1
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Bier SB, Toska J, Zhao W, Suthianthong P, Proespraiwong P, Robins WP, Mekalanos J. A coordinated attack by a bacterial secretion system and a small molecule drives prey specificity. Commun Biol 2024; 7:958. [PMID: 39117895 PMCID: PMC11310501 DOI: 10.1038/s42003-024-06637-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 07/26/2024] [Indexed: 08/10/2024] Open
Abstract
Vibrio species are recognized for their role in food- and water-borne diseases in humans, fish, and aquatic invertebrates. We screened bacterial strains isolated from raw food shrimp for those that are bactericidal to Vibrio strains. Here we identify and characterize Aeromonas dhakensis strain A603 which shows robust bactericidal activity specifically towards Vibrio and related taxa but less potency toward other Gram-negative species. Using the A603 genome and genetic analysis, we show that two antibacterial mechanisms account for its vibriocidal activity -- a highly potent Type Six Secretion System (T6SS) and biosynthesis of a vibriocidal phenazine-like small molecule, named here as Ad-Phen. Further analysis indicates coregulation between Ad-Phen and a pore-forming T6SS effector TseC, which potentiates V. cholerae to killing by Ad-Phen.
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Affiliation(s)
- S B Bier
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - J Toska
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - W Zhao
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease. The Sixth Affiliated Hospital, School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - P Suthianthong
- Charoen Pokphand Foods PCL. Aquatic Animal Health Research Center, Samutsakorn, Thailand
| | - P Proespraiwong
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - W P Robins
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.
| | - J Mekalanos
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.
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2
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Hernández-Martínez G, Ares MA, Rosales-Reyes R, Soria-Bustos J, Yañez-Santos JA, Cedillo ML, Girón JA, Martínez-Laguna Y, Leng F, Ibarra JA, De la Cruz MA. The nucleoid protein HU positively regulates the expression of type VI secretion systems in Enterobacter cloacae. mSphere 2024; 9:e0006024. [PMID: 38647313 PMCID: PMC11324020 DOI: 10.1128/msphere.00060-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 03/21/2024] [Indexed: 04/25/2024] Open
Abstract
Enterobacter cloacae is an emerging pathogen isolated in healthcare-associated infections. A major virulence factor of this bacterium is the type VI secretion system (T6SS). The genome of E. cloacae harbors two T6SS gene clusters (T6SS-1 and T6SS-2), and the functional characterization of both systems showed that these two T6SSs are not expressed under the same conditions. Here, we report that the major histone-like protein HU positively regulates the expression of both T6SSs and, therefore, the function that each T6SS exerts in E. cloacae. Single deletions of the genes encoding the HU subunits (hupA and hupB) decreased mRNA levels of both T6SS. In contrast, the hupA hupB double mutant dramatically affected the T6SS expression, diminishing its transcription. The direct binding of HU to the promoter regions of T6SS-1 and T6SS-2 was confirmed by electrophoretic mobility shift assay. In addition, single and double mutations in the hup genes affected the ability of inter-bacterial killing, biofilm formation, adherence to epithelial cells, and intestinal colonization, but these phenotypes were restored when such mutants were trans-complemented. Our data broaden our understanding of the regulation of HU-mediated T6SS in these pathogenic bacteria. IMPORTANCE T6SS is a nanomachine that functions as a weapon of bacterial destruction crucial for successful colonization in a specific niche. Enterobacter cloacae expresses two T6SSs required for bacterial competition, adherence, biofilm formation, and intestinal colonization. Expression of T6SS genes in pathogenic bacteria is controlled by multiple regulatory systems, including two-component systems, global regulators, and nucleoid proteins. Here, we reported that the HU nucleoid protein directly activates both T6SSs in E. cloacae, affecting the T6SS-related phenotypes. Our data describe HU as a new regulator involved in the transcriptional regulation of T6SS and its impact on E. cloacae pathogenesis.
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Affiliation(s)
- Gabriela Hernández-Martínez
- Unidad de
Investigación Médica en Enfermedades Infecciosas y
Parasitarias, Hospital de Pediatría, Centro Médico
Nacional Siglo XXI, Instituto Mexicano del Seguro
Social, Mexico City,
Mexico
- Escuela Nacional de
Ciencias Biológicas, Instituto Politécnico
Nacional, Mexico City,
Mexico
| | - Miguel A. Ares
- Unidad de
Investigación Médica en Enfermedades Infecciosas y
Parasitarias, Hospital de Pediatría, Centro Médico
Nacional Siglo XXI, Instituto Mexicano del Seguro
Social, Mexico City,
Mexico
- Escuela Nacional de
Ciencias Biológicas, Instituto Politécnico
Nacional, Mexico City,
Mexico
| | - Roberto Rosales-Reyes
- Unidad de Medicina
Experimental de la Facultad de Medicina, Universidad Autónoma de
México, Mexico
City, Mexico
| | - Jorge Soria-Bustos
- Pathogen and
Microbiome Division, Translational Genomics Research Institute (TGen)
North, Flagstaff,
Arizona, USA
- Instituto de Ciencias
de la Salud, Universidad Autónoma del Estado de
Hidalgo, Pachuca,
Hidalgo, Mexico
| | | | - María L. Cedillo
- Centro de
Detección Biomolecular, Benemérita Universidad
Autónoma de Puebla,
Puebla, Mexico
| | - Jorge A. Girón
- Centro de
Detección Biomolecular, Benemérita Universidad
Autónoma de Puebla,
Puebla, Mexico
| | - Ygnacio Martínez-Laguna
- Centro de
Investigación en Ciencias Microbiológicas,
Benemérita Universidad Autónoma de
Puebla, Puebla,
Mexico
| | - Fenfei Leng
- Biomolecular Sciences
Institute and Department of Chemistry and Biochemistry, Florida
International University,
Miami, Florida, USA
| | - J. Antonio Ibarra
- Escuela Nacional de
Ciencias Biológicas, Instituto Politécnico
Nacional, Mexico City,
Mexico
| | - Miguel A. De la Cruz
- Centro de
Detección Biomolecular, Benemérita Universidad
Autónoma de Puebla,
Puebla, Mexico
- Facultad de Medicina,
Benemérita Universidad Autónoma de
Puebla, Puebla,
Mexico
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3
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Bourigault Y, Dupont CA, Desjardins JB, Doan T, Bouteiller M, Le Guenno H, Chevalier S, Barbey C, Latour X, Cascales E, Merieau A. Pseudomonas fluorescens MFE01 delivers a putative type VI secretion amidase that confers biocontrol against the soft-rot pathogen Pectobacterium atrosepticum. Environ Microbiol 2023; 25:2564-2579. [PMID: 37622480 DOI: 10.1111/1462-2920.16492] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 08/15/2023] [Indexed: 08/26/2023]
Abstract
The type VI secretion system (T6SS) is a contractile nanomachine widespread in Gram-negative bacteria. The T6SS injects effectors into target cells including eukaryotic hosts and competitor microbial cells and thus participates in pathogenesis and intermicrobial competition. Pseudomonas fluorescens MFE01 possesses a single T6SS gene cluster that confers biocontrol properties by protecting potato tubers against the phytopathogen Pectobacterium atrosepticum (Pca). Here, we demonstrate that a functional T6SS is essential to protect potato tuber by reducing the pectobacteria population. Fluorescence microscopy experiments showed that MFE01 displays an aggressive behaviour with an offensive T6SS characterized by continuous and intense T6SS firing activity. Interestingly, we observed that T6SS firing is correlated with rounding of Pectobacterium cells, suggesting delivery of a potent cell wall targeting effector. Mutagenesis coupled with functional assays then revealed that a putative T6SS secreted amidase, Tae3Pf , is mainly responsible for MFE01 toxicity towards Pca. Further studies finally demonstrated that Tae3Pf is toxic when produced in the periplasm, and that its toxicity is counteracted by the Tai3Pf inner membrane immunity protein.
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Affiliation(s)
- Yvann Bourigault
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
| | - Charly A Dupont
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
| | - Jonas B Desjardins
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM, FR3479), CNRS-Aix-Marseille Univ, Marseille, France
| | - Thierry Doan
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM, FR3479), CNRS-Aix-Marseille Univ, Marseille, France
| | - Mathilde Bouteiller
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
| | - Hugo Le Guenno
- Plateforme de Microscopie, Institut de Microbiologie de la Méditerranée (IMM, FR3479), CNRS-Aix-Marseille Univ, Marseille, France
| | - Sylvie Chevalier
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
| | - Corinne Barbey
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
| | - Xavier Latour
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM, FR3479), CNRS-Aix-Marseille Univ, Marseille, France
| | - Annabelle Merieau
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA, UR 4312), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale, NORVEGE Fed4277, Mont-Saint-Aignan, France
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4
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Barnett MJ, Pinheiro J, Keown JR, Biboy J, Gray J, Lucinescu IW, Vollmer W, Hirt RP, Simoes-Barbosa A, Goldstone DC. NlpC/P60 peptidoglycan hydrolases of Trichomonas vaginalis have complementary activities that empower the protozoan to control host-protective lactobacilli. PLoS Pathog 2023; 19:e1011563. [PMID: 37585473 PMCID: PMC10461829 DOI: 10.1371/journal.ppat.1011563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 08/28/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023] Open
Abstract
Trichomonas vaginalis is a human protozoan parasite that causes trichomoniasis, a prevalent sexually transmitted infection. Trichomoniasis is accompanied by a shift to a dysbiotic vaginal microbiome that is depleted of lactobacilli. Studies on co-cultures have shown that vaginal bacteria in eubiosis (e.g. Lactobacillus gasseri) have antagonistic effects on T. vaginalis pathogenesis, suggesting that the parasite might benefit from shaping the microbiome to dysbiosis (e.g. Gardnerella vaginalis among other anaerobes). We have recently shown that T. vaginalis has acquired NlpC/P60 genes from bacteria, expanding them to a repertoire of nine TvNlpC genes in two distinct clans, and that TvNlpCs of clan A are active against bacterial peptidoglycan. Here, we expand this characterization to TvNlpCs of clan B. In this study, we show that the clan organisation of NlpC/P60 genes is a feature of other species of Trichomonas, and that Histomonas meleagridis has sequences related to one clan. We characterized the 3D structure of TvNlpC_B3 alone and with the inhibitor E64 bound, probing the active site of these enzymes for the first time. Lastly, we demonstrated that TvNlpC_B3 and TvNlpC_B5 have complementary activities with the previously described TvNlpCs of clan A and that exogenous expression of these enzymes empower this mucosal parasite to take over populations of vaginal lactobacilli in mixed cultures. TvNlpC_B3 helps control populations of L. gasseri, but not of G. vaginalis, which action is partially inhibited by E64. This study is one of the first to show how enzymes produced by a mucosal protozoan parasite may contribute to a shift on the status of a microbiome, helping explain the link between trichomoniasis and vaginal dysbiosis. Further understanding of this process might have significant implications for treatments in the future.
