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Chen Z, Mao Y, Song Y, Dou M, Shang K, Yu Z, Ding K, Chen S. Refined egoist: the toxin-antitoxin immune system of T6SS. Microb Pathog 2024; 196:106991. [PMID: 39369755 DOI: 10.1016/j.micpath.2024.106991] [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: 05/28/2024] [Revised: 09/30/2024] [Accepted: 10/01/2024] [Indexed: 10/08/2024]
Abstract
The Type VI secretory system (T6SS) is a key regulatory network in the bacterial system, which plays an important role in host-pathogen interactions and maintains cell homeostasis by regulating the release of effector proteins in specific competition. T6SS causes cell lysis or competitive inhibition by delivering effector molecules, such as toxic proteins and nucleic acids, directly from donor bacterial cells to eukaryotic or prokaryotic targets. Additionally, it orchestrates synthesis of immune effectors that counteract toxins thus preventing self-intoxication or antagonistic actions by competing microbes. Even so, the mechanism of toxin-antitoxin regulation in bacteria remains unclear. In response, this review discusses the bacterial T6SS's structure and function and the mechanism behind toxin-antitoxin secretion and the T6SS's expression in order to guide the further exploration of the pathogenic mechanism of the T6SS and the development of novel preparations for reducing and replacing toxins and antitoxins.
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Affiliation(s)
- Ziduo Chen
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Yikai Mao
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Yinzhou Song
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Mengxuan Dou
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Ke Shang
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Zuhua Yu
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China
| | - Ke Ding
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China.
| | - Songbiao Chen
- College of Animal Science and Technology/Laboratory of Functional Microbiology and Animal Health, Henan University of Science and Technology, Luoyang 471023, China; Luoyang Key Laboratory of Live Carrier Biomaterial and Animal Disease Prevention and Control, Henan University of Science and Technology, Luoyang 471003, China; The Key Lab of Animal Disease and Public Health, Henan University of Science and Technology, Luoyang 471023, China.
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2
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Han D, Ma S, He C, Yang Y, Li P, Lu L. Unveiling the genetic architecture and transmission dynamics of a novel multidrug-resistant plasmid harboring bla NDM-5 in E. Coli ST167: implications for antibiotic resistance management. BMC Microbiol 2024; 24:178. [PMID: 38783210 PMCID: PMC11112900 DOI: 10.1186/s12866-024-03333-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND The emergence of multidrug-resistant (MDR) Escherichia coli strains poses significant challenges in clinical settings, particularly when these strains harbor New Delhi metallo-ß-lactamase (NDM) gene, which confer resistance to carbapenems, a critical class of last-resort antibiotics. This study investigates the genetic characteristics and implications of a novel blaNDM-5-carrying plasmid pNDM-5-0083 isolated from an E. coli strain GZ04-0083 from clinical specimen in Zhongshan, China. RESULTS Phenotypic and genotypic evaluations confirmed that the E. coli ST167 strain GZ04-0083 is a multidrug-resistant organism, showing resistance to diverse classes of antibiotics including ß-lactams, carbapenems, fluoroquinolones, aminoglycosides, and sulfonamides, while maintaining susceptibility to monobactams. Investigations involving S1 pulsed-field gel electrophoresis, Southern blot analysis, and conjugation experiments, alongside genomic sequencing, confirmed the presence of the blaNDM-5 gene within a 146-kb IncFIB plasmid pNDM-5-0083. This evidence underscores a significant risk for the horizontal transfer of resistance genes among bacterial populations. Detailed annotations of genetic elements-such as resistance genes, transposons, and insertion sequences-and comparative BLAST analyses with other blaNDM-5-carrying plasmids, revealed a unique architectural configuration in the pNDM-5-0083. The MDR region of this plasmid shares a conserved gene arrangement (repA-IS15DIV-blaNDM-5-bleMBL-IS91-suI2-aadA2-dfrA12) with three previously reported plasmids, indicating a potential for dynamic genetic recombination and evolution within the MDR region. Additionally, the integration of virulence factors, including the iro and sit gene clusters and enolase, into its genetic architecture poses further therapeutic challenges by enhancing the strain's pathogenicity through improved host tissue colonization, immune evasion, and increased infection severity. CONCLUSIONS The detailed identification and characterization of pNDM-5-0083 enhance our understanding of the mechanisms facilitating the spread of carbapenem resistance. This study illuminates the intricate interplay among various genetic elements within the novel blaNDM-5-carrying plasmid, which are crucial for the stability and mobility of resistance genes across bacterial populations. These insights highlight the urgent need for ongoing surveillance and the development of effective strategies to curb the proliferation of antibiotic resistance.
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Affiliation(s)
- Dengke Han
- Department of Laboratory Medicine, Zhongshan City People's Hospital, Zhongshan, 528403, Guangdong, China
| | - Suzhen Ma
- Department of Laboratory Medicine, Zhongshan City People's Hospital, Zhongshan, 528403, Guangdong, China
| | - Chenhong He
- Department of Emergency, Zhongshan City People's Hospital, Zhongshan, 528403, Guangdong, China
| | - Yuxing Yang
- Department of Laboratory Medicine, Zhongshan City People's Hospital, Zhongshan, 528403, Guangdong, China
| | - Peng Li
- Chinese PLA Center for Disease Control and Prevention, 20 DongDa Street, Fengtai District, Beijing, 100071, China
| | - Lanfen Lu
- Department of Laboratory Medicine, Zhongshan City People's Hospital, Zhongshan, 528403, Guangdong, China.
