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Li P, Zhang S, Wang J, Al-Shamiri MM, Luo K, Liu S, Mi P, Wu X, Liu H, Tian H, Han B, Lei J, Han S, Han L. The role of type VI secretion system genes in antibiotic resistance and virulence in Acinetobacter baumannii clinical isolates. Front Cell Infect Microbiol 2024; 14:1297818. [PMID: 38384301 PMCID: PMC10879597 DOI: 10.3389/fcimb.2024.1297818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
Introduction The type VI secretion system (T6SS) is a crucial virulence factor in the nosocomial pathogen Acinetobacter baumannii. However, its association with drug resistance is less well known. Notably, the roles that different T6SS components play in the process of antimicrobial resistance, as well as in virulence, have not been systematically revealed. Methods The importance of three representative T6SS core genes involved in the drug resistance and virulence of A. baumannii, namely, tssB, tssD (hcp), and tssM was elucidated. Results A higher ratio of the three core genes was detected in drug-resistant strains than in susceptible strains among our 114 A. baumannii clinical isolates. Upon deletion of tssB in AB795639, increased antimicrobial resistance to cefuroxime and ceftriaxone was observed, alongside reduced resistance to gentamicin. The ΔtssD mutant showed decreased resistance to ciprofloxacin, norfloxacin, ofloxacin, tetracycline, and doxycycline, but increased resistance to tobramycin and streptomycin. The tssM-lacking mutant showed an increased sensitivity to ofloxacin, polymyxin B, and furazolidone. In addition, a significant reduction in biofilm formation was observed only with the ΔtssM mutant. Moreover, the ΔtssM strain, followed by the ΔtssD mutant, showed decreased survival in human serum, with attenuated competition with Escherichia coli and impaired lethality in Galleria mellonella. Discussion The above results suggest that T6SS plays an important role, participating in the antibiotic resistance of A. baumannii, especially in terms of intrinsic resistance. Meanwhile, tssM and tssD contribute to bacterial virulence to a greater degree, with tssM being associated with greater importance.
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Affiliation(s)
- Pu Li
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Sirui Zhang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Jingdan Wang
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Mona Mohamed Al-Shamiri
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Kai Luo
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Shuyan Liu
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Peng Mi
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Department of Laboratory Medicine, Shaanxi Provincial People’s Hospital, Xi’an, China
| | - Xiaokang Wu
- Department of Laboratory Medicine, the Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Haiping Liu
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Department of Laboratory Medicine, Xi’an Daxing Hospital, Xi’an, China
| | - Huohuan Tian
- Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Bei Han
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Jin’e Lei
- Department of Laboratory Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Shaoshan Han
- Department of Hepatobiliary Surgery, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Lei Han
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
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Ramamoorthy S, Pena M, Ghosh P, Liao YY, Paret M, Jones JB, Potnis N. Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism. Microbiol Spectr 2024; 12:e0285223. [PMID: 38018859 PMCID: PMC10782981 DOI: 10.1128/spectrum.02852-23] [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: 07/14/2023] [Accepted: 10/20/2023] [Indexed: 11/30/2023] Open
Abstract
IMPORTANCE T6SS has received attention due to its significance in mediating interorganismal competition through contact-dependent release of effector molecules into prokaryotic and eukaryotic cells. Reverse-genetic studies have indicated the role of T6SS in virulence in a variety of plant pathogenic bacteria, including the one studied here, Xanthomonas. However, it is not clear whether such effect on virulence is merely due to a shift in the microbiome-mediated protection or if T6SS is involved in a complex virulence regulatory network. In this study, we conducted in vitro transcriptome profiling in minimal medium to decipher the signaling pathways regulated by tssM-i3* in X. perforans AL65. We show that TssM-i3* regulates the expression of a suite of genes associated with virulence and metabolism either directly or indirectly by altering the transcription of several regulators. These findings further expand our knowledge on the intricate molecular circuits regulated by T6SS in phytopathogenic bacteria.
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Affiliation(s)
- Sivakumar Ramamoorthy
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Michelle Pena
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Palash Ghosh
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Ying-Yu Liao
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Mathews Paret
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
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Lin JS, Ali J, Lai EM. Protein-Protein Interactions: Co-immunoprecipitation. Methods Mol Biol 2024; 2715:273-283. [PMID: 37930535 DOI: 10.1007/978-1-0716-3445-5_18] [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: 11/07/2023]
Abstract
Proteins often do not function as single substances but rather as team players in a dynamic network. Growing evidences show that protein-protein interactions are crucial in many biological processes in living cells. Genetic (such as yeast two hybrid, Y2H) and biochemical (such as co-immunoprecipitation, co-IP) methods are the commonly used methods to identify the interacting proteins. Immunoprecipitation (IP), a method using a target protein-specific antibody in conjunction with Protein A/G affinity beads, is a powerful tool to identify the molecules interacting with specific proteins. Therefore, co-IP is considered to be one of the standard methods to identify and/or confirm the occurrence of the protein-protein interaction events in vivo. The co-IP experiments can identify proteins via direct or indirect interactions or in a protein complex. Here, we use two different co-Ip protocols as an example to describe the principle, procedure, and experimental problems of co-IP. First, we show the interaction of two Agrobacterium type VI secretion system (T6SS) sheath components TssB and TssC41, and secondly, we show the protocol we used for determining the interaction of an epitope-tagged T6SS effector, Tde1 expressed in Agrobacterium with endogenously expressing adaptor/chaperone protein Tap1.
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Affiliation(s)
- Jer-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Jemal Ali
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan.
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan.
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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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Petano-Duque JM, Rueda-García V, Rondón-Barragán IS. Virulence genes identification in Salmonella enterica isolates from humans, crocodiles, and poultry farms from two regions in Colombia. Vet World 2023; 16:2096-2103. [PMID: 38023281 PMCID: PMC10668553 DOI: 10.14202/vetworld.2023.2096-2103] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/11/2023] [Indexed: 12/01/2023] Open
Abstract
Background and Aim Salmonella spp. is frequently found in the digestive tract of birds and reptiles and transmitted to humans through food. Salmonellosis is a public health problem because of pathogenicity variability in strains for virulence factors. This study aimed to identify the virulence genes in Salmonella isolates from humans, crocodiles, broiler cloacas, and broiler carcasses from two departments of Colombia. Materials and Methods This study was conducted on 31 Salmonella enterica strains from humans with gastroenteritis (seven), crocodiles (seven), broiler cloacas (six), and broiler carcasses (12) from Tolima and Santander departments of Colombia, belonging to 21 serotypes. All samples were tested for Salmonella spp. using culture method on selective and non-selective mediums. Extraction of genomic DNA was performed from fresh colonies, DNA quality was verified by spectrophotometry and confirmed by amplification of InvA gene using conventional polymerase chain reaction (PCR). bapA, fimA, icmF, IroB, marT, mgtC, nlpI, oafA, pagN, siiD, spvC, spvR, spvB, Stn, and vexA genes were amplified by PCR. Results The most prevalent gene was bapA (100%), followed by marT (96.77%), mgtC (93.55%), and fimA (83.87%). Likewise, IroB (70.97%), Stn (67.74%), spvR (61.29%), pagN (54.84%), icmF (54.8%), and SiiD (45.16%) were positive for more than 50% of the strains. Furthermore, none of the isolates tested positive for the vexA gene. Salmonella isolates presented 26 virulence profiles. Conclusion This study reported 14 virulence genes in Salmonella spp. isolates from humans with gastroenteritis, crocodiles, and broiler cloacas and carcasses. The distribution of virulence genes differed among sources. This study could help in decision-making by health and sanitary authorities.
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Affiliation(s)
- Julieth Michel Petano-Duque
- Poultry Research Group, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
| | - Valentina Rueda-García
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
| | - Iang Schroniltgen Rondón-Barragán
- Poultry Research Group, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
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Mohamed NA, Alrawy MH, Makbol RM, Mohamed AM, Hemdan SB, Shafik NS. Type VI secretion system (T6SS) in Klebsiella pneumoniae, relation to antibiotic resistance and biofilm formation. IRANIAN JOURNAL OF MICROBIOLOGY 2023; 15:601-608. [PMID: 37941882 PMCID: PMC10628084 DOI: 10.18502/ijm.v15i5.13865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Background and Objectives The type VI secretion system (T6SS) was identified as a novel virulence factor in many Gram-negative bacteria. This study aimed to investigate the frequency of the T6SS genes in Klebsiella pneumoniae-causing different nosocomial infections, and to study the association between T6SS, antibiotic resistance, and biofilm formation in the isolated bacteria. Materials and Methods A total of fifty-six non-repetitive K. pneumoniae isolates were collected from different inpatients admitted at Sohag University Hospital from September 2022 to March 2023. Samples were cultured, colonies were identified, and antimicrobial sensitivity was done by VITEK® 2 Compact. Biofilm formation was checked using Congo red agar method. T6SS genes, and capsular serotypes were detected by PCR. Results Fifty-six K. pneumoniae isolates were obtained in culture. 38 isolates (67.86%) produced biofilm and 44 (78.57%) were positive for T6SS in PCR. There was a significant association between the presence of T6SS and resistance to the following antibiotics: meropenem, ciprofloxacin, and levofloxacin. All biofilm-forming bacteria had T6SS, with significant differences towards T6SS -positive bacteria. There was no significant association between T6SS, and the presence of certain capsular types. Conclusion The T6SS-positive K. pneumoniae has greater antibiotic resistance, and biofilm-forming ability which is considered a potential pathogenicity of this emerging gene cluster.
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Affiliation(s)
- Nesma A Mohamed
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Mohamed H Alrawy
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Reem M. Makbol
- Department of Tropical Medicine & Gastroenterology, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Arafat M Mohamed
- Department of Otorhinolaryngology, Sohag University, Sohag, Egypt
| | - Shimaa B Hemdan
- Department of Medical Biochemistry, Sohag University, Sohag, Egypt
| | - Noha S Shafik
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Sohag University, Sohag, Egypt
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Dutka P, Liu Y, Maggi S, Ghosal D, Wang J, Carter SD, Zhao W, Vijayrajratnam S, Vogel JP, Jensen GJ. Structure and Function of the Dot/Icm T4SS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.22.533729. [PMID: 36993699 PMCID: PMC10055428 DOI: 10.1101/2023.03.22.533729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
The Legionella pneumophila Dot/Icm type IV secretion system (T4SS) delivers effector proteins into host cells during infection. Despite its significance as a potential drug target, our current understanding of its atomic structure is limited to isolated subcomplexes. In this study, we used subtomogram averaging and integrative modeling to construct a nearly-complete model of the Dot/Icm T4SS accounting for seventeen protein components. We locate and provide insights into the structure and function of six new components including DotI, DotJ, DotU, IcmF, IcmT, and IcmX. We find that the cytosolic N-terminal domain of IcmF, a key protein forming a central hollow cylinder, interacts with DotU, providing insight into previously uncharacterized density. Furthermore, our model, in combination with analyses of compositional heterogeneity, explains how the cytoplasmic ATPase DotO is connected to the periplasmic complex via interactions with membrane-bound DotI/DotJ proteins. Coupled with in situ infection data, our model offers new insights into the T4SS-mediated secretion mechanism.
