussed the presence of TA modules in the various pathogens and their role in antibiotic persistence development as well as biofilm formation, by influencing the different cellular processes. In the end, assembling knowledge about ubiquitous TA systems from pathogenic bacteria facilitated us to propose multiple novel antibacterial strategies involving artificial activation of TA modules.
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Affiliation(s)
- Garima Singh
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
| | - Mohit Yadav
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
| | - Chaitali Ghosh
- Department of Zoology Gargi College, University of Delhi, New Delhi, India
| | - Jitendra Singh Rathore
- School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh, India
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Apura P, Gonçalves LG, Viegas SC, Arraiano CM. The world of ribonucleases from pseudomonads: a short trip through the main features and singularities. Microb Biotechnol 2021; 14:2316-2333. [PMID: 34427985 PMCID: PMC8601179 DOI: 10.1111/1751-7915.13890] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/30/2021] [Indexed: 11/27/2022] Open
Abstract
The development of synthetic biology has brought an unprecedented increase in the number molecular tools applicable into a microbial chassis. The exploration of such tools into different bacteria revealed not only the challenges of context dependency of biological functions but also the complexity and diversity of regulatory layers in bacterial cells. Most of the standardized genetic tools and principles/functions have been mostly based on model microorganisms, namely Escherichia coli. In contrast, the non-model pseudomonads lack a deeper understanding of their regulatory layers and have limited molecular tools. They are resistant pathogens and promising alternative bacterial chassis, making them attractive targets for further studies. Ribonucleases (RNases) are key players in the post-transcriptional control of gene expression by degrading or processing the RNA molecules in the cell. These enzymes act according to the cellular requirements and can also be seen as the recyclers of ribonucleotides, allowing a continuous input of these cellular resources. This makes these post-transcriptional regulators perfect candidates to regulate microbial physiology. This review summarizes the current knowledge and unique properties of ribonucleases in the world of pseudomonads, taking into account genomic context analysis, biological function and strategies to use ribonucleases to improve biotechnological processes.
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Affiliation(s)
- Patrícia Apura
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Luis G. Gonçalves
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Sandra C. Viegas
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Cecília M. Arraiano
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
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Cardoza E, Singh H. Involvement of CspC in response to diverse environmental stressors in Escherichia coli. J Appl Microbiol 2021; 132:785-801. [PMID: 34260797 DOI: 10.1111/jam.15219] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 07/07/2021] [Accepted: 07/12/2021] [Indexed: 12/23/2022]
Abstract
The ability of Escherichia coli surviving a cold shock lies mainly with the induction of a few Csps termed as 'Major cold shock proteins'. Regardless of high sequence similarity among the nine homologous members, CspC appears to be functionally diverse in conferring the cell adaptability to various stresses based on fundamental properties of the protein including nucleic acid binding, nucleic acid melting and regulatory activity. Spanning three different stress regulons of acid, oxidative and heat, CspC regulates gene expression and transcript stability of stress proteins and bestows upon the cell tolerance to lethal-inducing agents ultimately helping it adapt to severe environmental assaults. While its exact role in cellular physiology is still to be detailed, understanding the transcriptional and translational control will likely provide insights into the mechanistic role of CspC under stress conditions. To this end, we review the knowledge on stress protein regulation by CspC and highlight its activity in response to stressors thereby elucidating its role as a major Csp player in response to one too many environmental triggers. The knowledge presented here could see various downstream applications in engineering microbes for industrial, agricultural and research applications in order to achieve high product efficiency and to aid bacteria cope with environmentally harsh conditions.
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Affiliation(s)
- Evieann Cardoza
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Mumbai, India
| | - Harinder Singh
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Mumbai, India
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Genome-wide insights into population structure and host specificity of Campylobacter jejuni. Sci Rep 2021; 11:10358. [PMID: 33990625 PMCID: PMC8121833 DOI: 10.1038/s41598-021-89683-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/26/2021] [Indexed: 11/15/2022] Open
Abstract
The zoonotic pathogen Campylobacter jejuni is among the leading causes of foodborne diseases worldwide. While C. jejuni colonises many wild animals and livestock, persistence mechanisms enabling the bacterium to adapt to host species' guts are not fully understood. In order to identify putative determinants influencing host preferences of distinct lineages, bootstrapping based on stratified random sampling combined with a k-mer-based genome-wide association was conducted on 490 genomes from diverse origins in Germany and Canada. We show a strong association of both the core and the accessory genome characteristics with distinct host animal species, indicating multiple adaptive trajectories defining the evolution of C. jejuni lifestyle preferences in different ecosystems. Here, we demonstrate that adaptation towards a specific host niche ecology is most likely a long evolutionary and multifactorial process, expressed by gene absence or presence and allele variations of core genes. Several host-specific allelic variants from different phylogenetic backgrounds, including dnaE, rpoB, ftsX or pycB play important roles for genome maintenance and metabolic pathways. Thus, variants of genes important for C. jejuni to cope with specific ecological niches or hosts may be useful markers for both surveillance and future pathogen intervention strategies.
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Exposure to 1-Butanol Exemplifies the Response of the Thermoacidophilic Archaeon Sulfolobus acidocaldarius to Solvent Stress. Appl Environ Microbiol 2021; 87:AEM.02988-20. [PMID: 33741627 PMCID: PMC8208165 DOI: 10.1128/aem.02988-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/09/2021] [Indexed: 12/18/2022] Open
Abstract
Sulfolobus acidocaldarius is a thermoacidophilic crenarchaeon with optimal growth at 80°C and pH 2 to 3. Due to its unique physiological properties, allowing life at environmental extremes, and the recent availability of genetic tools, this extremophile has received increasing interest for biotechnological applications. In order to elucidate the potential of tolerating process-related stress conditions, we investigated the response of S. acidocaldarius toward the industrially relevant organic solvent 1-butanol. In response to butanol exposure, biofilm formation of S. acidocaldarius was enhanced and occurred at up to 1.5% (vol/vol) 1-butanol, while planktonic growth was observed at up to 1% (vol/vol) 1-butanol. Confocal laser-scanning microscopy revealed that biofilm architecture changed with the formation of denser and higher tower-like structures. Concomitantly, changes in the extracellular polymeric substances with enhanced carbohydrate and protein content were determined in 1-butanol-exposed biofilms. Using scanning electron microscopy, three different cell morphotypes were observed in response to 1-butanol. Transcriptome and proteome analyses were performed comparing the response of planktonic and biofilm cells in the absence and presence of 1-butanol. In response to 1% (vol/vol) 1-butanol, transcript levels of genes encoding motility and cell envelope structures, as well as membrane proteins, were reduced. Cell division and/or vesicle formation were upregulated. Furthermore, changes in immune and defense systems, as well as metabolism and general stress responses, were observed. Our findings show that the extreme lifestyle of S. acidocaldarius coincided with a high tolerance to organic solvents. This study provides what may be the first insights into biofilm formation and membrane/cell stress caused by organic solvents in S. acidocaldarius IMPORTANCE Archaea are unique in terms of metabolic and cellular processes, as well as the adaptation to extreme environments. In the past few years, the development of genetic systems and biochemical, genetic, and polyomics studies has provided deep insights into the physiology of some archaeal model organisms. In this study, we used S. acidocaldarius, which is adapted to the two extremes of low pH and high temperature, to study its tolerance and robustness as well as its global cellular response toward organic solvents, as exemplified by 1-butanol. We were able to identify biofilm formation as a primary cellular response to 1-butanol. Furthermore, the triggered cell/membrane stress led to significant changes in culture heterogeneity accompanied by changes in central cellular processes, such as cell division and cellular defense systems, thus suggesting a global response for the protection at the population level.
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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.
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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.
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Small-Molecule Acetylation by GCN5-Related N-Acetyltransferases in Bacteria. Microbiol Mol Biol Rev 2020; 84:84/2/e00090-19. [PMID: 32295819 DOI: 10.1128/mmbr.00090-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acetylation is a conserved modification used to regulate a variety of cellular pathways, such as gene expression, protein synthesis, detoxification, and virulence. Acetyltransferase enzymes transfer an acetyl moiety, usually from acetyl coenzyme A (AcCoA), onto a target substrate, thereby modulating activity or stability. Members of the GCN5- N -acetyltransferase (GNAT) protein superfamily are found in all domains of life and are characterized by a core structural domain architecture. These enzymes can modify primary amines of small molecules or of lysyl residues of proteins. From the initial discovery of antibiotic acetylation, GNATs have been shown to modify a myriad of small-molecule substrates, including tRNAs, polyamines, cell wall components, and other toxins. This review focuses on the literature on small-molecule substrates of GNATs in bacteria, including structural examples, to understand ligand binding and catalysis. Understanding the plethora and versatility of substrates helps frame the role of acetylation within the larger context of bacterial cellular physiology.