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3
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Cummins EA, Moran RA, Snaith AE, Hall RJ, Connor CH, Dunn SJ, McNally A. Parallel loss of type VI secretion systems in two multi-drug-resistant Escherichia coli lineages. Microb Genom 2023; 9. [PMID: 37970873 DOI: 10.1099/mgen.0.001133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023] Open
Abstract
The repeated emergence of multi-drug-resistant (MDR) Escherichia coli clones is a threat to public health globally. In recent work, drug-resistant E. coli were shown to be capable of displacing commensal E. coli in the human gut. Given the rapid colonization observed in travel studies, it is possible that the presence of a type VI secretion system (T6SS) may be responsible for the rapid competitive advantage of drug-resistant E. coli clones. We employed large-scale genomic approaches to investigate this hypothesis. First, we searched for T6SS genes across a curated dataset of over 20 000 genomes representing the full phylogenetic diversity of E. coli. This revealed large, non-phylogenetic variation in the presence of T6SS genes. No association was found between T6SS gene carriage and MDR lineages. However, multiple clades containing MDR clones have lost essential structural T6SS genes. We characterized the T6SS loci of ST410 and ST131 and identified specific recombination and insertion events responsible for the parallel loss of essential T6SS genes in two MDR clones.
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Affiliation(s)
- Elizabeth A Cummins
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Robert A Moran
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Ann E Snaith
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Rebecca J Hall
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Christopher H Connor
- Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne 3000, Australia
| | - Steven J Dunn
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
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De Sousa BFS, Domingo-Serrano L, Salinero-Lanzarote A, Palacios JM, Rey L. The T6SS-Dependent Effector Re78 of Rhizobium etli Mim1 Benefits Bacterial Competition. BIOLOGY 2023; 12:678. [PMID: 37237492 PMCID: PMC10215855 DOI: 10.3390/biology12050678] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/26/2023] [Accepted: 05/02/2023] [Indexed: 05/28/2023]
Abstract
The genes of the type VI secretion system (T6SS) from Rhizobium etli Mim1 (ReMim1) that contain possible effectors can be divided into three modules. The mutants in them indicated that they are not required for effective nodulation with beans. To analyze T6SS expression, a putative promoter region between the tssA and tssH genes was fused in both orientations to a reporter gene. Both fusions are expressed more in free living than in symbiosis. When the module-specific genes were studied using RT-qPCR, a low expression was observed in free living and in symbiosis, which was clearly lower than the structural genes. The secretion of Re78 protein from the T6SS gene cluster was dependent on the presence of an active T6SS. Furthermore, the expression of Re78 and Re79 proteins in E. coli without the ReMim1 nanosyringe revealed that these proteins behave as a toxic effector/immunity protein pair (E/I). The harmful action of Re78, whose mechanism is still unknown, would take place in the periplasmic space of the target cell. The deletion of this ReMim1 E/I pair resulted in reduced competitiveness for bean nodule occupancy and in lower survival in the presence of the wild-type strain.
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Affiliation(s)
- Bruna Fernanda Silva De Sousa
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo UPM, Universidad Politécnica de Madrid (UPM), 28223 Pozuelo de Alarcón, Spain; (B.F.S.D.S.)
| | - Lucía Domingo-Serrano
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo UPM, Universidad Politécnica de Madrid (UPM), 28223 Pozuelo de Alarcón, Spain; (B.F.S.D.S.)
| | - Alvaro Salinero-Lanzarote
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo UPM, Universidad Politécnica de Madrid (UPM), 28223 Pozuelo de Alarcón, Spain; (B.F.S.D.S.)
| | - José Manuel Palacios
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo UPM, Universidad Politécnica de Madrid (UPM), 28223 Pozuelo de Alarcón, Spain; (B.F.S.D.S.)
- Departamento de Biotecnología y Biología Vegetal, ETSI Agronómica Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Luis Rey
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo UPM, Universidad Politécnica de Madrid (UPM), 28223 Pozuelo de Alarcón, Spain; (B.F.S.D.S.)
- Departamento de Biotecnología y Biología Vegetal, ETSI Agronómica Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
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5
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Calder A, Snyder LAS. Diversity of the type VI secretion systems in the Neisseria spp. Microb Genom 2023; 9. [PMID: 37052605 DOI: 10.1099/mgen.0.000986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Complete Type VI Secretion Systems were identified in the genome sequence data of Neisseria subflava isolates sourced from throat swabs of human volunteers. The previous report was the first to describe two complete Type VI Secretion Systems in these isolates, both of which were distinct in terms of their gene organization and sequence homology. Since publication of the first report, Type VI Secretion System subtypes have been identified in Neisseria spp. The characteristics of each type in N. subflava are further investigated here and in the context of the other Neisseria spp., including identification of the lineages containing the different types and subtypes. Type VI Secretion Systems use VgrG for delivery of toxin effector proteins; several copies of vgrG and associated effector / immunity pairs are present in Neisseria spp. Based on sequence similarity between strains and species, these core Type VI Secretion System genes, vgrG, and effector / immunity genes may diversify via horizontal gene transfer, an instrument for gene acquisition and repair in Neisseria spp.