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Affiliation(s)
- Przemysław Dutka
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Yuxi Liu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Stefano Maggi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Debnath Ghosal
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Present address: Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Jue Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Stephen D. Carter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Present address: MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, UK
| | - Wei Zhao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | | | - Joseph P. Vogel
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Grant J. Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
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Guckes KR, Miyashiro TI. The type-VI secretion system of the beneficial symbiont Vibrio fischeri. MICROBIOLOGY (READING, ENGLAND) 2023; 169:10.1099/mic.0.001302. [PMID: 36809081 PMCID: PMC9972734 DOI: 10.1099/mic.0.001302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The mutualistic symbiosis between the Hawaiian bobtail squid Euprymna scolopes and the marine bacterium Vibrio fischeri is a powerful experimental system for determining how intercellular interactions impact animal-bacterial associations. In nature, this symbiosis features multiple strains of V. fischeri within each adult animal, which indicates that different strains initially colonize each squid. Various studies have demonstrated that certain strains of V. fischeri possess a type-VI secretion system (T6SS), which can inhibit other strains from establishing symbiosis within the same host habitat. The T6SS is a bacterial melee weapon that enables a cell to kill adjacent cells by translocating toxic effectors via a lancet-like apparatus. This review describes the progress that has been made in understanding the factors that govern the structure and expression of the T6SS in V. fischeri and its effect on the symbiosis.
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Li P, Zhang S, Wang J, Al-Shamiri MM, Han B, Chen Y, Han S, Han L. Uncovering the Secretion Systems of Acinetobacter baumannii: Structures and Functions in Pathogenicity and Antibiotic Resistance. Antibiotics (Basel) 2023; 12:antibiotics12020195. [PMID: 36830106 PMCID: PMC9952577 DOI: 10.3390/antibiotics12020195] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Infections led by Acinetobacter baumannii strains are of great concern in healthcare environments due to the strong ability of the bacteria to spread through different apparatuses and develop drug resistance. Severe diseases can be caused by A. baumannii in critically ill patients, but its biological process and mechanism are not well understood. Secretion systems have recently been demonstrated to be involved in the pathogenic process, and five types of secretion systems out of the currently known six from Gram-negative bacteria have been found in A. baumannii. They can promote the fitness and pathogenesis of the bacteria by releasing a variety of effectors. Additionally, antibiotic resistance is found to be related to some types of secretion systems. In this review, we describe the genetic and structural compositions of the five secretion systems that exist in Acinetobacter. In addition, the function and molecular mechanism of each secretion system are summarized to explain how they enable these critical pathogens to overcome eukaryotic hosts and prokaryotic competitors to cause diseases.
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Affiliation(s)
- Pu Li
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Sirui Zhang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Jingdan Wang
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Mona Mohamed Al-Shamiri
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Bei Han
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Yanjiong Chen
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Shaoshan Han
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710061, China
| | - Lei Han
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
- Correspondence:
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Nie W, Chen X, Tang Y, Xu N, Zhang H. Potential dsRNAs can be delivered to aquatic for defense pathogens. Front Bioeng Biotechnol 2022; 10:1066799. [PMID: 36466329 PMCID: PMC9712207 DOI: 10.3389/fbioe.2022.1066799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/03/2022] [Indexed: 10/29/2023] Open
Abstract
The use of antibiotics to facilitate resistance to pathogens in aquatic animals is a traditional method of pathogen control that is harmful to the environment and human health. RNAi is an emerging technology in which homologous small RNA molecules target specific genes for degradation, and it has already shown success in laboratory experiments. However, further research is needed before it can be applied in aquafarms. Many laboratories inject the dsRNA into aquatic animals for RNAi, which is obviously impractical and very time consuming in aquafarms. Therefore, to enable the use of RNAi on a large scale, the methods used to prepare dsRNA need to be continuously in order to be fast and efficient. At the same time, it is necessary to consider the issue of biological safety. This review summarizes the key harmful genes associated with aquatic pathogens (viruses, bacteria, and parasites) and provides potential targets for the preparation of dsRNA; it also lists some current examples where RNAi technology is used to control aquatic species, as well as how to deliver dsRNA to the target hydrobiont.
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Affiliation(s)
| | | | | | | | - Hao Zhang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, China
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Huang Y, Han Y, Li Z, Li X, Li Z, Liu P, Liu X, Cheng Q, Fan F, Kan B, Liang W. TssI2-TsiI2 of Vibrio fluvialis VflT6SS2 delivers pesticin domain-containing periplasmic toxin and cognate immunity that modulates bacterial competitiveness. Gut Microbes 2022; 14:2136460. [PMID: 36288406 PMCID: PMC9620997 DOI: 10.1080/19490976.2022.2136460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Vibrio fluvialis is a halophilic Gram-negative bacterium regarded as an emerging unusual enteric pathogen of increasing public health concern. Our previous work has identified two type VI secretion systems (T6SSs) in V. fluvialis, VflT6SS1, and VflT6SS2, and the latter is functional in mediating interbacterial competitiveness. However, its antibacterial effectors remain to be clarified. In this work, we focused on a new potential effector/immunity pair TssI2/TsiI2. Bioinformatics analysis revealed that the C-terminal domain of TssI2 belongs to a widespread family of pesticin, and its antibacterial toxicity and corresponding protection by TsiI2 were proved via bacterial killing assays, and their action sites were localized to the periplasm of bacterial cells. The interaction of TssI2 and TsiI2 was demonstrated by the bacterial adenylate cyclase two-hybrid, protein pull-down and isothermal titration calorimetry assays. Site-directed mutagenesis demonstrated that, in addition to Glu-844, Thr-863, and Asp-869, which correspond to three reported residues in pesticin of Yersinia pestis, additional residues including Phe-837, Gly-845, Tyr-851, Gly-867, Gln-963, Trp-975, and Arg-1000 were also proved to be crucial to the bactericidal activity of TssI2. Muramidase/lysozyme-related peptidoglycan (PG) hydrolase activities of TssI2 and its variants were validated with permeabilized Escherichia coli cells and purified PG substrate. Based on sequence homologies at C-terminals in various V. fluvialis isolates, TssI2 was subdivided into five clusters (12-22% identity among them), and the antibacterial activities of representative effectors from other four Clusters were also confirmed through periplasmic over-expression in E. coli host. Two selected cognate immunities were proved to confer protection against the toxicities of their effectors. Additionally, TsiI2, which belongs to Cluster I, exhibited cross-protection to effector from Cluster V. Together, current findings expand our knowledge of the diversity and consistency of evolved VgrG effectors in V. fluvialis and on how VflT6SS2 mediates a competitive advantage to gain a better survival.
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Affiliation(s)
- Yuanming Huang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yu Han
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhenpeng Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaorui Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhe Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ping Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaoshu Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qian Cheng
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Fenxia Fan
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Biao Kan
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China,CONTACT Biao Kan
| | - Weili Liang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China,Weili Liang State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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12
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VxrB Influences Antagonism within Biofilms by Controlling Competition through Extracellular Matrix Production and Type 6 Secretion. mBio 2022; 13:e0188522. [PMID: 35880882 PMCID: PMC9426512 DOI: 10.1128/mbio.01885-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human pathogen Vibrio cholerae grows as biofilms, communities of cells encased in an extracellular matrix. When growing in biofilms, cells compete for resources and space. One common competitive mechanism among Gram-negative bacteria is the type six secretion system (T6SS), which can deliver toxic effector proteins into a diverse group of target cells, including other bacteria, phagocytic amoebas, and human macrophages. The response regulator VxrB positively regulates both biofilm matrix and T6SS gene expression. Here, we directly observe T6SS activity within biofilms, which results in improved competition with strains lacking the T6SS. VxrB significantly contributes to both attack and defense via T6SS, while also influencing competition via regulation of biofilm matrix production. We further determined that both Vibrio polysaccharide (VPS) and the biofilm matrix protein RbmA can protect cells from T6SS attack within mature biofilms. By varying the spatial mixing of predator and prey cells in biofilms, we show that a high degree of mixing favors T6SS predator strains and that the presence of extracellular DNA in V. cholerae biofilms is a signature of T6SS killing. VxrB therefore regulates both T6SS attack and matrix-based T6SS defense, to control antagonistic interactions and competition outcomes during mixed-strain biofilm formation.
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13
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Lin L, Capozzoli R, Ferrand A, Plum M, Vettiger A, Basler M. Subcellular localization of Type VI secretion system assembly in response to cell–cell contact. EMBO J 2022; 41:e108595. [PMID: 35634969 PMCID: PMC9251886 DOI: 10.15252/embj.2021108595] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 04/18/2022] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
Bacteria require a number of systems, including the type VI secretion system (T6SS), for interbacterial competition and pathogenesis. The T6SS is a large nanomachine that can deliver toxins directly across membranes of proximal target cells. Since major reassembly of T6SS is necessary after each secretion event, accurate timing and localization of T6SS assembly can lower the cost of protein translocation. Although critically important, mechanisms underlying spatiotemporal regulation of T6SS assembly remain poorly understood. Here, we used super‐resolution live‐cell imaging to show that while Acinetobacter and Burkholderia thailandensis can assemble T6SS at any site, a significant subset of T6SS assemblies localizes precisely to the site of contact between neighboring bacteria. We identified a class of diverse, previously uncharacterized, periplasmic proteins required for this dynamic localization of T6SS to cell–cell contact (TslA). This precise localization is also dependent on the outer membrane porin OmpA. Our analysis links transmembrane communication to accurate timing and localization of T6SS assembly as well as uncovers a pathway allowing bacterial cells to respond to cell–cell contact during interbacterial competition.
