1
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Leinweber A, Laffont C, Lardi M, Eberl L, Pessi G, Kümmerli R. RNA-Seq reveals that Pseudomonas aeruginosa mounts growth medium-dependent competitive responses when sensing diffusible cues from Burkholderia cenocepacia. Commun Biol 2024; 7:995. [PMID: 39143311 PMCID: PMC11324955 DOI: 10.1038/s42003-024-06618-3] [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: 05/05/2023] [Accepted: 07/23/2024] [Indexed: 08/16/2024] Open
Abstract
Most habitats host diverse bacterial communities, offering opportunities for inter-species interactions. While competition might often dominate such interactions, little is known about whether bacteria can sense competitors and mount adequate responses. The competition sensing hypothesis proposes that bacteria can use cues such as nutrient stress and cell damage to prepare for battle. Here, we tested this hypothesis by measuring transcriptome changes in Pseudomonas aeruginosa exposed to the supernatant of its competitor Burkholderia cenocepacia. We found that P. aeruginosa exhibited significant growth-medium-dependent transcriptome changes in response to competition. In an iron-rich medium, P. aeruginosa upregulated genes encoding the type-VI secretion system and the siderophore pyoverdine, whereas genes encoding phenazine toxins and hydrogen cyanide were upregulated under iron-limited conditions. Moreover, general stress response and quorum sensing regulators were upregulated upon supernatant exposure. Altogether, our results reveal nuanced competitive responses of P. aeruginosa when confronted with B. cenocepacia supernatant, integrating both environmental and social cues.
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Affiliation(s)
- Anne Leinweber
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Clémentine Laffont
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
| | - Martina Lardi
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Gabriella Pessi
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
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2
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Kennedy NW, Comstock LE. Mechanisms of bacterial immunity, protection, and survival during interbacterial warfare. Cell Host Microbe 2024; 32:794-803. [PMID: 38870897 PMCID: PMC11216714 DOI: 10.1016/j.chom.2024.05.006] [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: 04/09/2024] [Revised: 05/06/2024] [Accepted: 05/10/2024] [Indexed: 06/15/2024]
Abstract
Most bacteria live in communities, often with closely related strains and species with whom they must compete for space and resources. Consequently, bacteria have acquired or evolved mechanisms to antagonize competitors through the production of antibacterial toxins. Similar to bacterial systems that combat phage infection and mechanisms to thwart antibiotics, bacteria have also acquired and evolved features to protect themselves from antibacterial toxins. Just as there is a large body of research identifying and characterizing antibacterial proteins and toxin delivery systems, studies of bacterial mechanisms to resist and survive assault from competitors' weapons have also expanded tremendously. Emerging data are beginning to reveal protective processes and mechanisms that are as diverse as the toxins themselves. Protection against antibacterial toxins can be acquired by horizontal gene transfer, receptor or target alteration, induction of protective functions, physical barriers, and other diverse processes. Here, we review recent studies in this rapidly expanding field.
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Affiliation(s)
- Nolan W Kennedy
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | - Laurie E Comstock
- Duchossois Family Institute and Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.
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3
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Booth SC, Smith WPJ, Foster KR. The evolution of short- and long-range weapons for bacterial competition. Nat Ecol Evol 2023; 7:2080-2091. [PMID: 38036633 PMCID: PMC10697841 DOI: 10.1038/s41559-023-02234-2] [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: 10/13/2022] [Accepted: 09/22/2023] [Indexed: 12/02/2023]
Abstract
Bacteria possess a diverse range of mechanisms for inhibiting competitors, including bacteriocins, tailocins, type VI secretion systems and contact-dependent inhibition (CDI). Why bacteria have evolved such a wide array of weapon systems remains a mystery. Here we develop an agent-based model to compare short-range weapons that require cell-cell contact, with long-range weapons that rely on diffusion. Our model predicts that contact weapons are useful when an attacking strain is outnumbered, facilitating invasion and establishment. By contrast, ranged weapons tend to be effective only when attackers are abundant. We test our predictions with the opportunistic pathogen Pseudomonas aeruginosa, which naturally carries multiple weapons, including CDI and diffusing tailocins. As predicted, short-range CDI can function at low and high frequencies, while long-range tailocins require high frequency and cell density to function effectively. Head-to-head competition experiments with the two weapon types further support our predictions: a tailocin attacker defeats CDI only when it is numerically dominant, but then we find it can be devastating. Finally, we show that the two weapons work well together when one strain employs both. We conclude that short- and long-range weapons serve different functions and allow bacteria to fight both as individuals and as a group.
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Affiliation(s)
- Sean C Booth
- Department of Biology, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - William P J Smith
- Department of Biology, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
- Division of Evolution, Infection and Genomics, University of Manchester, Manchester, UK
| | - Kevin R Foster
- Department of Biology, University of Oxford, Oxford, UK.
- Department of Biochemistry, University of Oxford, Oxford, UK.
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4
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Granada Agudelo M, Ruiz B, Capela D, Remigi P. The role of microbial interactions on rhizobial fitness. FRONTIERS IN PLANT SCIENCE 2023; 14:1277262. [PMID: 37877089 PMCID: PMC10591227 DOI: 10.3389/fpls.2023.1277262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/22/2023] [Indexed: 10/26/2023]
Abstract
Rhizobia are soil bacteria that can establish a nitrogen-fixing symbiosis with legume plants. As horizontally transmitted symbionts, the life cycle of rhizobia includes a free-living phase in the soil and a plant-associated symbiotic phase. Throughout this life cycle, rhizobia are exposed to a myriad of other microorganisms that interact with them, modulating their fitness and symbiotic performance. In this review, we describe the diversity of interactions between rhizobia and other microorganisms that can occur in the rhizosphere, during the initiation of nodulation, and within nodules. Some of these rhizobia-microbe interactions are indirect, and occur when the presence of some microbes modifies plant physiology in a way that feeds back on rhizobial fitness. We further describe how these interactions can impose significant selective pressures on rhizobia and modify their evolutionary trajectories. More extensive investigations on the eco-evolutionary dynamics of rhizobia in complex biotic environments will likely reveal fascinating new aspects of this well-studied symbiotic interaction and provide critical knowledge for future agronomical applications.