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Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
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6
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Guryanova SV, Kataeva A. Inflammation Regulation by Bacterial Molecular Patterns. Biomedicines 2023; 11:biomedicines11010183. [PMID: 36672691 PMCID: PMC9855958 DOI: 10.3390/biomedicines11010183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/13/2023] Open
Abstract
Stimulation of innate immunity by bacterial molecular patterns can induce an enhanced cellular immune response to pathogens that are associated with innate immune memory shaped by epigenetic changes. Immunological memory can be expressed in the acceleration/intensification of inflammation, as well as in the exact opposite-to maintain tolerance and non-response to a repeated stimulus. Tolerance is one of the central concepts of immunity and is ensured by the consistency of all parts of the immune response. The severe consequences of inflammation force researchers to study in detail all stages of the downstream pathways that are activated after exposure to a stimulus, while the formation of non-response to a pro-inflammatory stimulus has not yet received a detailed description. Elucidation of the mechanism of tolerance is an urgent task for the prevention and treatment of inflammatory diseases. The aim of this investigation was to study the dynamic changes in the gene expression of A20 and ATF3, the inflammation suppressors, against the background of the expression of the genes of the innate immunity receptors TLR4 and NOD2 and the pro-inflammatory cytokine TNF-α under the influence of TLR4 and NOD2 agonists, lipopolysaccharide (LPS) and glucosaminylmuramyl dipeptide (GMDP). The mechanism of inflammation regulation by bioregulators of bacterial origin-LPS and GMDP-was evaluated in vitro in human peripheral blood mononuclear cells and in vivo after i.p. administration of LPS and GMDP to mice. Gene expression was assessed by RT-PCR. Innate immune receptors and the pro-inflammatory cytokine TNF-α were found to develop early in response to LPS and GMDP, both in vitro and in vivo. Genes of cytosolic proteins controlling inflammation (A20 and ATF3) were expressed later. Prior exposure of the innate immune system to LPS and muramyl peptides may modulate host defense against acute inflammation. As a result of the study, new data were obtained on dynamic changes in deubiquitinase A20 and the transcription factor ATF3, which are involved in the limitation and suppression of inflammatory reactions caused by fragments of bacterial cell walls-LPS and GMDP. Thus, bioregulators of bacterial origin LPS and GMDP, along with pro-inflammatory factors, activate the expression of genes that suppress inflammation, which should be considered when analyzing data from studies of the pro-inflammatory properties of LPS and GMDP and when developing drugs based on them.
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Affiliation(s)
- Svetlana V. Guryanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of Russian Academy of Sciences, Ministry of Science and Higher Education of the Russian Federation, 117997 Moscow, Russia
- Medical Institute, Peoples’ Friendship University of Russia (RUDN University) of the Ministry of Science and Higher Education of the Russian Federation, 117198 Moscow, Russia
- Correspondence: ; Tel.: +7-9153150073
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7
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Guryanova SV. Regulation of Immune Homeostasis via Muramyl Peptides-Low Molecular Weight Bioregulators of Bacterial Origin. Microorganisms 2022; 10:1526. [PMID: 36013944 PMCID: PMC9413341 DOI: 10.3390/microorganisms10081526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/20/2022] [Accepted: 07/22/2022] [Indexed: 12/10/2022] Open
Abstract
Metabolites and fragments of bacterial cells play an important role in the formation of immune homeostasis. Formed in the course of evolution, symbiotic relationships between microorganisms and a macroorganism are manifested, in particular, in the regulation of numerous physiological functions of the human body by the innate immunity receptors. Low molecular weight bioregulators of bacterial origin have recently attracted more and more attention as drugs in the prevention and composition of complex therapy for a wide range of diseases of bacterial and viral etiology. Signaling networks show cascades of causal relationships of deterministic phenomena that support the homeostasis of multicellular organisms at different levels. To create networks, data from numerous biomedical and clinical research databases were used to prepare expert systems for use in pharmacological and biomedical research with an emphasis on muramyl dipeptides. Muramyl peptides are the fragments of the cell wall of Gram-positive and Gram-negative bacteria. Binding of muramyl peptides with intracellular NOD2 receptors is crucial for an immune response on pathogens. Depending on the microenvironment and duration of action, muramyl peptides possess positive or negative regulation of inflammation. Other factors, such as genetic, pollutions, method of application and stress also contribute and should be taken into account. A system biology approach should be used in order to systemize all experimental data for rigorous analysis, with the aim of understanding intrinsic pathways of homeostasis, in order to define precise medicine therapy and drug design.
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Affiliation(s)
- Svetlana V Guryanova
- Medical Institute, Peoples' Friendship University of Russia (RUDN University) of the Ministry of Science and Higher Education of the Russian Federation, 117198 Moscow, Russia
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8
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Li Y, Yan X, Tao Z. Two Type VI Secretion DNase Effectors are Utilized for Interbacterial Competition in the Fish Pathogen Pseudomonas plecoglossicida. Front Microbiol 2022; 13:869278. [PMID: 35464968 PMCID: PMC9020831 DOI: 10.3389/fmicb.2022.869278] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/17/2022] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas plecoglossicida is a facultative fish pathogen that possesses three distinct type VI secretion systems (named T6SS-1, T6SS-2, and T6SS-3). Our previous work indicated that only T6SS-2 of P. plecoglossicida mediates interbacterial competition. However, the antibacterial T6SS effectors and their functions are unclear. Here, we reported two T6SS effectors that mediate antibacterial activity. We first identified four putative antibacterial effectors (denoted as Txe1, Txe2, Txe3, and Txe4) and their cognate immunity proteins encoded in P. plecoglossicida strain XSDHY-P by analyzing the regions downstream of three vgrG genes. We showed that the growth of Escherichia coli cells expressing Txe1, Txe2, and Txe4 was inhibited, and these three effectors exhibited nuclease activity in vivo. The interbacterial competition assays with single- or multi-effector deletion mutants as attackers revealed that Txe1 was the predominant T6SS toxin of P. plecoglossicida strain XSDHY-P mediating the interbacterial killing. This work contributes to our understanding of bacterial effectors involved in the interbacterial competition.
