101
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Stolle AS, Meader BT, Toska J, Mekalanos JJ. Endogenous membrane stress induces T6SS activity in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2021; 118:e2018365118. [PMID: 33443205 PMCID: PMC7817224 DOI: 10.1073/pnas.2018365118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The type 6 secretion system (T6SS) is a dynamic organelle encoded by many gram-negative bacteria that can be used to kill competing bacterial prey species in densely occupied niches. Some predatory species, such as Vibrio cholerae, use their T6SS in an untargeted fashion while in contrast, Pseudomonas aeruginosa assembles and fires its T6SS apparatus only after detecting initial attacks by other bacterial prey cells; this targeted attack strategy has been termed the T6SS tit-for-tat response. Molecules that interact with the P. aeruginosa outer membrane such as polymyxin B can also trigger assembly of T6SS organelles via a signal transduction pathway that involves protein phosphorylation. Recent work suggests that a phospholipase T6SS effector (TseL) of V. cholerae can induce T6SS dynamic activity in P. aeruginosa when delivered to or expressed in the periplasmic space of this organism. Here, we report that inhibiting expression of essential genes involved in outer membrane biogenesis can also trigger T6SS activation in P. aeruginosa Specifically, we developed a CRISPR interference (CRISPRi) system to knock down expression of bamA, tolB, and lptD and found that these knockdowns activated T6SS activity. This increase in T6SS activity was dependent on the same signal transduction pathway that was previously shown to be required for the tit-for-tat response. We conclude that outer membrane perturbation can be sensed by P. aeruginosa to activate the T6SS even when the disruption is generated by aberrant cell envelope biogenesis.
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Affiliation(s)
- Anne-Sophie Stolle
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
- Institute of Infectiology, Center for Molecular Biology of Inflammation, University of Münster, 48149 Münster, Germany
| | | | - Jonida Toska
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
| | - John J Mekalanos
- Department of Microbiology, Harvard Medical School, Boston, MA 02115;
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102
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The β-encapsulation cage of rearrangement hotspot (Rhs) effectors is required for type VI secretion. Proc Natl Acad Sci U S A 2020; 117:33540-33548. [PMID: 33323487 DOI: 10.1073/pnas.1919350117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria deploy rearrangement hotspot (Rhs) proteins as toxic effectors against both prokaryotic and eukaryotic target cells. Rhs proteins are characterized by YD-peptide repeats, which fold into a large β-cage structure that encapsulates the C-terminal toxin domain. Here, we show that Rhs effectors are essential for type VI secretion system (T6SS) activity in Enterobacter cloacae (ECL). ECL rhs - mutants do not kill Escherichia coli target bacteria and are defective for T6SS-dependent export of hemolysin-coregulated protein (Hcp). The RhsA and RhsB effectors of ECL both contain Pro-Ala-Ala-Arg (PAAR) repeat domains, which bind the β-spike of trimeric valine-glycine repeat protein G (VgrG) and are important for T6SS activity in other bacteria. Truncated RhsA that retains the PAAR domain is capable of forming higher-order, thermostable complexes with VgrG, yet these assemblies fail to restore secretion activity to ∆rhsA ∆rhsB mutants. Full T6SS-1 activity requires Rhs that contains N-terminal transmembrane helices, the PAAR domain, and an intact β-cage. Although ∆rhsA ∆rhsB mutants do not kill target bacteria, time-lapse microscopy reveals that they assemble and fire T6SS contractile sheaths at ∼6% of the frequency of rhs + cells. Therefore, Rhs proteins are not strictly required for T6SS assembly, although they greatly increase secretion efficiency. We propose that PAAR and the β-cage provide distinct structures that promote secretion. PAAR is clearly sufficient to stabilize trimeric VgrG, but efficient assembly of T6SS-1 also depends on an intact β-cage. Together, these domains enforce a quality control checkpoint to ensure that VgrG is loaded with toxic cargo before assembling the secretion apparatus.
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103
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Wang P, Dong JF, Li RQ, Li L, Zou QH. Roles of the Hcp family proteins in the pathogenicity of Salmonella typhimurium 14028s. Virulence 2020; 11:1716-1726. [PMID: 33300449 PMCID: PMC7733977 DOI: 10.1080/21505594.2020.1854538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The type VI secretion system (T6SS) is a new secretion system that is widely distributed among Gram-negative bacteria. The core component hemolysin-coregulated protein (Hcp) can be used as both its structural protein and secretory protein or chaperone protein. Studies on Hcp are important to elucidate the overall virulence mechanism of T6SS. Salmonella typhimurium is an important foodborne pathogen. There are three copies of hcp genes identified in S. Typhimurium 14028s. This study aimed to characterize the functions of the three Hcp family proteins and to elucidate the interactions among them. The hcp gene deletion mutants were constructed by λ Red-based recombination system. Effects of hcp mutation on the pathogenicity of 14028s were studied by bacterial competition assays, Dictyostelium discoideum assays and mouse model. The three Hcp family proteins were found to play different roles. Hcp1 can affect the transcription of rpoS and type 2 flagellar gene and influence the motility of 14028s. It is also involved in the intracellular survival of 14028s in Dictyostelium discoideum; Hcp2 is involved in the early proliferative capacity of 14028s in mice and can prevent its excessive proliferation; Hcp3 did not show direct functions in these assays. Hcp1 can interact with Hcp2 and Hcp3. Deletion of one hcp gene can result in a transcription level variation in the other two hcp genes. Our findings elucidated the functions of the three Hcp family proteins in S.Typhimurium and illustrated that there are interactions between different Hcp proteins. This study will be helpful to fully understand how T6SS actions in an organism.
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Affiliation(s)
- Ping Wang
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Jun-Fang Dong
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Ren-Qing Li
- Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine , Beijing, China
| | - Lei Li
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China.,The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology , Beijing, China
| | - Qing-Hua Zou
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
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104
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Jurėnas D, Journet L. Activity, delivery, and diversity of Type VI secretion effectors. Mol Microbiol 2020; 115:383-394. [PMID: 33217073 DOI: 10.1111/mmi.14648] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/28/2022]
Abstract
The bacterial type VI secretion system (T6SS) system is a contractile secretion apparatus that delivers proteins to neighboring bacterial or eukaryotic cells. Antibacterial effectors are mostly toxins that inhibit the growth of other species and help to dominate the niche. A broad variety of these toxins cause cell lysis of the prey cell by disrupting the cell envelope. Other effectors are delivered into the cytoplasm where they affect DNA integrity, cell division or exhaust energy resources. The modular nature of T6SS machinery allows different means of recruitment of toxic effectors to secreted inner tube and spike components that act as carriers. Toxic effectors can be translationally fused to the secreted components or interact with them through specialized structural domains. These interactions can also be assisted by dedicated chaperone proteins. Moreover, conserved sequence motifs in effector-associated domains are subject to genetic rearrangements and therefore engage in the diversification of the arsenal of toxic effectors. This review discusses the diversity of T6SS secreted toxins and presents current knowledge about their loading on the T6SS machinery.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
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105
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Santoriello FJ, Michel L, Unterweger D, Pukatzki S. Pandemic Vibrio cholerae shuts down site-specific recombination to retain an interbacterial defence mechanism. Nat Commun 2020; 11:6246. [PMID: 33288753 PMCID: PMC7721734 DOI: 10.1038/s41467-020-20012-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 11/06/2020] [Indexed: 12/18/2022] Open
Abstract
Vibrio cholerae is an aquatic microbe that can be divided into three subtypes: harmless environmental strains, localised pathogenic strains, and pandemic strains causing global cholera outbreaks. Each type has a contact-dependent type VI secretion system (T6SS) that kills neighbouring competitors by translocating unique toxic effector proteins. Pandemic isolates possess identical effectors, indicating that T6SS effectors may affect pandemicity. Here, we show that one of the T6SS gene clusters (Aux3) exists in two states: a mobile, prophage-like element in a small subset of environmental strains, and a truncated Aux3 unique to and conserved in pandemic isolates. Environmental Aux3 can be readily excised from and integrated into the genome via site-specific recombination, whereas pandemic Aux3 recombination is reduced. Our data suggest that environmental Aux3 acquisition conferred increased competitive fitness to pre-pandemic V. cholerae, leading to grounding of the element in the chromosome and propagation throughout the pandemic clade. Vibrio cholerae uses a type VI secretion system (T6SS) to kill neighbouring competitors. Here, Santoriello et al. show that a T6SS gene cluster (Aux3) exists as a mobile, prophage-like element in some environmental strains, and as a stable truncated form in pandemic isolates. They propose that Aux3 acquisition increased competitive fitness of pre-pandemic V. cholerae.
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Affiliation(s)
- Francis J Santoriello
- Department of Immunology and Microbiology, University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA.,Department of Biology, The City College of New York, 160 Convent Ave, New York, NY, 10031, USA
| | - Lina Michel
- Department of Immunology and Microbiology, University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA.,Heidelberg University, Grabengasse 1, 69117, Heidelberg, Germany
| | - Daniel Unterweger
- Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, 24105, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306, Plön, Germany
| | - Stefan Pukatzki
- Department of Immunology and Microbiology, University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA. .,Department of Biology, The City College of New York, 160 Convent Ave, New York, NY, 10031, USA.