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Affiliation(s)
- Michael J. Barnett
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jully Pinheiro
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jeremy R. Keown
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Joe Gray
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert P. Hirt
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - David C. Goldstone
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
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5
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Taillefer B, Grandjean MM, Herrou J, Robert D, Mignot T, Sebban-Kreuzer C, Cascales E. Qualitative and Quantitative Methods to Measure Antibacterial Activity Resulting from Bacterial Competition. Bio Protoc 2023; 13:e4706. [PMID: 37449039 PMCID: PMC10336571 DOI: 10.21769/bioprotoc.4706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/06/2023] [Accepted: 04/16/2023] [Indexed: 07/18/2023] Open
Abstract
In the environment, bacteria compete for niche occupancy and resources; they have, therefore, evolved a broad variety of antibacterial weapons to destroy competitors. Current laboratory techniques to evaluate antibacterial activity are usually labor intensive, low throughput, costly, and time consuming. Typical assays rely on the outgrowth of colonies of prey cells on selective solid media after competition. Here, we present fast, inexpensive, and complementary optimized protocols to qualitatively and quantitively measure antibacterial activity. The first method is based on the degradation of a cell-impermeable chromogenic substrate of the β-galactosidase, a cytoplasmic enzyme released during lysis of the attacked reporter strain. The second method relies on the lag time required for the attacked cells to reach a defined optical density after the competition, which is directly dependent on the initial number of surviving cells. Key features First method utilizes the release of β-galactosidase as a proxy for bacterial lysis. Second method is based on the growth timing of surviving cells. Combination of two methods discriminates between cell death and lysis, cell death without lysis, or survival to quasi-lysis. Methods optimized to various bacterial species such as Escherichia coli, Pseudomonas aeruginosa, and Myxococcus xanthus. Graphical overview.
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Affiliation(s)
- Boris Taillefer
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7255, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Marie M. Grandjean
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7255, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Julien Herrou
- Laboratoire de Chimie Bactérienne (LCB), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7283, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Donovan Robert
- Laboratoire de Chimie Bactérienne (LCB), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7283, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne (LCB), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7283, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Corinne Sebban-Kreuzer
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7255, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Univ–CNRS, UMR7255, 31 Chemin Joseph Aiguier CS7071, 13402 Marseille Cedex 09, France
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6
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Trotta KL, Hayes BM, Schneider JP, Wang J, Todor H, Rockefeller Grimes P, Zhao Z, Hatleberg WL, Silvis MR, Kim R, Koo BM, Basler M, Chou S. Lipopolysaccharide transport regulates bacterial sensitivity to a cell wall-degrading intermicrobial toxin. PLoS Pathog 2023; 19:e1011454. [PMID: 37363922 PMCID: PMC10328246 DOI: 10.1371/journal.ppat.1011454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/07/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023] Open
Abstract
Gram-negative bacteria can antagonize neighboring microbes using a type VI secretion system (T6SS) to deliver toxins that target different essential cellular features. Despite the conserved nature of these targets, T6SS potency can vary across recipient species. To understand the functional basis of intrinsic T6SS susceptibility, we screened for essential Escherichia coli (Eco) genes that affect its survival when antagonized by a cell wall-degrading T6SS toxin from Pseudomonas aeruginosa, Tae1. We revealed genes associated with both the cell wall and a separate layer of the cell envelope, lipopolysaccharide, that modulate Tae1 toxicity in vivo. Disruption of genes in early lipopolysaccharide biosynthesis provided Eco with novel resistance to Tae1, despite significant cell wall degradation. These data suggest that Tae1 toxicity is determined not only by direct substrate damage, but also by indirect cell envelope homeostasis activities. We also found that Tae1-resistant Eco exhibited reduced cell wall synthesis and overall slowed growth, suggesting that reactive cell envelope maintenance pathways could promote, not prevent, self-lysis. Together, our study reveals the complex functional underpinnings of susceptibility to Tae1 and T6SS which regulate the impact of toxin-substrate interactions in vivo.
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Affiliation(s)
- Kristine L. Trotta
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Beth M. Hayes
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | | | - Jing Wang
- Biozentrum, University of Basel, Basel, Switzerland
| | - Horia Todor
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Patrick Rockefeller Grimes
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Ziyi Zhao
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | | | - Melanie R. Silvis
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Rachel Kim
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
| | - Byoung Mo Koo
- Department of Cell and Tissue Biology, University of California–San Francisco, San Francisco, California, United States of America
| | - Marek Basler
- Biozentrum, University of Basel, Basel, Switzerland
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California–San Francisco, San Francisco, California, United States of America
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7
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Trotta KL, Hayes BM, Schneider JP, Wang J, Todor H, Grimes PR, Zhao Z, Hatleberg WL, Silvis MR, Kim R, Koo BM, Basler M, Chou S. Lipopolysaccharide integrity primes bacterial sensitivity to a cell wall-degrading intermicrobial toxin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524922. [PMID: 36747731 PMCID: PMC9900751 DOI: 10.1101/2023.01.20.524922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Gram-negative bacteria can antagonize neighboring microbes using a type VI secretion system (T6SS) to deliver toxins that target different essential cellular features. Despite the conserved nature of these targets, T6SS potency can vary across recipient species. To understand the molecular basis of intrinsic T6SS susceptibility, we screened for essential Escherichia coli genes that affect its survival when antagonized by a cell wall-degrading T6SS toxin from Pseudomonas aeruginosa , Tae1. We revealed genes associated with both the cell wall and a separate layer of the cell envelope, surface lipopolysaccharide, that modulate Tae1 toxicity in vivo . Disruption of lipopolysaccharide synthesis provided Escherichia coli (Eco) with novel resistance to Tae1, despite significant cell wall degradation. These data suggest that Tae1 toxicity is determined not only by direct substrate damage, but also by indirect cell envelope homeostasis activities. We also found that Tae1-resistant Eco exhibited reduced cell wall synthesis and overall slowed growth, suggesting that reactive cell envelope maintenance pathways could promote, not prevent, self-lysis. Together, our study highlights the consequences of co-regulating essential pathways on recipient fitness during interbacterial competition, and how antibacterial toxins leverage cellular vulnerabilities that are both direct and indirect to their specific targets in vivo .
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Affiliation(s)
- Kristine L Trotta
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Beth M Hayes
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Jing Wang
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Horia Todor
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Patrick Rockefeller Grimes
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Ziyi Zhao
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | | | - Melanie R Silvis
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Rachel Kim
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
| | - Byoung Mo Koo
- Department of Cell and Tissue Biology, University of California – San Francisco, San Francisco, CA, USA
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH - 4056 Basel, Switzerland
| | - Seemay Chou
- Department of Biochemistry & Biophysics, University of California – San Francisco, San Francisco, CA, USA
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8
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Singh RP, Kumari K. Bacterial type VI secretion system (T6SS): an evolved molecular weapon with diverse functionality. Biotechnol Lett 2023; 45:309-331. [PMID: 36683130 DOI: 10.1007/s10529-023-03354-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/14/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Bacterial secretion systems are nanomolecular complexes that release a diverse set of virulence factors/or proteins into its surrounding or translocate to their target host cells. Among these systems, type VI secretion system 'T6SS' is a recently discovered molecular secretion system which is widely distributed in Gram-negative (-ve) bacteria, and shares structural similarity with the puncturing device of bacteriophages. The presence of T6SS is an advantage to many bacteria as it delivers toxins to its neighbour pathogens for competitive survival, and also translocates protein effectors to the host cells, leading to disruption of lipid membranes, cell walls, and cytoskeletons etc. Recent studies have characterized both anti-prokaryotic and anti-eukaryotic effectors, where T6SS is involved in diverse cellular functions including favouring colonization, enhancing the survival, adhesive modifications, internalization, and evasion of the immune system. With the evolution of advanced genomics and proteomics tools, there has been an increase in the number of characterized T6SS effector arsenals and also more clear information about the adaptive significance of this complex system. The functions of T6SS are generally regulated at the transcription, post-transcription and post-translational levels through diverse mechanisms. In the present review, we aimed to provide information about the distribution of T6SS in diverse bacteria, any structural similarity/or dissimilarity, effectors proteins, functional significance, and regulatory mechanisms. We also tried to provide information about the diverse roles played by T6SS in its natural environments and hosts, and further any changes in the microbiome.
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Affiliation(s)
- Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India.
| | - Kiran Kumari
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
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9
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Wang GZ, Warren EA, Haas AL, Peña AS, Kiedrowski MR, Lomenick B, Chou TF, Bomberger JM, Tirrell DA, Limoli DH. Staphylococcal secreted cytotoxins are competition sensing signals for Pseudomonas aeruginosa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.29.526047. [PMID: 36747623 PMCID: PMC9900984 DOI: 10.1101/2023.01.29.526047] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Coinfection with two notorious opportunistic pathogens, the Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus , dominates chronic pulmonary infections. While coinfection is associated with poor patient outcomes, the interspecies interactions responsible for such decline remain unknown. Here, we dissected molecular mechanisms of interspecies sensing between P. aeruginosa and S. aureus . We discovered that P. aeruginosa senses S. aureus secreted peptides and, counterintuitively, moves towards these toxins. P. aeruginosa tolerates such a strategy through "competition sensing", whereby it preempts imminent danger/competition by arming cells with type six secretion (T6S) and iron acquisition systems. Intriguingly, while T6S is predominantly described as weaponry targeting Gram-negative and eukaryotic cells, we find that T6S is essential for full P. aeruginosa competition with S. aureus , a previously undescribed role for T6S. Importantly, competition sensing was activated during coinfection of bronchial epithelia, including T6S islands targeting human cells. This study reveals critical insight into both interspecies competition and how antagonism may cause collateral damage to the host environment.