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16
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Yadav M, Rathore JS. The hipBA Xn operon from Xenorhabdus nematophila functions as a bonafide toxin-antitoxin module. Appl Microbiol Biotechnol 2020; 104:3081-3095. [PMID: 32043192 DOI: 10.1007/s00253-020-10441-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/28/2020] [Accepted: 02/05/2020] [Indexed: 10/25/2022]
Abstract
Here, for the first time, we have investigated the hipBAXn toxin-antitoxin (TA) module from entomopathogenic bacterium Xenorhabdus nematophila. It is a type II TA module that consists of HipAXn toxin and HipBXn antitoxin protein and located in the complementary strand of chromosome under XNC1_operon 0810 locus tag. For functional analysis, hipAXn toxin, hipBXn antitoxin, and an operon having both genes were cloned in pBAD/His C vector and transformed in Escherichia coli cells. The expression profiles and endogenous toxicity assay were performed in these cells. To determine the active amino acid residues responsible for the toxicity of HipAXn toxin, site-directed mutagenesis (SDM) was performed. SDM results showed that amino acid residues S149, D306, and D329 in HipAXn toxin protein were significantly essential for its toxicity. For transcriptional analysis, the 157 bp upstream region of the hipBAXn TA module was identified as a promoter with bioinformatics tools. Further, the LacZ reporter construct with promoter region was prepared and LacZ assays as well as reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed under different stress conditions. Electrophoretic mobility shift assay (EMSA) was also performed with recombinant HipAXn toxin, HipBXn antitoxin protein, and 157 bp promoter region. Results showed that the hipBAXn TA module is a well-regulated system in which the upregulation of gene expression was also found compulsive in different SOS conditions. KEY POINTS: •Functional characterization of hipBA Xn TA module from Xenorhabdus nematophila. •hipBA Xn TA module is a functional type II TA module. •Transcriptional characterization of hipBA Xn TA module. •hipBA Xn TA module is a well regulated TA module. Graphical abstract.
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Affiliation(s)
- Mohit Yadav
- School of Biotechnology, Gautam Buddha University, Yamuna Expressway, Greater Noida, Uttar Pradesh, India
| | - Jitendra Singh Rathore
- School of Biotechnology, Gautam Buddha University, Yamuna Expressway, Greater Noida, Uttar Pradesh, India.
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17
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Andrews ESV, Arcus VL. PhoH2 proteins couple RNA helicase and RNAse activities. Protein Sci 2020; 29:883-892. [PMID: 31886915 DOI: 10.1002/pro.3814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 01/29/2023]
Abstract
PhoH2 proteins are found in a very diverse range of microorganisms that span bacteria and archaea. These proteins are composed of two domains: an N-terminal PIN-domain fused with a C-terminal PhoH domain. Collectively this fusion functions as an RNA helicase and ribonuclease. In other genomic contexts, PINdomains and PhoHdomains are separate but adjacent suggesting association to achieve similar function. Exclusively among the mycobacteria, PhoH2 proteins are encoded in the genome with an upstream gene, phoAT, which is thought to play the role of an antitoxin (in place of the traditional VapB antitoxin that lies upstream of the 47 other PINdomains in the mycobacterial genome). This review examines PhoH2 proteins as a whole and describes the bioinformatics, biochemical, structural, and biological properties of the two domains that make up PhoH2: PIN and PhoH. We review the transcriptional regulators of phoH2 from two mycobacterial species and speculate on the function of PhoH2 proteins in the context of a Type II toxin-antitoxin system which are thought to play a role in the stress response in bacteria.
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Affiliation(s)
- Emma S V Andrews
- School of Science, Division of Health, Engineering, Computing and Science, University of Waikato, Hamilton, New Zealand
| | - Vickery L Arcus
- School of Science, Division of Health, Engineering, Computing and Science, University of Waikato, Hamilton, New Zealand
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18
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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.
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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
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Draft Genome Sequence of the UV-Resistant Antarctic Bacterium Sphingomonas sp. Strain UV9. Microbiol Resour Announc 2019; 8:MRA01651-18. [PMID: 30801068 PMCID: PMC6376427 DOI: 10.1128/mra.01651-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/23/2019] [Indexed: 12/02/2022] Open
Abstract
We report the draft genome sequence of the Antarctic UV-resistant bacterium Sphingomonas sp. strain UV9. The strain has a genome size of 4.25 Mb, a 65.62% GC content, and 3,879 protein-coding sequences. We report the draft genome sequence of the Antarctic UV-resistant bacterium Sphingomonas sp. strain UV9. The strain has a genome size of 4.25 Mb, a 65.62% GC content, and 3,879 protein-coding sequences. Among others, genes encoding the resolving of the DNA damage produced by the UV irradiation were identified.
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20
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Sulaiman JE, Lam H. Application of proteomics in studying bacterial persistence. Expert Rev Proteomics 2019; 16:227-239. [DOI: 10.1080/14789450.2019.1575207] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Jordy Evan Sulaiman
- Department of Chemical and Biological Engineering, The Hong Kong University of Science & Technology, Kowloon, Hong Kong
| | - Henry Lam
- Department of Chemical and Biological Engineering, The Hong Kong University of Science & Technology, Kowloon, Hong Kong
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21
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Mechanism of regulation and neutralization of the AtaR–AtaT toxin–antitoxin system. Nat Chem Biol 2019; 15:285-294. [DOI: 10.1038/s41589-018-0216-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 12/14/2018] [Indexed: 11/08/2022]
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22
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Roy M, Kundu A, Bhunia A, Das Gupta S, De S, Das AK. Structural characterization of VapB46 antitoxin from
Mycobacterium tuberculosis
: insights into VapB46–
DNA
binding. FEBS J 2019; 286:1174-1190. [DOI: 10.1111/febs.14737] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 10/24/2018] [Accepted: 12/17/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Madhurima Roy
- Department of Biotechnology Indian Institute of Technology Kharagpur India
| | - Anirban Kundu
- Department of Biotechnology Indian Institute of Technology Kharagpur India
| | | | | | - Soumya De
- School of Bioscience Indian Institute of Technology Kharagpur India
| | - Amit Kumar Das
- Department of Biotechnology Indian Institute of Technology Kharagpur India
- School of Bioscience Indian Institute of Technology Kharagpur India
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Thomet M, Trautwetter A, Ermel G, Blanco C. Characterization of HicAB toxin-antitoxin module of Sinorhizobium meliloti. BMC Microbiol 2019; 19:10. [PMID: 30630415 PMCID: PMC6327479 DOI: 10.1186/s12866-018-1382-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 12/26/2018] [Indexed: 02/06/2023] Open
Abstract
Background Toxin-antitoxin (TA) systems are little genetic units generally composed of two genes encoding antitoxin and toxin. These systems are known to be involved in many functions that can lead to growth arrest and cell death. Among the different types of TA systems, the type II gathers together systems where the antitoxin directly binds and inhibits the toxin. Among these type II TA systems, the HicAB module is widely distributed in free-living Bacteria and Archaea and the toxin HicA functions via RNA binding and cleavage. The genome of the symbiotic Sinorhizobium meliloti encodes numerous TA systems and only a few of them are functional. Among the predicted TA systems, there is one homologous to HicAB modules. Results In this study, we characterize the HicAB toxin-antitoxin module of S. meliloti. The production of the HicA of S. meliloti in Escherichia coli cells abolishes growth and decreases cell viability. We show that expression of the HicB of S. meliloti counteracts HicA toxicity. The results of double hybrid assays and co-purification experiments allow demonstrating the interaction of HicB with the toxin HicA. Purified HicA, but not HicAB complex, is able to degrade ribosomal RNA in vitro. The analysis of separated domains of HicB protein permits us to define the antitoxin activity and the operator-binding domain. Conclusions This study points out the first characterization of the HicAB system of the symbiotic S. meliloti whereas HicA is a toxin with ribonuclease activity and HicB has two domains: the COOH-terminal one that binds the operator and the NH2-terminal one that inhibits the toxin. Electronic supplementary material The online version of this article (10.1186/s12866-018-1382-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Manon Thomet
- Ribosome, bacteria and stress Team, Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, F35000, Rennes, France
| | - Annie Trautwetter
- Ribosome, bacteria and stress Team, Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, F35000, Rennes, France
| | - Gwennola Ermel
- Ribosome, bacteria and stress Team, Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, F35000, Rennes, France.