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Affiliation(s)
- Lin Lin
- Biozentrum University of Basel Basel Switzerland
| | | | - Alexia Ferrand
- Biozentrum Imaging Core Facility University of Basel Basel Switzerland
| | - Miro Plum
- Biozentrum University of Basel Basel Switzerland
| | | | - Marek Basler
- Biozentrum University of Basel Basel Switzerland
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14
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Wang S, Wu R, Lu J, Jiang Y, Huang T, Cai YD. Protein-protein interaction networks as miners of biological discovery. Proteomics 2022; 22:e2100190. [PMID: 35567424 DOI: 10.1002/pmic.202100190] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 03/28/2022] [Accepted: 04/29/2022] [Indexed: 11/12/2022]
Abstract
Protein-protein interactions (PPIs) form the basis of a myriad of biological pathways and mechanism, such as the formation of protein-complexes or the components of signaling cascades. Here, we reviewed experimental methods for identifying PPI pairs, including yeast two-hybrid, mass spectrometry, co-localization, and co-immunoprecipitation. Furthermore, a range of computational methods leveraging biochemical properties, evolution history, protein structures and more have enabled identification of additional PPIs. Given the wealth of known PPIs, we reviewed important network methods to construct and analyze networks of PPIs. These methods aid biological discovery through identifying hub genes and dynamic changes in the network, and have been thoroughly applied in various fields of biological research. Lastly, we discussed the challenges and future direction of research utilizing the power of PPI networks. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Steven Wang
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Runxin Wu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Jiaqi Lu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Yijia Jiang
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Tao Huang
- Bio-Med Big Data Center, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, China
| | - Yu-Dong Cai
- School of Life Sciences, Shanghai University, Shanghai, China
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15
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Zhang Y, Xu Y, Huang Y. Virulence Genotype and Correlation of Clinical Severeness with Presence of the Type VI Secretion System in Klebsiella pneumoniae Isolates Causing Bloodstream Infections. Infect Drug Resist 2022; 15:1487-1497. [PMID: 35411154 PMCID: PMC8994602 DOI: 10.2147/idr.s353858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/26/2022] [Indexed: 11/23/2022] Open
Abstract
Background Klebsiella pneumoniae (K. pneumoniae) causes bloodstream infection (BSI), which is responsible for a high rate of morbidity and mortality among different populations. In mainland China, data on the correlation and features of the type VI secretion system (T6SS) gene cluster in K. pneumoniae is currently scarce. As a result, we conducted a prospective investigation to determine the involvement of the T6SS in K. pneumoniae pathogenicity and antibiotic resistance. Methods In this prospective analysis, we enrolled 119 individuals who had been diagnosed with K. pneumoniae bloodstream infection between July 2019 and January 2021 and acquired demographic and clinical data from their medical records. The virulence genes rmpA, rmpA2, aerobactin, iroB, hcp, vgrG, and icmF were tested for K1 and K2, antimicrobial susceptibility. Five T6SS-positive and five T6SS-negative isolates were chosen for the competition, serum resistance, and biofilm formation experiments to further gain insights regarding the microbiological properties of T6SS-positive K. pneumoniae isolates. Results Among 119 isolates obtained from patients with BSIs, 20 (16.8%) were T6SS positive K. pneumoniae. T6SS positive strains had four virulence genes and a greater K1 capsular serotypes rate than T6SS negative bacteria. Among hvKP isolates, the T6SS positive rate was substantially greater than the T6SS negative rate (P = 0.001). T6SS-positive K. pneumoniae strains had a lower rate of antimicrobial resistance in comparison to T6SS-negative bacteria. T6SS-positive isolates may be more competitive with Escherichia coli than T6SS-negative isolates. T6SS-positive isolates, on the other hand, did not show stronger biofilm-forming activity or a higher survival rate in the presence of normal human serum in comparison to T6SS-negative isolates. Conclusion T6SS-positive K. pneumoniae was common in people who had BSIs. In T6SS‐containing K. pneumoniae, the system may play a major role in bacterial competition.
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Affiliation(s)
- Yin Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, People’s Republic of China
| | - Yuanhong Xu
- Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, People’s Republic of China
| | - Ying Huang
- Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, People’s Republic of China
- Correspondence: Ying Huang; Yuanhong Xu, Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, People’s Republic of China, Email ;
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16
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Liyanapathiranage P, Jones JB, Potnis N. Mutation of a Single Core Gene, tssM, of Type VI Secretion System of Xanthomonas perforans Influences Virulence, Epiphytic Survival, and Transmission During Pathogenesis on Tomato. PHYTOPATHOLOGY 2022; 112:752-764. [PMID: 34543058 DOI: 10.1094/phyto-02-21-0069-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Xanthomonas perforans is a seedborne hemibiotrophic pathogen that successfully establishes infection in the phyllosphere of tomato. While most studies investigating mechanistic basis of pathogenesis have focused on successful apoplastic growth, factors important during asymptomatic colonization in the early stages of disease development are not well understood. In this study, we show that tssM gene of the type VI secretion system cluster i3* (T6SS-i3*) plays a significant role during initial asymptomatic epiphytic colonization at different stages during the life cycle of the pathogen. Mutation in a core gene, tssM of T6SS-i3*, imparted higher aggressiveness to the pathogen, as indicated by higher overall disease severity, higher in planta growth, and shorter latent infection period compared with the wild-type upon dip inoculation of 4- to 5-week-old tomato plants. Contribution of tssM toward aggressiveness was evident during vertical transmission from seed to seedling, with wild-type showing reduced disease severity as well as lower in planta populations on seedlings compared with the mutant. Presence of functional TssM offered higher epiphytic fitness as well as higher dissemination potential to the pathogen when tested in an experimental setup mimicking transplant house high-humidity conditions. We showed higher osmotolerance being one mechanism by which TssM offers higher epiphytic fitness. Taken together, these data reveal that functional TssM plays a larger role in offering ecological advantage to the pathogen. TssM prolongs the association of hemibiotrophic pathogen with the host, minimizing overall disease severity yet facilitating successful dissemination.
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Affiliation(s)
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
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17
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Tan X, Qiao J, Li H, Huang D, Hu X, Wang X. Global metabolic regulation in Vibrio parahaemolyticus under polymyxin B stimulation. Microb Pathog 2021; 161:105260. [PMID: 34688850 DOI: 10.1016/j.micpath.2021.105260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/25/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022]
Abstract
Vibrio parahaemolyticus is responsible for infection diseases of people who consume the contaminated seafood, but its metabolic regulation profile in response to colistin, the last treatment option for multidrug-resistant Gram-negative bacteria, remains unclear. In this study, the metabolic regulation profile of V. parahaemolyticus ATCC33846 under polymyxin B stimulation has been investigated. V. parahaemolyticus exposed to polymyxin B resulted in 4597 differentially transcribed genes, including 673 significantly up-regulated genes and 569 significantly down-regulated genes. In V. parahaemolyticus under polymyxin B stimulation, the cellular antioxidant systems to prevent bacteria from oxidant stress was activated, the synthesis of some nonessential macromolecules was reduced, and the assembly and modification of lipopolysaccharide and peptidoglycan to resist the attack from other antibiotics were promoted. These findings provide new insights into polymyxin B-related stress response in V. parahaemolyticus which should be useful for developing novel drugs for infection.
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Affiliation(s)
- Xin Tan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Jun Qiao
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Hedan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Danyang Huang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Xiaoqing Hu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
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18
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Activation of the type VI secretion system in the squid symbiont Vibrio fischeri requires the transcriptional regulator TasR and the structural proteins TssM and TssA. J Bacteriol 2021; 203:e0039921. [PMID: 34370559 PMCID: PMC8508121 DOI: 10.1128/jb.00399-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria have evolved diverse strategies to compete for a niche, including the type VI secretion system (T6SS), a contact-dependent killing mechanism. T6SSs are common in bacterial pathogens, commensals, and beneficial symbionts, where they affect the diversity and spatial structure of host-associated microbial communities. Although T6SS gene clusters are often located on genomic islands (GIs), which may be transferred as a unit, the regulatory strategies that promote gene expression once the T6SS genes are transferred into a new cell are not known. We used the squid symbiont, Vibrio fischeri, to identify essential regulatory factors that control expression of a strain-specific T6SS encoded on a GI. We found that a transcriptional reporter for this T6SS is active only in strains that contain the T6SS-encoding GI, suggesting the GI encodes at least one essential regulator. A transposon screen identified seven mutants that could not activate the reporter. These mutations mapped exclusively to three genes on the T6SS-containing GI that encode two essential structural proteins (a TssA-like protein and TssM) and a transcriptional regulator (TasR). Using T6SS reporters, RT-PCR, competition assays, and differential proteomics, we found that all three genes are required for expression of many T6SS components, except for the TssA-like protein and TssM, which are constitutively expressed. Based on these findings, we propose a model whereby T6SS expression requires conserved structural proteins, in addition to the essential regulator TasR, and this ability to self-regulate may be a strategy to activate T6SS expression upon transfer of T6SS-encoding elements into a new bacterial host. Importance Interbacterial weapons like the T6SS are often located on mobile genetic elements and their expression is highly regulated. We found that two conserved structural proteins are required for T6SS expression in Vibrio fischeri. These structural proteins also contain predicted GTPase and GTP binding domains, suggesting their role in promoting T6SS expression may involve sensing the energetic state of the cell. Such a mechanism would provide a direct link between T6SS activation and cellular energy levels, providing a "checkpoint" to ensure the cell has sufficient energy to build such a costly weapon. Because these regulatory factors are encoded within the T6SS gene cluster, they are predicted to move with the genetic element to activate T6SS expression in a new host cell.