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10
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Lorente Cobo N, Sibinelli-Sousa S, Biboy J, Vollmer W, Bayer-Santos E, Prehna G. Molecular characterization of the type VI secretion system effector Tlde1a reveals a structurally altered LD-transpeptidase fold. J Biol Chem 2022; 298:102556. [PMID: 36183829 PMCID: PMC9638812 DOI: 10.1016/j.jbc.2022.102556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 12/01/2022] Open
Abstract
The type VI secretion system (T6SS) is a molecular machine that Gram-negative bacteria have adapted for multiple functions, including interbacterial competition. Bacteria use the T6SS to deliver protein effectors into adjacent cells to kill rivals and establish niche dominance. Central to T6SS-mediated bacterial competition is an arms race to acquire diverse effectors to attack and neutralize target cells. The peptidoglycan has a central role in bacterial cell physiology, and effectors that biochemically modify peptidoglycan structure effectively induce cell death. One such T6SS effector is Tlde1a from Salmonella Typhimurium. Tlde1a functions as an LD-carboxypeptidase to cleave tetrapeptide stems and as an LD-transpeptidase to exchange the terminal D-alanine of a tetrapeptide stem with a noncanonical D-amino acid. To understand how Tlde1a exhibits toxicity at the molecular level, we determined the X-ray crystal structure of Tlde1a alone and in complex with D-amino acids. Our structural data revealed that Tlde1a possesses a unique LD-transpeptidase fold consisting of a dual pocket active site with a capping subdomain. This includes an exchange pocket to bind a D-amino acid for exchange and a catalytic pocket to position the D-alanine of a tetrapeptide stem for cleavage. Our toxicity assays in Escherichia coli and in vitro peptidoglycan biochemical assays with Tlde1a variants correlate Tlde1a molecular features directly to its biochemical functions. We observe that the LD-carboxypeptidase and LD-transpeptidase activities of Tlde1a are both structurally and functionally linked. Overall, our data highlight how an LD-transpeptidase fold has been structurally altered to create a toxic effector in the T6SS arms race.
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Affiliation(s)
- Neil Lorente Cobo
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Stephanie Sibinelli-Sousa
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ethel Bayer-Santos
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Gerd Prehna
- Department of Microbiology, University of Manitoba, Winnipeg, Canada.
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11
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Radkov A, Sapiro AL, Flores S, Henderson C, Saunders H, Kim R, Massa S, Thompson S, Mateusiak C, Biboy J, Zhao Z, Starita LM, Hatleberg WL, Vollmer W, Russell AB, Simorre JP, Anthony-Cahill S, Brzovic P, Hayes B, Chou S. Antibacterial potency of Type VI amidase effector toxins is dependent on substrate topology and cellular context. eLife 2022; 11:79796. [PMID: 35762582 PMCID: PMC9270033 DOI: 10.7554/elife.79796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 06/23/2022] [Indexed: 11/15/2022] Open
Abstract
Members of the bacterial T6SS amidase effector (Tae) superfamily of toxins are delivered between competing bacteria to degrade cell wall peptidoglycan. Although Taes share a common substrate, they exhibit distinct antimicrobial potency across different competitor species. To investigate the molecular basis governing these differences, we quantitatively defined the functional determinants of Tae1 from Pseudomonas aeruginosa PAO1 using a combination of nuclear magnetic resonance and a high-throughput in vivo genetic approach called deep mutational scanning (DMS). As expected, combined analyses confirmed the role of critical residues near the Tae1 catalytic center. Unexpectedly, DMS revealed substantial contributions to enzymatic activity from a much larger, ring-like functional hot spot extending around the entire circumference of the enzyme. Comparative DMS across distinct growth conditions highlighted how functional contribution of different surfaces is highly context-dependent, varying alongside composition of targeted cell walls. These observations suggest that Tae1 engages with the intact cell wall network through a more distributed three-dimensional interaction interface than previously appreciated, providing an explanation for observed differences in antimicrobial potency across divergent Gram-negative competitors. Further binding studies of several Tae1 variants with their cognate immunity protein demonstrate that requirements to maintain protection from Tae activity may be a significant constraint on the mutational landscape of tae1 toxicity in the wild. In total, our work reveals that Tae diversification has likely been shaped by multiple independent pressures to maintain interactions with binding partners that vary across bacterial species and conditions.
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Affiliation(s)
- Atanas Radkov
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Anne L Sapiro
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | | | | | - Hayden Saunders
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Rachel Kim
- Pacific Northwest University of Health Sciences, Yakima, United States
| | - Steven Massa
- Department of Biology, Stanford University, Stanford, United States
| | - Samuel Thompson
- Department of Bioengineering, Stanford University, Stanford, United States
| | - Chase Mateusiak
- Computer Science Department, Washington University in St. Louis, St. Louis, United States
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ziyi Zhao
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Lea M Starita
- Department of Genome Sciences, University of Washington, Seattle, United States
| | | | - Waldemar Vollmer
- Center for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Alistair B Russell
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jean-Pierre Simorre
- Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
| | | | - Peter Brzovic
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Beth Hayes
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Seemay Chou
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
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12
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Pei T, Kan Y, Wang Z, Tang M, Li H, Yan S, Cui Y, Zheng H, Luo H, Liang X, Dong T. Delivery of an Rhs-family nuclease effector reveals direct penetration of the gram-positive cell envelope by a type VI secretion system in Acidovorax citrulli. MLIFE 2022; 1:66-78. [PMID: 38818323 PMCID: PMC10989746 DOI: 10.1002/mlf2.12007] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/16/2021] [Indexed: 06/01/2024]
Abstract
The type VI secretion system (T6SS) is a double-tubular nanomachine widely found in gram-negative bacteria. Its spear-like Hcp tube is capable of penetrating a neighboring cell for cytosol-to-cytosol protein delivery. However, gram-positive bacteria have been considered impenetrable to such T6SS action. Here we report that the T6SS of a plant pathogen, Acidovorax citrulli (AC), could deliver an Rhs-family nuclease effector RhsB to kill not only gram-negative but also gram-positive bacteria. Using bioinformatic, biochemical, and genetic assays, we systematically identified T6SS-secreted effectors and determined that RhsB is a crucial antibacterial effector. RhsB contains an N-terminal PAAR domain, a middle Rhs domain, and an unknown C-terminal domain. RhsB is subject to self-cleavage at both its N- and C-terminal domains and its secretion requires the upstream-encoded chaperone EagT2 and VgrG3. The toxic C-terminus of RhsB exhibits DNase activities and such toxicity is neutralized by either of the two downstream immunity proteins, RimB1 and RimB2. Deletion of rhsB significantly impairs the ability of killing Bacillus subtilis while ectopic expression of immunity proteins RimB1 or RimB2 confers protection. We demonstrate that the AC T6SS not only can effectively outcompete Escherichia coli and B. subtilis in planta but also is highly potent in killing other bacterial and fungal species. Collectively, these findings highlight the greatly expanded capabilities of T6SS in modulating microbiome compositions in complex environments.
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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 BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Yumin Kan
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Zeng‐Hang Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Ming‐Xuan Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Shuangquan Yan
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Yang Cui
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Hao‐Yu Zheng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Han Luo
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Tao Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
- Department of Immunology and MicrobiologySchool of Life Sciences, Southern University of Science and TechnologyGuangdongChina
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13
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Jurėnas D, Cascales E. T6SS: killing two bugs with one stone. Trends Microbiol 2021; 30:1-2. [PMID: 34753653 DOI: 10.1016/j.tim.2021.10.006] [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: 10/20/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 10/19/2022]
Abstract
Bacteria deploy the type VI secretion system (T6SS) to inject effectors into bacterial rivals. Contrary to the prevailing model, a recent study (Le et al.) expands the target range of the T6SS by demonstrating that it delivers and potentializes a peptidoglycan-targeting bifunctional toxin into Gram-positive bacteria.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Université - CNRS, UMR 7255, Marseille, France.
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IM2B), Aix-Marseille Université - CNRS, UMR 7255, Marseille, France.
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14
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Killing of Gram-negative and Gram-positive bacteria by a bifunctional cell wall-targeting T6SS effector. Proc Natl Acad Sci U S A 2021; 118:2106555118. [PMID: 34588306 DOI: 10.1073/pnas.2106555118] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2021] [Indexed: 11/18/2022] Open
Abstract
The type VI secretion system (T6SS) is a powerful tool deployed by Gram-negative bacteria to antagonize neighboring organisms. Here, we report that Acinetobacter baumannii ATCC 17978 (Ab17978) secretes D-lysine (D-Lys), increasing the extracellular pH and enhancing the peptidoglycanase activity of the T6SS effector Tse4. This synergistic effect of D-Lys on Tse4 activity enables Ab17978 to outcompete Gram-negative bacterial competitors, demonstrating that bacteria can modify their microenvironment to increase their fitness during bacterial warfare. Remarkably, this lethal combination also results in T6SS-mediated killing of Gram-positive bacteria. Further characterization revealed that Tse4 is a bifunctional enzyme consisting of both lytic transglycosylase and endopeptidase activities, thus representing a family of modularly organized T6SS peptidoglycan-degrading effectors with an unprecedented impact in antagonistic bacterial interactions.
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15
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Ticks Resist Skin Commensals with Immune Factor of Bacterial Origin. Cell 2021; 183:1562-1571.e12. [PMID: 33306955 DOI: 10.1016/j.cell.2020.10.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/13/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022]
Abstract
Ticks transmit a diverse array of microbes to vertebrate hosts, including human pathogens, which has led to a human-centric focus in this vector system. Far less is known about pathogens of ticks themselves. Here, we discover that a toxin in blacklegged ticks (Ixodes scapularis) horizontally acquired from bacteria-called domesticated amidase effector 2 (dae2)-has evolved to kill mammalian skin microbes with remarkable efficiency. Secreted into the saliva and gut of ticks, Dae2 limits skin-associated staphylococci in ticks while feeding. In contrast, Dae2 has no intrinsic ability to kill Borrelia burgdorferi, the tick-borne Lyme disease bacterial pathogen. These findings suggest ticks resist their own pathogens while tolerating symbionts. Thus, just as tick symbionts can be pathogenic to humans, mammalian commensals can be harmful to ticks. Our study underscores how virulence is context-dependent and bolsters the idea that "pathogen" is a status and not an identity.