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106
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Umrekar TR, Cohen E, Drobnič T, Gonzalez-Rodriguez N, Beeby M. CryoEM of bacterial secretion systems: A primer for microbiologists. Mol Microbiol 2020; 115:366-382. [PMID: 33140482 DOI: 10.1111/mmi.14637] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022]
Abstract
"CryoEM" has come of age, enabling considerable structural insights into many facets of molecular biology. Here, we present a primer for microbiologists to understand the capabilities and limitations of two complementary cryoEM techniques for studying bacterial secretion systems. The first, single particle analysis, determines the structures of purified protein complexes to resolutions sufficient for molecular modeling, while the second, electron cryotomography and subtomogram averaging, tends to determine more modest resolution structures of protein complexes in intact cells. We illustrate these abilities with examples of insights provided into how secretion systems work by cryoEM, with a focus on type III secretion systems.
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Affiliation(s)
| | - Eli Cohen
- Department of Life Sciences, Imperial College London, London, UK
| | - Tina Drobnič
- Department of Life Sciences, Imperial College London, London, UK
| | | | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, UK
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107
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González-Magaña A, Sainz-Polo MÁ, Pretre G, Çapuni R, Lucas M, Altuna J, Montánchez I, Fucini P, Albesa-Jové D. Structural insights into Pseudomonas aeruginosaType six secretion system exported effector 8. J Struct Biol 2020; 212:107651. [PMID: 33096229 DOI: 10.1016/j.jsb.2020.107651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/24/2022]
Abstract
Recent reports indicate that the Type six secretion system exported effector 8 (Tse8) is a cytoactive effector secreted by the Type VI secretion system (T6SS) of the human pathogen Pseudomonas aeruginosa. The T6SS is a nanomachine that assembles inside of the bacteria and injects effectors/toxins into target cells, providing a fitness advantage over competing bacteria and facilitating host colonisation. Here we present the first crystal structure of Tse8 revealing that it conserves the architecture of the catalytic triad Lys84-transSer162-Ser186 that characterises members of the Amidase Signature superfamily. Furthermore, using binding affinity experiments, we show that the interaction of phenylmethylsulfonyl fluoride (PMSF) to Tse8 is dependent on the putative catalytic residue Ser186, providing support for its nucleophilic reactivity. This work thus demonstrates that Tse8 belongs to the Amidase Signature (AS) superfamily. Furthermore, it highlights Tse8 similarity to two family members: the Stenotrophomonas maltophilia Peptide Amidase and the Glutamyl-tRNAGln amidotransferase subunit A from Staphylococcus aureus.
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Affiliation(s)
- Amaia González-Magaña
- Instituto Biofisika (UPV/EHU, CSIC), Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, University of the Basque Country, 48940 Leioa, Spain
| | - M Ángela Sainz-Polo
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - Gabriela Pretre
- Instituto Biofisika (UPV/EHU, CSIC), Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, University of the Basque Country, 48940 Leioa, Spain
| | - Retina Çapuni
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - María Lucas
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Cantabria. Santander, 39011 Cantabria, Spain
| | - Jon Altuna
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - Itxaso Montánchez
- Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940 Leioa, Spain
| | - Paola Fucini
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - David Albesa-Jové
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
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108
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Vibrio cholerae Type VI Activity Alters Motility Behavior in Mucin. J Bacteriol 2020; 202:JB.00261-20. [PMID: 32868403 DOI: 10.1128/jb.00261-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/11/2020] [Indexed: 01/16/2023] Open
Abstract
Motility is required for many bacterial pathogens to reach and colonize target sites. Vibrio cholerae traverses a thick mucus barrier coating the small intestine to reach the underlying epithelium. We screened a transposon library in motility medium containing mucin to identify factors that influence mucus transit. Lesions in structural genes of the type VI secretion system (T6SS) were among those recovered. Two-dimensional (2D) and 3D single-cell tracking was used to compare the motility behaviors of wild-type cells and a mutant that collectively lacked three essential T6SS structural genes (T6SS-). In the absence of mucin, wild-type and T6SS- cells exhibited similar speeds and run-reverse-flick (RRF) swimming patterns, in which forward-moving cells briefly backtrack before stochastically reorienting (flicking) in a new direction upon resuming forward movement. We show that mucin induced T6SS expression and activity in wild-type bacteria but significantly decreased their swimming speed and flicking, yielding curvilinear or near-surface circular traces for many cells. Conversely, mucin slowed T6SS- cells to a lesser extent, and many continued to flick and produce RRF-like traces. ΔcheY3 cells, which exclusively swim in the forward direction and thus cannot flick, also produced curvilinear traces with or without mucin present and, on occasion, near-surface circular traces in the presence of mucin. The dependence of flicking on swimming speed suggested that mucin-induced T6SS activity further decreased V. cholerae motility and thereby reduced flicking probability during reverse-to-forward transitions. We propose that this encourages cells to continue on their current trajectory rather than reorienting, which may benefit those tracking toward the epithelial surface.IMPORTANCE V. cholerae deploys an arsenal of virulence factors as it attempts to traverse a protective mucus layer and reach the epithelial surface of the distal small intestine. The T6SS used to cull bacterial competition during infection is induced by mucus. We show that this activity may serve an additional purpose by further decreasing motility in the presence of mucin, thereby reducing the probability of speed-dependent, near-perpendicular directional changes. We posit that this encourages cells to maintain course rather than change direction, which may aid those attempting to reach and colonize the epithelial surface.
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109
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Lin HH, Filloux A, Lai EM. Role of Recipient Susceptibility Factors During Contact-Dependent Interbacterial Competition. Front Microbiol 2020; 11:603652. [PMID: 33281802 PMCID: PMC7690452 DOI: 10.3389/fmicb.2020.603652] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/13/2020] [Indexed: 11/13/2022] Open
Abstract
Bacteria evolved multiple strategies to survive and develop optimal fitness in their ecological niche. They deployed protein secretion systems for robust and efficient delivery of antibacterial toxins into their target cells, therefore inhibiting their growth or killing them. To maximize antagonism, recipient factors on target cells can be recognized or hijacked to enhance the entry or toxicity of these toxins. To date, knowledge regarding recipient susceptibility (RS) factors and their mode of action is mostly originating from studies on the type Vb secretion system that is also known as the contact-dependent inhibition (CDI) system. Yet, recent studies on the type VI secretion system (T6SS), and the CDI by glycine-zipper protein (Cdz) system, also reported the emerging roles of RS factors in interbacterial competition. Here, we review these RS factors and their mechanistic impact in increasing susceptibility of recipient cells in response to CDI, T6SS, and Cdz. Past and future strategies for identifying novel RS factors are also discussed, which will help in understanding the interplay between attacker and prey upon secretion system-dependent competition. Understanding these mechanisms would also provide insights for developing novel antibacterial strategies to antagonize aggressive bacteria-killing pathogens.
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Affiliation(s)
- Hsiao-Han Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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110
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Ye C, Ge Y, Zhang Y, Zhou L, Chen W, Zhu X, Pan J. Deletion of vp0057, a Gene Encoding a Ser/Thr Protein Kinase, Impacts the Proteome and Promotes Iron Uptake and Competitive Advantage in Vibrio parahaemolyticus. J Proteome Res 2020; 20:250-260. [PMID: 33112629 DOI: 10.1021/acs.jproteome.0c00361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The marine bacterial pathogen Vibrio parahaemolyticus is a major cause of food-borne gastroenteritis. Recent findings have demonstrated that protein phosphorylation is fundamental to the regulation of many physiological processes in pathogenic bacteria, including bacterial virulence. However, the underlying mechanisms remain to be completely clarified. Using bioinformatics analysis, we found that VP0057 may be a potential Ser/Thr protein kinase with phosphorylation activity. Thus, we constructed the vp0057-deletion mutant (Δvp0057) from the wild-type V. parahaemolyticus serotype O3:K6 and employed a mass spectrometry-based proteomic strategy to characterize proteome-wide changes in response to vp0057 deletion, owing to the potential roles of VP0057 in V. parahaemolyticus. One hundred ninety-seven differentially expressed proteins were identified in the Δvp0057 strain compared with the wild-type strain, among which 135 proteins were upregulated and 62 proteins were downregulated. Detailed annotation of these differentially expressed proteins was conducted. Notably, iron-related and T6SS1-related proteins were upregulated in the Δvp0057 strain, corroborating the results by quantitative PCR. Further experiments proved that vp0057 deletion promotes Fe2+ and Fe3+ uptake and provides a growth competition advantage, which is controlled by iron-related and T6SS1-related proteins, respectively. Although the regulatory roles and mechanisms of VP0057 remain to be revealed in V. parahaemolyticus, our systemic analysis of the protein profile of Δvp0057 provides a promising starting point for the intensive exploration of VP0057.
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Affiliation(s)
- Chen Ye
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Yongze Ge
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Yue Zhang
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Lantian Zhou
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Wei Chen
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xuan Zhu
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Jianyi Pan
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China
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111
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Qin Z, Yang X, Chen G, Park C, Liu Z. Crosstalks Between Gut Microbiota and Vibrio Cholerae. Front Cell Infect Microbiol 2020; 10:582554. [PMID: 33194819 PMCID: PMC7644805 DOI: 10.3389/fcimb.2020.582554] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 09/17/2020] [Indexed: 12/11/2022] Open
Abstract
Vibrio cholerae, the causative agent of cholera, could proliferate in aquatic environment and infect humans through contaminated food and water. Enormous microorganisms residing in human gastrointestinal tract establish a special microecological system, which immediately responds to the invasion of V. cholerae, through “colonization resistance” mechanisms, such as antimicrobial peptide production, nutrients competition, and intestinal barrier maintenances. Meanwhile, V. cholerae could quickly sense those signals and modulate the expression of relevant genes to circumvent those stresses during infection, leading to successful colonization on the surface of small intestinal epithelial cells. In this review, we summarized the crosstalks profiles between gut microbiota and V. cholerae in the terms of Type VI Secretion System (T6SS), Quorum Sensing (QS), Reactive Oxygen Species (ROS)/pH stress, and Bioactive metabolites. These mechanisms can also be applied to molecular bacterial pathogenesis of other pathogens in host.