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Affiliation(s)
- Yanyan Li
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
| | - Xiaojun Yan
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
| | - Zhen Tao
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
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9
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Amaya FA, Blondel CJ, Barros-Infante MF, Rivera D, Moreno-Switt AI, Santiviago CA, Pezoa D. Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Salmonella Dublin. Front Microbiol 2022; 13:811932. [PMID: 35222335 PMCID: PMC8867033 DOI: 10.3389/fmicb.2022.811932] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/04/2022] [Indexed: 12/12/2022] Open
Abstract
The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells via a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In Salmonella, five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes. Salmonella enterica serotype Dublin (S. Dublin) is a cattle-adapted pathogen that harbors both T6SSSPI-6 and T6SSSPI-19. Interestingly, while both systems have been linked to virulence and host colonization in S. Dublin, an antibacterial activity has not been detected for T6SSSPI-6 in this serotype. In addition, there is limited information regarding the repertoire of effector proteins encoded within T6SSSPI-6 and T6SSSPI-19 gene clusters in S. Dublin. In the present study, we demonstrate that T6SSSPI-6 and T6SSSPI-19 of S. Dublin CT_02021853 contribute to interbacterial competition. Bioinformatic and comparative genomic analyses allowed us to identify genes encoding three candidate antibacterial effectors located within SPI-6 and two candidate effectors located within SPI-19. Each antibacterial effector gene is located upstream of a gene encoding a hypothetic immunity protein, thus conforming an effector/immunity (E/I) module. Of note, the genes encoding these effectors and immunity proteins are widely distributed in Salmonella genomes, suggesting a relevant role in interbacterial competition and virulence. Finally, we demonstrate that E/I modules SED_RS01930/SED_RS01935 (encoded in SPI-6), SED_RS06235/SED_RS06230, and SED_RS06335/SED_RS06340 (both encoded in SPI-19) contribute to interbacterial competition in S. Dublin CT_02021853.
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Affiliation(s)
- Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos J. Blondel
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | | | - Dácil Rivera
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Andrea I. Moreno-Switt
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millennium Initiative on Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| | - David Pezoa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
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10
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Zwe YH, Yadav M, Zhen Ten MM, Srinivasan M, Jobichen C, Sivaraman J, Li D. Bacterial Antagonism of Chromobacterium haemolyticum and Characterization of its Putative Type VI Secretion System. Res Microbiol 2021; 173:103918. [PMID: 34906677 DOI: 10.1016/j.resmic.2021.103918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/08/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
This study reports the isolation of a new Chromobacterium haemolyticum strain named WI5 from a hydroponic farming facility. WI5 exhibited remarkable bacterial antagonistic properties, eliminating Salmonella, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus (initial inoculum load ∼105 CFU/ml) in dual-species co-culture biofilms. Antagonism was strictly contact-dependent and highly influenced by nutrient availability. Next, we identified a complete suite of putative Type VI secretion system (T6SS) genes in the WI5 genome, annotated the gene locus architecture, and determined the crystal structure of hallmark T6SS tube protein Hcp1, which revealed a hexameric ring structure with an outer and inner diameter of 77 and 45Å, respectively. Structural comparison with homologs showed differences in the key loops connecting the β-strands in which the conserved residues are located, suggesting a role of these residues in the protein function. The T6SS is well-known to facilitate interbacterial competition, and the putative T6SS characterized herein might be responsible for the remarkable antagonism by C. haemolyticum WI5. Collectively, these findings shed light on the nature of bacterial antagonism and a putative key virulence determinant of C. haemolyticum, which might aid in further understanding its potential ecological role in natural habitats.
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Affiliation(s)
- Ye Htut Zwe
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Manisha Yadav
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Michelle Mei Zhen Ten
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Mahalashmi Srinivasan
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Chacko Jobichen
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - J Sivaraman
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Dan Li
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543.
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Killing of Gram-negative and Gram-positive bacteria by a bifunctional cell wall-targeting T6SS effector. Proc Natl Acad Sci U S A 2021; 118:2106555118. [PMID: 34588306 DOI: 10.1073/pnas.2106555118] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2021] [Indexed: 11/18/2022] Open
Abstract
The type VI secretion system (T6SS) is a powerful tool deployed by Gram-negative bacteria to antagonize neighboring organisms. Here, we report that Acinetobacter baumannii ATCC 17978 (Ab17978) secretes D-lysine (D-Lys), increasing the extracellular pH and enhancing the peptidoglycanase activity of the T6SS effector Tse4. This synergistic effect of D-Lys on Tse4 activity enables Ab17978 to outcompete Gram-negative bacterial competitors, demonstrating that bacteria can modify their microenvironment to increase their fitness during bacterial warfare. Remarkably, this lethal combination also results in T6SS-mediated killing of Gram-positive bacteria. Further characterization revealed that Tse4 is a bifunctional enzyme consisting of both lytic transglycosylase and endopeptidase activities, thus representing a family of modularly organized T6SS peptidoglycan-degrading effectors with an unprecedented impact in antagonistic bacterial interactions.
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12
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Guryanova SV, Khaitov RM. Strategies for Using Muramyl Peptides - Modulators of Innate Immunity of Bacterial Origin - in Medicine. Front Immunol 2021; 12:607178. [PMID: 33959120 PMCID: PMC8093441 DOI: 10.3389/fimmu.2021.607178] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 04/06/2021] [Indexed: 12/22/2022] Open
Abstract
The spread of infectious diseases is rampant. The emergence of new infections, the irrational use of antibiotics in medicine and their widespread use in agriculture contribute to the emergence of microorganisms that are resistant to antimicrobial drugs. By 2050, mortality from antibiotic-resistant strains of bacteria is projected to increase up to 10 million people per year, which will exceed mortality from cancer. Mutations in bacteria and viruses are occurring faster than new drugs and vaccines are being introduced to the market. In search of effective protection against infections, new strategies and approaches are being developed, one of which is the use of innate immunity activators in combination with etiotropic chemotherapy drugs. Muramyl peptides, which are part of peptidoglycan of cell walls of all known bacteria, regularly formed in the body during the breakdown of microflora and considered to be natural regulators of immunity. Their interaction with intracellular receptors launches a sequence of processes that ultimately leads to the increased expression of genes of MHC molecules, pro-inflammatory mediators, cytokines and their soluble and membrane-associated receptors. As a result, all subpopulations of immunocompetent cells are activated: macrophages and dendritic cells, neutrophils, T-, B- lymphocytes and natural killer cells for an adequate response to foreign or transformed antigens, manifested both in the regulation of the inflammatory response and in providing immunological tolerance. Muramyl peptides take part in the process of hematopoiesis, stimulating production of colony-stimulating factors, which is the basis for their use in the treatment of oncological diseases. In this review we highlight clinical trials of drugs based on muramyl peptides, as well as clinical efficacy of drugs mifamurtide, lycopid, liasten and polimuramil. Such a multifactorial effect of muramyl peptides and a well-known mechanism of activity make them promising drugs in the treatment and preventing of infectious, allergic and oncological diseases, and in the composition of vaccines.