| | - Carlos Blanco
- Ribosome, bacteria and stress Team, Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, F35000, Rennes, France
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24
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Hosseini N, Pourhajibagher M, Chiniforush N, Hosseinkhan N, Rezaie P, Bahador A. Modulation of Toxin-Antitoxin System Rnl AB Type II in Phage-Resistant Gammaproteobacteria Surviving Photodynamic Treatment. J Lasers Med Sci 2018; 10:21-28. [PMID: 31360364 DOI: 10.15171/jlms.2019.03] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Type II toxin-antitoxin (TA) systems are the particular type of TA modules which take part in different kinds of cellular actions, such as biofilm formation, persistence, stress endurance, defense of the bacterial cell against multiple phage attacks, plasmid maintenance, and programmed cell death in favor of bacterial population. Although several bioinformatics and Pet lab studies have already been conducted to understand the functionality of already discovered TA systems, still, more work in this area is required. Rnl AB type II TA module, which is composed of RnlA toxin and RnlB antitoxin, is a newly discovered type II TA module which takes part in the defense mechanism against T4 bacteriophage attack in Escherichia coli K-12 strain MH1 that has not been widely studied in other bacteria. Because of the significant role of class Gammaproteobacteriacea in a diverse range of health problems, we chose here to focus on this class to survey the presence of the Rnl AB TA module. For better categorization and description of the distribution of this module in this class of bacteria, the corresponding phylogenetic trees are illustrated here. Neighbor-joining and the maximum parsimony methods were used in this study to take a look at the distribution of domains present in RnlA and RnlB proteins, among members of Gammaproteobacteria. Also, the possible roles of photodynamic therapy (PDT) in providing a substrate for better phage therapy are herein discussed.
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Affiliation(s)
- Nava Hosseini
- Department of Microbiology, Faculty of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Maryam Pourhajibagher
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Nasim Chiniforush
- Laser Research Center of Dentistry (LRCD), Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Nazanin Hosseinkhan
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Parizad Rezaie
- Department of Microbiology, Faculty of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Abbas Bahador
- Dental Implant Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
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25
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Tan H, Yu Z, Wang C, Zhang Q, Zhao J, Zhang H, Zhai Q, Chen W. Pilot Safety Evaluation of a Novel Strain of Bacteroides ovatus. Front Genet 2018; 9:539. [PMID: 30459813 PMCID: PMC6232662 DOI: 10.3389/fgene.2018.00539] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
Bacteroides ovatus ELH-B2 is considered as a potential next-generation probiotic due to its preventive effects on lipopolysaccharides-associated inflammation and intestinal microbiota disorders in mice. To study safety issues associated with B. ovatus ELH-B2, we conducted comprehensive and systematic experiments, including in vitro genetic assessments of potential virulence and antimicrobial resistance genes, and an in vivo acute toxicity study of both immunocompetent and immunosuppressed mice via cyclophosphamide treatment. The results indicated that this novel strain is non-toxigenic, fragilysin is not expressed, and most of potential virulence genes are correlated with cellular structures such as capsular polysaccharide and polysaccharide utilizations. The antibiotic resistance features are unlikely be transferred to other intestinal microorganisms as no plasmids nor related genomic islands were identified. Side effects were not observed in mice. B. ovatus ELH-B2 also alleviated the damages caused by cyclophosphamide injection.
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Affiliation(s)
- Huizi Tan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Zhiming Yu
- Wuxi People's Hospital Affiliated to Nanjing Medical University, Wuxi, China
| | - Chen Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Qingsong Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Jianxin Zhao
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Hao Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China.,National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, China
| | - Qixiao Zhai
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China.,International Joint Research Laboratory for Probiotics, Jiangnan University, Wuxi, China
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.,School of Food Science and Technology, Jiangnan University, Wuxi, China.,National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China
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26
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Chan WT, Domenech M, Moreno-Córdoba I, Navarro-Martínez V, Nieto C, Moscoso M, García E, Espinosa M. The Streptococcus pneumoniaeyefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation. Toxins (Basel) 2018; 10:toxins10090378. [PMID: 30231554 PMCID: PMC6162744 DOI: 10.3390/toxins10090378] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/03/2018] [Accepted: 09/13/2018] [Indexed: 12/20/2022] Open
Abstract
Type II (proteic) toxin-antitoxin systems (TAs) are widely distributed among bacteria and archaea. They are generally organized as operons integrated by two genes, the first encoding the antitoxin that binds to its cognate toxin to generate a harmless protein–protein complex. Under stress conditions, the unstable antitoxin is degraded by host proteases, releasing the toxin to achieve its toxic effect. In the Gram-positive pathogen Streptococcus pneumoniae we have characterized four TAs: pezAT, relBE, yefM-yoeB, and phD-doc, although the latter is missing in strain R6. We have assessed the role of the two yefM-yoeB and relBE systems encoded by S. pneumoniae R6 by construction of isogenic strains lacking one or two of the operons, and by complementation assays. We have analyzed the phenotypes of the wild type and mutants in terms of cell growth, response to environmental stress, and ability to generate biofilms. Compared to the wild-type, the mutants exhibited lower resistance to oxidative stress. Further, strains deleted in yefM-yoeB and the double mutant lacking yefM-yoeB and relBE exhibited a significant reduction in their ability for biofilm formation. Complementation assays showed that defective phenotypes were restored to wild type levels. We conclude that these two loci may play a relevant role in these aspects of the S. pneumoniae lifestyle and contribute to the bacterial colonization of new niches.
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Affiliation(s)
- Wai Ting Chan
- i-DNA Biotechnology (M) Sdn Bhd. A-1-6 Pusat Perdagangan Kuchai, No. 2, Jalan 1/127, Kuchai Entrepreneurs Park, Kuala Lumpur 58200, Malaysia.
| | - Mirian Domenech
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28040 Madrid, Spain.
| | - Inmaculada Moreno-Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Verónica Navarro-Martínez
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Concha Nieto
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Miriam Moscoso
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Ernesto García
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28040 Madrid, Spain.
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
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27
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Graf JS, Mayr MJ, Marchant HK, Tienken D, Hach PF, Brand A, Schubert CJ, Kuypers MMM, Milucka J. Bloom of a denitrifying methanotroph, 'Candidatus Methylomirabilis limnetica', in a deep stratified lake. Environ Microbiol 2018; 20:2598-2614. [PMID: 29806730 DOI: 10.1111/1462-2920.14285] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 12/17/2022]
Abstract
Methanotrophic bacteria represent an important biological filter regulating methane emissions into the atmosphere. Planktonic methanotrophic communities in freshwater lakes are typically dominated by aerobic gamma-proteobacteria, with a contribution from alpha-proteobacterial methanotrophs and the NC10 bacteria. The NC10 clade encompasses methanotrophs related to 'Candidatus Methylomirabilis oxyfera', which oxidize methane using a unique pathway of denitrification that tentatively produces N2 and O2 from nitric oxide (NO). Here, we describe a new species of the NC10 clade, 'Ca. Methylomirabilis limnetica', which dominated the planktonic microbial community in the anoxic depths of the deep stratified Lake Zug in two consecutive years, comprising up to 27% of the total bacterial population. Gene transcripts assigned to 'Ca. M. limnetica' constituted up to one third of all metatranscriptomic sequences in situ. The reconstructed genome encoded a complete pathway for methane oxidation, and an incomplete denitrification pathway, including two putative nitric oxide dismutase genes. The genome of 'Ca. M. limnetica' exhibited features possibly related to genome streamlining (i.e. less redundancy of key metabolic genes) and adaptation to its planktonic habitat (i.e. gas vesicle genes). We speculate that 'Ca. M. limnetica' temporarily bloomed in the lake during non-steady-state conditions suggesting a niche for NC10 bacteria in the lacustrine methane and nitrogen cycle.