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Affiliation(s)
- Margarita Granada Agudelo
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Bryan Ruiz
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Delphine Capela
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Philippe Remigi
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
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5
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Manner C, Dias Teixeira R, Saha D, Kaczmarczyk A, Zemp R, Wyss F, Jaeger T, Laventie BJ, Boyer S, Malone JG, Qvortrup K, Andersen JB, Givskov M, Tolker-Nielsen T, Hiller S, Drescher K, Jenal U. A genetic switch controls Pseudomonas aeruginosa surface colonization. Nat Microbiol 2023; 8:1520-1533. [PMID: 37291227 DOI: 10.1038/s41564-023-01403-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 05/05/2023] [Indexed: 06/10/2023]
Abstract
Efficient colonization of mucosal surfaces is essential for opportunistic pathogens like Pseudomonas aeruginosa, but how bacteria collectively and individually adapt to optimize adherence, virulence and dispersal is largely unclear. Here we identified a stochastic genetic switch, hecR-hecE, which is expressed bimodally and generates functionally distinct bacterial subpopulations to balance P. aeruginosa growth and dispersal on surfaces. HecE inhibits the phosphodiesterase BifA and stimulates the diguanylate cyclase WspR to increase c-di-GMP second messenger levels and promote surface colonization in a subpopulation of cells; low-level HecE-expressing cells disperse. The fraction of HecE+ cells is tuned by different stress factors and determines the balance between biofilm formation and long-range cell dispersal of surface-grown communities. We also demonstrate that the HecE pathway represents a druggable target to effectively counter P. aeruginosa surface colonization. Exposing such binary states opens up new ways to control mucosal infections by a major human pathogen.
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Affiliation(s)
| | | | - Dibya Saha
- Biozentrum, University of Basel, Basel, Switzerland
| | | | | | - Fabian Wyss
- Biozentrum, University of Basel, Basel, Switzerland
| | - Tina Jaeger
- Biozentrum, University of Basel, Basel, Switzerland
- Department Biomedizin, University of Basel, Basel, Switzerland
| | | | - Sebastien Boyer
- sciCORE, Centre for Scientific Computing, University of Basel, Basel, Switzerland
| | - Jacob G Malone
- Biozentrum, University of Basel, Basel, Switzerland
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
| | - Katrine Qvortrup
- Department of Chemistry, Technical University of Denmark, Lyngby, Denmark
| | - Jens Bo Andersen
- Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Michael Givskov
- Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | | | | | | | - Urs Jenal
- Biozentrum, University of Basel, Basel, Switzerland.
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6
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Hespanhol JT, Nóbrega-Silva L, Bayer-Santos E. Regulation of type VI secretion systems at the transcriptional, posttranscriptional and posttranslational level. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001376. [PMID: 37552221 PMCID: PMC10482370 DOI: 10.1099/mic.0.001376] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Bacteria live in complex polymicrobial communities and are constantly competing for resources. The type VI secretion system (T6SS) is a widespread antagonistic mechanism used by Gram-negative bacteria to gain an advantage over competitors. T6SSs translocate toxic effector proteins inside target prokaryotic cells in a contact-dependent manner. In addition, some T6SS effectors can be secreted extracellularly and contribute to the scavenging scarce metal ions. Bacteria deploy their T6SSs in different situations, categorizing these systems into offensive, defensive and exploitative. The great variety of bacterial species and environments occupied by such species reflect the complexity of regulatory signals and networks that control the expression and activation of the T6SSs. Such regulation is tightly controlled at the transcriptional, posttranscriptional and posttranslational level by abiotic (e.g. pH, iron) or biotic (e.g. quorum-sensing) cues. In this review, we provide an update on the current knowledge about the regulatory networks that modulate the expression and activity of T6SSs across several species, focusing on systems used for interbacterial competition.
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Affiliation(s)
- Julia Takuno Hespanhol
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Luize Nóbrega-Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Ethel Bayer-Santos
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
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7
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Smith WPJ, Wucher BR, Nadell CD, Foster KR. Bacterial defences: mechanisms, evolution and antimicrobial resistance. Nat Rev Microbiol 2023:10.1038/s41579-023-00877-3. [PMID: 37095190 DOI: 10.1038/s41579-023-00877-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/26/2023]
Abstract
Throughout their evolutionary history, bacteria have faced diverse threats from other microorganisms, including competing bacteria, bacteriophages and predators. In response to these threats, they have evolved sophisticated defence mechanisms that today also protect bacteria against antibiotics and other therapies. In this Review, we explore the protective strategies of bacteria, including the mechanisms, evolution and clinical implications of these ancient defences. We also review the countermeasures that attackers have evolved to overcome bacterial defences. We argue that understanding how bacteria defend themselves in nature is important for the development of new therapies and for minimizing resistance evolution.
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Affiliation(s)
- William P J Smith
- Division of Genomics, Infection and Evolution, University of Manchester, Manchester, UK.
- Department of Biology, University of Oxford, Oxford, UK.
- Department of Biochemistry, University of Oxford, Oxford, UK.
| | - Benjamin R Wucher
- Department of Biological sciences, Dartmouth College, Hanover, NH, USA
| | - Carey D Nadell
- Department of Biological sciences, Dartmouth College, Hanover, NH, USA
| | - Kevin R Foster
- Department of Biology, University of Oxford, Oxford, UK.
- Department of Biochemistry, University of Oxford, Oxford, UK.