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19
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Kim JA, Jang BR, Kim YR, Jung YC, Kim KS, Lee KH. Vibrio vulnificus induces the death of a major bacterial species in the mouse gut via cyclo-Phe-Pro. MICROBIOME 2021; 9:161. [PMID: 34284824 PMCID: PMC8293591 DOI: 10.1186/s40168-021-01095-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 05/12/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND A foodborne pathogen, Vibrio vulnificus, encounters normal microflora inhabiting the gut environments prior to causing fatal septicemia or gastroenteritis and should overcome the barriers derived from the gut commensals for successful infection. Its interactions with gut commensals during the infection process, however, have not yet been understood. In the present study, the effect of V. vulnificus on the community structures of gut microbiota in mice was examined. RESULTS Analyses of microbiota in the fecal samples of mice that died due to V. vulnificus infection revealed the decreased abundance of bacteria belonged to Bacteroidetes, notably, the species Bacteroides vulgatus. In vitro coculturing of the two bacterial species resulted in the decreased survival of B. vulgatus. The antagonistic effect of V. vulnificus against B. vulgatus was found to be mediated by cyclo-Phe-Pro (cFP), one of the major compounds secreted by V. vulnificus. cFP-treated B. vulgatus showed collapsed cellular morphology with an undulated cell surface, enlarged periplasmic space, and lysed membranes, suggesting the occurrence of membrane disruption. The degree of membrane disruption caused by cFP was dependent upon the cellular levels of ObgE in B. vulgatus. Recombinant ObgE exhibited a high affinity to cFP at a 1:1 ratio. When mice were orally injected with cFP, their feces contained significantly reduced B. vulgatus levels, and their susceptibility to V. vulnificus infection was considerably increased. CONCLUSIONS This study demonstrates that V. vulnificus-derived cFP modulates the abundance of the predominant species among gut commensals, which made V. vulnificus increase its pathogenicity in the hosts. Video abstract.
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Affiliation(s)
- Jeong-A Kim
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea
| | - Bo-Ram Jang
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea
| | - Yu-Ra Kim
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea
| | - You-Chul Jung
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea
| | - Kun-Soo Kim
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea
| | - Kyu-Ho Lee
- Department of Life Science, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul, South Korea.
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20
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TssA-TssM-TagA interaction modulates type VI secretion system sheath-tube assembly in Vibrio cholerae. Nat Commun 2020; 11:5065. [PMID: 33033237 PMCID: PMC7545191 DOI: 10.1038/s41467-020-18807-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 09/07/2020] [Indexed: 01/20/2023] Open
Abstract
The type VI protein secretion system (T6SS) is a powerful needle-like machinery found in Gram-negative bacteria that can penetrate the cytosol of receiving cells in milliseconds by physical force. Anchored by its membrane-spanning complex (MC) and a baseplate (BP), the T6SS sheath-tube is assembled in a stepwise process primed by TssA and terminated by TagA. However, the molecular details of its assembly remain elusive. Here, we systematically examined the initiation and termination of contractile and non-contractile T6SS sheaths in MC-BP, tssA and tagA mutants by fluorescence microscopy. We observe long pole-to-pole sheath-tube structures in the non-contractile MC-BP defective mutants but not in the Hcp tube or VgrG spike mutants. Combining overexpression and genetic mutation data, we demonstrate complex effects of TssM, TssA and TagA interactions on T6SS sheath-tube dynamics. We also report promiscuous interactions of TagA with multiple T6SS components, similar to TssA. Our results demonstrate that priming of the T6SS sheath-tube assembly is not dependent on TssA, nor is the assembly termination dependent on the distal end TssA-TagA interaction, and highlight the tripartite control of TssA-TssM-TagA on sheath-tube initiation and termination.
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21
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Lin HH, Yu M, Sriramoju MK, Hsu STD, Liu CT, Lai EM. A High-Throughput Interbacterial Competition Screen Identifies ClpAP in Enhancing Recipient Susceptibility to Type VI Secretion System-Mediated Attack by Agrobacterium tumefaciens. Front Microbiol 2020; 10:3077. [PMID: 32117077 PMCID: PMC7012810 DOI: 10.3389/fmicb.2019.03077] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/19/2019] [Indexed: 12/30/2022] Open
Abstract
The type VI secretion system (T6SS) is an effector delivery system used by Gram-negative bacteria to kill other bacteria or eukaryotic hosts to gain fitness. The plant pathogen Agrobacterium tumefaciens utilizes its T6SS to kill other bacteria, such as Escherichia coli. We observed that the A. tumefaciens T6SS-dependent killing outcome differs when using different T6SS-lacking, K-12 E. coli strains as a recipient cell. Thus, we hypothesized that the A. tumefaciens T6SS killing outcome not only relies on the T6SS activity of the attacker cells but also depends on the recipient cells. Here, we developed a high-throughput interbacterial competition platform to test the hypothesis by screening for mutants with reduced killing outcomes caused by A. tumefaciens strain C58. Among the 3,909 strains in the E. coli Keio library screened, 16 mutants with less susceptibility to A. tumefaciens C58 T6SS-dependent killing were identified, and four of them were validated by complementation test. Among the four, the clpP encoding ClpP protease, which is universal and highly conserved in both prokaryotes and eukaryotic organelles, was selected for further characterizations. We demonstrated that ClpP is responsible for enhancing susceptibility to the T6SS killing. Because ClpP protease depends on other adapter proteins such as ClpA and ClpX for substrate recognition, further mutant studies followed by complementation tests were carried out to reveal that ClpP-associated AAA+ ATPase ClpA, but not ClpX, is involved in enhancing susceptibility to A. tumefaciens T6SS killing. Moreover, functional and biochemical studies of various ClpP amino acid substitution variants provided evidence that ClpA–ClpP interaction is critical in enhancing susceptibility to the T6SS killing. This study highlights the importance of recipient factors in determining the outcome of the T6SS killing and shows the universal ClpP protease as a novel recipient factor hijacked by the T6SS of A. tumefaciens.
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Affiliation(s)
- Hsiao-Han Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.,Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Manda Yu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | | | | | - Chi-Te Liu
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan.,Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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22
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Lopez J, Ly PM, Feldman MF. The Tip of the VgrG Spike Is Essential to Functional Type VI Secretion System Assembly in Acinetobacter baumannii. mBio 2020; 11:e02761-19. [PMID: 31937641 PMCID: PMC6960284 DOI: 10.1128/mbio.02761-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/25/2019] [Indexed: 12/11/2022] Open
Abstract
The type VI secretion system (T6SS) is a critical weapon in bacterial warfare between Gram-negative bacteria. Although invaluable for niche establishment, this machine represents an energetic burden to its host bacterium. Acinetobacter baumannii is an opportunistic pathogen that poses a serious threat to public health due to its high rates of multidrug resistance. In some A. baumannii strains, the T6SS is transcriptionally downregulated by large multidrug resistance plasmids. Other strains, such as the clinical isolate AbCAN2, express T6SS-related genes but lack T6SS activity under laboratory conditions, despite not harboring these plasmids. This suggests that alternative mechanisms exist to repress the T6SS. Here, we used a transposon mutagenesis approach in AbCAN2 to identify novel T6SS repressors. Our screen revealed that the T6SS of this strain is inhibited by a homolog of VgrG, an essential structural component of all T6SSs reported to date. We named this protein inhibitory VgrG (VgrGi). Biochemical and in silico analyses demonstrated that the unprecedented inhibitory capability of VgrGi is due to a single amino acid mutation in a widely conserved C-terminal domain of unknown function, DUF2345. We also show that unlike in other bacteria, the C terminus of VgrG is essential for functional T6SS assembly in A. baumannii Our study provides insight into the architectural requirements underlying functional assembly of the T6SS of A. baumannii We propose that T6SS-inactivating point mutations are beneficial to the host bacterium, since they eliminate the energy cost associated with maintaining a functional T6SS, which appears to be unnecessary for A. baumannii virulence.IMPORTANCE Despite the clinical relevance of A. baumannii, little is known about its fundamental biology. Here, we show that a single amino acid mutation in VgrG, a critical T6SS structural protein, abrogates T6SS function. Given that this mutation was found in a clinical isolate, we propose that the T6SS of A. baumannii is probably not involved in virulence; this idea is supported by multiple genomic analyses showing that the majority of clinical A. baumannii strains lack proteins essential to the T6SS. We also show that, unlike in other species, the C terminus of VgrG is a unique architectural requirement for functional T6SS assembly in A. baumannii, suggesting that over evolutionary time, bacteria have developed changes to their T6SS architecture, leading to specialized systems.
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Affiliation(s)
- Juvenal Lopez
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Pek Man Ly
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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23
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Wang J, Brodmann M, Basler M. Assembly and Subcellular Localization of Bacterial Type VI Secretion Systems. Annu Rev Microbiol 2019; 73:621-638. [DOI: 10.1146/annurev-micro-020518-115420] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacteria need to deliver large molecules out of the cytosol to the extracellular space or even across membranes of neighboring cells to influence their environment, prevent predation, defeat competitors, or communicate. A variety of protein-secretion systems have evolved to make this process highly regulated and efficient. The type VI secretion system (T6SS) is one of the largest dynamic assemblies in gram-negative bacteria and allows for delivery of toxins into both bacterial and eukaryotic cells. The recent progress in structural biology and live-cell imaging shows the T6SS as a long contractile sheath assembled around a rigid tube with associated toxins anchored to a cell envelope by a baseplate and membrane complex. Rapid sheath contraction releases a large amount of energy used to push the tube and toxins through the membranes of neighboring target cells. Because reach of the T6SS is limited, some bacteria dynamically regulate its subcellular localization to precisely aim at their targets and thus increase efficiency of toxin translocation.
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Affiliation(s)
- Jing Wang
- Biozentrum, University of Basel, CH 4056 Basel, Switzerland
| | - Maj Brodmann
- Biozentrum, University of Basel, CH 4056 Basel, Switzerland
| | - Marek Basler
- Biozentrum, University of Basel, CH 4056 Basel, Switzerland
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24
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Tekedar HC, Kumru S, Blom J, Perkins AD, Griffin MJ, Abdelhamed H, Karsi A, Lawrence ML. Comparative genomics of Aeromonas veronii: Identification of a pathotype impacting aquaculture globally. PLoS One 2019; 14:e0221018. [PMID: 31465454 PMCID: PMC6715197 DOI: 10.1371/journal.pone.0221018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 07/29/2019] [Indexed: 12/30/2022] Open
Abstract
Aeromonas veronii is a gram-negative species abundant in aquatic environments that causes disease in humans as well as terrestrial and aquatic animals. In the current study, 41 publicly available A. veronii genomes were compared to investigate distribution of putative virulence genes, global dissemination of pathotypes, and potential mechanisms of virulence. The complete genome of A. veronii strain ML09-123 from an outbreak of motile aeromonas septicemia in farm-raised catfish in the southeastern United States was included. Dissemination of A. veronii strain types was discovered in dispersed geographical locations. Isolate ML09-123 is highly similar to Chinese isolate TH0426, suggesting the two strains have a common origin and may represent a pathotype impacting aquaculture in both countries. Virulence of strain ML09-123 in catfish in a dose-dependent manner was confirmed experimentally. Subsystem category disposition showed the majority of genomes exhibit similar distribution of genomic elements. The type I secretion system (T1SS), type II secretion system (T2SS), type 4 pilus (T4P), and flagellum core elements are conserved in all A. veronii genomes, whereas the type III secretion system (T3SS), type V secretion system (T5SS), type VI secretion system (T6SS), and tight adherence (TAD) system demonstrate variable dispersal. Distribution of mobile elements is dependent on host and geographic origin, suggesting this species has undergone considerable genetic exchange. The data presented here lends insight into the genomic variation of A. veronii and identifies a pathotype impacting aquaculture globally.