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Affiliation(s)
- Jon S Graf
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
| | - Magdalena J Mayr
- Eawag, Surface Waters-Research and Management, Kastanienbaum, Switzerland.,ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich, Switzerland
| | - Hannah K Marchant
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
| | - Daniela Tienken
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
| | - Philipp F Hach
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
| | - Andreas Brand
- Eawag, Surface Waters-Research and Management, Kastanienbaum, Switzerland.,ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich, Switzerland
| | - Carsten J Schubert
- Eawag, Surface Waters-Research and Management, Kastanienbaum, Switzerland
| | - Marcel M M Kuypers
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
| | - Jana Milucka
- Max-Planck-Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany
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28
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Jurėnas D, Van Melderen L, Garcia-Pino A. Crystallization and X-ray analysis of all of the players in the autoregulation of the ataRT toxin-antitoxin system. Acta Crystallogr F Struct Biol Commun 2018; 74:391-401. [PMID: 29969102 PMCID: PMC6038448 DOI: 10.1107/s2053230x18007914] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 05/29/2018] [Indexed: 01/02/2023] Open
Abstract
The ataRT operon from enteropathogenic Escherichia coli encodes a toxin-antitoxin (TA) module with a recently discovered novel toxin activity. This new type II TA module targets translation initiation for cell-growth arrest. Virtually nothing is known regarding the molecular mechanisms of neutralization, toxin catalytic action or translation autoregulation. Here, the production, biochemical analysis and crystallization of the intrinsically disordered antitoxin AtaR, the toxin AtaT, the AtaR-AtaT complex and the complex of AtaR-AtaT with a double-stranded DNA fragment of the operator region of the promoter are reported. Because they contain large regions that are intrinsically disordered, TA antitoxins are notoriously difficult to crystallize. AtaR forms a homodimer in solution and crystallizes in space group P6122, with unit-cell parameters a = b = 56.3, c = 160.8 Å. The crystals are likely to contain an AtaR monomer in the asymmetric unit and diffracted to 3.8 Å resolution. The Y144F catalytic mutant of AtaT (AtaTY144F) bound to the cofactor acetyl coenzyme A (AcCoA) and the C-terminal neutralization domain of AtaR (AtaR44-86) were also crystallized. The crystals of the AtaTY144F-AcCoA complex diffracted to 2.5 Å resolution and the crystals of AtaR44-86 diffracted to 2.2 Å resolution. Analysis of these structures should reveal the full scope of the neutralization of the toxin AtaT by AtaR. The crystals belonged to space groups P6522 and P3121, with unit-cell parameters a = b = 58.1, c = 216.7 Å and a = b = 87.6, c = 125.5 Å, respectively. The AtaR-AtaT-DNA complex contains a 22 bp DNA duplex that was optimized to obtain high-resolution data based on the sequence of two inverted repeats detected in the operator region. It crystallizes in space group C2221, with unit-cell parameters a = 75.6, b = 87.9, c = 190.5 Å. These crystals diffracted to 3.5 Å resolution.
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Affiliation(s)
- Dukas Jurėnas
- Cellular and Molecular Microbiology, Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, B-6041 Gosselies, Belgium
- Department of Biochemistry and Molecular Biology, Vilnius University Joint Life Sciences Center, Sauletekio Ave. 7, LT-10257 Vilnius, Lithuania
| | - Laurence Van Melderen
- Cellular and Molecular Microbiology, Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, B-6041 Gosselies, Belgium
| | - Abel Garcia-Pino
- Cellular and Molecular Microbiology, Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, B-6041 Gosselies, Belgium
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Impact of Wastewater Treatment on the Prevalence of Integrons and the Genetic Diversity of Integron Gene Cassettes. Appl Environ Microbiol 2018; 84:AEM.02766-17. [PMID: 29475864 DOI: 10.1128/aem.02766-17] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 02/10/2018] [Indexed: 12/23/2022] Open
Abstract
The integron platform allows the acquisition, expression, and dissemination of antibiotic resistance genes within gene cassettes. Wastewater treatment plants (WWTPs) contain abundant resistance genes; however, knowledge about the impacts of wastewater treatment on integrons and their gene cassettes is limited. In this study, by using clone library analysis and high-throughput sequencing, we investigated the abundance of class 1, 2, and 3 integrons and their corresponding gene cassettes in three urban WWTPs. Our results showed that class 1 integrons were most abundant in WWTPs and that wastewater treatment significantly reduced the abundance of all integrons. The WWTP influents harbored the highest diversity of class 1 integron gene cassettes, whereas class 3 integron gene cassettes exhibited highest diversity in activated sludge. Most of the gene cassette arrays detected in class 1 integrons were novel. Aminoglycoside, beta-lactam, and trimethoprim resistance genes were highly prevalent in class 1 integron gene cassettes, while class 3 integrons mainly carried beta-lactam resistance gene cassettes. A core class 1 integron resistance gene cassette pool persisted during wastewater treatment, implying that these resistance genes could have high potential to spread into environments through WWTPs. These data provide new insights into the impact of wastewater treatment on integron pools and highlight the need for surveillance of resistance genes within both class 1 and 3 integrons.IMPORTANCE Wastewater treatment plants represent a significant sink and transport medium for antibiotic resistance bacteria and genes spreading into environments. Integrons are important genetic elements involved in the evolution of antibiotic resistance. To better understand the impact of wastewater treatment on integrons and their gene cassette contexts, we conducted clone library construction and high-throughput sequencing to analyze gene cassette contexts for class 1 and class 3 integrons during the wastewater treatment process. This study comprehensively profiled the distribution of integrons and their gene cassettes (especially class 3 integrons) in influents, activated sludge, and effluents of conventional municipal wastewater treatment plants. We further demonstrated that while wastewater treatment significantly reduced the abundance of integrons and the diversity of associated gene cassettes, a large fraction of integrons persisted in wastewater effluents and were consequentially discharged into downstream natural environments.
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Fei Q, Gao EB, Liu B, Wei Y, Ning D. A Toxin-Antitoxin System VapBC15 from Synechocystis sp. PCC 6803 Shows Distinct Regulatory Features. Genes (Basel) 2018; 9:E173. [PMID: 29561797 PMCID: PMC5924515 DOI: 10.3390/genes9040173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 12/26/2022] Open
Abstract
Type II toxin-antitoxin (TA) systems play important roles in bacterial stress survival by regulating cell growth or death. They are highly abundant in cyanobacteria yet remain poorly characterized. Here, we report the identification and regulation of a putative type II TA system from Synechocystis PCC6803, VapBC15. The VapBC15 system is encoded by the chromosomal operon vapBC15. Exogenous expression of VapC15 dramatically arrested cell growth of Escherichia coli and reduced the numbers of colony-forming units (CFU). The VapC15 toxicity could be which was counteracted neutralized by simultaneous or delayed production of VapB15. Biochemical analysis demonstrated the formation of VapB15-VapC15 complexes by the physical interaction between VapB15 and VapC15. Notably, the VapB15 antitoxin up-regulated the transcription of the vapBC15 operon by directly binding to the promoter region, and the VapC15 toxin abolished the up-regulatory effect by destabilizing the binding. Moreover, VapB15 can be degraded by the proteases Lons and ClpXP2s from Synechocystis PCC6803, thus activating the latent toxicity of VapBC15. These findings suggest that VapBC15 represents a genuine TA system that utilizes a distinct mechanism to regulate toxin activity.
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Affiliation(s)
- Qian Fei
- CAS Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - E-Bin Gao
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China.
| | - Biao Liu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China.
| | - Yao Wei
- Huai'an Research Center, Institute of Hydrobiology, Chinese Academy of Sciences, Huai'an 223005, China.
| | - Degang Ning
- CAS Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
- Huai'an Research Center, Institute of Hydrobiology, Chinese Academy of Sciences, Huai'an 223005, China.
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Phenotypic responses to interspecies competition and commensalism in a naturally-derived microbial co-culture. Sci Rep 2018; 8:297. [PMID: 29321512 PMCID: PMC5762899 DOI: 10.1038/s41598-017-18630-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/14/2017] [Indexed: 01/09/2023] Open
Abstract
The fundamental question of whether different microbial species will co-exist or compete in a given environment depends on context, composition and environmental constraints. Model microbial systems can yield some general principles related to this question. In this study we employed a naturally occurring co-culture composed of heterotrophic bacteria, Halomonas sp. HL-48 and Marinobacter sp. HL-58, to ask two fundamental scientific questions: 1) how do the phenotypes of two naturally co-existing species respond to partnership as compared to axenic growth? and 2) how do growth and molecular phenotypes of these species change with respect to competitive and commensal interactions? We hypothesized – and confirmed – that co-cultivation under glucose as the sole carbon source would result in competitive interactions. Similarly, when glucose was swapped with xylose, the interactions became commensal because Marinobacter HL-58 was supported by metabolites derived from Halomonas HL-48. Each species responded to partnership by changing both its growth and molecular phenotype as assayed via batch growth kinetics and global transcriptomics. These phenotypic responses depended on nutrient availability and so the environment ultimately controlled how they responded to each other. This simplified model community revealed that microbial interactions are context-specific and different environmental conditions dictate how interspecies partnerships will unfold.