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Affiliation(s)
- Svetlana V. Guryanova
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (RAS), Moscow, Russia
- Department of Biology and General Genetics, Medical Institute, RUDN University, Moscow, Russia
| | - Rahim M. Khaitov
- National Research Center – Institute of Immunology of Federal Medico-Biological Agency, Moscow, Russia
- Department of Immunology, Moscow State University of Medicine and Dentistry, Moscow, Russia
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13
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Sibinelli-Sousa S, Hespanhol JT, Bayer-Santos E. Targeting the Achilles' Heel of Bacteria: Different Mechanisms To Break Down the Peptidoglycan Cell Wall during Bacterial Warfare. J Bacteriol 2021; 203:e00478-20. [PMID: 33139480 PMCID: PMC8088523 DOI: 10.1128/jb.00478-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Bacteria commonly live in dense polymicrobial communities and compete for scarce resources. Consequently, they employ a diverse array of mechanisms to harm, inhibit, and kill their competitors. The cell wall is essential for bacterial survival by providing mechanical strength to resist osmotic stress. Because peptidoglycan is the major component of the cell wall and its synthesis is a complex multistep pathway that requires the coordinate action of several enzymes, it provides a target for rival bacteria, which have developed a large arsenal of antibacterial molecules to attack the peptidoglycan of competitors. These molecules include antibiotics, bacteriocins, and contact-dependent effectors that are either secreted into the medium or directly translocated into a target cell. In this minireview, we summarize the diversity of these molecules and highlight distinct mechanisms to disrupt the peptidoglycan, giving special attention to molecules that are known or have the potential to be used during interbacterial competitions.
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Affiliation(s)
- Stephanie Sibinelli-Sousa
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Julia Takuno Hespanhol
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Ethel Bayer-Santos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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14
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Jurėnas D, Journet L. Activity, delivery, and diversity of Type VI secretion effectors. Mol Microbiol 2020; 115:383-394. [PMID: 33217073 DOI: 10.1111/mmi.14648] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/28/2022]
Abstract
The bacterial type VI secretion system (T6SS) system is a contractile secretion apparatus that delivers proteins to neighboring bacterial or eukaryotic cells. Antibacterial effectors are mostly toxins that inhibit the growth of other species and help to dominate the niche. A broad variety of these toxins cause cell lysis of the prey cell by disrupting the cell envelope. Other effectors are delivered into the cytoplasm where they affect DNA integrity, cell division or exhaust energy resources. The modular nature of T6SS machinery allows different means of recruitment of toxic effectors to secreted inner tube and spike components that act as carriers. Toxic effectors can be translationally fused to the secreted components or interact with them through specialized structural domains. These interactions can also be assisted by dedicated chaperone proteins. Moreover, conserved sequence motifs in effector-associated domains are subject to genetic rearrangements and therefore engage in the diversification of the arsenal of toxic effectors. This review discusses the diversity of T6SS secreted toxins and presents current knowledge about their loading on the T6SS machinery.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
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15
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Liu Y, Zhang Z, Wang F, Li DD, Li YZ. Identification of type VI secretion system toxic effectors using adaptors as markers. Comput Struct Biotechnol J 2020; 18:3723-3733. [PMID: 33304467 PMCID: PMC7714669 DOI: 10.1016/j.csbj.2020.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/18/2022] Open
Abstract
Each class of adaptors can be used as an effective marker to identify T6SS effectors. The PRK06147 homolog may be a novel adaptor. 1356 putative toxic effectors related to adaptors from 92 families were identified.
Toxic effectors secreted by the type VI secretion system (T6SS) facilitate interbacterial warfare, as well as pathogenesis toward humans, animals and plants. However, systematically predicting T6SS effectors remains challenging due to their sequence and functional diversity. In this study, we systematically identified putative T6SS toxic effectors in prokaryotic genomes on the basis of the observation that genes encoding adaptor proteins and genes encoding cognate effector proteins are generally adjacent in the genome. Adaptor proteins are mediators that help to load their cognate effectors onto the T6SS spike complex. The contextual genes of the known adaptor proteins (DUF1795, DUF2169 or DUF4123) all exhibited a high proportion of encoding T6SS spike complex protein (VgrG or PAAR) and effector proteins. On the basis of the genomic context, we found that PRK06147 might be a novel adaptor protein. These four adaptors are widely distributed among the bacterial genomes. From neighbors of 5297 adaptor genes, we identified 1356 putative effector genes from 92 different families, and two-thirds were currently annotated as hypothetical proteins or as having unknown functions. Our results indicate that each class of adaptors can be used as an effective marker to identify T6SS toxic effectors, moreover, this approach can promote the discovery of new effectors.