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8
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de Mattos CD, Faith DR, Nemudryi AA, Schmidt AK, Bublitz DC, Hammond L, Kinnersley MA, Schwartzkopf CM, Robinson AJ, Joyce A, Michaels LA, Brzozowski RS, Coluccio A, Xing DD, Uchiyama J, Jennings LK, Eswara P, Wiedenheft B, Secor PR. Polyamines and linear DNA mediate bacterial threat assessment of bacteriophage infection. Proc Natl Acad Sci U S A 2023; 120:e2216430120. [PMID: 36802441 PMCID: PMC9992862 DOI: 10.1073/pnas.2216430120] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 01/10/2023] [Indexed: 02/23/2023] Open
Abstract
Monitoring the extracellular environment for danger signals is a critical aspect of cellular survival. However, the danger signals released by dying bacteria and the mechanisms bacteria use for threat assessment remain largely unexplored. Here, we show that lysis of Pseudomonas aeruginosa cells releases polyamines that are subsequently taken up by surviving cells via a mechanism that relies on Gac/Rsm signaling. While intracellular polyamines spike in surviving cells, the duration of this spike varies according to the infection status of the cell. In bacteriophage-infected cells, intracellular polyamines are maintained at high levels, which inhibits replication of the bacteriophage genome. Many bacteriophages package linear DNA genomes and linear DNA is sufficient to trigger intracellular polyamine accumulation, suggesting that linear DNA is sensed as a second danger signal. Collectively, these results demonstrate how polyamines released by dying cells together with linear DNA allow P. aeruginosa to make threat assessments of cellular injury.
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Affiliation(s)
| | - Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Artem A. Nemudryi
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT59717
| | - Amelia K. Schmidt
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - DeAnna C. Bublitz
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Lauren Hammond
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL33620
| | | | | | - Autumn J. Robinson
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Alex Joyce
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Lia A. Michaels
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | | | - Alison Coluccio
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Denghui David Xing
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Jumpei Uchiyama
- Department of Bacteriology, Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama University, Okayama700-8558, Japan
| | - Laura K. Jennings
- Division of Biological Sciences, University of Montana, Missoula, MT59812
| | - Prahathees Eswara
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL33620
| | - Blake Wiedenheft
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT59717
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, MT59812
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9
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Hansen ML, Wibowo M, Jarmusch SA, Larsen TO, Jelsbak L. Sequential interspecies interactions affect production of antimicrobial secondary metabolites in Pseudomonas protegens DTU9.1. THE ISME JOURNAL 2022; 16:2680-2690. [PMID: 36123523 PMCID: PMC9666462 DOI: 10.1038/s41396-022-01322-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 12/15/2022]
Abstract
Soil and rhizosphere microbiomes play important roles in suppression of plant pathogens through production of antagonistic secondary metabolites, yet mechanisms that determine the strength of pathogen control are not well understood. Many Pseudomonas species are associated with soil and rhizosphere microbiomes, and their ability to suppress pathogens is well documented. Here, we investigate how interactions within the Pseudomonas genus affect their production of antimicrobial metabolites. From a biosensor-based screen, we identify P. capeferrum species as capable of modulating secondary metabolite production in P. protegens. We show that P. capeferrum alters production of pyoluteorin and 2,4-diacetylphloroglucinol (DAPG) in P. protegens via two distinct and sequential mechanisms that depends on spatial proximity of the two species. Specifically, P. capeferrum secretes a diffusible signal that induce pyoluteorin production up to 100-fold in neighboring P. protegens colonies. In contrast, the interaction results in reduced DAPG production, but only within mixed-species colonies. Additionally, we found that increased pyoluteorin production and cell lysis of P. capeferrum is required for inhibition of DAPG production, suggesting that pyoluteorin-facilitated antibiosis of P. protegens on P. capeferrum leads to release of cell-associated metabolites and subsequent inhibition of DAPG production in P. protegens. As the interaction modulates in vitro bioactivity of the species, genus-specific interactions may assist in improving efficacy of biocontrol strains and consortia.
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Affiliation(s)
- Morten Lindqvist Hansen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads bldg. 221, DK-2800, Kgs Lyngby, Denmark
| | - Mario Wibowo
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads bldg. 221, DK-2800, Kgs Lyngby, Denmark
| | - Scott Alexander Jarmusch
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads bldg. 221, DK-2800, Kgs Lyngby, Denmark
| | - Thomas Ostenfeld Larsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads bldg. 221, DK-2800, Kgs Lyngby, Denmark
| | - Lars Jelsbak
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads bldg. 221, DK-2800, Kgs Lyngby, Denmark.
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10
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Chen X, Li Y, Bao X, Zhang E, Cui C, Liu X, Luo Q, Yang J, Li Z, Xu X. Transcriptome profiling based on protein-protein networks provides a core set of genes for understanding blood immune response mechanisms against LPS stress in Amphioctopus fangsiao. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 136:104509. [PMID: 35963309 DOI: 10.1016/j.dci.2022.104509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Gram-negative bacteria are significant pathogens in the ocean, posing serious threats to marine organisms. Lipopolysaccharide (LPS) is a characteristic chemical constituent in Gram-negative bacteria that can be recognized by the pattern recognition receptor (PRR) of immune cells. This system is often used to simulate the invasion of bacteria. Blood is a transport channel for immune cells, and its transcriptome information obtained from Amphioctopus fangsiao stimulated by LPS is essential for understanding the antibacterial biological mechanisms of this species. In this study, we analyzed the gene expression profiles of A. fangsiao blood within 24h under LPS stress and found 778 and 561 differentially expressed genes (DEGs) at 6 and 24h, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were performed to search for immune-related DEGs. The relationships among immune genes were examined by constructing a protein-protein interaction (PPI) network. Finally, 16 hub genes were identified based on the PPI network and KEGG enrichment analysis. The expression profiles of these genes were verified using quantitative RT-PCR (qRT-PCR). This research provides valuable resources for the healthy culture of A. fangsiao and helps us understand the molecular mechanisms of innate immunity.
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Affiliation(s)
- Xipan Chen
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Yan Li
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Xiaokai Bao
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Enshuo Zhang
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Cuiju Cui
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Xiumei Liu
- College of Life Sciences, Yantai University, Yantai, 264005, China
| | - Qihao Luo
- School of Agriculture, Ludong University, Yantai, 264025, China; Yantai Haiyu Marine Science and Technology Co. Ltd., Yantai, 264004, China
| | - Jianmin Yang
- School of Agriculture, Ludong University, Yantai, 264025, China
| | - Zan Li
- School of Agriculture, Ludong University, Yantai, 264025, China.
| | - Xiaohui Xu
- School of Agriculture, Ludong University, Yantai, 264025, China.