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16
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Lisboa J, Pereira C, Rifflet A, Ayala J, Terceti MS, Barca AV, Rodrigues I, Pereira PJB, Osorio CR, García-Del Portillo F, Gomperts Boneca I, do Vale A, Dos Santos NMS. A Secreted NlpC/P60 Endopeptidase from Photobacterium damselae subsp. piscicida Cleaves the Peptidoglycan of Potentially Competing Bacteria. mSphere 2021; 6:e00736-20. [PMID: 33536321 PMCID: PMC7860986 DOI: 10.1128/msphere.00736-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 01/08/2021] [Indexed: 11/20/2022] Open
Abstract
Peptidoglycan (PG) is a major component of the bacterial cell wall, forming a mesh-like structure enwrapping the bacteria that is essential for maintaining structural integrity and providing support for anchoring other components of the cell envelope. PG biogenesis is highly dynamic and requires multiple enzymes, including several hydrolases that cleave glycosidic or amide bonds in the PG. This work describes the structural and functional characterization of an NlpC/P60-containing peptidase from Photobacterium damselae subsp. piscicida (Phdp), a Gram-negative bacterium that causes high mortality of warm-water marine fish with great impact for the aquaculture industry. PnpA ( PhotobacteriumNlpC-like protein A) has a four-domain structure with a hydrophobic and narrow access to the catalytic center and specificity for the γ-d-glutamyl-meso-diaminopimelic acid bond. However, PnpA does not cleave the PG of Phdp or PG of several Gram-negative and Gram-positive bacterial species. Interestingly, it is secreted by the Phdp type II secretion system and degrades the PG of Vibrio anguillarum and Vibrio vulnificus This suggests that PnpA is used by Phdp to gain an advantage over bacteria that compete for the same resources or to obtain nutrients in nutrient-scarce environments. Comparison of the muropeptide composition of PG susceptible and resistant to the catalytic activity of PnpA showed that the global content of muropeptides is similar, suggesting that susceptibility to PnpA is determined by the three-dimensional organization of the muropeptides in the PG.IMPORTANCE Peptidoglycan (PG) is a major component of the bacterial cell wall formed by long chains of two alternating sugars interconnected by short peptides, generating a mesh-like structure that enwraps the bacterial cell. Although PG provides structural integrity and support for anchoring other components of the cell envelope, it is constantly being remodeled through the action of specific enzymes that cleave or join its components. Here, it is shown that Photobacterium damselae subsp. piscicida, a bacterium that causes high mortality in warm-water marine fish, produces PnpA, an enzyme that is secreted into the environment and is able to cleave the PG of potentially competing bacteria, either to gain a competitive advantage and/or to obtain nutrients. The specificity of PnpA for the PG of some bacteria and its inability to cleave others may be explained by differences in the structure of the PG mesh and not by different muropeptide composition.
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Affiliation(s)
- Johnny Lisboa
- Fish Immunology and Vaccinology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Cassilda Pereira
- Fish Immunology and Vaccinology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Aline Rifflet
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- INSERM Groupe Avenir, Paris, France
- CNRS, UMR "Integrated and Molecular Microbiology," Paris, France
| | - Juan Ayala
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Mateus S Terceti
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Alba V Barca
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Inês Rodrigues
- Fish Immunology and Vaccinology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Pedro José Barbosa Pereira
- Biomolecular Structure Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Macromolecular Structure Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Francisco García-Del Portillo
- Laboratorio de Patógenos Bacterianos Intracelulares, Centro Nacional de Biotecnología (CNB), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Ivo Gomperts Boneca
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- INSERM Groupe Avenir, Paris, France
- CNRS, UMR "Integrated and Molecular Microbiology," Paris, France
| | - Ana do Vale
- Fish Immunology and Vaccinology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Nuno M S Dos Santos
- Fish Immunology and Vaccinology Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
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17
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Li HS, Tang XF, Huang YH, Xu ZY, Chen ML, Du XY, Qiu BY, Chen PT, Zhang W, Ślipiński A, Escalona HE, Waterhouse RM, Zwick A, Pang H. Horizontally acquired antibacterial genes associated with adaptive radiation of ladybird beetles. BMC Biol 2021; 19:7. [PMID: 33446206 PMCID: PMC7807722 DOI: 10.1186/s12915-020-00945-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/22/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Horizontal gene transfer (HGT) has been documented in many herbivorous insects, conferring the ability to digest plant material and promoting their remarkable ecological diversification. Previous reports suggest HGT of antibacterial enzymes may have contributed to the insect immune response and limit bacterial growth. Carnivorous insects also display many evolutionary successful lineages, but in contrast to the plant feeders, the potential role of HGTs has been less well-studied. RESULTS Using genomic and transcriptomic data from 38 species of ladybird beetles, we identified a set of bacterial cell wall hydrolase (cwh) genes acquired by this group of beetles. Infection with Bacillus subtilis led to upregulated expression of these ladybird cwh genes, and their recombinantly produced proteins limited bacterial proliferation. Moreover, RNAi-mediated cwh knockdown led to downregulation of other antibacterial genes, indicating a role in antibacterial immune defense. cwh genes are rare in eukaryotes, but have been maintained in all tested Coccinellinae species, suggesting that this putative immune-related HGT event played a role in the evolution of this speciose subfamily of predominant predatory ladybirds. CONCLUSION Our work demonstrates that, in a manner analogous to HGT-facilitated plant feeding, enhanced immunity through HGT might have played a key role in the prey adaptation and niche expansion that promoted the diversification of carnivorous beetle lineages. We believe that this represents the first example of immune-related HGT in carnivorous insects with an association with a subsequent successful species radiation.
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Affiliation(s)
- Hao-Sen Li
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Xue-Fei Tang
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yu-Hao Huang
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Ze-Yu Xu
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Mei-Lan Chen
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
- School of Environment and Life Science, Nanning Normal University, Nanning, 530001, China
| | - Xue-Yong Du
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Bo-Yuan Qiu
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Pei-Tao Chen
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Wei Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Adam Ślipiński
- Australian National Insect Collection, CSIRO, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - Hermes E Escalona
- Australian National Insect Collection, CSIRO, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - Robert M Waterhouse
- Department of Ecology and Evolution, University of Lausanne and Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Andreas Zwick
- Australian National Insect Collection, CSIRO, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - Hong Pang
- State Key Laboratory of Biocontrol, School of Life Sciences / School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China.
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18
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Lin CSH, Chan ACK, Vermeulen J, Brockerman J, Soni AS, Tanner ME, Gaynor EC, McIntosh LP, Simorre JP, Murphy MEP. Peptidoglycan binding by a pocket on the accessory NTF2-domain of Pgp2 directs helical cell shape of Campylobacter jejuni. J Biol Chem 2021; 296:100528. [PMID: 33711341 PMCID: PMC8038945 DOI: 10.1016/j.jbc.2021.100528] [Citation(s) in RCA: 4] [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: 11/27/2020] [Revised: 03/01/2021] [Accepted: 03/08/2021] [Indexed: 01/25/2023] Open
Abstract
The helical morphology of Campylobacter jejuni, a bacterium involved in host gut colonization and pathogenesis in humans, is determined by the structure of the peptidoglycan (PG) layer. This structure is dictated by trimming of peptide stems by the LD-carboxypeptidase Pgp2 within the periplasm. The interaction interface between Pgp2 and PG to select sites for peptide trimming is unknown. We determined a 1.6 Å resolution crystal structure of Pgp2, which contains a conserved LD-carboxypeptidase domain and a previously uncharacterized domain with an NTF2-like fold (NTF2). We identified a pocket in the NTF2 domain formed by conserved residues and located ∼40 Å from the LD-carboxypeptidase active site. Expression of pgp2 in trans with substitutions of charged (Lys257, Lys307, Glu324) and hydrophobic residues (Phe242 and Tyr233) within the pocket did not restore helical morphology to a pgp2 deletion strain. Muropeptide analysis indicated a decrease of murotripeptides in the deletion strain expressing these mutants, suggesting reduced Pgp2 catalytic activity. Pgp2 but not the K307A mutant was pulled down by C. jejuni Δpgp2 PG sacculi, supporting a role for the pocket in PG binding. NMR spectroscopy was used to define the interaction interfaces of Pgp2 with several PG fragments, which bound to the active site within the LD-carboxypeptidase domain and the pocket of the NTF2 domain. We propose a model for Pgp2 binding to PG strands involving both the LD-carboxypeptidase domain and the accessory NTF2 domain to induce a helical cell shape.
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Affiliation(s)
- Chang Sheng-Huei Lin
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anson C K Chan
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jenny Vermeulen
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jacob Brockerman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Arvind S Soni
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Martin E Tanner
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Erin C Gaynor
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lawrence P McIntosh
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada; Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
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19
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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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20
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Le NH, Peters K, Espaillat A, Sheldon JR, Gray J, Di Venanzio G, Lopez J, Djahanschiri B, Mueller EA, Hennon SW, Levin PA, Ebersberger I, Skaar EP, Cava F, Vollmer W, Feldman MF. Peptidoglycan editing provides immunity to Acinetobacter baumannii during bacterial warfare. SCIENCE ADVANCES 2020; 6:eabb5614. [PMID: 32832672 PMCID: PMC7439305 DOI: 10.1126/sciadv.abb5614] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/09/2020] [Indexed: 05/02/2023]
Abstract
Peptidoglycan (PG) is essential in most bacteria. Thus, it is often targeted by various assaults, including interbacterial attacks via the type VI secretion system (T6SS). Here, we report that the Gram-negative bacterium Acinetobacter baumannii strain ATCC 17978 produces, secretes, and incorporates the noncanonical d-amino acid d-lysine into its PG during stationary phase. We show that PG editing increases the competitiveness of A. baumannii during bacterial warfare by providing immunity against peptidoglycan-targeting T6SS effectors from various bacterial competitors. In contrast, we found that d-Lys production is detrimental to pathogenesis due, at least in part, to the activity of the human enzyme d-amino acid oxidase (DAO), which degrades d-Lys producing H2O2 toxic to bacteria. Phylogenetic analyses indicate that the last common ancestor of A. baumannii had the ability to produce d-Lys. However, this trait was independently lost multiple times, likely reflecting the evolution of A. baumannii as a human pathogen.