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Affiliation(s)
- Ya Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Zheng Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China.,Suzhou Research Institute, Shandong University, Suzhou 215123, China
| | - Feng Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Dan-Dan Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, China
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16
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Yang M, Ren S, Shen D, Yang N, Wang B, Han S, Shen X, Chou SH, Qian G. An intrinsic mechanism for coordinated production of the contact-dependent and contact-independent weapon systems in a soil bacterium. PLoS Pathog 2020; 16:e1008967. [PMID: 33035267 PMCID: PMC7577485 DOI: 10.1371/journal.ppat.1008967] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 10/21/2020] [Accepted: 09/07/2020] [Indexed: 11/29/2022] Open
Abstract
Soil bacteria possess multiple weapons to fend off microbial competitors. Currently, we poorly understand the factors guiding bacterial decisions about weapon systems deployment. In this study, we investigated how such decisions are made by the soil bacterium Lysobacter enzymogenes, used in antifungal plant protection. We found that weapons production is guided by environmental cues. In rich media, which likely mimic environments crowded with other microbes, L. enzymogenes produces a contact-dependent weapon, type six secretion system (T6SS). In nutrient-poor media, likely dominated by filamentous oomycetes and fungi, L. enzymogenes synthesizes and secretes a heat-stable antifungal factor (HSAF), a contact-independent weapon. Surprisingly, the T6SS inner tube protein Hcp is accumulated intracellularly even in nutrient-poor media, when the T6SS is not assembled. We found that Hcp interacts with the transcription factor Clp required for activating HSAF biosynthesis operon expression. Hcp protects Clp from binding to c-di-GMP, an intracellular second messenger inhibiting DNA binding. The increased concentration of c-di-GMP-free Clp thus leads to higher gene expression and HSAF production. Therefore, when the contact-dependent weapon, T6SS, is not in use, accumulation of one of its structural components, Hcp, serves as a signal to enhance production of the contact-independent weapon, HSAF. The uncovered environment-dependent and auto-regulatory mechanisms shed light on the processes governing deployment of various weapon systems in environmental bacteria. Soil bacteria face competition from diverse microbial species. To stay competitive, they deploy a variety of weapons. At present, we know little about factors influencing decisions about which weapons to produce at any given time, and about mechanisms through which these decisions are carried out. In this study, we show that in the soil bacterium, Lysobacter enzymogenes, synthesis of the contact-dependent weapon, known as type six secretion system (T6SS) occurs under different conditions, compared to those conductive to the production of the contact-independent weapon, toxin HSAF. Further, when T6SS is not assembled, one of its structural components, Hcp, coactivates HSAF operon expression and HSAF synthesis. This study reveals that decisions about contact-dependent and contact-independent weapon production in bacteria are governed by both environmental cues and intrinsic coordination mechanisms.
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Affiliation(s)
- Mingming Yang
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Shuangshuang Ren
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Danyu Shen
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Nianda Yang
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Bingxin Wang
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Sen Han
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Xi Shen
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
| | - Shan-Ho Chou
- Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, ROC, Taiwan
| | - Guoliang Qian
- College of Plant Protection (Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, P.R. China
- * E-mail:
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17
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Calder A, Menkiti CJ, Çağdaş A, Lisboa Santos J, Streich R, Wong A, Avini AH, Bojang E, Yogamanoharan K, Sivanesan N, Ali B, Ashrafi M, Issa A, Kaur T, Latif A, Mohamed HAS, Maqsood A, Tamang L, Swager E, Stringer AJ, Snyder LAS. Virulence genes and previously unexplored gene clusters in four commensal Neisseria spp. isolated from the human throat expand the neisserial gene repertoire. Microb Genom 2020; 6. [PMID: 32845827 PMCID: PMC7643975 DOI: 10.1099/mgen.0.000423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Commensal non-pathogenic Neisseria spp. live within the human host alongside the pathogenic Neisseria meningitidis and Neisseria gonorrhoeae and due to natural competence, horizontal gene transfer within the genus is possible and has been observed. Four distinct Neisseria spp. isolates taken from the throats of two human volunteers have been assessed here using a combination of microbiological and bioinformatics techniques. Three of the isolates have been identified as Neisseria subflava biovar perflava and one as Neisseria cinerea. Specific gene clusters have been identified within these commensal isolate genome sequences that are believed to encode a Type VI Secretion System, a newly identified CRISPR system, a Type IV Secretion System unlike that in other Neisseria spp., a hemin transporter, and a haem acquisition and utilization system. This investigation is the first to investigate these systems in either the non-pathogenic or pathogenic Neisseria spp. In addition, the N. subflava biovar perflava possess previously unreported capsule loci and sequences have been identified in all four isolates that are similar to genes seen within the pathogens that are associated with virulence. These data from the four commensal isolates provide further evidence for a Neisseria spp. gene pool and highlight the presence of systems within the commensals with functions still to be explored.
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Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Chukwuma Jude Menkiti
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Aylin Çağdaş
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Jefferson Lisboa Santos
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Ricarda Streich
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Alice Wong
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Amir H Avini
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Ebrima Bojang
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Karththeepan Yogamanoharan
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Nivetha Sivanesan
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Besma Ali
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Mariam Ashrafi
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Abdirizak Issa
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Tajinder Kaur
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Aisha Latif
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Hani A Sheik Mohamed
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Atifa Maqsood
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Laxmi Tamang
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Emily Swager
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Alex J Stringer
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
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18
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Hernandez RE, Gallegos‐Monterrosa R, Coulthurst SJ. Type
VI
secretion system effector proteins: Effective weapons for bacterial competitiveness. Cell Microbiol 2020; 22:e13241. [DOI: 10.1111/cmi.13241] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/08/2020] [Accepted: 06/15/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Ruth E. Hernandez
- Division of Molecular Microbiology, School of Life SciencesUniversity of Dundee Dundee UK
| | | | - Sarah J. Coulthurst
- Division of Molecular Microbiology, School of Life SciencesUniversity of Dundee Dundee UK
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19
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Chien CF, Liu CY, Lu YY, Sung YH, Chen KY, Lin NC. HSI-II Gene Cluster of Pseudomonas syringae pv. tomato DC3000 Encodes a Functional Type VI Secretion System Required for Interbacterial Competition. Front Microbiol 2020; 11:1118. [PMID: 32582082 PMCID: PMC7283901 DOI: 10.3389/fmicb.2020.01118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 05/05/2020] [Indexed: 11/13/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread bacterial nanoweapon used for delivery of toxic proteins into cell targets and contributes to virulence, anti-inflammatory processes, and interbacterial competition. In the model phytopathogenic bacterium Pseudomonas syringae pv. tomato (Pst) DC3000, two T6SS gene clusters, HSI-I and HSI-II, were identified, but their functions remain unclear. We previously reported that hcp2, located in HSI-II, is involved in competition with enterobacteria and yeast. Here, we demonstrated that interbacterial competition of Pst DC3000 against several Gram-negative plant-associated bacteria requires mainly HSI-II activity. By means of a systematic approach using in-frame deletion mutants for each gene in the HSI-II cluster, we identified genes indispensable for Hcp2 expression, Hcp2 secretion and interbacterial competition ability. Deletion of PSPTO_5413 only affected growth in interbacterial competition assays but not Hcp2 secretion, which suggests that PSPTO_5413 might be a putative effector. Moreover, PSPTO_5424, encoding a putative σ54-dependent transcriptional regulator, positively regulated the expression of all three operons in HSI-II. Our discovery that the HSI-II gene cluster gives Pst DC3000 the ability to compete with other plant-associated bacteria could help in understanding a possible mechanism of how phytopathogenic bacteria maintain their ecological niches.