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11
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Hashem I, Van Impe JFM. The territorial nature of aggression in biofilms. Front Microbiol 2022; 13:878223. [PMID: 36081784 PMCID: PMC9445555 DOI: 10.3389/fmicb.2022.878223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Microbial conflicts have a particularly aggressive nature. In addition to other chemical, mechanical, and biological weapons in their repertoire, bacteria have evolved bacteriocins, which are narrow-spectrum toxins that kill closely related strains. Bacterial cells are known to frequently use their arsenal while competing against each other for nutrients and space. This stands in contrast with the animal world, where conflicts over resources and mating opportunities are far less lethal, and get commonly resolved via ritualized fighting or “limited war” tactics. Prevalence of aggression in microbial communities is usually explained as due to their limited ability to resolve conflicts via signaling as well as their limited ability to pull out from conflicts due to the sessile nature of their life within biofilms. We use an approach that combines Evolutionary Game Theory (EGT) and Individual-based Modeling (IbM) to investigate the origins of aggression in microbial conflicts. In order to understand how the spatial mode of growth affects the cost of a fight, we compare the growth dynamics emerging from engaging in aggression in a well-mixed system to a spatially structured system. To this end, a mathematical model is constructed for the competition between two bacterial strains where each strain produces a diffusible toxin to which the other strain is sensitive. It is observed that in the biofilm growth mode, starting from a mixed layer of two strains, mutual aggression gives rise to an exceedingly high level of spatial segregation, which in turn reduces the cost of aggression on both strains compared to when the same competition occurs in a well-mixed culture. Another observation is that the transition from a mixed layer to segregated growth is characterized by a switch in the overall growth dynamics. An increased “lag time” is observed in the overall population growth curve that is associated with the earlier stages of growth, when each strain is still experiencing the inhibiting effect of the toxin produced by its competitor. Afterwards, an exponential phase of growth kicks in once the competing strains start segregating from each other. The emerging “lag time” arises from the spiteful interactions between the two strains rather than acclimation of cells' internal physiology. Our analysis highlights the territorial nature of microbial conflicts as the key driver to their elevated levels of aggression as it increases the benefit-to-cost ratio of participating in antagonistic interactions.
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12
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Unni R, Pintor KL, Diepold A, Unterweger D. Presence and absence of type VI secretion systems in bacteria. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35467500 DOI: 10.1099/mic.0.001151] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The type VI secretion system (T6SS) is a molecular puncturing device that enables Gram-negative bacteria to kill competitors, manipulate host cells and take up nutrients. Who would want to miss such superpowers? Indeed, many studies show how widespread the secretion apparatus is among microbes. However, it is becoming evident that, on multiple taxonomic levels, from phyla to species and strains, some bacteria lack a T6SS. Here, we review who does and does not have a type VI secretion apparatus and speculate on the dynamic process of gaining and losing the secretion system to better understand its spread and distribution across the microbial world.
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Affiliation(s)
- Rahul Unni
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany.,Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, 24105 Kiel, Germany
| | - Katherine L Pintor
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Daniel Unterweger
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany.,Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, 24105 Kiel, Germany
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13
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Smakman F, Hall AR. Exposure to lysed bacteria can promote or inhibit growth of neighbouring live bacteria depending on local abiotic conditions. FEMS Microbiol Ecol 2022; 98:6524834. [PMID: 35138381 PMCID: PMC8902688 DOI: 10.1093/femsec/fiac011] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/17/2022] [Accepted: 02/07/2022] [Indexed: 11/14/2022] Open
Abstract
Microbial death is extremely common in nature, yet the ecological role of dead bacteria is unclear. Dead cells are assumed to provide nutrients to surrounding microbes, but may also affect them in other ways. We found adding lysate prepared from dead bacteria to cultures of E. coli in nutrient-rich conditions suppressed their final population density. This is in stark contrast with the notion that the primary role of dead cells is nutritional, although we also observed this type of effect when we added dead bacteria to cultures that were not supplied with other nutrients. We only observed the growth-suppressive effect of our dead-bacteria treatment after they had undergone significant lysis, suggesting a key role for cellular contents released during lysis. Transcriptomic analysis indicated changes in gene expression in response to dead cells in growing populations, particularly in genes involved in motility. This was supported by experiments with genetic knockouts and copy-number manipulation. Because lysis is commonplace in natural and clinical settings, the growth-suppressive effect of dead cells we describe here may be a widespread and previously unrecognized constraint on bacterial population growth.
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Affiliation(s)
- Fokko Smakman
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16 8092 Zürich Switzerland
| | - Alex R Hall
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16 8092 Zürich Switzerland
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14
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Ting SY, LaCourse KD, Ledvina HE, Zhang R, Radey MC, Kulasekara HD, Somavanshi R, Bertolli SK, Gallagher LA, Kim J, Penewit KM, Salipante SJ, Xu L, Peterson SB, Mougous JD. Discovery of coordinately regulated pathways that provide innate protection against interbacterial antagonism. eLife 2022; 11:74658. [PMID: 35175195 PMCID: PMC8926400 DOI: 10.7554/elife.74658] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
Bacterial survival is fraught with antagonism, including that deriving from viruses and competing bacterial cells. It is now appreciated that bacteria mount complex antiviral responses; however, whether a coordinated defense against bacterial threats is undertaken is not well understood. Previously, we showed that Pseudomonas aeruginosa possess a danger-sensing pathway that is a critical fitness determinant during competition against other bacteria. Here, we conducted genome-wide screens in P. aeruginosa that reveal three conserved and widespread interbacterial antagonism resistance clusters (arc1-3). We find that although arc1-3 are coordinately activated by the Gac/Rsm danger-sensing system, they function independently and provide idiosyncratic defense capabilities, distinguishing them from general stress response pathways. Our findings demonstrate that Arc3 family proteins provide specific protection against phospholipase toxins by preventing the accumulation of lysophospholipids in a manner distinct from previously characterized membrane repair systems. These findings liken the response of P. aeruginosa to bacterial threats to that of eukaryotic innate immunity, wherein threat detection leads to the activation of specialized defense systems.