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Affiliation(s)
- Nguyen-Hung Le
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, NE2 4AX Newcastle upon Tyne, UK
| | - Akbar Espaillat
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, 90187 Umeå, Sweden
| | - Jessica R. Sheldon
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Joe Gray
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Juvenal Lopez
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bardya Djahanschiri
- Applied Bioinformatics Group, Institute of Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt am Main 60438, Germany
| | - Elizabeth A. Mueller
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63105, USA
| | - Seth W. Hennon
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63105, USA
| | - Ingo Ebersberger
- Applied Bioinformatics Group, Institute of Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt am Main 60438, Germany
- LOEWE Center for Translational Biodiversity Genomics (TBG), Senckenberganlage 25, D-60325 Frankfurt am Main, Germany
- Senckenberg Biodiversity and Climate Research Center (S-BIKF), Senckenberganlage 25, D-60325 Frankfurt am Main, Germany
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, 90187 Umeå, Sweden
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, NE2 4AX Newcastle upon Tyne, UK
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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21
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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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22
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Hersch SJ, Watanabe N, Stietz MS, Manera K, Kamal F, Burkinshaw B, Lam L, Pun A, Li M, Savchenko A, Dong TG. Envelope stress responses defend against type six secretion system attacks independently of immunity proteins. Nat Microbiol 2020; 5:706-714. [PMID: 32094588 PMCID: PMC7190449 DOI: 10.1038/s41564-020-0672-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 01/16/2020] [Indexed: 11/23/2022]
Abstract
The arms race among microbes is a key driver in the evolution of not only the weapons but also defence mechanisms. Many gram-negative bacteria use the type six secretion system (T6SS) to deliver toxic effectors directly into neighbouring cells. Defence against effectors requires cognate immunity proteins. However, here we show immunity-independent protection mediated by envelope stress responses in Escherichia coli and Vibrio cholerae against a V. cholerae T6SS effector, TseH. We demonstrate that TseH is a PAAR-dependent species-specific effector highly potent against Aeromonas species but not against its V. cholerae immunity mutant or E. coli. Structural analysis reveals TseH is likely a NlpC/P60 family cysteine endopeptidase. We determine that two envelope stress response pathways, Rcs and BaeSR, protect E. coli from TseH toxicity by mechanisms including capsule synthesis. The two-component system WigKR (VxrAB) is critical for protecting V. cholerae from its own T6SS despite expressing immunity genes. WigR also regulates T6SS expression, suggesting a dual role in attack and defence. This deepens our understanding of how bacteria survive T6SS attacks and suggests that defending against the T6SS represents a major selective pressure driving the evolution of species-specific effectors and protective mechanisms mediated by envelope stress responses and capsule synthesis.
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Affiliation(s)
- Steven J Hersch
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Nobuhiko Watanabe
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada
| | - Maria Silvina Stietz
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Kevin Manera
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Fatima Kamal
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Brianne Burkinshaw
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Linh Lam
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Alexander Pun
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Meixin Li
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada
| | - Alexei Savchenko
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada
| | - Tao G Dong
- Department of Ecosystem and Public Health, University of Calgary, Calgary, Canada. .,State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
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23
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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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24
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Vermassen A, Leroy S, Talon R, Provot C, Popowska M, Desvaux M. Cell Wall Hydrolases in Bacteria: Insight on the Diversity of Cell Wall Amidases, Glycosidases and Peptidases Toward Peptidoglycan. Front Microbiol 2019; 10:331. [PMID: 30873139 PMCID: PMC6403190 DOI: 10.3389/fmicb.2019.00331] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/08/2019] [Indexed: 11/13/2022] Open
Abstract
The cell wall (CW) of bacteria is an intricate arrangement of macromolecules, at least constituted of peptidoglycan (PG) but also of (lipo)teichoic acids, various polysaccharides, polyglutamate and/or proteins. During bacterial growth and division, there is a constant balance between CW degradation and biosynthesis. The CW is remodeled by bacterial hydrolases, whose activities are carefully regulated to maintain cell integrity or lead to bacterial death. Each cell wall hydrolase (CWH) has a specific role regarding the PG: (i) cell wall amidase (CWA) cleaves the amide bond between N-acetylmuramic acid and L-alanine residue at the N-terminal of the stem peptide, (ii) cell wall glycosidase (CWG) catalyses the hydrolysis of the glycosidic linkages, whereas (iii) cell wall peptidase (CWP) cleaves amide bonds between amino acids within the PG chain. After an exhaustive overview of all known conserved catalytic domains responsible for CWA, CWG, and CWP activities, this review stresses that the CWHs frequently display a modular architecture combining multiple and/or different catalytic domains, including some lytic transglycosylases as well as CW binding domains. From there, direct physiological and collateral roles of CWHs in bacterial cells are further discussed.
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Affiliation(s)
- Aurore Vermassen
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Sabine Leroy
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Régine Talon
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | | | - Magdalena Popowska
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
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25
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Vacheron J, Péchy-Tarr M, Brochet S, Heiman CM, Stojiljkovic M, Maurhofer M, Keel C. T6SS contributes to gut microbiome invasion and killing of an herbivorous pest insect by plant-beneficial Pseudomonas protegens. ISME JOURNAL 2019; 13:1318-1329. [PMID: 30683920 DOI: 10.1038/s41396-019-0353-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 12/31/2022]
Abstract
Pseudomonas protegens are multi-talented plant-colonizing bacteria that suppress plant pathogens and stimulate plant defenses. In addition, they are capable of invading and killing agriculturally important plant pest insects that makes them promising candidates for biocontrol applications. Here we assessed the role of type VI secretion system (T6SS) components of type strain CHA0 during interaction with larvae of the cabbage pest Pieris brassicae. We show that the T6SS core apparatus and two VgrG modules, encompassing the respective T6SS spikes (VgrG1a and VgrG1b) and associated effectors (RhsA and Ghh1), contribute significantly to insect pathogenicity of P. protegens in oral infection assays but not when bacteria are injected directly into the hemolymph. Monitoring of the colonization levels of P. protegens in the gut, hemolymph, and excrements of the insect larvae revealed that the invader relies on T6SS and VgrG1a module function to promote hemocoel invasion. A 16S metagenomic analysis demonstrated that T6SS-supported invasion by P. protegens induces significant changes in the insect gut microbiome affecting notably Enterobacteriaceae, a dominant group of the commensal gut bacteria. Our study supports the concept that pathogens deploy T6SS-based strategies to disrupt the commensal microbiota in order to promote host colonization and pathogenesis.
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Affiliation(s)
- Jordan Vacheron
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Maria Péchy-Tarr
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Silvia Brochet
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Clara Margot Heiman
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Marina Stojiljkovic
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Monika Maurhofer
- Plant Pathology, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
| | - Christoph Keel
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
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26
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Pinheiro J, Biboy J, Vollmer W, Hirt RP, Keown JR, Artuyants A, Black MM, Goldstone DC, Simoes-Barbosa A. The Protozoan Trichomonas vaginalis Targets Bacteria with Laterally Acquired NlpC/P60 Peptidoglycan Hydrolases. mBio 2018; 9:e01784-18. [PMID: 30538181 PMCID: PMC6299479 DOI: 10.1128/mbio.01784-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/01/2018] [Indexed: 02/01/2023] Open
Abstract
The human eukaryotic pathogen Trichomonas vaginalis causes trichomoniasis, a prevalent sexually transmitted infection. This extracellular protozoan is intimately associated with the human vaginal mucosa and microbiota, but key aspects of the complex interactions between the parasite and the vaginal bacteria remain elusive. We report that T. vaginalis has acquired, by lateral gene transfer from bacteria, genes encoding peptidoglycan hydrolases of the NlpC/P60 family. Two of the T. vaginalis enzymes were active against bacterial peptidoglycan, retaining the active-site fold and specificity as dl-endopeptidases. The endogenous NlpC/P60 genes are transcriptionally upregulated in T. vaginalis in the presence of bacteria. The overexpression of an exogenous copy enables the parasite to outcompete bacteria from mixed cultures, consistent with the biochemical activity of the enzyme. Our study results highlight the relevance of the interactions of this eukaryotic pathogen with bacteria, a poorly understood aspect of the biology of this important human parasite.IMPORTANCETrichomonas vaginalis is a parasitic protozoan of the human urogenital tract that causes trichomoniasis, a very common sexually transmitted disease. Despite residing extracellularly and in close association with the vaginal bacteria (i.e., the microbiota), very little is known about the nature of the parasite-bacterium interactions. Our study showed that this parasite had acquired genes from bacteria which retained their original function. They produce active enzymes capable of degrading peptidoglycan, a unique polymer of the bacterial cell envelope, helping the parasite to outcompete bacteria in mixed cultures. This study was the first to show that a laterally acquired group of genes enables a eukaryotic mucosal pathogen to control bacterial population. We highlight the importance of understanding the interactions between pathogens and microbiota, as the outcomes of these interactions are increasingly understood to have important implications on health and disease.
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Affiliation(s)
- Jully Pinheiro
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert P Hirt
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jeremy R Keown
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | | | - Moyra M Black
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - David C Goldstone
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
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27
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Molecular Basis for Immunity Protein Recognition of a Type VII Secretion System Exported Antibacterial Toxin. J Mol Biol 2018; 430:4344-4358. [PMID: 30194969 PMCID: PMC6193138 DOI: 10.1016/j.jmb.2018.08.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/29/2018] [Accepted: 08/30/2018] [Indexed: 02/07/2023]
Abstract
Gram-positive bacteria deploy the type VII secretion system (T7SS) to facilitate interactions between eukaryotic and prokaryotic cells. In recent work, we identified the TelC protein from Streptococcus intermedius as a T7SS-exported lipid II phosphatase that mediates interbacterial competition. TelC exerts toxicity in the inner wall zone of Gram-positive bacteria; however, intercellular intoxication of sister cells does not occur because they express the TipC immunity protein. In the present study, we sought to characterize the molecular basis of self-protection by TipC. Using sub-cellular localization and protease protection assays, we show that TipC is a membrane protein with an N-terminal transmembrane segment and a C-terminal TelC-inhibitory domain that protrudes into the inner wall zone. The 1.9-Å X-ray crystal structure of a non-protective TipC paralogue reveals that the soluble domain of TipC proteins adopts a crescent-shaped fold that is composed of three α-helices and a seven-stranded β-sheet. Subsequent homology-guided mutagenesis demonstrates that a concave surface formed by the predicted β-sheet of TipC is required for both its interaction with TelC and its TelC-inhibitory activity. S. intermedius cells lacking the tipC gene are susceptible to growth inhibition by TelC delivered between cells; however, we find that the growth of this strain is unaffected by endogenous or overexpressed TelC, although the toxin accumulates in culture supernatants. Together, these data indicate that the TelC-inhibitory activity of TipC is only required for intercellularly transferred TelC and that the T7SS apparatus transports TelC across the cell envelope in a single step, bypassing the cellular compartment in which it exerts toxicity en route. Antibacterial TelC toxin is neutralized in the inner wall zone by membrane-anchored TipC immunity protein. TipC is a crescent-shaped protein that interacts with TelC via its concave surface. TelC and TipC are physically separated by the plasma membrane in TelC-producing cells. The type VII secretion system prevents TelC access to the inner wall zone in TelC-producing bacteria.