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Affiliation(s)
- Hasan C. Tekedar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Salih Kumru
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Jochen Blom
- Bioinformatics & Systems Biology, Justus-Liebig-University Giessen, Giessen, Hesse, Germany
| | - Andy D. Perkins
- Department of Computer Science and Engineering, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Matt J. Griffin
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
- Thad Cochran National Warmwater Aquaculture Center, Stoneville, Mississippi State, United States of America
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Attila Karsi
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Mark L. Lawrence
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
- * E-mail:
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25
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Wu CF, Santos MNM, Cho ST, Chang HH, Tsai YM, Smith DA, Kuo CH, Chang JH, Lai EM. Plant-Pathogenic Agrobacterium tumefaciens Strains Have Diverse Type VI Effector-Immunity Pairs and Vary in In-Planta Competitiveness. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:961-971. [PMID: 30830835 DOI: 10.1094/mpmi-01-19-0021-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The type VI secretion system (T6SS) is used by gram-negative bacteria to translocate effectors that can antagonize other bacterial cells. Models predict the variation in collections of effector and cognate immunity genes determine competitiveness and can affect the dynamics of populations and communities of bacteria. However, the outcomes of competition cannot be entirely explained by compatibility of effector-immunity (EI) pairs. Here, we characterized the diversity of T6SS loci of plant-pathogenic Agrobacterium tumefaciens and showed that factors other than EI pairs can impact interbacterial competition. All examined strains encode T6SS active in secretion and antagonism against Escherichia coli. The spectra of EI pairs as well as compositions of gene neighborhoods are diverse. Almost 30 in-planta competitions were tested between different genotypes of A. tumefaciens. Fifteen competitions between members of different species-level groups resulted in T6SS-dependent suppression in in-planta growth of prey genotypes. In contrast, ten competitions between members within species-level groups resulted in no significant effect on the growth of prey genotypes. One strain was an exceptional case and, despite encoding a functional T6SS and toxic effector protein, could not compromise the growth of the four tested prey genotypes. The data suggest T6SS-associated EI pairs can influence the competitiveness of strains of A. tumefaciens, but genetic features have a significant role on the efficacy of interbacterial antagonism.
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Affiliation(s)
- Chih-Feng Wu
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Mary Nia M Santos
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Shu-Ting Cho
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hsing-Hua Chang
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Ming Tsai
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Delaney A Smith
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Chih-Horng Kuo
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Jeff H Chang
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
- 3Center for Genome Research and Biocomputing, Oregon State University
| | - Erh-Min Lai
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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26
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Liebl D, Robert-Genthon M, Job V, Cogoni V, Attrée I. Baseplate Component TssK and Spatio-Temporal Assembly of T6SS in Pseudomonas aeruginosa. Front Microbiol 2019; 10:1615. [PMID: 31379775 PMCID: PMC6657622 DOI: 10.3389/fmicb.2019.01615] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/28/2019] [Indexed: 11/22/2022] Open
Abstract
The Gram-negative bacteria use the contractile multi-molecular structure, called the Type VI Secretion System (T6SS) to inject toxic products into eukaryotic and prokaryotic cells. In this study, we use fluorescent protein fusions and time-lapse microscopy imaging to study the assembly dynamics of the baseplate protein TssK in Pseudomonas aeruginosa T6SS. TssK formed transient higher-order structures that correlated with dynamics of sheath component TssB. Assembly of peri-membrane TssK structures occurred de novo upon contact with competing bacteria. We show that this assembly required presence of TagQ-TagR envelope sensors, activity of PpkA kinase and anchoring to the inner membrane via TssM. Disassembly and repositioning of TssK component was dependent on PppA phosphatase and indispensable for repositioning and deployment of the entire contractile apparatus toward a new target cell. We also show that TssE is necessary for correct elongation and stability of TssB-sheath, but not for TssK assembly. Therefore, in P. aeruginosa, assembly of the TssK-containing structure relays on the post-translational regulatory envelope module and acts as spatio-temporal marker for further recruitment and subsequent assembly of the contractile apparatus.
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Affiliation(s)
- David Liebl
- Univ. Grenoble Alpes, CNRS, Bacterial Pathogenesis and Cellular Responses, ERL 5261, INSERM, UMR-S 1036, CEA, Grenoble, France
| | - Mylène Robert-Genthon
- Univ. Grenoble Alpes, CNRS, Bacterial Pathogenesis and Cellular Responses, ERL 5261, INSERM, UMR-S 1036, CEA, Grenoble, France
| | - Viviana Job
- Univ. Grenoble Alpes, CNRS, Bacterial Pathogenesis and Cellular Responses, ERL 5261, INSERM, UMR-S 1036, CEA, Grenoble, France.,Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Valentina Cogoni
- Univ. Grenoble Alpes, CNRS, Bacterial Pathogenesis and Cellular Responses, ERL 5261, INSERM, UMR-S 1036, CEA, Grenoble, France
| | - Ina Attrée
- Univ. Grenoble Alpes, CNRS, Bacterial Pathogenesis and Cellular Responses, ERL 5261, INSERM, UMR-S 1036, CEA, Grenoble, France
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27
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Wang S, Yan Q, Zhang M, Huang L, Mao L, Zhang M, Xu X, Chen L, Qin Y. The role and mechanism of icmF in Aeromonas hydrophila survival in fish macrophages. JOURNAL OF FISH DISEASES 2019; 42:895-904. [PMID: 30919989 DOI: 10.1111/jfd.12991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/22/2019] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
Survival in host macrophages is an effective strategy for pathogenic bacteria to spread. Aeromonas hydrophila has been found to survive in fish macrophages, but the mechanisms remain unknown. In this paper, the roles and possible mechanisms of IcmF in bacterial survival in fish macrophages were investigated. First, a stable silencing strain icmF-RNAi was constructed by shRNA and RT-qPCR confirmed the expression of icmF was down-regulated by 94.42%. The expression of Hcp, DotU and VgrG was also decreased in icmF-RNAi. The intracellular survival rate of the wild-type strain was 92.3%, while the survival rate of icmF-RNAi was only 20.58%. The escape rate of the wild-type strain was 20%, while that of the icmF-RNAi was only 7.5%. Further studies indicated that the expression of icmF can significantly affect the adhesion, biofilm formation, motility and acid resistance of A. hydrophila, but has no significant effect on the growth of A. hydrophila even under the stress of H2 O2 . The results indicated that IcmF of A. hydrophila not only acts as a structural protein which participates in virulence-related characteristics such as bacterial motility, adhesion and biofilm formation, but also acts as a key functional protein which participates in the interaction between bacteria and host macrophages.
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Affiliation(s)
- Suyun Wang
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Qingpi Yan
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Meimei Zhang
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Lixing Huang
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Leilei Mao
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Mengmeng Zhang
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Xiaojin Xu
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Liwei Chen
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
| | - Yingxue Qin
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, China
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28
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Aas CG, Drabløs F, Haugum K, Afset JE. Comparative Transcriptome Profiling Reveals a Potential Role of Type VI Secretion System and Fimbriae in Virulence of Non-O157 Shiga Toxin-Producing Escherichia coli. Front Microbiol 2018; 9:1416. [PMID: 30008706 PMCID: PMC6033998 DOI: 10.3389/fmicb.2018.01416] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/08/2018] [Indexed: 01/18/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) cause both sporadic infections and outbreaks of enteric disease in humans, with symptoms ranging from asymptomatic carriage to severe disease like haemolytic uremic syndrome (HUS). Bacterial virulence factors like subtypes of the Shiga toxin (Stx) and the locus of enterocyte effacement (LEE) pathogenicity island, as well as host factors like young age, are strongly associated with development of HUS. However, these factors alone do not accurately differentiate between strains that cause HUS and those that do not cause severe disease, which is important in the context of diagnosis, treatment, as well as infection control. We have used RNA sequencing to compare transcriptomes of 30 stx2a and eae positive STEC strains of non-O157 serogroups isolated from children <5 years of age. The strains were from children with HUS (HUS group, n = 15), and children with asymptomatic or mild disease (non-HUS group, n = 15), either induced with mitomycin C or non-induced, to reveal potential differences in gene expression levels between groups. When the HUS and non-HUS group were compared for differential expression of protein-encoding gene families, 399 of 6,119 gene families were differentially expressed (log2 fold change ≥ 1, FDR < 0.05) in the non-induced condition, whereas only one gene family was differentially expressed in the induced condition. Gene ontology and cluster analysis showed that several fimbrial operons, as well as a putative type VI secretion system (T6SS) were more highly expressed in the HUS group than in the non-HUS group, indicating a role of these in the virulence of STEC strains causing severe disease.
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Affiliation(s)
- Christina G Aas
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.,Clinic of Laboratory Medicine, Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Finn Drabløs
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Kjersti Haugum
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.,Clinic of Laboratory Medicine, Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Jan E Afset
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.,Clinic of Laboratory Medicine, Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
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29
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Huang L, Liu W, Jiang Q, Zuo Y, Su Y, Zhao L, Qin Y, Yan Q. Integration of Transcriptomic and Proteomic Approaches Reveals the Temperature-Dependent Virulence of Pseudomonas plecoglossicida. Front Cell Infect Microbiol 2018; 8:207. [PMID: 29977868 PMCID: PMC6021524 DOI: 10.3389/fcimb.2018.00207] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/05/2018] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas plecoglossicida is a facultative pathogen that is associated with diseases of multiple fish, mainly at 15–20°C. Although fish disease caused by P. plecoglossicida has led to significant economic losses, the mechanisms of the temperature-dependent virulence are unclear. Here, we identify potential pathogenicity mechanisms and demonstrate the direct regulation of several virulence factors by temperature with transcriptomic and proteomic analyses, quantitative real-time PCR (qRT-PCR), RNAi, pyoverdine (PVD) quantification, the chrome azurol S (CAS) assay, growth curve measurements, a biofilm assay, and artificial infection. The principal component analysis, the heat map generation and hierarchical clustering, together with the functional annotations of the differentially expressed genes (DEGs) demonstrated that, under different growth temperatures, the animation and focus of P. plecoglossicida are quite different, which may be the key to pathogenicity. Genes involved in PVD synthesis and in the type VI secretion system (T6SS) are specifically upregulated at the virulent temperature of 18°C. Silencing of the PVD-synthesis-related genes reduces the iron acquisition, growth, biofilm formation, distribution in host organs and virulence of the bacteria. Silencing of the T6SS genes also leads to the reduction of biofilm formation, distribution in host organs and virulence. These findings reveal that temperature regulates multiple virulence mechanisms in P. plecoglossicida, especially through iron acquisition and T6SS secretion. Meanwhile, integration of transcriptomic and proteomic data provide us with a new perspective into the pathogenesis of P. plecoglossicida, which would not have been easy to catch at either the protein or mRNA differential analyses alone, thus illustrating the power of multi-omics analyses in microbiology.