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Kang SM, Kim DH, Lee KY, Park SJ, Yoon HJ, Lee SJ, Im H, Lee BJ. Functional details of the Mycobacterium tuberculosis VapBC26 toxin-antitoxin system based on a structural study: insights into unique binding and antibiotic peptides. Nucleic Acids Res 2017; 45:8564-8580. [PMID: 28575388 PMCID: PMC5737657 DOI: 10.1093/nar/gkx489] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/25/2017] [Indexed: 11/16/2022] Open
Abstract
Toxin-antitoxin (TA) systems are essential for bacterial persistence under stressful conditions. In particular, Mycobacterium tuberculosis express VapBC TA genes that encode the stable VapC toxin and the labile VapB antitoxin. Under normal conditions, these proteins interact to form a non-toxic TA complex, but the toxin is activated by release from the antitoxin in response to unfavorable conditions. Here, we present the crystal structure of the M. tuberculosis VapBC26 complex and show that the VapC26 toxin contains a pilus retraction protein (PilT) N-terminal (PIN) domain that is essential for ribonuclease activity and that, the VapB26 antitoxin folds into a ribbon-helix-helix DNA-binding motif at the N-terminus. The active site of VapC26 is sterically blocked by the flexible C-terminal region of VapB26. The C-terminal region of free VapB26 adopts an unfolded conformation but forms a helix upon binding to VapC26. The results of RNase activity assays show that Mg2+ and Mn2+ are essential for the ribonuclease activity of VapC26. As shown in the nuclear magnetic resonance spectra, several residues of VapB26 participate in the specific binding to the promoter region of the VapBC26 operon. In addition, toxin-mimicking peptides were designed that inhibit TA complex formation and thereby increase toxin activity, providing a novel approach to the development of new antibiotics.
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Affiliation(s)
- Sung-Min Kang
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Do-Hee Kim
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Ki-Young Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Sung Jean Park
- College of Pharmacy, Gachon University, 534-2 Yeonsu-dong, Yeonsu-gu, Incheon 406-799, Republic of Korea
| | - Hye-Jin Yoon
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Sang Jae Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Hookang Im
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Bong-Jin Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea
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Hadži S, Mernik A, Podlipnik Č, Loris R, Lah J. The Thermodynamic Basis of the Fuzzy Interaction of an Intrinsically Disordered Protein. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201707853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- San Hadži
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Andrej Mernik
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Črtomir Podlipnik
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Remy Loris
- Structural Biology Brussels; Department of Biotechnology; Vrije Universiteit Brussel and Center for Structural Biology; Vlaams Instituut voor Biotechnologie; Pleinlaan 2 1050 Brussel Belgium
| | - Jurij Lah
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
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Hadži S, Mernik A, Podlipnik Č, Loris R, Lah J. The Thermodynamic Basis of the Fuzzy Interaction of an Intrinsically Disordered Protein. Angew Chem Int Ed Engl 2017; 56:14494-14497. [DOI: 10.1002/anie.201707853] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Indexed: 12/22/2022]
Affiliation(s)
- San Hadži
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Andrej Mernik
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Črtomir Podlipnik
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
| | - Remy Loris
- Structural Biology Brussels; Department of Biotechnology; Vrije Universiteit Brussel and Center for Structural Biology; Vlaams Instituut voor Biotechnologie; Pleinlaan 2 1050 Brussel Belgium
| | - Jurij Lah
- Faculty of Chemistry and Chemical Technology; University of Ljubljana; Večna pot 113 Ljubljana Slovenia
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35
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Hadži S, Garcia-Pino A, Haesaerts S, Jurenas D, Gerdes K, Lah J, Loris R. Ribosome-dependent Vibrio cholerae mRNAse HigB2 is regulated by a β-strand sliding mechanism. Nucleic Acids Res 2017; 45:4972-4983. [PMID: 28334932 PMCID: PMC5416850 DOI: 10.1093/nar/gkx138] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 02/25/2017] [Indexed: 11/12/2022] Open
Abstract
Toxin–antitoxin (TA) modules are small operons involved in bacterial stress response and persistence. higBA operons form a family of TA modules with an inverted gene organization and a toxin belonging to the RelE/ParE superfamily. Here, we present the crystal structures of chromosomally encoded Vibrio cholerae antitoxin (VcHigA2), toxin (VcHigB2) and their complex, which show significant differences in structure and mechanisms of function compared to the higBA module from plasmid Rts1, the defining member of the family. The VcHigB2 is more closely related to Escherichia coli RelE both in terms of overall structure and the organization of its active site. VcHigB2 is neutralized by VcHigA2, a modular protein with an N-terminal intrinsically disordered toxin-neutralizing segment followed by a C-terminal helix-turn-helix dimerization and DNA binding domain. VcHigA2 binds VcHigB2 with picomolar affinity, which is mainly a consequence of entropically favorable de-solvation of a large hydrophobic binding interface and enthalpically favorable folding of the N-terminal domain into an α-helix followed by a β-strand. This interaction displaces helix α3 of VcHigB2 and at the same time induces a one-residue shift in the register of β-strand β3, thereby flipping the catalytically important Arg64 out of the active site.
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Affiliation(s)
- San Hadži
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium.,Molecular Recognition Unit, Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050 Brussel, Belgium.,Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Abel Garcia-Pino
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium.,Biologie Structurale et Biophysique, IBMM-DBM, Université Libre de Bruxelles (ULB), B-6041 Gosselies, Belgium
| | - Sarah Haesaerts
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium.,Molecular Recognition Unit, Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050 Brussel, Belgium
| | - Dukas Jurenas
- Biologie Structurale et Biophysique, IBMM-DBM, Université Libre de Bruxelles (ULB), B-6041 Gosselies, Belgium
| | - Kenn Gerdes
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Jurij Lah
- Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium.,Molecular Recognition Unit, Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050 Brussel, Belgium
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36
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Yang J, Xu B, Gao Z, Zhou K, Liu P, Dong Y, Zhang J, Liu Q. HicAB toxin-antitoxin complex from Escherichia coli: expression and crystallization. Acta Crystallogr F Struct Biol Commun 2017; 73:505-510. [PMID: 28876228 PMCID: PMC5619741 DOI: 10.1107/s2053230x17011529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/04/2017] [Indexed: 11/11/2022] Open
Abstract
Toxin-antitoxin (TA) systems are widespread in both bacteria and archaea, where they enable cells to adapt to environmental cues. TA systems play crucial roles in various cellular processes, such as programmed cell death, cell growth, persistence and virulence. Here, two distinct forms of the type II toxin-antitoxin complex HicAB were identified and characterized in Escherichia coli K-12, and both were successfully overexpressed and purified. The two proposed forms, HicABL and HicABS, differed in the presence or absence of a seven-amino-acid segment at the N-terminus in the antitoxin HicB. The short form HicABS readily crystallized under the conditions 0.1 M Tris-HCl pH 8.0, 20%(w/v) PEG 6000, 0.2 M ammonium sulfate. The HicABS crystal diffracted and data were collected to 2.5 Å resolution. The crystal belonged to space group I222 or I212121, with unit-cell parameters a = 67.04, b = 66.31, c = 120.78 Å. Matthews coefficient calculation suggested the presence of two molecules each of HicA and HicBS in the asymmetric unit, with a solvent content of 55.28% and a Matthews coefficient (VM) of 2.75 Å3 Da-1.
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Affiliation(s)
- Jingsi Yang
- College of Chemistry, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian 116024, People’s Republic of China
| | - Bingshuang Xu
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
| | - Zengqiang Gao
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
| | - Ke Zhou
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
| | - Peng Liu
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
| | - Yuhui Dong
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
| | - Jianjun Zhang
- College of Chemistry, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian 116024, People’s Republic of China
| | - Quansheng Liu
- Multi-Discipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Yuquan Road 19B, Beijing 100049, People’s Republic of China
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Ghosh P, Sowdhamini R. Bioinformatics comparisons of RNA-binding proteins of pathogenic and non-pathogenic Escherichia coli strains reveal novel virulence factors. BMC Genomics 2017; 18:658. [PMID: 28836963 PMCID: PMC5571608 DOI: 10.1186/s12864-017-4045-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 08/09/2017] [Indexed: 12/03/2022] Open
Abstract
Background Pathogenic bacteria have evolved various strategies to counteract host defences. They are also exposed to environments that are undergoing constant changes. Hence, in order to survive, bacteria must adapt themselves to the changing environmental conditions by performing regulations at the transcriptional and/or post-transcriptional levels. Roles of RNA-binding proteins (RBPs) as virulence factors have been very well studied. Here, we have used a sequence search-based method to compare and contrast the proteomes of 16 pathogenic and three non-pathogenic E. coli strains as well as to obtain a global picture of the RBP landscape (RBPome) in E. coli. Results Our results show that there are no significant differences in the percentage of RBPs encoded by the pathogenic and the non-pathogenic E. coli strains. The differences in the types of Pfam domains as well as Pfam RNA-binding domains, encoded by these two classes of E. coli strains, are also insignificant. The complete and distinct RBPome of E. coli has been established by studying all known E. coli strains till date. We have also identified RBPs that are exclusive to pathogenic strains, and most of them can be exploited as drug targets since they appear to be non-homologous to their human host proteins. Many of these pathogen-specific proteins were uncharacterised and their identities could be resolved on the basis of sequence homology searches with known proteins. Detailed structural modelling, molecular dynamics simulations and sequence comparisons have been pursued for selected examples to understand differences in stability and RNA-binding. Conclusions The approach used in this paper to cross-compare proteomes of pathogenic and non-pathogenic strains may also be extended to other bacterial or even eukaryotic proteomes to understand interesting differences in their RBPomes. The pathogen-specific RBPs reported in this study, may also be taken up further for clinical trials and/or experimental validations. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-4045-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pritha Ghosh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore, Karnataka, 560 065, India
| | - Ramanathan Sowdhamini
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore, Karnataka, 560 065, India.