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Affiliation(s)
- See-Yeun Ting
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kaitlyn D LaCourse
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hannah E Ledvina
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - Matthew C Radey
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hemantha D Kulasekara
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rahul Somavanshi
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Larry A Gallagher
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Jennifer Kim
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kelsi M Penewit
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Stephen J Salipante
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - S Brook Peterson
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States,Department of Biochemistry, University of Washington School of MedicineSeattleUnited States,Howard Hughes Medical Institute, University of WashingtonSeattleUnited States
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15
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Defending against the Type Six Secretion System: beyond Immunity Genes. Cell Rep 2021; 33:108259. [PMID: 33053336 DOI: 10.1016/j.celrep.2020.108259] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/10/2020] [Accepted: 09/21/2020] [Indexed: 02/07/2023] Open
Abstract
The bacterial type six secretion system (T6SS) delivers toxic effector proteins into neighboring cells, but bacteria must protect themselves against their own T6SS. Immunity genes are the best-characterized defenses, protecting against specific cognate effectors. However, the prevalence of the T6SS and the coexistence of species with heterologous T6SSs suggest evolutionary pressure selecting for additional defenses against it. Here we review defenses against the T6SS beyond self-associated immunity genes, such as diverse stress responses that can recognize T6SS-inflicted damage and coordinate induction of molecular armor, repair pathways, and overall survival. Some of these stress responses are required for full survival even in the presence of immunity genes. Finally, we propose that immunity gene-independent protection is, mechanistically, bacterial innate immunity and that such defenses and the T6SS have co-evolved and continue to shape one another in polymicrobial communities.
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16
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Niehus R, Oliveira NM, Li A, Fletcher AG, Foster KR. The evolution of strategy in bacterial warfare via the regulation of bacteriocins and antibiotics. eLife 2021; 10:69756. [PMID: 34488940 PMCID: PMC8423443 DOI: 10.7554/elife.69756] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 08/01/2021] [Indexed: 12/21/2022] Open
Abstract
Bacteria inhibit and kill one another with a diverse array of compounds, including bacteriocins and antibiotics. These attacks are highly regulated, but we lack a clear understanding of the evolutionary logic underlying this regulation. Here, we combine a detailed dynamic model of bacterial competition with evolutionary game theory to study the rules of bacterial warfare. We model a large range of possible combat strategies based upon the molecular biology of bacterial regulatory networks. Our model predicts that regulated strategies, which use quorum sensing or stress responses to regulate toxin production, will readily evolve as they outcompete constitutive toxin production. Amongst regulated strategies, we show that a particularly successful strategy is to upregulate toxin production in response to an incoming competitor’s toxin, which can be achieved via stress responses that detect cell damage (competition sensing). Mirroring classical game theory, our work suggests a fundamental advantage to reciprocation. However, in contrast to classical results, we argue that reciprocation in bacteria serves not to promote peaceful outcomes but to enable efficient and effective attacks.
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Affiliation(s)
- Rene Niehus
- Center for Communicable Disease Dynamics, Harvard TH Chan School of Public Health, Harvard University, Boston, United States
| | - Nuno M Oliveira
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom.,Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Aming Li
- Center for Systems and Control, College of Engineering, Peking University, Beijing, China.,Institue for Artificial Intelligence, Peking University, Beijing, China
| | - Alexander G Fletcher
- School of Mathematics and Statistics, University of Sheffield, Sheffield, United Kingdom.,The Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Kevin R Foster
- Department of Zoology, University of Oxford, Oxford, United Kingdom.,Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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17
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Peterson SB, Bertolli SK, Mougous JD. The Central Role of Interbacterial Antagonism in Bacterial Life. Curr Biol 2021; 30:R1203-R1214. [PMID: 33022265 DOI: 10.1016/j.cub.2020.06.103] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The study of bacteria interacting with their environment has historically centered on strategies for obtaining nutrients and resisting abiotic stresses. We argue this focus has deemphasized a third facet of bacterial life that is equally central to their existence: namely, the threat to survival posed by antagonizing bacteria. The diversity and ubiquity of interbacterial antagonism pathways is becoming increasingly apparent, and the insidious manner by which interbacterial toxins disarm their targets emphasizes the highly evolved nature of these processes. Studies examining the role of antagonism in natural communities reveal it can serve many functions, from facilitating colonization of naïve habitats to maintaining bacterial community stability. The pervasiveness of antagonistic pathways is necessarily matched by an equally extensive array of defense strategies. These overlap with well characterized, central stress response pathways, highlighting the contribution of bacterial interactions to shaping cell physiology. In this review, we build the case for the ubiquity and importance of interbacterial antagonism.
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Affiliation(s)
- S Brook Peterson
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA.
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18
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Molina-Santiago C, Vela-Corcía D, Petras D, Díaz-Martínez L, Pérez-Lorente AI, Sopeña-Torres S, Pearson J, Caraballo-Rodríguez AM, Dorrestein PC, de Vicente A, Romero D. Chemical interplay and complementary adaptative strategies toggle bacterial antagonism and co-existence. Cell Rep 2021; 36:109449. [PMID: 34320359 PMCID: PMC8333196 DOI: 10.1016/j.celrep.2021.109449] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/18/2021] [Accepted: 07/02/2021] [Indexed: 02/06/2023] Open
Abstract
Bacterial communities are in a continuous adaptive and evolutionary race for survival. In this work we expand our knowledge on the chemical interplay and specific mutations that modulate the transition from antagonism to co-existence between two plant-beneficial bacteria, Pseudomonas chlororaphis PCL1606 and Bacillus amyloliquefaciens FZB42. We reveal that the bacteriostatic activity of bacillaene produced by Bacillus relies on an interaction with the protein elongation factor FusA of P. chlororaphis and how mutations in this protein lead to tolerance to bacillaene and other protein translation inhibitors. Additionally, we describe how the unspecific tolerance of B. amyloliquefaciens to antimicrobials associated with mutations in the glycerol kinase GlpK is provoked by a decrease of Bacillus cell membrane permeability, among other pleiotropic responses. We conclude that nutrient specialization and mutations in basic biological functions are bacterial adaptive dynamics that lead to the coexistence of two primary competitive bacterial species rather than their mutual eradication. Bacillus and Pseudomonas interaction ranges from antagonism to co-existence Bacillaene from Bacillus is a bacteriostatic that targets FusA of Pseudomonas GlpK mutations in Bacillus confer unspecific antimicrobial resistance
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Affiliation(s)
- Carlos Molina-Santiago
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - David Vela-Corcía
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - Daniel Petras
- University of California San Diego, Scripps Institution of Oceanography, La Jolla, CA, USA; University of California San Diego, Collaborative Mass Spectrometry Innovation Center, La Jolla, CA, USA
| | - Luis Díaz-Martínez
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - Alicia Isabel Pérez-Lorente
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - Sara Sopeña-Torres
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - John Pearson
- Nano-imaging Unit, Andalusian Centre for Nanomedicine and Biotechnology, BIONAND, Málaga, Spain
| | | | - Pieter C Dorrestein
- University of California San Diego, Collaborative Mass Spectrometry Innovation Center, La Jolla, CA, USA
| | - Antonio de Vicente
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain
| | - Diego Romero
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora," Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31 (Campus Universitario de Teatinos), 29071 Málaga, Spain.