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Affiliation(s)
- Lixing Huang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Wenjia Liu
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingling Jiang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yanfei Zuo
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yongquan Su
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China.,College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Lingmin Zhao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yingxue Qin
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China.,State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
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30
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Clemens DL, Lee BY, Horwitz MA. The Francisella Type VI Secretion System. Front Cell Infect Microbiol 2018; 8:121. [PMID: 29740542 PMCID: PMC5924787 DOI: 10.3389/fcimb.2018.00121] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/03/2018] [Indexed: 12/27/2022] Open
Abstract
Francisella tularensisis subsp. tularensis is an intracellular bacterial pathogen and the causative agent of the life-threatening zoonotic disease tularemia. The Francisella Pathogenicity Island encodes a large secretion apparatus, known as a Type VI Secretion System (T6SS), which is essential for Francisella to escape from its phagosome and multiply within host macrophages and to cause disease in animals. The T6SS, found in one-quarter of Gram-negative bacteria including many highly pathogenic ones, is a recently discovered secretion system that is not yet fully understood. Nevertheless, there have been remarkable advances in our understanding of the structure, composition, and function of T6SSs of several bacteria in the past few years. The system operates like an inside-out headless contractile phage that is anchored to the bacterial membrane via a baseplate and membrane complex. The system injects effector molecules across the inner and outer bacterial membrane and into host prokaryotic or eukaryotic targets to kill, intoxicate, or in the case of Francisella, hijack the target cell. Recent advances include an atomic model of the contractile sheath, insights into the mechanics of sheath contraction, the composition of the baseplate and membrane complex, the process of assembly of the apparatus, and identification of numerous effector molecules and activities. While Francisella T6SS appears to be an outlier among T6SSs, with limited or no sequence homology with other systems, its structure and organization are strikingly similar to other systems. Nevertheless, we have only scratched the surface in uncovering the mysteries of the Francisella T6SS, and there are numerous questions that remain to be answered.
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Affiliation(s)
- Daniel L. Clemens
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | | | - Marcus A. Horwitz
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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31
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Lin JS, Pissaridou P, Wu HH, Tsai MD, Filloux A, Lai EM. TagF-mediated repression of bacterial type VI secretion systems involves a direct interaction with the cytoplasmic protein Fha. J Biol Chem 2018; 293:8829-8842. [PMID: 29599293 PMCID: PMC5995506 DOI: 10.1074/jbc.ra117.001618] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/09/2018] [Indexed: 01/09/2023] Open
Abstract
The bacterial type VI secretion system (T6SS) delivers effectors into eukaryotic host cells or toxins into bacterial competitor for survival and fitness. The T6SS is positively regulated by the threonine phosphorylation pathway (TPP) and negatively by the T6SS-accessory protein TagF. Here, we studied the mechanisms underlying TagF-mediated T6SS repression in two distinct bacterial pathogens, Agrobacterium tumefaciens and Pseudomonas aeruginosa. We found that in A. tumefaciens, T6SS toxin secretion and T6SS-dependent antibacterial activity are suppressed by a two-domain chimeric protein consisting of TagF and PppA, a putative phosphatase. Remarkably, this TagF domain is sufficient to post-translationally repress the T6SS, and this inhibition is independent of TPP. This repression requires interaction with a cytoplasmic protein, Fha, critical for activating T6SS assembly. In P. aeruginosa, PppA and TagF are two distinct proteins that repress T6SS in TPP-dependent and -independent pathways, respectively. P. aeruginosa TagF interacts with Fha1, suggesting that formation of this complex represents a conserved TagF-mediated regulatory mechanism. Using TagF variants with substitutions of conserved amino acid residues at predicted protein–protein interaction interfaces, we uncovered evidence that the TagF–Fha interaction is critical for TagF-mediated T6SS repression in both bacteria. TagF inhibits T6SS without affecting T6SS protein abundance in A. tumefaciens, but TagF overexpression reduces the protein levels of all analyzed T6SS components in P. aeruginosa. Our results indicate that TagF interacts with Fha, which in turn could impact different stages of T6SS assembly in different bacteria, possibly reflecting an evolutionary divergence in T6SS control.
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Affiliation(s)
- Jer-Sheng Lin
- From the Institute of Plant and Microbial Biology and
| | - Panayiota Pissaridou
- the Medical Research Council Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hsin-Hui Wu
- the Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan and
| | - Ming-Daw Tsai
- the Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan and
| | - Alain Filloux
- the Medical Research Council Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Erh-Min Lai
- From the Institute of Plant and Microbial Biology and
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32
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IcmF and DotU are required for the virulence of Acidovorax oryzae strain RS-1. Arch Microbiol 2018; 200:897-910. [DOI: 10.1007/s00203-018-1497-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 02/06/2018] [Accepted: 02/16/2018] [Indexed: 10/18/2022]
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33
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Douzi B, Logger L, Spinelli S, Blangy S, Cambillau C, Cascales E. Structure-Function Analysis of the C-Terminal Domain of the Type VI Secretion TssB Tail Sheath Subunit. J Mol Biol 2017; 430:297-309. [PMID: 29223729 DOI: 10.1016/j.jmb.2017.11.015] [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: 09/30/2017] [Revised: 11/26/2017] [Accepted: 11/30/2017] [Indexed: 11/16/2022]
Abstract
The type VI secretion system (T6SS) is a specialized macromolecular complex dedicated to the delivery of protein effectors into both eukaryotic and bacterial cells. The general mechanism of action of the T6SS is similar to the injection of DNA by contractile bacteriophages. The cytoplasmic portion of the T6SS is evolutionarily, structurally and functionally related to the phage tail complex. It is composed of an inner tube made of stacked Hcp hexameric rings, engulfed within a sheath and built on a baseplate. This sheath undergoes cycles of extension and contraction, and the current model proposes that the sheath contraction propels the inner tube toward the target cell for effector delivery. The sheath comprises two subunits: TssB and TssC that polymerize under an extended conformation. Here, we show that isolated TssB forms trimers, and we report the crystal structure of a C-terminal fragment of TssB. This fragment comprises a long helix followed by a helical hairpin that presents surface-exposed charged residues. Site-directed mutagenesis coupled to functional assay further showed that these charges are required for proper assembly of the sheath. Positioning of these residues in the extended T6SS sheath structure suggests that they may mediate contacts with the baseplate.
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Affiliation(s)
- Badreddine Douzi
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Laureen Logger
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Silvia Spinelli
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Stéphanie Blangy
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France.
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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34
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Abstract
The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell. Although the assembly and the mechanism of action are conserved across species, the repertoire of secreted toxins and the diversity of the regulatory mechanisms and of target cells make the T6SS a highly versatile secretion system. The T6SS is particularly represented in Escherichia coli pathotypes and Salmonella serotypes. In this review we summarize the current knowledge regarding the prevalence, the assembly, the regulation, and the roles of the T6SS in E. coli, Salmonella, and related species.
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35
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Abstract
Bacterial type VI secretion systems (T6SSs) function as contractile nanomachines to puncture target cells and deliver lethal effectors. In the 10 years since the discovery of the T6SS, much has been learned about the structure and function of this versatile protein secretion apparatus. Most of the conserved protein components that comprise the T6SS apparatus itself have been identified and ascribed specific functions. In addition, numerous effector proteins that are translocated by the T6SS have been identified and characterized. These protein effectors usually represent toxic cargoes that are delivered by the attacker cell to a target cell. Researchers in the field are beginning to better understand the lifestyle or physiology that dictates when bacteria normally express their T6SS. In this article, we consider what is known about the structure and regulation of the T6SS, the numerous classes of antibacterial effector T6SS substrates, and how the action of the T6SS relates to a given lifestyle or behavior in certain bacteria.
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Lien YW, Lai EM. Type VI Secretion Effectors: Methodologies and Biology. Front Cell Infect Microbiol 2017; 7:254. [PMID: 28664151 PMCID: PMC5471719 DOI: 10.3389/fcimb.2017.00254] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/31/2017] [Indexed: 12/26/2022] Open
Abstract
The type VI secretion system (T6SS) is a nanomachine deployed by many Gram-negative bacteria as a weapon against eukaryotic hosts or prokaryotic competitors. It assembles into a bacteriophage tail-like structure that can transport effector proteins into the environment or target cells for competitive survival or pathogenesis. T6SS effectors have been identified by a variety of approaches, including knowledge/hypothesis-dependent and discovery-driven approaches. Here, we review and discuss the methods that have been used to identify T6SS effectors and the biological and biochemical functions of known effectors. On the basis of the nature and transport mechanisms of T6SS effectors, we further propose potential strategies that may be applicable to identify new T6SS effectors.
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Affiliation(s)
- Yun-Wei Lien
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan.,Department of Plant Pathology and Microbiology, National Taiwan UniversityTaipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan.,Department of Plant Pathology and Microbiology, National Taiwan UniversityTaipei, Taiwan
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Abstract
Proteins often do not function as single substances but rather as team players in a dynamic network. Growing evidence shows that protein-protein interactions are crucial in many biological processes in living cells. Genetic (such as yeast two-hybrid, Y2H) and biochemical (such as co-immunoprecipitation, co-IP) methods are the methods commonly used at the beginning of a study to identify the interacting proteins. Immunoprecipitation (IP), a method using a target protein-specific antibody in conjunction with Protein A/G affinity beads, is a powerful tool to identify molecules that interact with specific proteins. Therefore, co-IP is considered to be one of the standard methods of identifying or confirming the occurrence of protein-protein interaction events in vivo. Co-IP experiments can identify proteins via direct or indirect interactions or in a protein complex. Here, we use Agrobacterium type VI secretion system (T6SS) sheath components TssB-TssC41 interaction as an example to describe the principle, procedure, and experimental problems of co-IP.