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Genetic analysis of a PER-2-producing Shewanella sp. strain harbouring a variety of mobile genetic elements and antibiotic resistance determinants. J Glob Antimicrob Resist 2017; 11:81-86. [PMID: 28760680 DOI: 10.1016/j.jgar.2017.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/07/2017] [Accepted: 06/10/2017] [Indexed: 11/23/2022] Open
Abstract
The objective of this study was to investigate the molecular mechanisms explaining the multidrug-resistant (MDR) phenotype found in a novel clinical Shewanella sp. strain (Shew256) recovered from a diabetic patient. Whole-genome shotgun sequencing was performed using Illumina MiSeq-I and Nextera XT DNA library. De novo assembly was performed with SPAdes. RAST Server was used to predict the open-reading frames and the predictions were confirmed using BLAST. Further genomic analysis was carried out using average nucleotide identity (ANI), ACT (Artemis), OrthoMCL, ARG-ANNOT, ISfinder, PHAST, tRNAscan-SE, plasmidSPAdes, PlasmidFinder and MAUVE. PCR and plasmid extraction were also performed. Genomic analysis revealed a total of 456 predicted genes unique to Shew256 compared with other Shewanella genomes. Moreover, the presence of different resistance genes, including blaPER-2, was found. A complex class 1 integron containing the ISCR1 gene, disrupted by two putative transposase genes, was identified. Furthermore, other resistance genes, a transposon containing aph(3'), insertion sequences, phages and non-coding RNAs were also found. In conclusion, evidence of acquisition of resistance genes and mobile elements that could explain the MDR phenotype were observed. This Shewanella sp. represents a prime example of how antibiotic resistance determinants can be acquired by uncommon pathogens.
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Andersen SB, Ghoul M, Griffin AS, Petersen B, Johansen HK, Molin S. Diversity, Prevalence, and Longitudinal Occurrence of Type II Toxin-Antitoxin Systems of Pseudomonas aeruginosa Infecting Cystic Fibrosis Lungs. Front Microbiol 2017; 8:1180. [PMID: 28690609 PMCID: PMC5481352 DOI: 10.3389/fmicb.2017.01180] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 06/09/2017] [Indexed: 12/15/2022] Open
Abstract
Type II toxin-antitoxin (TA) systems are most commonly composed of two genes encoding a stable toxin, which harms the cell, and an unstable antitoxin that can inactivate it. TA systems were initially characterized as selfish elements, but have recently gained attention for regulating general stress responses responsible for pathogen virulence, formation of drug-tolerant persister cells and biofilms—all implicated in causing recalcitrant chronic infections. We use a bioinformatics approach to explore the distribution and evolution of type II TA loci of the opportunistic pathogen, Pseudomonas aeruginosa, across longitudinally sampled isolates from cystic fibrosis lungs. We identify their location in the genome, mutations, and gain/loss during infection to elucidate their function(s) in stabilizing selfish elements and pathogenesis. We found (1) 26 distinct TA systems, where all isolates harbor four in their core genome and a variable number of the remaining 22 on genomic islands; (2) limited mutations in core genome TA loci, suggesting they are not under negative selection; (3) no evidence for horizontal transmission of elements with TA systems between clone types within patients, despite their ability to mobilize; (4) no gain and limited loss of TA-bearing genomic islands, and of those elements partially lost, the remnant regions carry the TA systems supporting their role in genomic stabilization; (5) no significant correlation between frequency of TA systems and strain ability to establish as chronic infection, but those with a particular TA, are more successful in establishing a chronic infection.
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Affiliation(s)
- Sandra B Andersen
- Department of Zoology, University of OxfordOxford, United Kingdom.,The Novo Nordisk Foundation Center for Biosustainability, Technical University of DenmarkLyngby, Denmark
| | - Melanie Ghoul
- Department of Zoology, University of OxfordOxford, United Kingdom
| | | | - Bent Petersen
- Department of Bio and Health Informatics, Technical University of DenmarkLyngby, Denmark
| | - Helle K Johansen
- Department of Clinical Microbiology, RigshospitaletCopenhagen, Denmark
| | - Søren Molin
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of DenmarkLyngby, Denmark
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Armbruster CE, Forsyth-DeOrnellas V, Johnson AO, Smith SN, Zhao L, Wu W, Mobley HLT. Genome-wide transposon mutagenesis of Proteus mirabilis: Essential genes, fitness factors for catheter-associated urinary tract infection, and the impact of polymicrobial infection on fitness requirements. PLoS Pathog 2017; 13:e1006434. [PMID: 28614382 PMCID: PMC5484520 DOI: 10.1371/journal.ppat.1006434] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/26/2017] [Accepted: 05/25/2017] [Indexed: 12/31/2022] Open
Abstract
The Gram-negative bacterium Proteus mirabilis is a leading cause of catheter-associated urinary tract infections (CAUTIs), which are often polymicrobial. Numerous prior studies have uncovered virulence factors for P. mirabilis pathogenicity in a murine model of ascending UTI, but little is known concerning pathogenesis during CAUTI or polymicrobial infection. In this study, we utilized five pools of 10,000 transposon mutants each and transposon insertion-site sequencing (Tn-Seq) to identify the full arsenal of P. mirabilis HI4320 fitness factors for single-species versus polymicrobial CAUTI with Providencia stuartii BE2467. 436 genes in the input pools lacked transposon insertions and were therefore concluded to be essential for P. mirabilis growth in rich medium. 629 genes were identified as P. mirabilis fitness factors during single-species CAUTI. Tn-Seq from coinfection with P. stuartii revealed 217/629 (35%) of the same genes as identified by single-species Tn-Seq, and 1353 additional factors that specifically contribute to colonization during coinfection. Mutants were constructed in eight genes of interest to validate the initial screen: 7/8 (88%) mutants exhibited the expected phenotypes for single-species CAUTI, and 3/3 (100%) validated the expected phenotypes for polymicrobial CAUTI. This approach provided validation of numerous previously described P. mirabilis fitness determinants from an ascending model of UTI, the discovery of novel fitness determinants specifically for CAUTI, and a stringent assessment of how polymicrobial infection influences fitness requirements. For instance, we describe a requirement for branched-chain amino acid biosynthesis by P. mirabilis during coinfection due to high-affinity import of leucine by P. stuartii. Further investigation of genes and pathways that provide a competitive advantage during both single-species and polymicrobial CAUTI will likely provide robust targets for therapeutic intervention to reduce P. mirabilis CAUTI incidence and severity. Proteus mirabilis is a common cause of single-species and polymicrobial catheter-associated urinary tract infections (CAUTIs). Prior studies have uncovered P. mirabilis virulence factors for single-species ascending UTI, but little is known concerning pathogenesis during CAUTI or polymicrobial infection. Using transposon insertion-site sequencing (Tn-Seq), we performed a global assessment of P. mirabilis fitness factors for CAUTI while simultaneously determining how coinfection with another CAUTI pathogen, Providencia stuartii, alters P. mirabilis fitness requirements. This approach provides six important contributions to the field: 1) the first global estimation of P. mirabilis genes essential for growth, 2) validation of a role for known P. mirabilis fitness factors during CAUTI, 3) identification of novel fitness factors, 4) identification of core fitness factors for both single-species and polymicrobial CAUTI, 5) identification of single-species fitness factors that are complemented during polymicrobial infection, and 6) identification of factors that only provide a competitive advantage during polymicrobial infection. We further demonstrate that the CAUTI model can be used to examine the interplay between fitness requirements of both species during coinfection. Investigation of fitness requirements for other pathogens during single-species and polymicrobial CAUTI will elucidate complex interactions that contribute to disease severity and uncover conserved targets for therapeutic intervention.