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Affiliation(s)
- Zixin Qin
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoman Yang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Guozhong Chen
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Chaiwoo Park
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi Liu
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
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112
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Vibrio cholerae-Symbiont Interactions Inhibit Intestinal Repair in Drosophila. Cell Rep 2020; 30:1088-1100.e5. [PMID: 31995751 DOI: 10.1016/j.celrep.2019.12.094] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/28/2019] [Accepted: 12/27/2019] [Indexed: 11/20/2022] Open
Abstract
Pathogen-mediated damage to the intestinal epithelium activates compensatory growth and differentiation repair programs in progenitor cells. Accelerated progenitor growth replenishes damaged tissue and maintains barrier integrity. Despite the importance of epithelial renewal to intestinal homeostasis, we know little about the effects of pathogen-commensal interactions on progenitor growth. We find that the enteric pathogen Vibrio cholerae blocks critical growth and differentiation pathways in Drosophila progenitors, despite extensive damage to epithelial tissue. We show that the inhibition of epithelial repair requires interactions between the Vibrio cholerae type six secretion system and a community of common symbiotic bacteria, as elimination of the gut microbiome is sufficient to restore homeostatic growth in infected intestines. This work highlights the importance of pathogen-symbiont interactions for intestinal immune responses and outlines the impact of the type six secretion system on pathogenesis.
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113
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Monjarás Feria J, Valvano MA. An Overview of Anti-Eukaryotic T6SS Effectors. Front Cell Infect Microbiol 2020; 10:584751. [PMID: 33194822 PMCID: PMC7641602 DOI: 10.3389/fcimb.2020.584751] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/22/2020] [Indexed: 12/24/2022] Open
Abstract
The type VI secretion system (T6SS) is a transmembrane multiprotein nanomachine employed by many Gram-negative bacterial species to translocate, in a contact-dependent manner, effector proteins into adjacent prokaryotic or eukaryotic cells. Typically, the T6SS gene cluster encodes at least 13 conserved core components for the apparatus assembly and other less conserved accessory proteins and effectors. It functions as a contractile tail machine comprising a TssB/C sheath and an expelled puncturing device consisting of an Hcp tube topped by a spike complex of VgrG and PAAR proteins. Contraction of the sheath propels the tube out of the bacterial cell into a target cell and leads to the injection of toxic proteins. Different bacteria use the T6SS for specific roles according to the niche and versatility of the organism. Effectors are present both as cargo (by non-covalent interactions with one of the core components) or specialized domains (fused to structural components). Although several anti-prokaryotic effectors T6SSs have been studied, recent studies have led to a substantial increase in the number of characterized anti-eukaryotic effectors. Against eukaryotic cells, the T6SS is involved in modifying and manipulating diverse cellular processes that allows bacteria to colonize, survive and disseminate, including adhesion modification, stimulating internalization, cytoskeletal rearrangements and evasion of host innate immune responses.
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Affiliation(s)
| | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
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114
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Wood TE, Aksoy E, Hachani A. From Welfare to Warfare: The Arbitration of Host-Microbiota Interplay by the Type VI Secretion System. Front Cell Infect Microbiol 2020; 10:587948. [PMID: 33194832 PMCID: PMC7604300 DOI: 10.3389/fcimb.2020.587948] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/22/2020] [Indexed: 12/17/2022] Open
Abstract
The health of mammals depends on a complex interplay with their microbial ecosystems. Compartments exposed to external environments such as the mucosal surfaces of the gastrointestinal tract accommodate the gut microbiota, composed by a wide range of bacteria. The gut microbiome confers benefits to the host, including expansion of metabolic potential and the development of an immune system that can robustly protect from external and internal insults. The cooperation between gut microbiome and host is enabled in part by the formation of partitioned niches that harbor diverse bacterial phyla. Bacterial secretion systems are commonly employed to manipulate the composition of these local environments. Here, we explore the roles of the bacterial type VI secretion system (T6SS), present in ~25% of gram-negative bacteria, including many symbionts, in the establishment and perturbation of bacterial commensalism, and symbiosis in host mucosal sites. This versatile apparatus drives bacterial competition, although in some cases can also interfere directly with host cells and facilitate nutrient acquisition. In addition, some bacterial pathogens cause disease when their T6SS leads to dysbiosis and subverts host immune responses in defined animal models. This review explores our knowledge of the T6SS in the context of the “host-microbiota-pathogen” triumvirate and examines contexts in which the importance of this secretion system may be underappreciated.
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Affiliation(s)
- Thomas E Wood
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA, United States.,Department of Microbiology, Harvard Medical School, Boston, MA, United States
| | - Ezra Aksoy
- Centre for Biochemical Pharmacology, William Harvey Research Institute, Queen Mary University of London, London, United Kingdom
| | - Abderrahman Hachani
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
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115
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Perault AI, Chandler CE, Rasko DA, Ernst RK, Wolfgang MC, Cotter PA. Host Adaptation Predisposes Pseudomonas aeruginosa to Type VI Secretion System-Mediated Predation by the Burkholderia cepacia Complex. Cell Host Microbe 2020; 28:534-547.e3. [PMID: 32755549 PMCID: PMC7554260 DOI: 10.1016/j.chom.2020.06.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/05/2020] [Accepted: 06/24/2020] [Indexed: 12/14/2022]
Abstract
Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc) species are opportunistic lung pathogens of cystic fibrosis (CF) patients. While P. aeruginosa can initiate long-term infections in younger CF patients, Bcc infections only arise in teenagers and adults. Both P. aeruginosa and Bcc use type VI secretion systems (T6SSs) to mediate interbacterial competition. Here, we show P. aeruginosa isolates from teenage and adult CF patients, but not those from young CF patients, are outcompeted by the epidemic Bcc isolate Burkholderia cenocepacia strain AU1054 in a T6SS-dependent manner. The genomes of susceptible P. aeruginosa isolates harbor T6SS-abrogating mutations, the repair of which, in some cases, rendered the isolates resistant. Moreover, seven of eight Bcc strains outcompeted P. aeruginosa strains isolated from the same patients. Our findings suggest certain mutations that arise as P. aeruginosa adapts to the CF lung abrogate T6SS activity, making P. aeruginosa and its human host susceptible to potentially fatal Bcc superinfection.
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Affiliation(s)
- Andrew I Perault
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Courtney E Chandler
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - David A Rasko
- Institute for Genome Sciences, University of Maryland, Baltimore, Baltimore, MD 21201, USA; Department of Microbiology and Immunology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Matthew C Wolfgang
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Marsio Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Peggy A Cotter
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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116
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Drebes Dörr NC, Blokesch M. Interbacterial competition and anti-predatory behaviour of environmental Vibrio cholerae strains. Environ Microbiol 2020; 22:4485-4504. [PMID: 32885535 PMCID: PMC7702109 DOI: 10.1111/1462-2920.15224] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 12/21/2022]
Abstract
Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of environmental V. cholerae with eukaryotic predators or competing bacteria and tested the contributions of the haemolysin and the type VI secretion system (T6SS) to those interactions. Both of these molecular weapons are constitutively active in environmental isolates but subject to tight regulation in the pandemic clade. We showed that several environmental isolates resist amoebal grazing and that this anti‐grazing defense relies on the strains' T6SS and its actincross‐linking domain (ACD)‐containing tip protein. Strains lacking the ACD were unable to defend themselves against grazing amoebae but maintained high levels of T6SS‐dependent interbacterial killing. We explored the latter phenotype through whole‐genome sequencing of 14 isolates, which unveiled a wide array of novel T6SS effector and (orphan) immunity proteins. By combining these in silico predictions with experimental validations, we showed that highly similar but non‐identical immunity proteins were insufficient to provide cross‐immunity among those wild strains.
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Affiliation(s)
- Natália C Drebes Dörr
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
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117
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Rocchi I, Ericson CF, Malter KE, Zargar S, Eisenstein F, Pilhofer M, Beyhan S, Shikuma NJ. A Bacterial Phage Tail-like Structure Kills Eukaryotic Cells by Injecting a Nuclease Effector. Cell Rep 2020; 28:295-301.e4. [PMID: 31291567 DOI: 10.1016/j.celrep.2019.06.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/09/2019] [Accepted: 06/05/2019] [Indexed: 11/28/2022] Open
Abstract
Many bacteria interact with target organisms using syringe-like structures called contractile injection systems (CISs). CISs structurally resemble headless bacteriophages and share evolutionarily related proteins such as the tail tube, sheath, and baseplate complex. In many cases, CISs mediate trans-kingdom interactions between bacteria and eukaryotes by delivering effectors to target cells. However, the specific effectors and their modes of action are often unknown. Here, we establish an ex vivo model to study an extracellular CIS (eCIS) called metamorphosis-associated contractile structures (MACs) that target eukaryotic cells. MACs kill two eukaryotic cell lines, fall armyworm Sf9 cells and J774A.1 murine macrophage cells, by translocating an effector termed Pne1. Before the identification of Pne1, no CIS effector exhibiting nuclease activity against eukaryotic cells had been described. Our results define a new mechanism of CIS-mediated bacteria-eukaryote interaction and are a step toward developing CISs as novel delivery systems for eukaryotic hosts.