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Affiliation(s)
- Ching-Fang Chien
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Cheng-Ying Liu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Yew-Yee Lu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - You-Hsing Sung
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Kuo-Yau Chen
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Nai-Chun Lin
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
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20
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A Family of T6SS Antibacterial Effectors Related to l,d-Transpeptidases Targets the Peptidoglycan. Cell Rep 2020; 31:107813. [DOI: 10.1016/j.celrep.2020.107813] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/20/2020] [Accepted: 06/03/2020] [Indexed: 12/17/2022] Open
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21
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Ma S, Dong Y, Wang N, Liu J, Lu C, Liu Y. Identification of a new effector-immunity pair of Aeromonas hydrophila type VI secretion system. Vet Res 2020; 51:71. [PMID: 32448355 PMCID: PMC7245790 DOI: 10.1186/s13567-020-00794-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 04/26/2020] [Indexed: 12/23/2022] Open
Abstract
The type VI secretion system (T6SS) is a multiprotein weapon that kills eukaryotic predators or prokaryotic competitors by delivering toxic effectors. Despite the importance of T6SS in bacterial environmental adaptation, it is still challenging to systematically identify T6SS effectors because of their high diversity and lack of conserved domains. In this report, we discovered a putative effector gene, U876-17730, in the whole genome of Aeromonas hydrophila NJ-35 based on the reported conservative domain DUF4123 (domain of unknown function), with two cognate immunity proteins encoded downstream. Phylogenetic tree analysis of amino acids indicates that AH17730 belongs to the Tle1 (type VI lipase effector) family, and therefore was named Tle1AH. The deletion of tle1AH resulted in significantly decreased biofilm formation, antibacterial competition ability and virulence in zebrafish (Danio rerio) when compared to the wild-type strain. Only when the two immunity proteins coexist can bacteria protect themselves from the toxicity of Tle1AH. Further study shows that Tle1AH is a kind of phospholipase that possesses a conserved lipase motif, Gly-X-Ser-X-Gly (X is for any amino acid). Tle1AH is secreted by T6SS, and this secretion requires its interaction with an associated VgrG (valine-glycine repeat protein G). In conclusion, we identified a T6SS effector-immunity pair and verified its function, which lays the foundation for future research on the role of T6SS in the pathogenic mechanism of A. hydrophila.
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Affiliation(s)
- Shuiyan Ma
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuhao Dong
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Nannan Wang
- College of Animal Science and Technology, Jinling Institute of Technology, Nanjing, 211169, China
| | - Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
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22
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Jana B, Salomon D. Type VI secretion system: a modular toolkit for bacterial dominance. Future Microbiol 2019; 14:1451-1463. [DOI: 10.2217/fmb-2019-0194] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria use toxin delivery systems, such as the type VI secretion system (T6SS), to antagonize competitors. The T6SS transports toxins, called effectors, directly into recipient cells. In the absence of cognate immunity proteins that protect against kin-intoxication, these effectors target conserved and essential cell components resulting in growth arrest or cell death. Here, we focus on antibacterial T6SS effectors and explore their different activities, modes of delivery, and the domains and proteins that are associated with them to provide a modular and dynamic toxin arsenal. We conclude that these natural machines present a lucrative pool and platform for future antibacterial treatments.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Dor Salomon
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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23
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Repizo GD, Espariz M, Seravalle JL, Salcedo SP. Bioinformatic Analysis of the Type VI Secretion System and Its Potential Toxins in the Acinetobacter Genus. Front Microbiol 2019; 10:2519. [PMID: 31736933 PMCID: PMC6838775 DOI: 10.3389/fmicb.2019.02519] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii as the species of greatest concern worldwide due to its multi-drug resistance and recent appearance of hyper-virulent strains in the clinical setting. Acinetobacter colonization of the environment and the host is associated with a multitude of factors which remain poorly characterized. Among them, the secretion systems (SS) encoded by Acinetobacter species confer adaptive advantages depending on the niche occupied. Different SS have been characterized in this group of microorganisms, including T6SS used by several Acinetobacter species to outcompete other bacteria and in some A. baumannii strains for Galleria mellonella colonization. Therefore, to better understand the distribution of the T6SS in this genus we carried out an in-depth comparative genomic analysis of the T6SS in 191 sequenced strains. To this end, we analyzed the gene content, sequence similarity, synteny and operon structure of each T6SS loci. The presence of a single conserved T6SS-main cluster (T6SS-1), with two different genetic organizations, was detected in the genomes of several ecologically diverse species. Furthermore, a second main cluster (T6SS-2) was detected in a subgroup of 3 species of environmental origin. Detailed analysis also showed an impressive genetic versatility in T6SS-associated islands, carrying VgrG, PAAR and putative toxin-encoding genes. This in silico study represents the first detailed intra-species comparative analysis of T6SS-associated genes in the Acinetobacter genus, that should contribute to the future experimental characterization of T6SS proteins and effectors.