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28
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Effector⁻Immunity Pairs Provide the T6SS Nanomachine its Offensive and Defensive Capabilities. Molecules 2018; 23:molecules23051009. [PMID: 29701633 PMCID: PMC6099711 DOI: 10.3390/molecules23051009] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/13/2018] [Accepted: 04/23/2018] [Indexed: 01/23/2023] Open
Abstract
Type VI protein secretion systems (T6SSs) are specialized transport apparatus which can target both eukaryotic and prokaryotic cells and play key roles in host⁻pathogen⁻microbiota interactions. Therefore, T6SSs have attracted much attention as a research topic during the past ten years. In this review, we particularly summarized the T6SS antibacterial function, which involves an interesting offensive and defensive mechanism of the effector⁻immunity (E⁻I) pairs. The three main categories of effectors that target the cell wall, membranes, and nucleic acids during bacterial interaction, along with their corresponding immunity proteins are presented. We also discuss structural analyses of several effectors and E⁻I pairs, which explain the offensive and defensive mechanisms underpinning T6SS function during bacterial competition for niche-space, as well as the bioinformatics, proteomics, and protein⁻protein interaction (PPI) methods used to identify and characterize T6SS mediated E⁻I pairs. Additionally, we described PPI methods for verifying E⁻I pairs.
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29
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Wilmoth JL, Doak PW, Timm A, Halsted M, Anderson JD, Ginovart M, Prats C, Portell X, Retterer ST, Fuentes-Cabrera M. A Microfluidics and Agent-Based Modeling Framework for Investigating Spatial Organization in Bacterial Colonies: The Case of Pseudomonas Aeruginosa and H1-Type VI Secretion Interactions. Front Microbiol 2018; 9:33. [PMID: 29467721 PMCID: PMC5808251 DOI: 10.3389/fmicb.2018.00033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 01/09/2018] [Indexed: 12/17/2022] Open
Abstract
The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P. aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density and local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models.
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Affiliation(s)
- Jared L Wilmoth
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Peter W Doak
- Computational Sciences and Engineering Division, Oak Ridge, TN, United States
| | - Andrea Timm
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Michelle Halsted
- The Bredesen Center, University of Tennessee, Knoxville, TN, United States
| | - John D Anderson
- The Bredesen Center, University of Tennessee, Knoxville, TN, United States
| | - Marta Ginovart
- Department of Mathematics, Universitat Politecnica de Catalunya, Barcelona, Spain
| | - Clara Prats
- Department of Physics, Universitat Politecnica de Catalunya, Barcelona, Spain
| | - Xavier Portell
- School of Water, Energy and Environment, Cranfield University, Cranfield, United Kingdom
| | - Scott T Retterer
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.,Computational Sciences and Engineering Division, Oak Ridge, TN, United States
| | - Miguel Fuentes-Cabrera
- Computational Sciences and Engineering Division, Oak Ridge, TN, United States.,Computational Sciences and Engineering Division, Oak Ridge, TN, United States
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30
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Structure and activity of ChiX: a peptidoglycan hydrolase required for chitinase secretion by Serratia marcescens. Biochem J 2018; 475:415-428. [PMID: 29229757 PMCID: PMC5778951 DOI: 10.1042/bcj20170633] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 12/05/2017] [Accepted: 12/07/2017] [Indexed: 11/17/2022]
Abstract
The Gram-negative bacterium Serratia marcescens secretes many proteins that are involved in extracellular chitin degradation. This so-called chitinolytic machinery includes three types of chitinase enzymes and a lytic polysaccharide monooxygenase. An operon has been identified in S. marcescens, chiWXYZ, that is thought to be involved in the secretion of the chitinolytic machinery. Genetic evidence points to the ChiX protein being a key player in the secretion mechanism, since deletion of the chiX gene in S. marcescens led to a mutant strain blocked for secretion of all members of the chitinolytic machinery. In this work, a detailed structural and biochemical characterisation of ChiX is presented. The high-resolution crystal structure of ChiX reveals the protein to be a member of the LAS family of peptidases. ChiX is shown to be a zinc-containing metalloenzyme, and in vitro assays demonstrate that ChiX is an l-Ala d-Glu endopeptidase that cleaves the cross-links in bacterial peptidoglycan. This catalytic activity is shown to be intimately linked with the secretion of the chitinolytic machinery, since substitution of the ChiX Asp-120 residue results in a variant protein that is both unable to digest peptidoglycan and cannot rescue the phenoytype of a chiX mutant strain.
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Ge X, Wei W, Li G, Sun M, Li H, Wu J, Hu F. Isolated Pseudomonas aeruginosa strain VIH2 and antagonistic properties against Ralstonia solanacearum. Microb Pathog 2017; 111:519-526. [PMID: 28847494 DOI: 10.1016/j.micpath.2017.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/10/2017] [Accepted: 08/16/2017] [Indexed: 11/29/2022]
Abstract
The aim of this study was to isolates with antagonist activity against R. solanacearum. Thirty-two bacterial isolates were obtained from samples, and they were screened for potential antagonistic activity against R. Solanacearum. Using the agar spot method, ten out of the 21 tested bacteria showed antilisterial activity. VIH2 had the highest inhibitory effect on the growth of R. Solanacearum. Based on 16S rDNA and Biolog test analysis, the strain VIH2 was identified as Pseudomonas aeruginosa. Single-factor and Response Surface Methodology experiments were used to optimize the culture medium and conditions. This study was to explore whether the hemolysin-co-regulated protein secretion island I (HSI-I)-encoded type VI secretion system (T6SS) in Pseudomonas can be used as a biological control approach against Ralstonia solanacearum under field conditions. Bacterial competition assay showed that the HSI-I type T6SS of strain VIH2 exhibited dramatic antibacterial killing activity against R. solanacearum. The HSI-I T6SS of P. aeruginosa was regulated by the ppKA gene. We disrupted the gene ppKA in VIH2 by a single crossover to yield the VIH2 (ΔppKA) mutant. The antagonism of VIH2 was significantly decreased by ppKA gene disruption. In conclusion, our data supported the idea that HSI-I T6SS plays a crucial role in the antagonistic action of strain VIH2 against R. solanacearum. This alternative approach for antagonism against R. solanacearum might help develop attenuated strains of engineered bacteria for biological control.
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Affiliation(s)
- Xincheng Ge
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China
| | - Wei Wei
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China
| | - Gen Li
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China
| | - Mingming Sun
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China
| | - Huixin Li
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China
| | - Jun Wu
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
| | - Feng Hu
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
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Abstract
Bacterial type VI secretion systems (T6SSs) function as contractile nanomachines to puncture target cells and deliver lethal effectors. In the 10 years since the discovery of the T6SS, much has been learned about the structure and function of this versatile protein secretion apparatus. Most of the conserved protein components that comprise the T6SS apparatus itself have been identified and ascribed specific functions. In addition, numerous effector proteins that are translocated by the T6SS have been identified and characterized. These protein effectors usually represent toxic cargoes that are delivered by the attacker cell to a target cell. Researchers in the field are beginning to better understand the lifestyle or physiology that dictates when bacteria normally express their T6SS. In this article, we consider what is known about the structure and regulation of the T6SS, the numerous classes of antibacterial effector T6SS substrates, and how the action of the T6SS relates to a given lifestyle or behavior in certain bacteria.
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Joshi A, Kostiuk B, Rogers A, Teschler J, Pukatzki S, Yildiz FH. Rules of Engagement: The Type VI Secretion System in Vibrio cholerae. Trends Microbiol 2017; 25:267-279. [PMID: 28027803 PMCID: PMC5365375 DOI: 10.1016/j.tim.2016.12.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/04/2016] [Accepted: 12/07/2016] [Indexed: 11/16/2022]
Abstract
Microbial species often exist in complex communities where they must avoid predation and compete for favorable niches. The type VI secretion system (T6SS) is a contact-dependent bacterial weapon that allows for direct killing of competitors through the translocation of proteinaceous toxins. Vibrio cholerae is a Gram-negative pathogen that can use its T6SS during antagonistic interactions with neighboring prokaryotic and eukaryotic competitors. The T6SS not only promotes V. cholerae's survival during its aquatic and host life cycles, but also influences its evolution by facilitating horizontal gene transfer. This review details the recent insights regarding the structure and function of the T6SS as well as the diverse signals and regulatory pathways that control its activation in V. cholerae.
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Affiliation(s)
- Avatar Joshi
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Benjamin Kostiuk
- Department of Medical Microbiology and Immunology, University of Alberta, Alberta, Canada
| | - Andrew Rogers
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Jennifer Teschler
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Stefan Pukatzki
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA.
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Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS). PLoS Pathog 2017; 13:e1006246. [PMID: 28288207 PMCID: PMC5363993 DOI: 10.1371/journal.ppat.1006246] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 03/23/2017] [Accepted: 02/16/2017] [Indexed: 01/19/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is one major type of contagious and foodborne pathogens. The type VI secretion system (T6SS) has been shown to be involved in the bacterial pathogenicity and bacteria-bacteria competition. Here, we show that EHEC could secrete a novel effector KatN, a Mn-containing catalase, in a T6SS-dependent manner. Expression of katN is promoted by RpoS and OxyR and repressed by H-NS, and katN contributes to bacterial growth under oxidative stress in vitro. KatN could be secreted into host cell cytosol after EHEC is phagocytized by macrophage, which leads to decreased level of intracellular reactive oxygen species (ROS) and facilitates the intramacrophage survival of EHEC. Finally, animal model results show that the deletion mutant of T6SS was attenuated in virulence compared with the wild type strain, while the deletion mutant of katN had comparable virulence to the wild type strain. Taken together, our findings suggest that EHEC could sense oxidative stress in phagosome and decrease the host cell ROS by secreting catalase KatN to facilitate its survival in the host cells.