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19
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Affiliation(s)
- Felicity Alcock
- Microbes in Health and Disease Theme, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Tracy Palmer
- Microbes in Health and Disease Theme, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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20
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All living cells are cognitive. Biochem Biophys Res Commun 2020; 564:134-149. [PMID: 32972747 DOI: 10.1016/j.bbrc.2020.08.120] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/28/2020] [Accepted: 08/19/2020] [Indexed: 12/24/2022]
Abstract
All living cells sense and respond to changes in external or internal conditions. Without that cognitive capacity, they could not obtain nutrition essential for growth, survive inevitable ecological changes, or correct accidents in the complex processes of reproduction. Wherever examined, even the smallest living cells (prokaryotes) display sophisticated regulatory networks establishing appropriate adaptations to stress conditions that maximize the probability of survival. Supposedly "simple" prokaryotic organisms also display remarkable capabilities for intercellular signalling and multicellular coordination. These observations indicate that all living cells are cognitive.
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21
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Fur-Dam Regulatory Interplay at an Internal Promoter of the Enteroaggregative Escherichia coli Type VI Secretion sci1 Gene Cluster. J Bacteriol 2020; 202:JB.00075-20. [PMID: 32152218 DOI: 10.1128/jb.00075-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 02/28/2020] [Indexed: 12/17/2022] Open
Abstract
The type VI secretion system (T6SS) is a weapon for delivering effectors into target cells that is widespread in Gram-negative bacteria. The T6SS is a highly versatile machine, as it can target both eukaryotic and prokaryotic cells, and it has been proposed that T6SSs are adapted to the specific needs of each bacterium. The expression of T6SS gene clusters and the activation of the secretion apparatus are therefore tightly controlled. In enteroaggregative Escherichia coli (EAEC), the sci1 T6SS gene cluster is subject to a complex regulation involving both the ferric uptake regulator (Fur) and DNA adenine methylase (Dam)-dependent DNA methylation. In this study, an additional, internal, promoter was identified within the sci1 gene cluster using +1 transcriptional mapping. Further analyses demonstrated that this internal promoter is controlled by a mechanism strictly identical to that of the main promoter. The Fur binding box overlaps the -10 transcriptional element and a Dam methylation site, GATC-32. Hence, the expression of the distal sci1 genes is repressed and the GATC-32 site is protected from methylation in iron-rich conditions. The Fur-dependent protection of GATC-32 was confirmed by an in vitro methylation assay. In addition, the methylation of GATC-32 negatively impacted Fur binding. The expression of the sci1 internal promoter is therefore controlled by iron availability through Fur regulation, whereas Dam-dependent methylation maintains a stable ON expression in iron-limited conditions.IMPORTANCE Bacteria use weapons to deliver effectors into target cells. One of these weapons, the type VI secretion system (T6SS), assembles a contractile tail acting as a spring to propel a toxin-loaded needle. Its expression and activation therefore need to be tightly regulated. Here, we identified an internal promoter within the sci1 T6SS gene cluster in enteroaggregative E. coli We show that this internal promoter is controlled by Fur and Dam-dependent methylation. We further demonstrate that Fur and Dam compete at the -10 transcriptional element to finely tune the expression of T6SS genes. We propose that this elegant regulatory mechanism allows the optimum production of the T6SS in conditions where enteroaggregative E. coli encounters competing species.
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22
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Gonzalez D, Mavridou DA. Making the Best of Aggression: The Many Dimensions of Bacterial Toxin Regulation. Trends Microbiol 2019; 27:897-905. [DOI: 10.1016/j.tim.2019.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/15/2019] [Accepted: 05/23/2019] [Indexed: 12/14/2022]
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23
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Benomar S, Evans KC, Unckless RL, Chandler JR. Efflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition Model. Appl Environ Microbiol 2019; 85:e00908-19. [PMID: 31324628 PMCID: PMC6752006 DOI: 10.1128/aem.00908-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/11/2019] [Indexed: 12/18/2022] Open
Abstract
Members of the Chromobacterium genus include opportunistic but often-fatal pathogens and soil saprophytes with highly versatile metabolic capabilities. In previous studies of Chromobacterium subtsugae (formerly C. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM) that confers resistance to several antibiotics, including the bactobolin antibiotic produced by the soil saprophyte Burkholderia thailandensis Here, we show the cdeAB-oprM genes increase C. subtsugae survival in a laboratory competition model with B. thailandensis We also demonstrate that adding sublethal bactobolin concentrations to the coculture increases C. subtsugae survival, but this effect is not through CdeAB-OprM. Instead, the increased survival requires a second, previously unreported pump we call CseAB-OprN. We show that in cells exposed to sublethal bactobolin concentrations, the cseAB-oprN genes are transcriptionally induced, and this corresponds to an increase in bactobolin resistance. Induction of this pump is highly specific and sensitive to bactobolin, while CdeAB-OprM appears to have a broader range of antibiotic recognition. We examine the distribution of cseAB-oprN and cdeAB-oprM gene clusters in members of the Chromobacterium genus and find the cseAB-oprN genes are limited to the nonpathogenic C. subtsugae strains, whereas the cdeAB-oprM genes are more widely distributed among members of the Chromobacterium genus. Our results provide new information on the antibiotic resistance mechanisms of Chromobacterium species and highlight the importance of efflux pumps for saprophytic bacteria existing in multispecies communities.IMPORTANCE Antibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member of the Chromobacterium genus and increases resistance to a broad range of antibiotics. The other gene cluster has more narrow antibiotic specificity and is found only in Chromobacterium subtsugae, a subset of entirely nonpathogenic species. We demonstrate the role of both pumps in increasing antibiotic resistance and demonstrate the importance of efflux-dependent resistance induction for C. subtsugae survival in a dual-species competition model. These results have implications for managing antibiotic-resistant Chromobacterium infections and for understanding the evolution of efflux pumps outside the host.