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Affiliation(s)
- Jer-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, 128, Sec. 2, Academia Road, Nankang, Taipei, 11529, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, 128, Sec. 2, Academia Road, Nankang, Taipei, 11529, Taiwan.
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Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties. PLoS One 2016; 11:e0165500. [PMID: 27798649 PMCID: PMC5087951 DOI: 10.1371/journal.pone.0165500] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/12/2016] [Indexed: 11/19/2022] Open
Abstract
Vibrio vulnificus is a bacterium responsible for severe gastroenteritis, sepsis and wound infections. Gastroenteritis and sepsis are commonly associated with the consumption of raw oysters, whereas wound infection is often associated with the handling of contaminated fish. Although classical virulence factors of this emerging pathogen are well characterised, there remains a paucity of knowledge regarding the general biology of this species. To investigate the presence of previously unreported virulence factors, we applied whole genome sequencing to a panel of ten V. vulnificus strains with varying virulence potentials. This identified two novel type 6 secretion systems (T6SSs), systems that are known to have a role in bacterial virulence and population dynamics. By utilising a range of molecular techniques and assays we have demonstrated the functionality of one of these T6SSs. Furthermore, we have shown that this system is subject to thermoregulation and is negatively regulated by increasing salinity concentrations. This secretion system was also shown to be involved in the killing of V. vulnificus strains that did not possess this system and a model is proposed as to how this interaction may contribute to population dynamics within V. vulnificus strains. In addition to this intra-species killing, this system also contributes to the killing of inter bacterial species and may have a role in the general composition of Vibrio species in the environment.
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Rigard M, Bröms JE, Mosnier A, Hologne M, Martin A, Lindgren L, Punginelli C, Lays C, Walker O, Charbit A, Telouk P, Conlan W, Terradot L, Sjöstedt A, Henry T. Francisella tularensis IglG Belongs to a Novel Family of PAAR-Like T6SS Proteins and Harbors a Unique N-terminal Extension Required for Virulence. PLoS Pathog 2016; 12:e1005821. [PMID: 27602570 PMCID: PMC5014421 DOI: 10.1371/journal.ppat.1005821] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 07/20/2016] [Indexed: 12/12/2022] Open
Abstract
The virulence of Francisella tularensis, the etiological agent of tularemia, relies on an atypical type VI secretion system (T6SS) encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). While the importance of the FPI in F. tularensis virulence is clearly established, the precise role of most of the FPI-encoded proteins remains to be deciphered. In this study, using highly virulent F. tularensis strains and the closely related species F. novicida, IglG was characterized as a protein featuring a unique α-helical N-terminal extension and a domain of unknown function (DUF4280), present in more than 250 bacterial species. Three dimensional modeling of IglG and of the DUF4280 consensus protein sequence indicates that these proteins adopt a PAAR-like fold, suggesting they could cap the T6SS in a similar way as the recently described PAAR proteins. The newly identified PAAR-like motif is characterized by four conserved cysteine residues, also present in IglG, which may bind a metal atom. We demonstrate that IglG binds metal ions and that each individual cysteine is required for T6SS-dependent secretion of IglG and of the Hcp homologue, IglC and for the F. novicida intracellular life cycle. In contrast, the Francisella-specific N-terminal α-helical extension is not required for IglG secretion, but is critical for F. novicida virulence and for the interaction of IglG with another FPI-encoded protein, IglF. Altogether, our data suggest that IglG is a PAAR-like protein acting as a bi-modal protein that may connect the tip of the Francisella T6SS with a putative T6SS effector, IglF. Francisella tularensis is a highly pathogenic bacterium causing tularemia. Its ability to cause disease is linked to its ability to replicate in the macrophage cytosol. The intracellular life cycle of Francisella is controlled by a type VI secretion system (T6SS), which is thought to inject effectors into the host cell to allow bacterial escape into the host cytosol. The molecular mechanisms behind this process are still largely unclear. In this work, we identify IglG as a protein with two important domains, one conserved in proteins from more than 250 bacterial species (DUF4280, renamed here as PAAR-like domain) and one specific for the Francisella genus. Using protein sequence analysis and three-dimensional structure predictions, comparative modeling and biochemistry approaches, our data demonstrate that IglG is a metal-binding protein that based on its PAAR-like domain might cap the VgrG spike of the T6SS and act as a membrane-puncturing protein. Furthermore, we identified that the Francisella-specific domain is directly involved in forming a protein complex with another virulence protein, IglF. This work, in addition to enhancing the molecular understanding of the Francisella T6SS, defines the features of the conserved DUF4280, a novel PAAR-like domain involved in type VI secretion (T6S) of many bacterial species.
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Affiliation(s)
- Mélanie Rigard
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
| | - Jeanette E. Bröms
- Department of Clinical Microbiology, Clinical Bacteriology, and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Amandine Mosnier
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
| | - Maggy Hologne
- Institut des Sciences Analytiques, CNRS, UMR 5280, Université de Lyon, Université Claude Bernard Lyon 1, ENS de Lyon, Villeurbanne, France
| | - Amandine Martin
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
| | - Lena Lindgren
- Department of Clinical Microbiology, Clinical Bacteriology, and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Claire Punginelli
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
| | - Claire Lays
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
| | - Olivier Walker
- Institut des Sciences Analytiques, CNRS, UMR 5280, Université de Lyon, Université Claude Bernard Lyon 1, ENS de Lyon, Villeurbanne, France
| | - Alain Charbit
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment Leriche, Paris, France
- Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections Systémiques, Paris, France
| | - Philippe Telouk
- University of Lyon, Lyon, France
- Laboratoire de Geologie de Lyon; Ecole Normale Supérieure de Lyon, Lyon, France
| | - Wayne Conlan
- National Research Council Canada, Human Health Therapeutics Portfolio, Ottawa, Ontario, Canada
| | - Laurent Terradot
- Molecular Microbiology and Structural Biochemistry, UMR 5086, CNRS-Université de Lyon, Institut de Biologie et Chimie des Protéines, Lyon, France
- * E-mail: (LT); (AS); (TH)
| | - Anders Sjöstedt
- Department of Clinical Microbiology, Clinical Bacteriology, and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
- * E-mail: (LT); (AS); (TH)
| | - Thomas Henry
- CIRI, International Center for Infectiology Research, Inserm U1111, CNRS, UMR5308, Lyon, France
- University of Lyon, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- * E-mail: (LT); (AS); (TH)
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Molecular Dissection of the Interface between the Type VI Secretion TssM Cytoplasmic Domain and the TssG Baseplate Component. J Mol Biol 2016; 428:4424-4437. [PMID: 27600411 DOI: 10.1016/j.jmb.2016.08.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 08/29/2016] [Accepted: 08/30/2016] [Indexed: 11/22/2022]
Abstract
The type VI secretion system (T6SS) is a multiprotein complex that catalyses toxin secretion through the bacterial cell envelope of various Gram-negative bacteria including important human pathogens. This machine uses a bacteriophage-like contractile tail to puncture the prey cell and inject harmful toxins. The T6SS tail comprises an inner tube capped by the cell-puncturing spike and wrapped by the contractile sheath. This structure is built on an assembly platform, the baseplate, which is anchored to the bacterial cell envelope by the TssJLM membrane complex (MC). This MC serves as both a tail docking station and a channel for the passage of the inner tube. The TssM transmembrane protein is a key component of the MC as it connects the inner and outer membranes. In this study, we define the TssM topology, highlighting a large but poorly studied 35-kDa cytoplasmic domain, TssMCyto, located between two transmembrane segments. Protein-protein interaction assays further show that TssMCyto oligomerises and makes contacts with several baseplate components. Using computer predictions, we delineate two subdomains in TssMCyto, including a nucleotide triphosphatase (NTPase) domain, followed by a 110-aa extension. Finally, site-directed mutagenesis coupled to functional assays reveals the contribution of these subdomains and conserved motifs to the interaction with T6SS partners and to the function of the secretion apparatus.
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Basler M. Type VI secretion system: secretion by a contractile nanomachine. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0021. [PMID: 26370934 PMCID: PMC4632598 DOI: 10.1098/rstb.2015.0021] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action.
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Affiliation(s)
- Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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42
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Aim, Load, Fire: The Type VI Secretion System, a Bacterial Nanoweapon. Trends Microbiol 2016; 24:51-62. [DOI: 10.1016/j.tim.2015.10.005] [Citation(s) in RCA: 267] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/30/2015] [Accepted: 10/09/2015] [Indexed: 12/31/2022]
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Tang L, Liang X, Moore R, Dong TG. Commentary: The icmF3 Locus is Involved in Multiple Adaptation- and Virulence-related Characteristics in Pseudomonas aeruginosa PAO1. Front Cell Infect Microbiol 2015; 5:83. [PMID: 26636045 PMCID: PMC4649053 DOI: 10.3389/fcimb.2015.00083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/03/2015] [Indexed: 11/25/2022] Open
Affiliation(s)
- Le Tang
- Ecosystem and Public Health, University of Calgary Calgary, AB, Canada
| | - Xiaoye Liang
- Ecosystem and Public Health, University of Calgary Calgary, AB, Canada
| | - Richard Moore
- Ecosystem and Public Health, University of Calgary Calgary, AB, Canada
| | - Tao G Dong
- Ecosystem and Public Health, University of Calgary Calgary, AB, Canada
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Lin J, Cheng J, Chen K, Guo C, Zhang W, Yang X, Ding W, Ma L, Wang Y, Shen X. The icmF3 locus is involved in multiple adaptation- and virulence-related characteristics in Pseudomonas aeruginosa PAO1. Front Cell Infect Microbiol 2015; 5:70. [PMID: 26484316 PMCID: PMC4589678 DOI: 10.3389/fcimb.2015.00070] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 09/18/2015] [Indexed: 11/24/2022] Open
Abstract
The type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria. Three separate T6SSs called H1-, H2-, and H3-T6SS have been discovered in Pseudomonas aeruginosa PAO1. Recent studies suggest that, in contrast to the H1-T6SS that targets prokaryotic cells, H2- and H3-T6SS are involved in interactions with both prokaryotic and eukaryotic cells. However, the detailed functions of T6SS components are still uncharacterized. The intracellular multiplication factor (IcmF) protein is conserved in type VI secretion systems (T6SS) of all different bacterial pathogens. Bioinformatic analysis revealed that IcmF3 in P. aeruginosa PAO1 is different from other IcmF homologs and may represent a new branch of these proteins with distinct functions. Herein, we have investigated the function of IcmF3 in this strain. We have shown that deletion of the icmF3 gene in P. aeruginosa PAO1 is associated with pleiotropic phenotypes. The icmF3 mutant has variant colony morphology and an hypergrowth phenotype in iron-limiting medium. Surprisingly, this mutant is also defective for the production of pyoverdine, as well as defects in swimming motility and virulence in a C. elegans worm model. The icmF3 mutant exhibits higher conjugation frequency than the wild type and increased biofilm formation on abiotic surfaces. Additionally, expression of two phenazine biosynthetic loci is increased in the icmF3 mutant, leading to the overproduction of pyocyanin. Finally, the mutant exhibits decreased susceptibility to aminoglycosides such as tobramycin and gentamicin. And the detected phenotypes can be restored completely or partially by trans complementation of wild type icmF3 gene. The pleiotropic effects observed upon icmF3 deletion demonstrate that icmF3 plays critical roles in both pathogenesis and environmental adaptation in P. aeruginosa PAO1.