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Affiliation(s)
- Iara Rocchi
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Charles F Ericson
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Kyle E Malter
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Sahar Zargar
- Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Fabian Eisenstein
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Martin Pilhofer
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Sinem Beyhan
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA.
| | - Nicholas J Shikuma
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA.
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118
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Wood TE, Howard SA, Förster A, Nolan LM, Manoli E, Bullen NP, Yau HCL, Hachani A, Hayward RD, Whitney JC, Vollmer W, Freemont PS, Filloux A. The Pseudomonas aeruginosa T6SS Delivers a Periplasmic Toxin that Disrupts Bacterial Cell Morphology. Cell Rep 2020; 29:187-201.e7. [PMID: 31577948 PMCID: PMC6899460 DOI: 10.1016/j.celrep.2019.08.094] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/02/2019] [Accepted: 08/27/2019] [Indexed: 01/10/2023] Open
Abstract
The type VI secretion system (T6SS) is crucial in interbacterial competition and is a virulence determinant of many Gram-negative bacteria. Several T6SS effectors are covalently fused to secreted T6SS structural components such as the VgrG spike for delivery into target cells. In Pseudomonas aeruginosa, the VgrG2b effector was previously proposed to mediate bacterial internalization into eukaryotic cells. In this work, we find that the VgrG2b C-terminal domain (VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein. We resolve the structure of VgrG2bC-ter and confirm it is a member of the zinc-metallopeptidase family of enzymes. We show that this effector causes membrane blebbing at midcell, which suggests a distinct type of T6SS-mediated growth inhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Our study introduces a further effector family to the T6SS arsenal and demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells. The structure of the VgrG2b C-terminal domain presents a metallopeptidase fold VgrG2b exerts antibacterial activity in the periplasmic space Toxicity of VgrG2b is counteracted by a cognate periplasmic immunity protein VgrG2bC-ter-intoxicated prey cells bleb at the midcell and lyse
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Affiliation(s)
- Thomas E Wood
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Sophie A Howard
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Andreas Förster
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Laura M Nolan
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Nathan P Bullen
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Hamish C L Yau
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Abderrahman Hachani
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Richard D Hayward
- Division of Microbiology and Parasitology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
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119
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Chen L, Song N, Liu B, Zhang N, Alikhan NF, Zhou Z, Zhou Y, Zhou S, Zheng D, Chen M, Hapeshi A, Healey J, Waterfield NR, Yang J, Yang G. Genome-wide Identification and Characterization of a Superfamily of Bacterial Extracellular Contractile Injection Systems. Cell Rep 2020; 29:511-521.e2. [PMID: 31597107 PMCID: PMC6899500 DOI: 10.1016/j.celrep.2019.08.096] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/11/2019] [Accepted: 08/28/2019] [Indexed: 11/30/2022] Open
Abstract
Several phage-tail-like nanomachines were shown to play an important role in the interactions between bacteria and their eukaryotic hosts. These apparatuses appear to represent a new injection paradigm. Here, with three verified extracellular contractile injection systems (eCISs), a protein profile and genomic context-based iterative approach was applied to identify 631 eCIS-like loci from the 11,699 publicly available complete bacterial genomes. The eCIS superfamily, which is phylogenetically diverse and sub-divided into six families, is distributed among Gram-negative and -positive bacteria in addition to archaea. Our results show that very few bacteria are seen to possess intact operons of both eCIS and type VI secretion systems (T6SSs). An open access online database of all detected eCIS-like loci is presented to facilitate future studies. The presence of this bacterial injection machine in a multitude of organisms suggests that it may play an important ecological role in the life cycles of many bacteria. eCIS loci are widely distributed among bacteria genomes eCIS loci encode phage-tail-like proteinaceous machines eCIS superfamily is grouped into six families with distinct genetic features
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Affiliation(s)
- Lihong Chen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China
| | - Nan Song
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China; Beijing Institute of Tropical Medicine, Beijing 100050, China
| | - Bo Liu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China
| | - Nan Zhang
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China; Beijing Institute of Tropical Medicine, Beijing 100050, China
| | - Nabil-Fareed Alikhan
- Warwick Medical School, Warwick University, Coventry CV4 7AL, UK; Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UG, UK
| | - Zhemin Zhou
- Warwick Medical School, Warwick University, Coventry CV4 7AL, UK
| | - Yanyan Zhou
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Siyu Zhou
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China
| | - Dandan Zheng
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China
| | - Mingxing Chen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China
| | - Alexia Hapeshi
- Warwick Medical School, Warwick University, Coventry CV4 7AL, UK
| | - Joseph Healey
- Warwick Medical School, Warwick University, Coventry CV4 7AL, UK
| | | | - Jian Yang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100176, China.
| | - Guowei Yang
- Emergency and Critical Care Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China; Beijing Institute of Tropical Medicine, Beijing 100050, China.
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120
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Kreuzer M, Hardt WD. How Food Affects Colonization Resistance Against Enteropathogenic Bacteria. Annu Rev Microbiol 2020; 74:787-813. [DOI: 10.1146/annurev-micro-020420-013457] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Food has a major impact on all aspects of health. Recent data suggest that food composition can also affect susceptibility to infections by enteropathogenic bacteria. Here, we discuss how food may alter the microbiota as well as mucosal defenses and how this can affect infection. Salmonella Typhimurium diarrhea serves as a paradigm, and complementary evidence comes from other pathogens. We discuss the effects of food composition on colonization resistance, host defenses, and the infection process as well as the merits and limitations of mouse models and experimental foods, which are available to decipher the underlying mechanisms.
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Affiliation(s)
- Markus Kreuzer
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
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121
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Using proteomics to identify host cell interaction partners for VgrG and IglJ. Sci Rep 2020; 10:14612. [PMID: 32884055 PMCID: PMC7471685 DOI: 10.1038/s41598-020-71641-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/23/2020] [Indexed: 11/17/2022] Open
Abstract
Francisella tularensis is a highly virulent intracellular bacterium and the causative agent of tularemia. The disease is characterized by the suboptimal innate immune response and consequently by the impaired adaptive immunity. The virulence of this pathogen depends on proteins encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). However, the precise biological roles of most of the FPI-encoded proteins remain to be clarified. In this study, we employed stable isotope labeling by amino acids in cell culture (SILAC) in combination with affinity protein purification coupled with liquid chromatography–mass spectrometry to identify potential protein-effector binding pairs for two FPI virulence effectors IglJ and VgrG. Our results may indicate that while the IglJ protein interactions primarily affect mitochondria, the VgrG interactions affect phagosome and/or autophagosome biogenesis via targeting components of the host’s exocyst complex.
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122
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Knittel V, Sadana P, Seekircher S, Stolle AS, Körner B, Volk M, Jeffries CM, Svergun DI, Heroven AK, Scrima A, Dersch P. RovC - a novel type of hexameric transcriptional activator promoting type VI secretion gene expression. PLoS Pathog 2020; 16:e1008552. [PMID: 32966346 PMCID: PMC7535981 DOI: 10.1371/journal.ppat.1008552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 10/05/2020] [Accepted: 08/01/2020] [Indexed: 12/05/2022] Open
Abstract
Type VI secretion systems (T6SSs) are complex macromolecular injection machines which are widespread in Gram-negative bacteria. They are involved in host-cell interactions and pathogenesis, required to eliminate competing bacteria, or are important for the adaptation to environmental stress conditions. Here we identified regulatory elements controlling the T6SS4 of Yersinia pseudotuberculosis and found a novel type of hexameric transcription factor, RovC. RovC directly interacts with the T6SS4 promoter region and activates T6SS4 transcription alone or in cooperation with the LysR-type regulator RovM. A higher complexity of regulation was achieved by the nutrient-responsive global regulator CsrA, which controls rovC expression on the transcriptional and post-transcriptional level. In summary, our work unveils a central mechanism in which RovC, a novel key activator, orchestrates the expression of the T6SS weapons together with a global regulator to deploy the system in response to the availability of nutrients in the species' native environment.