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Affiliation(s)
- Chelsie E. Armbruster
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
- * E-mail: (CEA); (HLTM)
| | - Valerie Forsyth-DeOrnellas
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Alexandra O. Johnson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Sara N. Smith
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Lili Zhao
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, United States of America
| | - Weisheng Wu
- Department of Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Harry L. T. Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail: (CEA); (HLTM)
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A Toxin Involved in Salmonella Persistence Regulates Its Activity by Acetylating Its Cognate Antitoxin, a Modification Reversed by CobB Sirtuin Deacetylase. mBio 2017; 8:mBio.00708-17. [PMID: 28559487 PMCID: PMC5449658 DOI: 10.1128/mbio.00708-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial toxin-antitoxin systems trigger the onset of a persister state by inhibiting essential cellular processes. The TacT toxin of Salmonella enterica is known to induce a persister state in macrophages through the acetylation of aminoacyl-tRNAs. Here, we show that the TacT toxin and the TacA antitoxin work as a complex that modulates TacT activity via the acetylation state of TacA. TacT acetylates TacA at residue K44, a modification that is removed by the NAD+-dependent CobB sirtuin deacetylase. TacA acetylation increases the activity of TacT, downregulating protein synthesis. TacA acetylation altered binding to its own promoter, although this did not change tacAT expression levels. These claims are supported by results from in vitro protein synthesis experiments used to monitor TacT activity, in vivo growth analyses, electrophoretic mobility shift assays, and quantitative reverse transcription-PCR (RT-qPCR) analysis. TacT is the first example of a Gcn5-related N-acetyltransferase that modifies nonprotein and protein substrates. During host infection, pathogenic bacteria can modulate their physiology to evade host defenses. Some pathogens use toxin-antitoxin systems to modulate a state of self-toxicity that can decrease their cellular activity, triggering the onset of a persister state. The lower metabolic activity of persister cells allows them to escape host defenses and antibiotic treatments. Hence a better understanding of the mechanisms used by pathogens to ingress and egress the persister state is of relevance to human health.
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Physical and Functional Interplay between MazF 1Bif and Its Noncognate Antitoxins from Bifidobacterium longum. Appl Environ Microbiol 2017; 83:AEM.03232-16. [PMID: 28213540 DOI: 10.1128/aem.03232-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/09/2017] [Indexed: 11/20/2022] Open
Abstract
Bifidobacterium longum strain JDM301, a widely used commercial strain in China, encodes at least two MazEF-like modules and one RelBE-like toxin-antitoxin (TA) system in its chromosome, designated MazE1F1Bif, MazE2F2Bif, and RelBEBif, respectively. Bacterial TA systems play an important role in several stress responses, but the relationship between these TA systems is largely unknown. In this study, the interactions between MazF1Bif and MazE2Bif or RelBBif were assessed in B. longum strain JDM301. MazF1Bif caused the degradation of tufABif mRNA, and its toxicity was inhibited by forming a protein complex with its cognate antitoxin, MazE1Bif Notably, MazF1Bif toxicity was also partially neutralized when jointly expressed with noncognate antitoxin MazE2Bif or RelBBif Our results show that the two noncognate antitoxins also inhibited mRNA degradation caused by MazF1Bif toxin. Furthermore, the physical interplay between MazF1Bif and its noncognate antitoxins was confirmed by immunoprecipitation. These results suggest that MazF1Bif can arrest cell growth and that MazF1Bif toxicity can be neutralized by its cognate and noncognate antitoxins. These results imply that JDM301 uses a sophisticated toxin-antitoxin interaction network to alter its physiology when coping with environmental stress.IMPORTANCE Although toxin-antitoxin (TA) systems play an important role in several stress responses, the regulatory mechanisms of multiple TA system homologs in the bacterial genome remain largely unclear. In this study, the relationships between MazE1F1Bif and the other two TA systems of Bifidobacterium longum strain JDM301 were explored, and the interactions between MazF1Bif and MazE2Bif or RelBBif were characterized. In addition, the mRNA degradation activity of MazF1Bif was demonstrated. In particular, the interaction of the toxin with noncognate antitoxins was shown, even between different TA families (MazF1Bif toxin and RelBBif antitoxin) in JDM301. This work provides insight into the regulatory mechanisms of TA systems implicated in the stress responses of bifidobacteria.
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Peddireddy V, Doddam SN, Ahmed N. Mycobacterial Dormancy Systems and Host Responses in Tuberculosis. Front Immunol 2017; 8:84. [PMID: 28261197 PMCID: PMC5309233 DOI: 10.3389/fimmu.2017.00084] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/18/2017] [Indexed: 12/15/2022] Open
Abstract
Tuberculosis (TB) caused by the intracellular pathogen, Mycobacterium tuberculosis (Mtb), claims more than 1.5 million lives worldwide annually. Despite promulgation of multipronged strategies to prevent and control TB, there is no significant downfall occurring in the number of new cases, and adding to this is the relapse of the disease due to the emergence of antibiotic resistance and the ability of Mtb to remain dormant after primary infection. The pathology of Mtb is complex and largely attributed to immune-evading strategies that this pathogen adopts to establish primary infection, its persistence in the host, and reactivation of pathogenicity under favorable conditions. In this review, we present various biochemical, immunological, and genetic strategies unleashed by Mtb inside the host for its survival. The bacterium enables itself to establish a niche by evading immune recognition via resorting to masking, establishment of dormancy by manipulating immune receptor responses, altering innate immune cell fate, enhancing granuloma formation, and developing antibiotic tolerance. Besides these, the regulatory entities, such as DosR and its regulon, encompassing various putative effector proteins play a vital role in maintaining the dormant nature of this pathogen. Further, reactivation of Mtb allows relapse of the disease and is favored by the genes of the Rtf family and the conditions that suppress the immune system of the host. Identification of target genes and characterizing the function of their respective antigens involved in primary infection, dormancy, and reactivation would likely provide vital clues to design novel drugs and/or vaccines for the control of dormant TB.
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Affiliation(s)
- Vidyullatha Peddireddy
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad , Hyderabad , India
| | - Sankara Narayana Doddam
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad , Hyderabad , India
| | - Niyaz Ahmed
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India; Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
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RnlB Antitoxin of the Escherichia coli RnlA-RnlB Toxin-Antitoxin Module Requires RNase HI for Inhibition of RnlA Toxin Activity. Toxins (Basel) 2017; 9:toxins9010029. [PMID: 28085056 PMCID: PMC5308261 DOI: 10.3390/toxins9010029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 12/28/2016] [Accepted: 01/05/2017] [Indexed: 12/03/2022] Open
Abstract
The Escherichia coli RnlA-RnlB toxin–antitoxin system is related to the anti-phage mechanism. Under normal growth conditions, an RnlA toxin with endoribonuclease activity is inhibited by binding of its cognate RnlB antitoxin. After bacteriophage T4 infection, RnlA is activated by the disappearance of RnlB, resulting in the rapid degradation of T4 mRNAs and consequently no T4 propagation when T4 dmd encoding a phage antitoxin against RnlA is defective. Intriguingly, E. coli RNase HI, which plays a key role in DNA replication, is required for the activation of RnlA and stimulates the RNA cleavage activity of RnlA. Here, we report an additional role of RNase HI in the regulation of RnlA-RnlB system. Both RNase HI and RnlB are associated with NRD (one of three domains of RnlA). The interaction between RnlB and NRD depends on RNase HI. Exogenous expression of RnlA in wild-type cells has no effect on cell growth because of endogenous RnlB and this inhibition of RnlA toxicity requires RNase HI and NRD. These results suggest that RNase HI recruits RnlB to RnlA through NRD for inhibiting RnlA toxicity and thus plays two contrary roles in the regulation of RnlA-RnlB system.
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Abstract
We report here the draft genome sequence of Aeromonas sp. strain EERV15 isolated from sand filter. The organism most closely related to Aeromonas sp. EERV15 is Aeromonas veronii B565, with an average 83% amino acid sequence similarity of putatively encoded protein open reading frames.