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Affiliation(s)
- Jinshui Lin
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Juanli Cheng
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China ; Life Sciences Department, Yuncheng University Yuncheng, China
| | - Keqi Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Chenghao Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Weipeng Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Xu Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Wei Ding
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Li Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University Yangling, China
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Durand E, Nguyen VS, Zoued A, Logger L, Péhau-Arnaudet G, Aschtgen MS, Spinelli S, Desmyter A, Bardiaux B, Dujeancourt A, Roussel A, Cambillau C, Cascales E, Fronzes R. Biogenesis and structure of a type VI secretion membrane core complex. Nature 2015. [PMID: 26200339 DOI: 10.1038/nature14667] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bacteria share their ecological niches with other microbes. The bacterial type VI secretion system is one of the key players in microbial competition, as well as being an important virulence determinant during bacterial infections. It assembles a nano-crossbow-like structure in the cytoplasm of the attacker cell that propels an arrow made of a haemolysin co-regulated protein (Hcp) tube and a valine-glycine repeat protein G (VgrG) spike and punctures the prey's cell wall. The nano-crossbow is stably anchored to the cell envelope of the attacker by a membrane core complex. Here we show that this complex is assembled by the sequential addition of three type VI subunits (Tss)-TssJ, TssM and TssL-and present a structure of the fully assembled complex at 11.6 Å resolution, determined by negative-stain electron microscopy. With overall C5 symmetry, this 1.7-megadalton complex comprises a large base in the cytoplasm. It extends in the periplasm via ten arches to form a double-ring structure containing the carboxy-terminal domain of TssM (TssMct) and TssJ that is anchored in the outer membrane. The crystal structure of the TssMct-TssJ complex coupled to whole-cell accessibility studies suggest that large conformational changes induce transient pore formation in the outer membrane, allowing passage of the attacking Hcp tube/VgrG spike.
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Affiliation(s)
- Eric Durand
- 1] Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France [2] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [3] G5 Biologie structurale de la sécrétion bactérienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [4] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [5] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Van Son Nguyen
- 1] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Abdelrahim Zoued
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Laureen Logger
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | | | - Marie-Stéphanie Aschtgen
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Silvia Spinelli
- 1] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Aline Desmyter
- 1] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Benjamin Bardiaux
- 1] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [2] Unité de Bioinformatique Structurale, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France
| | - Annick Dujeancourt
- 1] G5 Biologie structurale de la sécrétion bactérienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [2] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France
| | - Alain Roussel
- 1] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Christian Cambillau
- 1] Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Université, IHU Méditerranée Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Rémi Fronzes
- 1] G5 Biologie structurale de la sécrétion bactérienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [2] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France
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Shyntum DY, Theron J, Venter SN, Moleleki LN, Toth IK, Coutinho TA. Pantoea ananatis Utilizes a Type VI Secretion System for Pathogenesis and Bacterial Competition. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:420-431. [PMID: 25411959 DOI: 10.1094/mpmi-07-14-0219-r] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Type VI secretion systems (T6SSs) are a class of macromolecular machines that are recognized as an important virulence mechanism in several gram-negative bacteria. The genome of Pantoea ananatis LMG 2665(T), a pathogen of pineapple fruit and onion plants, carries two gene clusters whose predicted products have homology with T6SS-associated gene products from other bacteria. Nothing is known regarding the role of these T6SS-1 and T6SS-3 gene clusters in the biology of P. ananatis. Here, we present evidence that T6SS-1 plays an important role in the pathogenicity of P. ananatis LMG 2665(T) in onion plants, while a strain lacking T6SS-3 remains as pathogenic as the wild-type strain. We also investigated the role of the T6SS-1 system in bacterial competition, the results of which indicated that several bacteria compete less efficiently against wild-type LMG 2665(T) than a strain lacking T6SS-1. Additionally, we demonstrated that these phenotypes of strain LMG 2665(T) were reliant on the core T6SS products TssA and TssD (Hcp), thus indicating that the T6SS-1 gene cluster encodes a functioning T6SS. Collectively, our data provide the first evidence demonstrating that the T6SS-1 system is a virulence determinant of P. ananatis LMG 2665(T) and plays a role in bacterial competition.
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Affiliation(s)
- Divine Y Shyntum
- 1 Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Sciences, and
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Ma LS, Hachani A, Lin JS, Filloux A, Lai EM. Agrobacterium tumefaciens deploys a superfamily of type VI secretion DNase effectors as weapons for interbacterial competition in planta. Cell Host Microbe 2014; 16:94-104. [PMID: 24981331 PMCID: PMC4096383 DOI: 10.1016/j.chom.2014.06.002] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/06/2014] [Accepted: 05/27/2014] [Indexed: 01/02/2023]
Abstract
The type VI secretion system (T6SS) is a widespread molecular weapon deployed by many Proteobacteria to target effectors/toxins into both eukaryotic and prokaryotic cells. We report that Agrobacterium tumefaciens, a soil bacterium that triggers tumorigenesis in plants, produces a family of type VI DNase effectors (Tde) that are distinct from previously known polymorphic toxins and nucleases. Tde exhibits an antibacterial DNase activity that relies on a conserved HxxD motif and can be counteracted by a cognate immunity protein, Tdi. In vitro, A. tumefaciens T6SS could kill Escherichia coli but triggered a lethal counterattack by Pseudomonas aeruginosa upon injection of the Tde toxins. However, in an in planta coinfection assay, A. tumefaciens used Tde effectors to attack both siblings cells and P. aeruginosa to ultimately gain a competitive advantage. Such acquired T6SS-dependent fitness in vivo and conservation of Tde-Tdi couples in bacteria highlights a widespread antibacterial weapon beneficial for niche colonization.
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Affiliation(s)
- Lay-Sun Ma
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Abderrahman Hachani
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Jer-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
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Abstract
UNLABELLED The genome sequences of intestinal Bacteroidales strains reveal evidence of extensive horizontal gene transfer. In vitro studies of Bacteroides and other bacteria have addressed mechanisms of conjugative transfer and some phenotypic outcomes of these DNA acquisitions in the recipient, such as the acquisition of antibiotic resistance. However, few studies have addressed the horizontal transfer of genetic elements between bacterial species coresident in natural microbial communities, especially microbial ecosystems of humans. Here, we examine the genomes of Bacteroidales species from two human adults to identify genetic elements that were likely transferred among these Bacteroidales while they were coresident in the intestine. Using seven coresident Bacteroidales species from one individual and eight from another, we identified five large chromosomal regions, each present in a minimum of three of the coresident strains at near 100% DNA identity. These five regions are not found in any other sequenced Bacteroidetes genome at this level of identity and are likely all integrative conjugative elements (ICEs). Such highly similar and unique regions occur in only 0.4% of phylogenetically representative mock communities, providing strong evidence that these five regions were transferred between coresident strains in these subjects. In addition to the requisite proteins necessary for transfer, these elements encode proteins predicted to increase fitness, including orphan DNA methylases that may alter gene expression, fimbriae synthesis proteins that may facilitate attachment and the utilization of new substrates, putative secreted antimicrobial molecules, and a predicted type VI secretion system (T6SS), which may confer a competitive ecological advantage to these strains in their complex microbial ecosystem. IMPORTANCE By analyzing Bacteroidales strains coresident in the gut microbiota of two human adults, we provide strong evidence for extensive interspecies and interfamily transfer of integrative conjugative elements within the intestinal microbiota of individual humans. In the recipient strain, we show that the conjugative elements themselves can be modified by the transposition of insertion sequences and retroelements from the recipient's genome, with subsequent transfer of these modified elements to other members of the microbiota. These data suggest that the genomes of our gut bacteria are substantially modified by other, coresident members of the ecosystem, resulting in highly personalized Bacteroidales strains likely unique to that individual. The genetic content of these ICEs suggests that their transfer from successful adapted members of an ecosystem confers beneficial properties to the recipient, increasing its fitness and allowing it to better compete within its particular personalized gut microbial ecosystem.
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Zoued A, Brunet YR, Durand E, Aschtgen MS, Logger L, Douzi B, Journet L, Cambillau C, Cascales E. Architecture and assembly of the Type VI secretion system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1664-73. [PMID: 24681160 DOI: 10.1016/j.bbamcr.2014.03.018] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 12/31/2022]
Abstract
The Type VI secretion system (T6SS) delivers protein effectors to diverse cell types including prokaryotic and eukaryotic cells, therefore it participates in inter-bacterial competition and pathogenesis. The T6SS is constituted of an envelope-spanning complex anchoring a cytoplasmic tubular edifice. This tubular structure is evolutionarily, functionally and structurally related to the tail of contractile phages. It is composed of an inner tube tipped by a spike complex, and engulfed within a sheath-like structure. This structure assembles onto a platform called "baseplate" that is connected to the membrane sub-complex. The T6SS functions as a nano-crossbow: upon contraction of the sheath, the inner tube is propelled towards the target cell, allowing effector delivery. This review focuses on the architecture and biogenesis of this fascinating secretion machine, highlighting recent advances regarding the assembly of the membrane or tail complexes. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Abdelrahim Zoued
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Yannick R Brunet
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Eric Durand
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Marie-Stéphanie Aschtgen
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Laureen Logger
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Badreddine Douzi
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Laure Journet
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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