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Affiliation(s)
- Vanessa Knittel
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Pooja Sadana
- Young Investigator Group Structural Biology of Autophagy, Department of Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stephanie Seekircher
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Anne-Sophie Stolle
- Institute for Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Germany
| | - Britta Körner
- Institute for Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Germany
| | - Marcel Volk
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Germany
| | - Cy M. Jeffries
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Ann Kathrin Heroven
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Andrea Scrima
- Young Investigator Group Structural Biology of Autophagy, Department of Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Germany
- German Center for Infection Research, Baunschweig, Germany
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123
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Kim N, Kim JJ, Kim I, Mannaa M, Park J, Kim J, Lee H, Lee S, Park D, Sul WJ, Seo Y. Type VI secretion systems of plant-pathogenic Burkholderia glumae BGR1 play a functionally distinct role in interspecies interactions and virulence. MOLECULAR PLANT PATHOLOGY 2020; 21:1055-1069. [PMID: 32643866 PMCID: PMC7368126 DOI: 10.1111/mpp.12966] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/28/2020] [Accepted: 05/31/2020] [Indexed: 05/02/2023]
Abstract
In the environment, bacteria show close association, such as interspecies interaction, with other bacteria as well as host organisms. The type VI secretion system (T6SS) in gram-negative bacteria is involved in bacterial competition or virulence. The plant pathogen Burkholderia glumae BGR1, causing bacterial panicle blight in rice, has four T6SS gene clusters. The presence of at least one T6SS gene cluster in an organism indicates its distinct role, like in the bacterial and eukaryotic cell targeting system. In this study, deletion mutants targeting four tssD genes, which encode the main component of T6SS needle formation, were constructed to functionally dissect the four T6SSs in B. glumae BGR1. We found that both T6SS group_4 and group_5, belonging to the eukaryotic targeting system, act independently as bacterial virulence factors toward host plants. In contrast, T6SS group_1 is involved in bacterial competition by exerting antibacterial effects. The ΔtssD1 mutant lost the antibacterial effect of T6SS group_1. The ΔtssD1 mutant showed similar virulence as the wild-type BGR1 in rice because the ΔtssD1 mutant, like the wild-type BGR1, still has key virulence factors such as toxin production towards rice. However, metagenomic analysis showed different bacterial communities in rice infected with the ΔtssD1 mutant compared to wild-type BGR1. In particular, the T6SS group_1 controls endophytic plant-associated bacteria such as Luteibacter and Dyella in rice plants and may have an advantage in competing with endophytic plant-associated bacteria for settlement inside rice plants in the environment. Thus, B. glumae BGR1 causes disease using T6SSs with functionally distinct roles.
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Affiliation(s)
- Namgyu Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Jin Ju Kim
- Department of Systems BiotechnologyChung‐Ang UniversityAnseongKorea
| | - Inyoung Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Mohamed Mannaa
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Jungwook Park
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Juyun Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Hyun‐Hee Lee
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | | | | | - Woo Jun Sul
- Department of Systems BiotechnologyChung‐Ang UniversityAnseongKorea
| | - Young‐Su Seo
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
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124
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Hernandez RE, Gallegos‐Monterrosa R, Coulthurst SJ. Type
VI
secretion system effector proteins: Effective weapons for bacterial competitiveness. Cell Microbiol 2020; 22:e13241. [DOI: 10.1111/cmi.13241] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/08/2020] [Accepted: 06/15/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Ruth E. Hernandez
- Division of Molecular Microbiology, School of Life SciencesUniversity of Dundee Dundee UK
| | | | - Sarah J. Coulthurst
- Division of Molecular Microbiology, School of Life SciencesUniversity of Dundee Dundee UK
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125
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Ruhe ZC, Low DA, Hayes CS. Polymorphic Toxins and Their Immunity Proteins: Diversity, Evolution, and Mechanisms of Delivery. Annu Rev Microbiol 2020; 74:497-520. [PMID: 32680451 DOI: 10.1146/annurev-micro-020518-115638] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
All bacteria must compete for growth niches and other limited environmental resources. These existential battles are waged at several levels, but one common strategy entails the transfer of growth-inhibitory protein toxins between competing cells. These antibacterial effectors are invariably encoded with immunity proteins that protect cells from intoxication by neighboring siblings. Several effector classes have been described, each designed to breach the cell envelope of target bacteria. Although effector architectures and export pathways tend to be clade specific, phylogenetically distant species often deploy closely related toxin domains. Thus, diverse competition systems are linked through a common reservoir of toxin-immunity pairs that is shared via horizontal gene transfer. These toxin-immunity protein pairs are extraordinarily diverse in sequence, and this polymorphism underpins an important mechanism of self/nonself discrimination in bacteria. This review focuses on the structures, functions, and delivery mechanisms of polymorphic toxin effectors that mediate bacterial competition.
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Affiliation(s)
- Zachary C Ruhe
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA;
| | - David A Low
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA; .,Biomolecular Science and Engineering Program, University of California, Santa Barbara, California 93106, USA
| | - Christopher S Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA; .,Biomolecular Science and Engineering Program, University of California, Santa Barbara, California 93106, USA
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126
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Zheng L, Wang S, Ling M, Lv Z, Lin S. Salmonella enteritidis Hcp distribute in the cytoplasm and regulate TNF signaling pathway in BHK-21 cells. 3 Biotech 2020; 10:301. [PMID: 32550118 PMCID: PMC7292845 DOI: 10.1007/s13205-020-02296-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 06/09/2020] [Indexed: 02/06/2023] Open
Abstract
Hemolysin-coregulated protein (Hcp) of Salmonella enteritidis is known to be a structural and effector protein of the T6SS, but little is known about the role of Hcp in host cells. In this study, Hcp was expressed by plasmid pEGFP-N1-hcp in BHK-21 cells and the results showed that the subcellular localization of Hcp was predominantly in the cytoplasm of BHK-21 cells. When Hcp was over-expressed by transfecting plasmid pCI-neo-hcp in BHK-21 cells and mRNA sequencing was performed to analyze differentially expressed genes, the results showed a change in the expression levels of 307 mRNAs (fold change > 2, and p < 0.01). Amongst these, 125 mRNAs were up-regulated and 182 mRNAs were down-regulated. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that differentially expressed genes were enriched in tumor necrosis factor (TNF) signaling pathway, IL-17 signaling pathway, and cytokine-cytokine receptor interaction. Subsequently, we selected differentially expressed genes of TNF signaling pathway and verified the changes by real-time PCR. The results were consistent with the trend observed for the sequencing results. In conclusion, we demonstrated that Hcp of Salmonella enteritidis caused the change of mRNAs expression of TNF signaling pathway in the cytoplasm of BHK-21 cells.
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Affiliation(s)
- Liming Zheng
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Shenghua Wang
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Mengyu Ling
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Zhengmei Lv
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Shuai Lin
- Anhui Medical University, Hefei, 230032 People’s Republic of China
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127
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Hubert CL, Michell SL. A universal oyster infection model demonstrates that
Vibrio vulnificus
Type 6
secretion systems have antibacterial activity
in vivo. Environ Microbiol 2020; 22:4381-4393. [DOI: 10.1111/1462-2920.15123] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/01/2020] [Accepted: 06/07/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Cameron L. Hubert
- College of Life and Environmental Sciences University of Exeter Exeter EX4 4QD UK
| | - Stephen Ll. Michell
- College of Life and Environmental Sciences University of Exeter Exeter EX4 4QD UK
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128
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Abstract
Bacteria have evolved a wide range of mechanisms to harm and kill their competitors, including chemical, mechanical and biological weapons. Here we review the incredible diversity of bacterial weapon systems, which comprise antibiotics, toxic proteins, mechanical weapons that stab and pierce, viruses, and more. The evolution of bacterial weapons is shaped by many factors, including cell density and nutrient abundance, and how strains are arranged in space. Bacteria also employ a diverse range of combat behaviours, including pre-emptive attacks, suicidal attacks, and reciprocation (tit-for-tat). However, why bacteria carry so many weapons, and why they are so often used, remains poorly understood. By comparison with animals, we argue that the way that bacteria live - often in dense and genetically diverse communities - is likely to be key to their aggression as it encourages them to dig in and fight alongside their clonemates. The intensity of bacterial aggression is such that it can strongly affect communities, via complex coevolutionary and eco-evolutionary dynamics, which influence species over space and time. Bacterial warfare is a fascinating topic for ecology and evolution, as well as one of increasing relevance. Understanding how bacteria win wars is important for the goal of manipulating the human microbiome and other important microbial systems.
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129
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Vazquez-Lopez J, Navarro-Garcia F. In silico Analyses of Core Proteins and Putative Effector and Immunity Proteins for T6SS in Enterohemorrhagic E. coli. Front Cell Infect Microbiol 2020; 10:195. [PMID: 32432054 PMCID: PMC7216683 DOI: 10.3389/fcimb.2020.00195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 04/14/2020] [Indexed: 12/29/2022] Open
Abstract
Shiga-toxin-producing Escherichia coli (STEC) has become an important pathogen that can cause diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. Recent reports show that the type VI secretion system (T6SS) from EHEC is required to produce infection in a murine model and its expression has been related to a higher prevalence of HUS. In this work, we use bioinformatics analyses to identify the core genes of the T6SS and compared the differences between these components among the two published genomes for EHEC O157:H7 strain EDL933. Prototype strain EDL933 was further compared with other O157:H7 genomes. Unlike other typical T6SS effectors found in E. coli, we identified that there are several rhs family genes in EHEC, which could serve as T6SS effectors. In-silico and PCR analyses of the differences between rhs genes in the two existing genomes, allowed us to determine that the most recently published genome is more reliable to study the rhs genes. Analyzing the putative tridimensional structure of Rhs proteins, as well as the motifs found in their C-terminal end, allowed us to predict their possible functions. A phylogenetic analysis showed that the orphan rhs genes are more closely related between them than the rhs genes belonging to vgrG islands and that they are divided into three clades. Analyses of the downstream region of the rhs genes for identifying hypothetical immunity proteins showed that every gene has an associated small ORF (129-609 nucleotides). These genes could serve as immunity proteins as they had several interaction motifs as well as structural homology with other known immunity proteins. Our findings highlight the relevance of the T6SS in EHEC as well as the possible function of the Rhs effectors of EHEC O157:H7 during pathogenesis and bacterial competition, and the identification of novel effectors for the T6SS using a structural approach.