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Affiliation(s)
- Saida Benomar
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Kara C Evans
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Josephine R Chandler
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
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24
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Doekes HM, de Boer RJ, Hermsen R. Toxin production spontaneously becomes regulated by local cell density in evolving bacterial populations. PLoS Comput Biol 2019; 15:e1007333. [PMID: 31469819 PMCID: PMC6742444 DOI: 10.1371/journal.pcbi.1007333] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 09/12/2019] [Accepted: 08/14/2019] [Indexed: 11/18/2022] Open
Abstract
The production of anticompetitor toxins is widespread among bacteria. Because production of such toxins is costly, it is typically regulated. In particular, many toxins are produced only when the local cell density is high. It is unclear which selection pressures shaped the evolution of density-dependent regulation of toxin production. Here, we study the evolution of toxin production, resistance and the response to a cell-density cue in a model of an evolving bacterial population with spatial structure. We present results for two growth regimes: (i) an undisturbed, fixed habitat in which only small fluctuations of cell density occur, and (ii) a serial-transfer regime with large fluctuations in cell density. We find that density-dependent toxin production can evolve under both regimes. However, the selection pressures driving the evolution of regulation differ. In the fixed habitat, regulation evolves because it allows cells to produce toxin only when opportunities for reproduction are highly limited (because of a high local cell density), and the effective fitness costs of toxin production are hence low. Under serial transfers, regulation evolves because it allows cells to switch from a fast-growing non-toxic phenotype when colonising a new habitat, to a slower-growing competitive toxic phenotype when the cell density increases. Colonies of such regulating cells rapidly expand into unoccupied space because their edges consist of fast-growing, non-toxin-producing cells, but are also combative because cells at the interfaces with competing colonies do produce toxin. Because under the two growth regimes different types of regulation evolve, our results underscore the importance of growth conditions in the evolution of social behaviour in bacteria. Bacteria live in microbial communities, in which they compete with many other microbes for nutrients and space. In this competitive environment, almost all known bacterial strains produce toxins that impair or kill other bacteria. This chemical warfare is thought to be one of the major factors shaping microbial diversity. Many toxins are produced only if the local density of bacteria is high. To achieve this, bacteria respond to cell-density cues: signalling molecules or other indicators of the presence of other cells. Here, we use a computational model to study the evolution of density-based regulation of toxin production in bacterial populations. We show that such regulation can arise under various growth conditions, and analyse the selection pressures driving its evolution. In particular, we find that if bacteria regularly need to colonise a new habitat, density-based regulation allows them to express a fast-growing, non-toxic phenotype when expanding into uncolonised territory, and a slower-growing, toxin-producing phenotype when competing with other strains. Colonies of regulating cells show a typical structure, with cells of the fast-growing, sensitive phenotype at their expanding edges, and toxin-producing cells in the colony interior and at interfaces between colonies.
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Affiliation(s)
- Hilje M. Doekes
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands
- * E-mail:
| | - Rob J. de Boer
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - Rutger Hermsen
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands
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25
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Cherrak Y, Flaugnatti N, Durand E, Journet L, Cascales E. Structure and Activity of the Type VI Secretion System. Microbiol Spectr 2019; 7:10.1128/microbiolspec.psib-0031-2019. [PMID: 31298206 PMCID: PMC10957189 DOI: 10.1128/microbiolspec.psib-0031-2019] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Indexed: 12/16/2022] Open
Abstract
The type VI secretion system (T6SS) is a multiprotein machine that uses a spring-like mechanism to inject effectors into target cells. The injection apparatus is composed of a baseplate on which is built a contractile tail tube/sheath complex. The inner tube, topped by the spike complex, is propelled outside of the cell by the contraction of the sheath. The injection system is anchored to the cell envelope and oriented towards the cell exterior by a trans-envelope complex. Effectors delivered by the T6SS are loaded within the inner tube or on the spike complex and can target prokaryotic and/or eukaryotic cells. Here we summarize the structure, assembly, and mechanism of action of the T6SS. We also review the function of effectors and their mode of recruitment and delivery.
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Affiliation(s)
- Yassine Cherrak
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, UMR 7255, 13402 Marseille Cedex 20, France
- Y.C. and N.F. contributed equally to this review
| | - Nicolas Flaugnatti
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, UMR 7255, 13402 Marseille Cedex 20, France
- Y.C. and N.F. contributed equally to this review
- Present address: Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Eric Durand
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, UMR 7255, 13402 Marseille Cedex 20, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, UMR 7255, 13402 Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, UMR 7255, 13402 Marseille Cedex 20, France
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26
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García-Bayona L, Comstock LE. Bacterial antagonism in host-associated microbial communities. Science 2018; 361:361/6408/eaat2456. [PMID: 30237322 DOI: 10.1126/science.aat2456] [Citation(s) in RCA: 175] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/20/2018] [Indexed: 12/13/2022]
Abstract
Antagonistic interactions are abundant in microbial communities and contribute not only to the composition and relative proportions of their members but also to the longer-term stability of a community. This Review will largely focus on bacterial antagonism mediated by ribosomally synthesized peptides and proteins produced by members of host-associated microbial communities. We discuss recent findings on their diversity, functions, and ecological impacts. These systems play key roles in ecosystem defense, pathogen invasion, spatial segregation, and diversity but also confer indirect gains to the aggressor from products released by killed cells. Investigations into antagonistic bacterial interactions are important for our understanding of how the microbiota establish within hosts, influence health and disease, and offer insights into potential translational applications.