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Yakimov MM, Crisafi F, Messina E, Smedile F, Lopatina A, Denaro R, Pieper DH, Golyshin PN, Giuliano L. Analysis of defence systems and a conjugative IncP-1 plasmid in the marine polyaromatic hydrocarbons-degrading bacterium Cycloclasticus sp. 78-ME. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:508-519. [PMID: 27345842 DOI: 10.1111/1758-2229.12424] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/24/2016] [Indexed: 06/06/2023]
Abstract
Marine prokaryotes have evolved a broad repertoire of defence systems to protect their genomes from lateral gene transfer including innate or acquired immune systems and infection-induced programmed cell suicide and dormancy. Here we report on the analysis of multiple defence systems present in the genome of the strain Cycloclasticus sp. 78-ME isolated from petroleum deposits of the tanker 'Amoco Milford Haven'. Cycloclasticus are ubiquitous bacteria globally important in polyaromatic hydrocarbons degradation in marine environments. Two 'defence islands' were identified in 78-ME genome: the first harbouring CRISPR-Cas with toxin-antitoxin system, while the second was composed by an array of genes for toxin-antitoxin and restriction-modification proteins. Among all identified spacers of CRISPR-Cas system only seven spacers match sequences of phages and plasmids. Furthermore, a conjugative plasmid p7ME01, which belongs to a new IncP-1θ ancestral archetype without any accessory mobile elements was found in 78-ME. Our results provide the context to the co-occurrence of diverse defence mechanisms in the genome of Cycloclasticus sp. 78-ME, which protect the genome of this highly specialized PAH-degrader. This study contributes to the further understanding of complex networks established in petroleum-based microbial communities.
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Affiliation(s)
- Michail M Yakimov
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
| | - Francesca Crisafi
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
| | - Enzo Messina
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
| | - Francesco Smedile
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
| | - Anna Lopatina
- Institute of Molecular Genetics and Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Renata Denaro
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
| | - Dietmar H Pieper
- Microbial Interactions and Processes Research Group, HZI - Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig, D-38124, Germany
| | - Peter N Golyshin
- School of Biological Sciences, Bangor University, ECW Bldg Deiniol Rd, Bangor, Gwynedd, LL57 2UW, United Kingdom
| | - Laura Giuliano
- Institute for Coastal Marine Environment, CNR, Spianata S. Raineri 86, Messina, 98122, Italy
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Toxin-Antitoxin Modules Are Pliable Switches Activated by Multiple Protease Pathways. Toxins (Basel) 2016; 8:toxins8070214. [PMID: 27409636 PMCID: PMC4963847 DOI: 10.3390/toxins8070214] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 06/24/2016] [Accepted: 06/27/2016] [Indexed: 02/06/2023] Open
Abstract
Toxin-antitoxin (TA) modules are bacterial regulatory switches that facilitate conflicting outcomes for cells by promoting a pro-survival phenotypic adaptation and/or by directly mediating cell death, all through the toxin activity upon degradation of antitoxin. Intensive study has revealed specific details of TA module functions, but significant gaps remain about the molecular details of activation via antitoxin degradation used by different bacteria and in different environments. This review summarizes the current state of knowledge about the interaction of antitoxins with cellular proteases Lon and ClpP to mediate TA module activation. An understanding of these processes can answer long-standing questions regarding stochastic versus specific activation of TA modules and provide insight into the potential for manipulation of TA modules to alter bacterial growth.
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48
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Emerging Roles of Toxin-Antitoxin Modules in Bacterial Pathogenesis. Molecules 2016; 21:molecules21060790. [PMID: 27322231 PMCID: PMC6273597 DOI: 10.3390/molecules21060790] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/06/2016] [Accepted: 06/13/2016] [Indexed: 11/17/2022] Open
Abstract
Toxin-antitoxin (TA) cassettes are encoded widely by bacteria. The modules typically comprise a protein toxin and protein or RNA antitoxin that sequesters the toxin factor. Toxin activation in response to environmental cues or other stresses promotes a dampening of metabolism, most notably protein translation, which permits survival until conditions improve. Emerging evidence also implicates TAs in bacterial pathogenicity. Bacterial persistence involves entry into a transient semi-dormant state in which cells survive unfavorable conditions including killing by antibiotics, which is a significant clinical problem. TA complexes play a fundamental role in inducing persistence by downregulating cellular metabolism. Bacterial biofilms are important in numerous chronic inflammatory and infectious diseases and cause serious therapeutic problems due to their multidrug tolerance and resistance to host immune system actions. Multiple TAs influence biofilm formation through a network of interactions with other factors that mediate biofilm production and maintenance. Moreover, in view of their emerging contributions to bacterial virulence, TAs are potential targets for novel prophylactic and therapeutic approaches that are required urgently in an era of expanding antibiotic resistance. This review summarizes the emerging evidence that implicates TAs in the virulence profiles of a diverse range of key bacterial pathogens that trigger serious human disease.
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Wan H, Otsuka Y, Gao ZQ, Wei Y, Chen Z, Masuda M, Yonesaki T, Zhang H, Dong YH. Structural insights into the inhibition mechanism of bacterial toxin LsoA by bacteriophage antitoxin Dmd. Mol Microbiol 2016; 101:757-69. [PMID: 27169810 DOI: 10.1111/mmi.13420] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 01/18/2023]
Abstract
Bacteria have obtained a variety of resistance mechanisms including toxin-antitoxin (TA) systems against bacteriophages (phages), whereas phages have also evolved to overcome bacterial anti-phage mechanisms. Dmd from T4 phage can suppress the toxicities of homologous toxins LsoA and RnlA from Escherichia coli, representing the first example of a phage antitoxin against multiple bacterial toxins in known TA systems. Here, the crystal structure of LsoA-Dmd complex showed Dmd is inserted into the deep groove between the N-terminal repeated domain (NRD) and the Dmd-binding domain (DBD) of LsoA. The NRD shifts significantly from a 'closed' to an 'open' conformation upon Dmd binding. Site-directed mutagenesis of Dmd revealed the conserved residues (W31 and N40) are necessary for LsoA binding and the toxicity suppression as determined by pull-down and cell toxicity assays. Further mutagenesis identified the conserved Dmd-binding residues (R243, E246 and R305) of LsoA are vital for its toxicity, and suggested Dmd and LsoB may possess different inhibitory mechanisms against LsoA toxicity. Our structure-function studies demonstrate Dmd can recognize LsoA and inhibit its toxicity by occupying the active site possibly via substrate mimicry. These findings have provided unique insights into the defense and counter-defense mechanisms between bacteria and phages in their co-evolution.
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Affiliation(s)
- Hua Wan
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuichi Otsuka
- Department of Microbiology, School of Medicine, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
| | - Zeng-Qiang Gao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yong Wei
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhen Chen
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Michiaki Masuda
- Department of Microbiology, School of Medicine, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
| | - Tetsuro Yonesaki
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka-shi, Osaka, 560-0043, Japan
| | - Heng Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu-Hui Dong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
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50
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Garcia-Pino A, De Gieter S, Talavera A, De Greve H, Efremov RG, Loris R. An intrinsically disordered entropic switch determines allostery in Phd-Doc regulation. Nat Chem Biol 2016; 12:490-6. [PMID: 27159580 DOI: 10.1038/nchembio.2078] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 03/11/2016] [Indexed: 12/31/2022]
Abstract
Conditional cooperativity is a common mechanism involved in transcriptional regulation of prokaryotic type II toxin-antitoxin operons and is intricately related to bacterial persistence. It allows the toxin component of a toxin-antitoxin module to act as a co-repressor at low doses of toxin as compared to antitoxin. When toxin level exceeds a certain threshold, however, the toxin becomes a de-repressor. Most antitoxins contain an intrinsically disordered region (IDR) that typically is involved in toxin neutralization and repressor complex formation. To address how the antitoxin IDR is involved in transcription regulation, we studied the phd-doc operon from bacteriophage P1. We provide evidence that the IDR of Phd provides an entropic barrier precluding full operon repression in the absence of Doc. Binding of Doc results in a cooperativity switch and consequent strong operon repression, enabling context-specific modulation of the regulatory process. Variations of this theme are likely to be a common mechanism in the autoregulation of bacterial operons that involve intrinsically disordered regions.
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Affiliation(s)
- Abel Garcia-Pino
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Biologie Structurale et Biophysique, Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Steven De Gieter
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Structural Biology Research Center, VIB, Brussels, Belgium
| | - Ariel Talavera
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Structural Biology Research Center, VIB, Brussels, Belgium
| | - Henri De Greve
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Structural Biology Research Center, VIB, Brussels, Belgium
| | - Rouslan G Efremov
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Structural Biology Research Center, VIB, Brussels, Belgium
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Structural Biology Research Center, VIB, Brussels, Belgium
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