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Affiliation(s)
- Jaime Vazquez-Lopez
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Mexico City, Mexico
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Mexico City, Mexico
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130
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The Evolution of Protein Secretion Systems by Co-option and Tinkering of Cellular Machineries. Trends Microbiol 2020; 28:372-386. [DOI: 10.1016/j.tim.2020.01.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 11/21/2019] [Accepted: 01/16/2020] [Indexed: 02/07/2023]
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131
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Pei TT, Li H, Liang X, Wang ZH, Liu G, Wu LL, Kim H, Xie Z, Yu M, Lin S, Xu P, Dong TG. Intramolecular chaperone-mediated secretion of an Rhs effector toxin by a type VI secretion system. Nat Commun 2020; 11:1865. [PMID: 32313027 PMCID: PMC7170923 DOI: 10.1038/s41467-020-15774-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 03/27/2020] [Indexed: 12/31/2022] Open
Abstract
Bacterial Rhs proteins containing toxic domains are often secreted by type VI secretion systems (T6SSs) through unclear mechanisms. Here, we show that the T6SS Rhs-family effector TseI of Aeromonas dhakensis is subject to self-cleavage at both the N- and the C-terminus, releasing the middle Rhs core and two VgrG-interacting domains (which we name VIRN and VIRC). VIRC is an endonuclease, and the immunity protein TsiI protects against VIRC toxicity through direct interaction. Proteolytic release of VIRC and VIRN is mediated, respectively, by an internal aspartic protease activity and by two conserved glutamic residues in the Rhs core. Mutations abolishing self-cleavage do not block secretion, but reduce TseI toxicity. Deletion of VIRN or the Rhs core abolishes secretion. TseI homologs from Pseudomonas syringae, P. aeruginosa, and Vibrio parahaemolyticus are also self-cleaved. VIRN and VIRC interact with protein VgrG1, while the Rhs core interacts with protein TecI. We propose that VIRN and the Rhs core act as T6SS intramolecular chaperones to facilitate toxin secretion and function.
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Affiliation(s)
- Tong-Tong Pei
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China.,Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada
| | - Zeng-Hang Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, 201204, Shanghai, China
| | - Li-Li Wu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Haeun Kim
- Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Ming Yu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Tao G Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Department of Ecosystem and Public Health, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N4Z6, Canada.
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132
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Tipping MJ, Gibbs KA. Biofilms: Managing Stress to Navigate Group Dynamics. Curr Biol 2020; 30:R324-R326. [PMID: 32259509 DOI: 10.1016/j.cub.2020.02.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
To thrive in dense communities, organisms have to navigate neighbors and resources. A new study reveals that bacteria integrate cues of communal living through stress pathways. The primary source of the stress - at least for one bacterium - is a direct conflict with neighbors.
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Affiliation(s)
- Murray J Tipping
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Karine A Gibbs
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
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133
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Jana B, Salomon D, Bosis E. A novel class of polymorphic toxins in Bacteroidetes. Life Sci Alliance 2020; 3:e201900631. [PMID: 32169897 PMCID: PMC7073777 DOI: 10.26508/lsa.201900631] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 01/03/2023] Open
Abstract
Bacteroidetes are Gram-negative bacteria that are abundant in the environment as well as in the gut microbiota of animals. Many bacteroidetes encode large proteins containing an N-terminal domain of unknown function, named TANFOR. In this work, we show that TANFOR-containing proteins carry polymorphic C-terminal toxin domains with predicted antibacterial and anti-eukaryotic activities. We also show that a C-terminal domain that is prevalent in TANFOR-containing proteins represents a novel family of antibacterial DNase toxins, which we named BaCT (Bacteroidetes C-terminal Toxin). Finally, we discover that TANFOR-encoding gene neighborhoods are enriched with genes that encode substrates of the type IX secretion system (T9SS), which is involved in exporting proteins from the periplasm across the outer membrane. Based on these findings, we conclude that TANFOR-containing proteins are a new class of polymorphic toxins, and we hypothesize that they are T9SS substrates.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College of Engineering, Karmiel, Israel
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134
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Crisan CV, Hammer BK. The
Vibrio cholerae
type VI secretion system: toxins, regulators and consequences. Environ Microbiol 2020; 22:4112-4122. [DOI: 10.1111/1462-2920.14976] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/01/2020] [Accepted: 03/02/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Cristian V. Crisan
- Center for Microbial Dynamics and Infection Georgia Institute of Technology Atlanta GA USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology Atlanta GA USA
- School of Biological Sciences, Georgia Institute of Technology Atlanta GA USA
| | - Brian K. Hammer
- Center for Microbial Dynamics and Infection Georgia Institute of Technology Atlanta GA USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology Atlanta GA USA
- School of Biological Sciences, Georgia Institute of Technology Atlanta GA USA
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135
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The Bacterial Enhancer Binding Protein VasH Promotes Expression of a Type VI Secretion System in Vibrio fischeri during Symbiosis. J Bacteriol 2020; 202:JB.00777-19. [PMID: 31964698 DOI: 10.1128/jb.00777-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 01/13/2020] [Indexed: 11/20/2022] Open
Abstract
Vibrio fischeri is a bacterial symbiont that colonizes the light organ of the Hawaiian bobtail squid, Euprymna scolopes Certain strains of V. fischeri express a type VI secretion system (T6SS), which delivers effectors into neighboring cells that result in their death. Strains that are susceptible to the T6SS fail to establish symbiosis with a T6SS-positive strain within the same location of the squid light organ, which is a phenomenon termed strain incompatibility. This study investigates the regulation of the T6SS in V. fischeri strain FQ-A001. Here, we report that the expression of Hcp, a necessary structural component of the T6SS, depends on the alternative sigma factor σ54 and the bacterial enhancer binding protein VasH. VasH is necessary for FQ-A001 to kill other strains, suggesting that VasH-dependent regulation is essential for the T6SS of V. fischeri to affect intercellular interactions. In addition, this study demonstrates VasH-dependent transcription of hcp within host-associated populations of FQ-A001, suggesting that the T6SS is expressed within the host environment. Together, these findings establish a model for transcriptional control of hcp in V. fischeri within the squid light organ, thereby increasing understanding of how the T6SS is regulated during symbiosis.IMPORTANCE Animals harbor bacterial symbionts with specific traits that promote host fitness. Mechanisms that facilitate intercellular interactions among bacterial symbionts impact which bacterial lineages ultimately establish symbiosis with the host. How these mechanisms are regulated is poorly characterized in nonhuman bacterial symbionts. This study establishes a model for the transcriptional regulation of a contact-dependent killing machine, thereby increasing understanding of mechanisms by which different strains compete while establishing symbiosis.
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136
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Arteaga M, Velasco J, Rodriguez S, Vidal M, Arellano C, Silva F, Carreño LJ, Vidal R, Montero DA. Genomic characterization of the non-O1/non-O139 Vibrio cholerae strain that caused a gastroenteritis outbreak in Santiago, Chile, 2018. Microb Genom 2020; 6:e000340. [PMID: 32100707 PMCID: PMC7200058 DOI: 10.1099/mgen.0.000340] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/29/2020] [Indexed: 02/06/2023] Open
Abstract
Vibrio cholerae is a human pathogen, which is transmitted by the consumption of contaminated food or water. V. cholerae strains belonging to the serogroups O1 and O139 can cause cholera outbreaks and epidemics, a severe life-threatening diarrheal disease. In contrast, serogroups other than O1 and O139, denominated as non-O1/non-O139, have been mainly associated with sporadic cases of moderate or mild diarrhea, bacteremia and wound infections. Here we investigated the virulence determinants and phylogenetic origin of a non-O1/non-O139 V. cholerae strain that caused a gastroenteritis outbreak in Santiago, Chile, 2018. We found that this outbreak strain lacks the classical virulence genes harboured by O1 and O139 strains, including the cholera toxin (CT) and the toxin-coregulated pilus (TCP). However, this strain carries genomic islands (GIs) encoding Type III and Type VI secretion systems (T3SS/T6SS) and antibiotic resistance genes. Moreover, we found these GIs are wide distributed among several lineages of non-O1/non-O139 strains. Our results suggest that the acquisition of these GIs may enhance the virulence of non-O1/non-O139 strains that lack the CT and TCP-encoding genes. Our results highlight the pathogenic potential of these V. cholerae strains.
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Affiliation(s)
- Mónica Arteaga
- Servicio de Urgencia Infantil, Hospital Clínico de la Universidad de Chile “Dr. José Joaquín Aguirre”, Santiago, Chile
| | - Juliana Velasco
- Servicio de Urgencia Infantil, Hospital Clínico de la Universidad de Chile “Dr. José Joaquín Aguirre”, Santiago, Chile
| | - Shelly Rodriguez
- Servicio de Urgencia Infantil, Hospital Clínico de la Universidad de Chile “Dr. José Joaquín Aguirre”, Santiago, Chile
| | - Maricel Vidal
- Laboratorio de Salud Pública Ambiental y Laboral, Secretaría Regional Ministerial de Salud Región Metropolitana, Santiago, Chile
| | - Carolina Arellano
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Francisco Silva
- Servicio de Laboratorio Clínico, Hospital Clínico de la Universidad de Chile “Dr. José Joaquín Aguirre”, Santiago, Chile
| | - Leandro J. Carreño
- Programa de Inmunología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Roberto Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - David A. Montero
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Programa de Inmunología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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137
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A comparative genomics methodology reveals a widespread family of membrane-disrupting T6SS effectors. Nat Commun 2020; 11:1085. [PMID: 32109231 PMCID: PMC7046647 DOI: 10.1038/s41467-020-14951-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/13/2020] [Indexed: 01/01/2023] Open
Abstract
Gram-negative bacteria deliver effectors via the type VI secretion system (T6SS) to outcompete their rivals. Each bacterial strain carries a different arsenal of effectors; the identities of many remain unknown. Here, we present an approach to identify T6SS effectors encoded in bacterial genomes of interest, without prior knowledge of the effectors’ domain content or genetic neighborhood. Our pipeline comprises a comparative genomics analysis followed by screening using a surrogate T6SS+ strain. Using this approach, we identify an antibacterial effector belonging to the T6SS1 of Vibrio parahaemolyticus, representing a widespread family of T6SS effectors sharing a C-terminal domain that we name Tme (Type VI membrane-disrupting effector). Tme effectors function in the periplasm where they intoxicate bacteria by disrupting membrane integrity. We believe our approach can be scaled up to identify additional T6SS effectors in various bacterial genera. Gram-negative bacteria deliver effectors via the type VI secretion system (T6SS) to outcompete their rivals. Here, Fridman et al. present an approach to identify T6SS effectors encoded in bacterial genomes without prior knowledge of their domain content or genetic neighbourhood, and identify a new family of membrane-disrupting effectors.