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Edson JA, Kwon YJ. Design, challenge, and promise of stimuli-responsive nanoantibiotics. NANO CONVERGENCE 2016; 3:26. [PMID: 28191436 PMCID: PMC5271158 DOI: 10.1186/s40580-016-0085-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/22/2016] [Indexed: 05/18/2023]
Abstract
Over the past few years, there have been calls for novel antimicrobials to combat the rise of drug-resistant bacteria. While some promising new discoveries have met this call, it is not nearly enough. The major problem is that although these new promising antimicrobials serve as a short-term solution, they lack the potential to provide a long-term solution. The conventional method of creating new antibiotics relies heavily on the discovery of an antimicrobial compound from another microbe. This paradigm of development is flawed due to the fact that microbes can easily transfer a resistant mechanism if faced with an environmental pressure. Furthermore, there has been some evidence to indicate that the environment of the microbe can provide a hint as to their virulence. Because of this, the use of materials with antimicrobial properties has been garnering interest. Nanoantibiotics, (nAbts), provide a new way to circumvent the current paradigm of antimicrobial discovery and presents a novel mechanism of attack not found in microbes yet; which may lead to a longer-term solution against drug-resistance formation. This allows for environment-specific activation and efficacy of the nAbts but may also open up and create new design methods for various applications. These nAbts provide promise, but there is still ample work to be done in their development. This review looks at possible ways of improving and optimizing nAbts by making them stimuli-responsive, then consider the challenges ahead, and industrial applications.Graphical abstractA graphic detailing how the current paradigm of antibiotic discovery can be circumvented by the use of nanoantibiotics.
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Affiliation(s)
- Julius A. Edson
- Department of Chemical Engineering and Material Science, University of California, Irvine, Irvine, CA USA
| | - Young Jik Kwon
- Department of Chemical Engineering and Material Science, University of California, Irvine, Irvine, CA USA
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA USA
- 132 Sprague Hall, Irvine, CA USA
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Abstract
Microbial communities span many orders of magnitude, ranging in scale from hundreds of cells on a single particle of soil to billions of cells within the lumen of the gastrointestinal tract. Bacterial cells in all habitats are members of densely populated local environments that facilitate competition between neighboring cells. Accordingly, bacteria require dynamic systems to respond to the competitive challenges and the fluctuations in environmental circumstances that tax their fitness. The assemblage of bacteria into communities provides an environment where competitive mechanisms are developed into new strategies for survival. In this minireview, we highlight a number of mechanisms used by bacteria to compete between species. We focus on recent discoveries that illustrate the dynamic and multifaceted functions used in bacterial competition and discuss how specific mechanisms provide a foundation for understanding bacterial community development and function.
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Basler M. Type VI secretion system: secretion by a contractile nanomachine. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0021. [PMID: 26370934 PMCID: PMC4632598 DOI: 10.1098/rstb.2015.0021] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action.
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Affiliation(s)
- Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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Sana TG, Berni B, Bleves S. The T6SSs of Pseudomonas aeruginosa Strain PAO1 and Their Effectors: Beyond Bacterial-Cell Targeting. Front Cell Infect Microbiol 2016; 6:61. [PMID: 27376031 PMCID: PMC4899435 DOI: 10.3389/fcimb.2016.00061] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/23/2016] [Indexed: 02/05/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases such as chronic lung colonization in cystic fibrosis patients and acute infections in hospitals. The capacity of P. aeruginosa to be pathogenic toward several hosts is notably due to different secretion systems. Amongst them, P. aeruginosa encodes three Type Six Secretion Systems (T6SS), named H1- to H3-T6SS, that act against either prokaryotes and/or eukaryotic cells. They are independent from each other and inject diverse toxins that interact with different components in the host cell. Here we summarize the roles of these T6SSs in the PAO1 strain, as well as the toxins injected and their targets. While H1-T6SS is only involved in antiprokaryotic activity through at least seven different toxins, H2-T6SS and H3-T6SS are also able to target prokaryotic as well as eukaryotic cells. Moreover, recent studies proposed that H2- and H3-T6SS have a role in epithelial cells invasion by injecting at least three different toxins. The diversity of T6SS effectors is astounding and other effectors still remain to be discovered. In this review, we present a table with other putative P. aeruginosa strain PAO1 T6SS-dependent effectors. Altogether, the T6SSs of P. aeruginosa are important systems that help fight other bacteria for their ecological niche, and are important in the pathogenicity process.
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Affiliation(s)
- Thibault G Sana
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, Centre National de la Recherche Scientifique and Aix-Marseille UniversityMarseille, France; Department of Microbiology and Immunology, Stanford School of Medicine, Stanford UniversityStanford, CA, USA
| | - Benjamin Berni
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, Centre National de la Recherche Scientifique and Aix-Marseille University Marseille, France
| | - Sophie Bleves
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, Centre National de la Recherche Scientifique and Aix-Marseille University Marseille, France
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Expression, secretion and bactericidal activity of type VI secretion system in Vibrio anguillarum. Arch Microbiol 2016; 198:751-60. [DOI: 10.1007/s00203-016-1236-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/21/2016] [Accepted: 05/05/2016] [Indexed: 10/21/2022]
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Alcoforado Diniz J, Liu YC, Coulthurst SJ. Molecular weaponry: diverse effectors delivered by the Type VI secretion system. Cell Microbiol 2015; 17:1742-51. [PMID: 26432982 PMCID: PMC4832377 DOI: 10.1111/cmi.12532] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/22/2015] [Accepted: 09/25/2015] [Indexed: 12/18/2022]
Abstract
The Type VI secretion system is a widespread bacterial nanomachine, used to deliver toxins directly into eukaryotic or prokaryotic target cells. These secreted toxins, or effectors, act on diverse cellular targets, and their action provides the attacking bacterial cell with a significant fitness advantage, either against rival bacteria or eukaryotic host organisms. In this review, we discuss the delivery of diverse effectors by the Type VI secretion system, the modes of action of the so-called 'anti-bacterial' and 'anti-eukaryotic' effectors, the mechanism of self-resistance against anti-bacterial effectors and the evolutionary implications of horizontal transfer of Type VI secretion system-associated toxins. Whilst it is likely that many more effectors remain to be identified, it is already clear that toxins delivered by this secretion system represent efficient weapons against both bacteria and eukaryotes.
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Affiliation(s)
- Juliana Alcoforado Diniz
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Yi-Chia Liu
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Sarah J Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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Shyntum DY, Theron J, Venter SN, Moleleki LN, Toth IK, Coutinho TA. Pantoea ananatis Utilizes a Type VI Secretion System for Pathogenesis and Bacterial Competition. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:420-431. [PMID: 25411959 DOI: 10.1094/mpmi-07-14-0219-r] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Type VI secretion systems (T6SSs) are a class of macromolecular machines that are recognized as an important virulence mechanism in several gram-negative bacteria. The genome of Pantoea ananatis LMG 2665(T), a pathogen of pineapple fruit and onion plants, carries two gene clusters whose predicted products have homology with T6SS-associated gene products from other bacteria. Nothing is known regarding the role of these T6SS-1 and T6SS-3 gene clusters in the biology of P. ananatis. Here, we present evidence that T6SS-1 plays an important role in the pathogenicity of P. ananatis LMG 2665(T) in onion plants, while a strain lacking T6SS-3 remains as pathogenic as the wild-type strain. We also investigated the role of the T6SS-1 system in bacterial competition, the results of which indicated that several bacteria compete less efficiently against wild-type LMG 2665(T) than a strain lacking T6SS-1. Additionally, we demonstrated that these phenotypes of strain LMG 2665(T) were reliant on the core T6SS products TssA and TssD (Hcp), thus indicating that the T6SS-1 gene cluster encodes a functioning T6SS. Collectively, our data provide the first evidence demonstrating that the T6SS-1 system is a virulence determinant of P. ananatis LMG 2665(T) and plays a role in bacterial competition.