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Affiliation(s)
- Guillermo D Repizo
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Martín Espariz
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Joana L Seravalle
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Suzana P Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, CNRS UMR 5086, University of Lyon, Lyon, France
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Navarro-Garcia F, Ruiz-Perez F, Cataldi Á, Larzábal M. Type VI Secretion System in Pathogenic Escherichia coli: Structure, Role in Virulence, and Acquisition. Front Microbiol 2019; 10:1965. [PMID: 31543869 PMCID: PMC6730261 DOI: 10.3389/fmicb.2019.01965] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/09/2019] [Indexed: 12/18/2022] Open
Abstract
Bacterial pathogens utilize a myriad of mechanisms to invade mammalian hosts, damage tissue sites, and evade the immune system. One essential strategy of Gram-negative bacteria is the secretion of virulence factors through both inner and outer membranes to reach a potential target. Most secretion systems are harbored in mobile elements including transposons, plasmids, pathogenicity islands, and phages, and Escherichia coli is one of the more versatile bacteria adopting this genetic information by horizontal gene transfer. Additionally, E. coli is a bacterial species with members of the commensal intestinal microbiota and pathogens associated with numerous types of infections such as intestinal, urinary, and systemic in humans and other animals. T6SS cluster plasticity suggests evolutionarily divergent systems were acquired horizontally. T6SS is a secretion nanomachine that is extended through the bacterial double membrane; from this apparatus, substrates are conveyed straight from the cytoplasm of the bacterium into a target cell or to the extracellular space. This nanomachine consists of three main complexes: proteins in the inner membrane that are T4SS component-like, the baseplate complex, and the tail complex, which are formed by components evolutionarily related to contractile bacteriophage tails. Advances in the T6SS understanding include the functional and structural characterization of at least 13 subunits (so-called core components), which are thought to comprise the minimal apparatus. So far, the main role of T6SS is on bacterial competition by using it to kill neighboring non-immune bacteria for which antibacterial proteins are secreted directly into the periplasm of the bacterial target after cell-cell contact. Interestingly, a few T6SSs have been associated directly to pathogenesis, e.g., roles in biofilm formation and macrophage survival. Here, we focus on the advances on T6SS from the perspective of E. coli pathotypes with emphasis in the secretion apparatus architecture, the mechanisms of pathogenicity of effector proteins, and the events of lateral gene transfer that led to its spread.
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Affiliation(s)
- Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Mexico City, Mexico
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Ángel Cataldi
- Laboratorio de Escherichia coli, Instituto de Agrobiotecnología y Biología Molecular (IABIMO) INTA-CONICET, Buenos Aires, Argentina
| | - Mariano Larzábal
- Laboratorio de Escherichia coli, Instituto de Agrobiotecnología y Biología Molecular (IABIMO) INTA-CONICET, Buenos Aires, Argentina
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25
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Coulthurst S. The Type VI secretion system: a versatile bacterial weapon. Microbiology (Reading) 2019; 165:503-515. [DOI: 10.1099/mic.0.000789] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Sarah Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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26
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Abstract
The Type VI secretion system (T6SS) is a protein nanomachine that is widespread in Gram-negative bacteria and is used to translocate effector proteins directly into neighbouring cells. It represents a versatile bacterial weapon that can deliver effectors into distinct classes of target cells, playing key roles in inter-bacterial competition and bacterial interactions with eukaryotic cells. This versatility is underpinned by the ability of the T6SS to deliver a vast array of effector proteins, with many distinct activities and modes of interaction with the secretion machinery. Recent work has highlighted the importance and diversity of interactions mediated by T6SSs within polymicrobial communities, and offers new molecular insights into effector delivery and action in target cells.
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Affiliation(s)
- Sarah Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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27
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Vacheron J, Péchy-Tarr M, Brochet S, Heiman CM, Stojiljkovic M, Maurhofer M, Keel C. T6SS contributes to gut microbiome invasion and killing of an herbivorous pest insect by plant-beneficial Pseudomonas protegens. ISME JOURNAL 2019; 13:1318-1329. [PMID: 30683920 DOI: 10.1038/s41396-019-0353-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 12/31/2022]
Abstract
Pseudomonas protegens are multi-talented plant-colonizing bacteria that suppress plant pathogens and stimulate plant defenses. In addition, they are capable of invading and killing agriculturally important plant pest insects that makes them promising candidates for biocontrol applications. Here we assessed the role of type VI secretion system (T6SS) components of type strain CHA0 during interaction with larvae of the cabbage pest Pieris brassicae. We show that the T6SS core apparatus and two VgrG modules, encompassing the respective T6SS spikes (VgrG1a and VgrG1b) and associated effectors (RhsA and Ghh1), contribute significantly to insect pathogenicity of P. protegens in oral infection assays but not when bacteria are injected directly into the hemolymph. Monitoring of the colonization levels of P. protegens in the gut, hemolymph, and excrements of the insect larvae revealed that the invader relies on T6SS and VgrG1a module function to promote hemocoel invasion. A 16S metagenomic analysis demonstrated that T6SS-supported invasion by P. protegens induces significant changes in the insect gut microbiome affecting notably Enterobacteriaceae, a dominant group of the commensal gut bacteria. Our study supports the concept that pathogens deploy T6SS-based strategies to disrupt the commensal microbiota in order to promote host colonization and pathogenesis.
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Affiliation(s)
- Jordan Vacheron
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Maria Péchy-Tarr
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Silvia Brochet
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Clara Margot Heiman
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Marina Stojiljkovic
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Monika Maurhofer
- Plant Pathology, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
| | - Christoph Keel
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
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