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138
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Wettstadt S, Filloux A. Manipulating the type VI secretion system spike to shuttle passenger proteins. PLoS One 2020; 15:e0228941. [PMID: 32101557 PMCID: PMC7043769 DOI: 10.1371/journal.pone.0228941] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/27/2020] [Indexed: 12/21/2022] Open
Abstract
The type VI secretion system (T6SS) is a contractile injection apparatus that translocates a spike loaded with various effectors directly into eukaryotic or prokaryotic target cells. Pseudomonas aeruginosa can load either one of its three T6SSs with a variety of toxic bullets using different but specific modes. The T6SS spike, which punctures the bacterial cell envelope allowing effector transport, consists of a torch-like VgrG trimer on which sits a PAAR protein sharpening the VgrG tip. VgrG itself sits on the Hcp tube and all elements, packed into a T6SS sheath, are propelled out of the cell and into target cells. On occasion, effectors are covalent extensions of VgrG, PAAR or Hcp proteins, which are then coined "evolved" components as opposed to canonical. Here, we show how various passenger domains could be fused to the C terminus of a canonical VgrG, VgrG1a from P. aeruginosa, and be sent into the bacterial culture supernatant. There is no restriction on the passenger type, although the efficacy may vary greatly, since we used either an unrelated T6SS protein, β-lactamase, a covalent extension of an "evolved" VgrG, VgrG2b, or a Hcp-dependent T6SS toxin, Tse2. Our data further highlights an exceptional modularity/flexibility for loading the T6SS nano-weapon. Refining the parameters to optimize delivery of passenger proteins of interest would have attractive medical and industrial applications. This may for example involve engineering the T6SS as a delivery system to shuttle toxins into either bacterial pathogens or tumour cells which would be an original approach in the fight against antimicrobial resistant bacteria or cancer.
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Affiliation(s)
- Sarah Wettstadt
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
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139
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Klein TA, Ahmad S, Whitney JC. Contact-Dependent Interbacterial Antagonism Mediated by Protein Secretion Machines. Trends Microbiol 2020; 28:387-400. [PMID: 32298616 DOI: 10.1016/j.tim.2020.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/18/2019] [Accepted: 01/16/2020] [Indexed: 12/29/2022]
Abstract
To establish and maintain an ecological niche, bacteria employ a wide range of pathways to inhibit the growth of their microbial competitors. Some of these pathways, such as those that produce antibiotics or bacteriocins, exert toxicity on nearby cells in a cell contact-independent manner. More recently, however, several mechanisms of interbacterial antagonism requiring cell-to-cell contact have been identified. This form of microbial competition is mediated by antibacterial protein toxins whose delivery to target bacteria uses protein secretion apparatuses embedded within the cell envelope of toxin-producing bacteria. In this review, we discuss recent work implicating the bacterial Type I, IV, VI, and VII secretion systems in the export of antibacterial 'effector' proteins that mediate contact-dependent interbacterial antagonism.
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Affiliation(s)
- Timothy A Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Shehryar Ahmad
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1; David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ON, Canada L8S 4K1.
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140
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Wood TE, Howard SA, Wettstadt S, Filloux A. PAAR proteins act as the 'sorting hat' of the type VI secretion system. MICROBIOLOGY-SGM 2020; 165:1203-1218. [PMID: 31380737 PMCID: PMC7376260 DOI: 10.1099/mic.0.000842] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bacteria exist in polymicrobial environments and compete to prevail in a niche. The type VI secretion system (T6SS) is a nanomachine employed by Gram-negative bacteria to deliver effector proteins into target cells. Consequently, T6SS-positive bacteria produce a wealth of antibacterial effector proteins to promote their survival among a prokaryotic community. These toxins are loaded onto the VgrG–PAAR spike and Hcp tube of the T6SS apparatus and recent work has started to document the specificity of effectors for certain spike components. Pseudomonas aeruginosa encodes several PAAR proteins, whose roles have been poorly investigated. Here we describe a phospholipase family antibacterial effector immunity pair from Pseudomonas aeruginosa and demonstrate that a specific PAAR protein is necessary for the delivery of the effector and its cognate VgrG. Furthermore, the PAAR protein appears to restrict the delivery of other phospholipase effectors that utilise distinct VgrG proteins. We provide further evidence for competition for PAAR protein recruitment to the T6SS apparatus, which determines the identities of the delivered effectors.
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Affiliation(s)
- Thomas E Wood
- Present address: Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.,Present address: Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, MA, USA.,MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, London, SW7 2AZ, UK
| | - Sophie A Howard
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, London, SW7 2AZ, UK
| | - Sarah Wettstadt
- Present address: Department of Environmental Protection, Estación Experimental de Zaidín - Consejo Superior de Investigaciones Científicas, Granada, Spain.,MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, London, SW7 2AZ, UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, London, SW7 2AZ, UK
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141
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French CT, Bulterys PL, Woodward CL, Tatters AO, Ng KR, Miller JF. Virulence from the rhizosphere: ecology and evolution of Burkholderia pseudomallei-complex species. Curr Opin Microbiol 2020; 54:18-32. [PMID: 32028234 DOI: 10.1016/j.mib.2019.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Christopher T French
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Bldg. 114, 4538 West, Los Angeles, CA 90095, United States; Department of Microbiology, Immunology, and Molecular Genetics, UCLA, 609 Charles E. Young Drive East, Los Angeles, CA 90095, United States; Northern Arizona University, Department of Biological Sciences, Pathogen and Microbiome Institute 1395 S Knoles Drive, Flagstaff, AZ 86011, United States.
| | - Philip L Bulterys
- Department of Pathology, Stanford University, Lane Building, L235, 300 Pasteur Drive, Stanford, CA, 94305, United States
| | - Cora L Woodward
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Bldg. 114, 4538 West, Los Angeles, CA 90095, United States
| | - Avery O Tatters
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Bldg. 114, 4538 West, Los Angeles, CA 90095, United States
| | - Ken R Ng
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Bldg. 114, 4538 West, Los Angeles, CA 90095, United States
| | - Jeff F Miller
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Bldg. 114, 4538 West, Los Angeles, CA 90095, United States; Molecular Biology Institute, UCLA, 611 Charles E. Young Drive East, Los Angeles, CA 90095, United States; Department of Microbiology, Immunology, and Molecular Genetics, UCLA, 609 Charles E. Young Drive East, Los Angeles, CA 90095, United States
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142
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Guillemette R, Ushijima B, Jalan M, Häse CC, Azam F. Insight into the resilience and susceptibility of marine bacteria to T6SS attack by Vibrio cholerae and Vibrio coralliilyticus. PLoS One 2020; 15:e0227864. [PMID: 31990915 PMCID: PMC6986712 DOI: 10.1371/journal.pone.0227864] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/31/2019] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a nanomachine capable of killing adjacent microbial cells in a contact-dependent manner. Due to limited studies, relatively little is known about the range of marine bacteria that are susceptible to T6SS attack. Here, 15 diverse marine bacterial isolates from the phyla Bacteroidetes and Ɣ-Proteobacteria were challenged against the marine bacterium and human pathogen, Vibrio cholerae, which has a well described T6SS. V. cholerae killed several of the tested Ɣ-Proteobacteria, including members of the orders Vibrionales, Alteromonadales, Oceanospirillales, and Pseudomonadales. In contrast, V. cholerae co-existed with multiple Bacteroidetes and Ɣ-Proteobacteria isolates, but was killed by Vibrio coralliilyticus. Follow-up experiments revealed that five V. coralliilyticus strains, including known coral and shellfish pathogens survived the T6SS challenge and killed V. cholerae. By using predicted protein comparisons and mutagenesis, we conclude that V. coralliilyticus protected itself in the challenge by using its own T6SS to kill V. cholerae. This study provides valuable insight into the resilience and susceptibility of marine bacteria to the V. cholerae T6SS, and provides the first evidence for a functional T6SS in V. coralliilyticus, both of which have implications for human and ocean health.