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Affiliation(s)
- Divine Y Shyntum
- 1 Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Sciences, and
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42
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LeRoux M, Kirkpatrick RL, Montauti EI, Tran BQ, Peterson SB, Harding BN, Whitney JC, Russell AB, Traxler B, Goo YA, Goodlett DR, Wiggins PA, Mougous JD. Kin cell lysis is a danger signal that activates antibacterial pathways of Pseudomonas aeruginosa. eLife 2015; 4. [PMID: 25643398 PMCID: PMC4348357 DOI: 10.7554/elife.05701] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/30/2015] [Indexed: 12/21/2022] Open
Abstract
The perception and response to cellular death is an important aspect of multicellular eukaryotic life. For example, damage-associated molecular patterns activate an inflammatory cascade that leads to removal of cellular debris and promotion of healing. We demonstrate that lysis of Pseudomonas aeruginosa cells triggers a program in the remaining population that confers fitness in interspecies co-culture. We find that this program, termed P. aeruginosa response to antagonism (PARA), involves rapid deployment of antibacterial factors and is mediated by the Gac/Rsm global regulatory pathway. Type VI secretion, and, unexpectedly, conjugative type IV secretion within competing bacteria, induce P. aeruginosa lysis and activate PARA, thus providing a mechanism for the enhanced capacity of P. aeruginosa to target bacteria that elaborate these factors. Our finding that bacteria sense damaged kin and respond via a widely distributed pathway to mount a complex response raises the possibility that danger sensing is an evolutionarily conserved process. DOI:http://dx.doi.org/10.7554/eLife.05701.001 Bacteria live in diverse and changing environments where resources such as nutrients and space are often limited. They have thus evolved many survival strategies, including competitive and cooperative behaviors. In the first case, bacteria antagonize or prevent the growth of other microorganisms competing with them for resources, such as by generating antibiotics that specifically target rivals. During cooperation, bacteria may coordinate the production of compounds that have a shared benefit for members of their community. In multicellular organisms, some cell types sense harmful microorganisms by the injury they cause in neighboring cells. This triggers a process that can lead to the production of molecules that kill the invaders and factors that promote the repair of cellular damage. An equivalent process has so far not been described for single-celled organisms such as bacteria. However, bacteria often live in structured groups containing many different species. In this type of growth environment, the ability of bacteria to sense when others of their species are attacked and to respond by taking measures to defend themselves could improve their chances of survival. Now, LeRoux et al. reveal that the bacterium Pseudomonas aeruginosa is able to detect ‘danger signals’ released when neighboring P. aeruginosa cells are killed by other bacteria. These signals trigger a response in surviving cells by turning on a pathway that controls a number of antibacterial factors. These include the production of the so-called ‘type VI secretion system’, a molecular machine that delivers a potent cocktail of antibacterial toxins directly into nearby bacteria. This process, which LeRoux et al. have named ‘P. aeruginosa response to antagonism’, or PARA for short, enables P. aeruginosa to thrive when grown with competing bacterial species. P. aeruginosa is notorious for infecting the lungs of people with the genetic disease cystic fibrosis, as well as chronic wounds often found in people with diabetes. In both cases, when P. aeruginosa is present, the numbers of other, often less harmful organisms, tend to decrease. PARA may be one reason for the success of P. aeruginosa in these multi-species infections. DOI:http://dx.doi.org/10.7554/eLife.05701.002
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Affiliation(s)
- Michele LeRoux
- Department of Microbiology, University of Washington, Seattle, United States
| | - Robin L Kirkpatrick
- Department of Microbiology, University of Washington, Seattle, United States
| | - Elena I Montauti
- Department of Microbiology, University of Washington, Seattle, United States
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - S Brook Peterson
- Department of Microbiology, University of Washington, Seattle, United States
| | - Brittany N Harding
- Department of Microbiology, University of Washington, Seattle, United States
| | - John C Whitney
- Department of Microbiology, University of Washington, Seattle, United States
| | - Alistair B Russell
- Department of Microbiology, University of Washington, Seattle, United States
| | - Beth Traxler
- Department of Microbiology, University of Washington, Seattle, United States
| | - Young Ah Goo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - David R Goodlett
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, United States
| | - Paul A Wiggins
- Department of Physics, University of Washington, Seattle, United States
| | - Joseph D Mougous
- Department of Microbiology, University of Washington, Seattle, United States
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Büttner FM, Renner-Schneck M, Stehle T. X-ray crystallography and its impact on understanding bacterial cell wall remodeling processes. Int J Med Microbiol 2015; 305:209-16. [DOI: 10.1016/j.ijmm.2014.12.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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44
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Transferred interbacterial antagonism genes augment eukaryotic innate immune function. Nature 2014; 518:98-101. [PMID: 25470067 DOI: 10.1038/nature13965] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 10/13/2014] [Indexed: 12/29/2022]
Abstract
Horizontal gene transfer allows organisms to rapidly acquire adaptive traits. Although documented instances of horizontal gene transfer from bacteria to eukaryotes remain rare, bacteria represent a rich source of new functions potentially available for co-option. One benefit that genes of bacterial origin could provide to eukaryotes is the capacity to produce antibacterials, which have evolved in prokaryotes as the result of eons of interbacterial competition. The type VI secretion amidase effector (Tae) proteins are potent bacteriocidal enzymes that degrade the cell wall when delivered into competing bacterial cells by the type VI secretion system. Here we show that tae genes have been transferred to eukaryotes on at least six occasions, and that the resulting domesticated amidase effector (dae) genes have been preserved for hundreds of millions of years through purifying selection. We show that the dae genes acquired eukaryotic secretion signals, are expressed within recipient organisms, and encode active antibacterial toxins that possess substrate specificity matching extant Tae proteins of the same lineage. Finally, we show that a dae gene in the deer tick Ixodes scapularis limits proliferation of Borrelia burgdorferi, the aetiologic agent of Lyme disease. Our work demonstrates that a family of horizontally acquired toxins honed to mediate interbacterial antagonism confers previously undescribed antibacterial capacity to eukaryotes. We speculate that the selective pressure imposed by competition between bacteria has produced a reservoir of genes encoding diverse antimicrobial functions that are tailored for co-option by eukaryotic innate immune systems.
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A disordered region in the EvpP protein from the type VI secretion system of Edwardsiella tarda is essential for EvpC binding. PLoS One 2014; 9:e110810. [PMID: 25401506 PMCID: PMC4234509 DOI: 10.1371/journal.pone.0110810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 09/21/2014] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) of pathogenic bacteria plays important roles in both virulence and inter-bacterial competitions. The effectors of T6SS are presumed to be transported either by attaching to the tip protein or by interacting with HcpI (haemolysin corregulated protein 1). In Edwardsiella tarda PPD130/91, the T6SS secreted protein EvpP (E. tardavirulent protein P) is found to be essential for virulence and directly interacts with EvpC (Hcp-like), suggesting that it could be a potential effector. Using limited protease digestion, nuclear magnetic resonance heteronuclear Nuclear Overhauser Effects, and hydrogen-deuterium exchange mass spectrometry, we confirmed that the dimeric EvpP (40 kDa) contains a substantial proportion (40%) of disordered regions but still maintains an ordered and folded core domain. We show that an N-terminal, 10-kDa, protease-resistant fragment in EvpP connects to a shorter, 4-kDa protease-resistant fragment through a highly flexible region, which is followed by another disordered region at the C-terminus. Within this C-terminal disordered region, residues Pro143 to Ile168 are essential for its interaction with EvpC. Unlike the highly unfolded T3SS effector, which has a lower molecular weight and is maintained in an unfolded conformation with a dedicated chaperone, the T6SS effector seems to be relatively larger, folded but partially disordered and uses HcpI as a chaperone.
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Durand E, Cambillau C, Cascales E, Journet L. VgrG, Tae, Tle, and beyond: the versatile arsenal of Type VI secretion effectors. Trends Microbiol 2014; 22:498-507. [DOI: 10.1016/j.tim.2014.06.004] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 06/16/2014] [Accepted: 06/18/2014] [Indexed: 12/20/2022]
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Hu H, Zhang H, Gao Z, Wang D, Liu G, Xu J, Lan K, Dong Y. Structure of the type VI secretion phospholipase effector Tle1 provides insight into its hydrolysis and membrane targeting. ACTA ACUST UNITED AC 2014; 70:2175-85. [DOI: 10.1107/s1399004714012899] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 06/03/2014] [Indexed: 08/30/2023]
Abstract
A diverse superfamily of phospholipases consisting of the type VI lipase effectors Tle1–Tle5 secreted by the bacterial type VI secretion system (T6SS) have recently been identified as antibacterial effectors that hydrolyze membrane phospholipids. These effectors show no significant homology to known lipases, and their mechanism of membrane targeting and hydrolysis of phospholipids remains unknown. Here, the crystal structure of Tle1 (∼96.5 kDa) fromPseudomonas aeruginosarefined to 2.0 Å resolution is reported, representing the first structure of this superfamily. Its overall structure can be divided into two distinct parts, the phospholipase catalytic module and the putative membrane-anchoring module; this arrangement has not previously been observed in known lipase structures. The phospholipase catalytic module has a canonical α/β-hydrolase fold and mutation of any residue in the Ser-Asp-His catalytic triad abolishes its toxicity. The putative membrane-anchoring module adopts an open conformation composed of three amphipathic domains, and its partial folds are similar to those of several periplasmic or membrane proteins. A cell-toxicity assay revealed that the putative membrane-anchoring module is critical to Tle1 antibacterial activity. A molecular-dynamics (MD) simulation system in which the putative membrane-anchoring module embedded into a bilayer was stable over 50 ns. These structure–function studies provide insight into the hydrolysis and membrane-targeting process of the unique phospholipase Tle1.
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Ghequire MGK, De Mot R. Ribosomally encoded antibacterial proteins and peptides from Pseudomonas. FEMS Microbiol Rev 2014; 38:523-68. [PMID: 24923764 DOI: 10.1111/1574-6976.12079] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/05/2014] [Accepted: 05/16/2014] [Indexed: 12/26/2022] Open
Abstract
Members of the Pseudomonas genus produce diverse secondary metabolites affecting other bacteria, fungi or predating nematodes and protozoa but are also equipped with the capacity to secrete different types of ribosomally encoded toxic peptides and proteins, ranging from small microcins to large tailocins. Studies with the human pathogen Pseudomonas aeruginosa have revealed that effector proteins of type VI secretion systems are part of the antibacterial armamentarium deployed by pseudomonads. A novel class of antibacterial proteins with structural similarity to plant lectins was discovered by studying antagonism among plant-associated Pseudomonas strains. A genomic perspective on pseudomonad bacteriocinogeny shows that the modular architecture of S pyocins of P. aeruginosa is retained in a large diversified group of bacteriocins, most of which target DNA or RNA. Similar modularity is present in as yet poorly characterized Rhs (recombination hot spot) proteins and CDI (contact-dependent inhibition) proteins. Well-delimited domains for receptor recognition or cytotoxicity enable the design of chimeric toxins with novel functionalities, which has been applied successfully for S and R pyocins. Little is known regarding how these antibacterials are released and ultimately reach their targets. Other remaining issues concern the identification of environmental triggers activating these systems and assessment of their ecological impact in niches populated by pseudomonads.
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Bartual SG, Straume D, Stamsås GA, Muñoz IG, Alfonso C, Martínez-Ripoll M, Håvarstein LS, Hermoso JA. Structural basis of PcsB-mediated cell separation in Streptococcus pneumoniae. Nat Commun 2014; 5:3842. [DOI: 10.1038/ncomms4842] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 04/08/2014] [Indexed: 01/01/2023] Open
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Lu D, Shang G, Zhang H, Yu Q, Cong X, Yuan J, He F, Zhu C, Zhao Y, Yin K, Chen Y, Hu J, Zhang X, Yuan Z, Xu S, Hu W, Cang H, Gu L. Structural insights into the T6SS effector protein Tse3 and the Tse3-Tsi3 complex fromPseudomonas aeruginosareveal a calcium-dependent membrane-binding mechanism. Mol Microbiol 2014; 92:1092-112. [DOI: 10.1111/mmi.12616] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Defen Lu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
- The Liver Centre of Fujian Province; MengChao Hepatobiliary Hospital of Fujian Medical University; Fuzhou 350025 Fujian China
| | - Guijun Shang
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Heqiao Zhang
- Institute of Biophysics; Chinese Academy of Sciences; Beijing 100101 China
- School of Life Sciences; Tsinghua University; Beijing 100084 China
| | - Qian Yu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Xiaoyan Cong
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Jupeng Yuan
- Institute of Medical Genetics; Shandong University School of Medicine; Jinan 250012 Shandong China
| | - Fengjuan He
- Institute of Medical Genetics; Shandong University School of Medicine; Jinan 250012 Shandong China
| | - Chunyuan Zhu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Yanyu Zhao
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Kun Yin
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Yuanyuan Chen
- Institute of Biophysics; Chinese Academy of Sciences; Beijing 100101 China
| | - Junqiang Hu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Xiaodan Zhang
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Zenglin Yuan
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Sujuan Xu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Wei Hu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
| | - Huaixing Cang
- Institute of Biophysics; Chinese Academy of Sciences; Beijing 100101 China
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 Shandong China
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