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Affiliation(s)
- Ryan Guillemette
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, San Diego, CA, United States of America
| | - Blake Ushijima
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States of America
| | - Mihika Jalan
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, San Diego, CA, United States of America
| | - Claudia C. Häse
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States of America
| | - Farooq Azam
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, San Diego, CA, United States of America
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143
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Davoodi S, Foley E. Host-Microbe-Pathogen Interactions: A Review of Vibrio cholerae Pathogenesis in Drosophila. Front Immunol 2020; 10:3128. [PMID: 32038640 PMCID: PMC6993214 DOI: 10.3389/fimmu.2019.03128] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/23/2019] [Indexed: 12/14/2022] Open
Abstract
Most animals maintain mutually beneficial symbiotic relationships with their intestinal microbiota. Resident microbes in the gastrointestinal tract breakdown indigestible food, provide essential nutrients, and, act as a barrier against invading microbes, such as the enteric pathogen Vibrio cholerae. Over the last decades, our knowledge of V. cholerae pathogenesis, colonization, and transmission has increased tremendously. A number of animal models have been used to study how V. cholerae interacts with host-derived resources to support gastrointestinal colonization. Here, we review studies on host-microbe interactions and how infection with V. cholerae disrupts these interactions, with a focus on contributions from the Drosophila melanogaster model. We will discuss studies that highlight the connections between symbiont, host, and V. cholerae metabolism; crosstalk between V. cholerae and host microbes; and the impact of the host immune system on the lethality of V. cholerae infection. These studies suggest that V. cholerae modulates host immune-metabolic responses in the fly and improves Vibrio fitness through competition with intestinal microbes.
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Affiliation(s)
| | - Edan Foley
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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144
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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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145
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Double Tubular Contractile Structure of the Type VI Secretion System Displays Striking Flexibility and Elasticity. J Bacteriol 2019; 202:JB.00425-19. [PMID: 31636107 DOI: 10.1128/jb.00425-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/14/2019] [Indexed: 12/22/2022] Open
Abstract
Antimicrobial treatment can induce many bacterial pathogens to enter a cell wall-deficient state that contributes to persistent infections. The effect of this physiological state on the assembly of transenvelope-anchored organelles is not well understood. The type VI secretion system (T6SS) is a widespread molecular weapon for interspecies interactions and virulence, comprising a long double tubular structure and a transenvelope/baseplate complex. Here, we report that cell wall-deficient spheroplasts assembled highly flexible and elastic T6SS structures forming U, O, or S shapes. Upon contacting the inner membrane, the T6SS tubes did not contract but rather continued to grow along the membrane. Such deformation likely results from continual addition of sheath/tube subunits at the distal end. Induction of TagA repressed curved sheath formation. Curved sheaths could also contract and deliver T6SS substrates and were readily disassembled by the ClpV ATPase after contraction. Our data highlight the dramatic effect of cell wall deficiency on the shape of the T6SS structures and reveal the elastic nature of this double tubular contractile injection nanomachine.IMPORTANCE The cell wall is a physical scaffold that all transenvelope complexes have to cross for assembly. However, the cell wall-deficient state has been described as a common condition found in both Gram-negative and Gram-positive pathogens during persistent infections. Loss of cell wall is known to have pleiotropic physiological effects, but how membrane-anchored large cellular organelles adapt to this unique state is less completely understood. Our study examined the assembly of the T6SS in cell wall-deficient spheroplast cells. We report the elastic nature of contractile T6SS tubules under such conditions, providing key insights for understanding how large intracellular structures such as the T6SS accommodate the multifaceted changes in cell wall-deficient cells.
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146
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Peñil-Celis A, Garcillán-Barcia MP. Crosstalk Between Type VI Secretion System and Mobile Genetic Elements. Front Mol Biosci 2019; 6:126. [PMID: 31799257 PMCID: PMC6863884 DOI: 10.3389/fmolb.2019.00126] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 10/28/2019] [Indexed: 12/11/2022] Open
Abstract
Many bacterial processes require cell-cell contacts. Such are the cases of bacterial conjugation, one of the main horizontal gene transfer mechanisms that physically spreads DNA, and the type VI secretion systems (T6SSs), which deploy antibacterial activity. Bacteria depend on conjugation to adapt to changing environments, while T6SS killing activity could pose a threat to mating partners. Here we review the experimental evidences of overlapping and interaction between the T6SSs, bacterial conjugation, and conjugative genetic elements.
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Affiliation(s)
- Arancha Peñil-Celis
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, Santander, Spain
| | - M Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, Santander, Spain
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147
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Jana B, Salomon D. Type VI secretion system: a modular toolkit for bacterial dominance. Future Microbiol 2019; 14:1451-1463. [DOI: 10.2217/fmb-2019-0194] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria use toxin delivery systems, such as the type VI secretion system (T6SS), to antagonize competitors. The T6SS transports toxins, called effectors, directly into recipient cells. In the absence of cognate immunity proteins that protect against kin-intoxication, these effectors target conserved and essential cell components resulting in growth arrest or cell death. Here, we focus on antibacterial T6SS effectors and explore their different activities, modes of delivery, and the domains and proteins that are associated with them to provide a modular and dynamic toxin arsenal. We conclude that these natural machines present a lucrative pool and platform for future antibacterial treatments.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Dor Salomon
- Department of Clinical Microbiology & Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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148
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Lin L, Ringel PD, Vettiger A, Dürr L, Basler M. DNA Uptake upon T6SS-Dependent Prey Cell Lysis Induces SOS Response and Reduces Fitness of Acinetobacter baylyi. Cell Rep 2019; 29:1633-1644.e4. [DOI: 10.1016/j.celrep.2019.09.083] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 08/23/2019] [Accepted: 09/27/2019] [Indexed: 11/29/2022] Open
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149
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Repizo GD, Espariz M, Seravalle JL, Salcedo SP. Bioinformatic Analysis of the Type VI Secretion System and Its Potential Toxins in the Acinetobacter Genus. Front Microbiol 2019; 10:2519. [PMID: 31736933 PMCID: PMC6838775 DOI: 10.3389/fmicb.2019.02519] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii as the species of greatest concern worldwide due to its multi-drug resistance and recent appearance of hyper-virulent strains in the clinical setting. Acinetobacter colonization of the environment and the host is associated with a multitude of factors which remain poorly characterized. Among them, the secretion systems (SS) encoded by Acinetobacter species confer adaptive advantages depending on the niche occupied. Different SS have been characterized in this group of microorganisms, including T6SS used by several Acinetobacter species to outcompete other bacteria and in some A. baumannii strains for Galleria mellonella colonization. Therefore, to better understand the distribution of the T6SS in this genus we carried out an in-depth comparative genomic analysis of the T6SS in 191 sequenced strains. To this end, we analyzed the gene content, sequence similarity, synteny and operon structure of each T6SS loci. The presence of a single conserved T6SS-main cluster (T6SS-1), with two different genetic organizations, was detected in the genomes of several ecologically diverse species. Furthermore, a second main cluster (T6SS-2) was detected in a subgroup of 3 species of environmental origin. Detailed analysis also showed an impressive genetic versatility in T6SS-associated islands, carrying VgrG, PAAR and putative toxin-encoding genes. This in silico study represents the first detailed intra-species comparative analysis of T6SS-associated genes in the Acinetobacter genus, that should contribute to the future experimental characterization of T6SS proteins and effectors.
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Affiliation(s)
- Guillermo D Repizo
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Martín Espariz
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Joana L Seravalle
- Departamento de Microbiologia, Facultad de Ciencias Bioquimicas y Farmaceuticas, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Suzana P Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, CNRS UMR 5086, University of Lyon, Lyon, France
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150
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Lewis JM, Deveson Lucas D, Harper M, Boyce JD. Systematic Identification and Analysis of Acinetobacter baumannii Type VI Secretion System Effector and Immunity Components. Front Microbiol 2019; 10:2440. [PMID: 31736890 PMCID: PMC6833914 DOI: 10.3389/fmicb.2019.02440] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 10/10/2019] [Indexed: 12/17/2022] Open
Abstract
Many Gram-negative bacteria use a type VI secretion system (T6SS) for microbial warfare and/or host manipulation. Acinetobacter baumannii is an important nosocomial pathogen and many A. baumannii strains utilize a T6SS to deliver toxic effector proteins to surrounding bacterial cells. These toxic effectors are usually delivered together with VgrG proteins, which form part of the T6SS tip complex. All previously identified A. baumannii T6SS effectors are encoded within a three- or four-gene locus that also encodes a cognate VgrG and immunity protein, and sometimes a chaperone. In order to characterize the diversity and distribution of T6SS effectors and immunity proteins in this species, we first identified all vgrG genes in 97 A. baumannii strains via the presence of the highly conserved VgrG domain. Most strains encoded between two and four different VgrG proteins. We then analyzed the regions downstream of the identified vgrG genes and identified more than 240 putative effectors. The presence of conserved domains in these effectors suggested a range of functions, including peptidoglycan hydrolases, lipases, nucleases, and nucleic acid deaminases. However, 10 of the effector groups had no functionally characterized domains. Phylogenetic analysis of these putative effectors revealed that they clustered into 32 distinct groups that appear to have been acquired from a diverse set of ancestors. Corresponding immunity proteins were identified for all but two of the effector groups. Effectors from eight of the 32 groups contained N-terminal rearrangement hotspot (RHS) domains. The C-terminal regions of these RHS proteins, which are predicted to confer the toxic effector function, were very diverse, but the N-terminal RHS domains clustered into just two groups. While the majority of A. baumannii strains contained an RHS type effector, no strains encoded two RHS effectors with similar N-terminal sequences, suggesting that the presence of similar N-terminal RHS domains leads to competitive exclusion. Together, these analyses define the extreme diversity of T6SS effectors within A. baumannii and, as many have unknown functions, future detailed characterization of these effectors may lead to the identification of proteins with novel antibacterial properties.
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Affiliation(s)
- Jessica M Lewis
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Marina Harper
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - John D Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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