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Affiliation(s)
- Leonor García-Bayona
- Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Laurie E Comstock
- Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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27
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Abstract
Many bacteria use a cell-cell communication system called quorum sensing to coordinate population density-dependent changes in behavior. Quorum sensing involves production of and response to diffusible or secreted signals, which can vary substantially across different types of bacteria. In many species, quorum sensing modulates virulence functions and is important for pathogenesis. Over the past half-century, there has been a significant accumulation of knowledge of the molecular mechanisms, signal structures, gene regulons, and behavioral responses associated with quorum-sensing systems in diverse bacteria. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have revealed how quorum sensing coordinates interactions both within a species and between species. Such studies of quorum sensing as a social behavior have relied on the development of "synthetic ecological" models that use nonclonal bacterial populations. In this review, we discuss some of these models and recent advances in understanding how microbes might interact with one another using quorum sensing. The knowledge gained from these lines of investigation has the potential to guide studies of microbial sociality in natural settings and the design of new medicines and therapies to treat bacterial infections.
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28
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Chassaing B, Cascales E. Antibacterial Weapons: Targeted Destruction in the Microbiota. Trends Microbiol 2018; 26:329-338. [PMID: 29452951 DOI: 10.1016/j.tim.2018.01.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 01/18/2018] [Accepted: 01/23/2018] [Indexed: 01/18/2023]
Abstract
The intestinal microbiota plays an important role in health, particularly in promoting intestinal metabolic capacity and in maturing the immune system. The intestinal microbiota also mediates colonization resistance against pathogenic bacteria, hence protecting the host from infections. In addition, some bacterial pathogens deliver toxins that target phylogenetically related or distinct bacterial species in order to outcompete and establish within the microbiota. The most widely distributed weapons include bacteriocins, as well as contact-dependent growth inhibition and type VI secretion systems. In this review, we discuss important advances about the impact of such antibacterial systems on shaping the intestinal microbiota.
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Affiliation(s)
- Benoit Chassaing
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA; Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA.
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ - Centre National de la Recherche Scientifique (CNRS) UMR7255, Marseille, France.
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29
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Valentini M, Gonzalez D, Mavridou DA, Filloux A. Lifestyle transitions and adaptive pathogenesis of Pseudomonas aeruginosa. Curr Opin Microbiol 2017; 41:15-20. [PMID: 29166621 DOI: 10.1016/j.mib.2017.11.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/31/2017] [Accepted: 11/04/2017] [Indexed: 02/06/2023]
Abstract
Pseudomonas aeruginosa acute and chronic infections are of great concern to human health, especially in hospital settings. It is currently assumed that P. aeruginosa has two antagonistic pathogenic strategies that parallel two different lifestyles; free-living cells are predominantly cytotoxic and induce an acute inflammatory reaction, while biofilm-forming communities cause refractory chronic infections. Recent findings suggest that the planktonic-to-sessile transition is a complex, reversible and overall dynamic differentiation process. Here, we examine how the Gac/Rsm regulatory cascade, a key player in this lifestyle switch, endows P. aeruginosa with both a permissive lifecycle in nature and flexible virulence strategy during infection.
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Affiliation(s)
- Martina Valentini
- MRC Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, SW7 2AZ London, United Kingdom.
| | - Diego Gonzalez
- Département de Microbiologie Fondamentale, Université de Lausanne, CH-1015 Lausanne, Switzerland
| | - Despoina Ai Mavridou
- MRC Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, SW7 2AZ London, United Kingdom
| | - Alain Filloux
- MRC Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, SW7 2AZ London, United Kingdom.
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30
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David PT, Hongwei L, John TN, Zipporah P, Zogbo L, Charles FK, Melissa SS, Victor MV. Biological control of potential antagonistic bacteria isolates to restrict Magnaporthe grisea infection on rice. ACTA ACUST UNITED AC 2017. [DOI: 10.5897/ajmr2017.8562] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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31
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Niehus R, Picot A, Oliveira NM, Mitri S, Foster KR. The evolution of siderophore production as a competitive trait. Evolution 2017; 71:1443-1455. [DOI: 10.1111/evo.13230] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/03/2017] [Accepted: 03/12/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Rene Niehus
- Department of Zoology; University of Oxford; South Parks Road OX1 3PS Oxford United Kingdom
- Mahidol Oxford Tropical Medicine Research Unit (MORU); 10400 Bangkok Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine; University of Oxford; Oxford United Kingdom
| | - Aurore Picot
- Department of Zoology; University of Oxford; South Parks Road OX1 3PS Oxford United Kingdom
- Sorbonne Universités, UPMC Univ Paris 6, UPEC, Univ Paris Diderot, Univ Paris-Est Créteil, CNRS, INRA, IRD; Institute of Ecology and Environmental Sciences-Paris (iEES Paris); 7 quai Saint-Bernard 75 252 Paris France
| | - Nuno M. Oliveira
- Department of Zoology; University of Oxford; South Parks Road OX1 3PS Oxford United Kingdom
- Department of Applied Mathematics and Theoretical Physics (DAMTP); Centre for Mathematical Sciences; Wilberforce Road Cambridge CB3 0WA United Kingdom
| | - Sara Mitri
- Department of Fundamental Microbiology; University of Lausanne; CH-1015 Lausanne Switzerland
| | - Kevin R. Foster
- Department of Zoology; University of Oxford; South Parks Road OX1 3PS Oxford United Kingdom
- Oxford Centre for Integrative Systems Biology; University of Oxford; South Parks Road Oxford OX1 3QU United Kingdom
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32
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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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33
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Westhoff S, van Wezel GP, Rozen DE. Distance-dependent danger responses in bacteria. Curr Opin Microbiol 2017; 36:95-101. [PMID: 28258981 DOI: 10.1016/j.mib.2017.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 01/27/2017] [Accepted: 02/01/2017] [Indexed: 12/23/2022]
Abstract
The last decade has seen a resurgence in our understanding of the diverse mechanisms that bacteria use to kill one another. We are also beginning to uncover the responses and countermeasures that bacteria use when faced with specific threats or general cues of potential danger from bacterial competitors. In this Perspective, we propose that diverse offensive and defensive responses in bacteria have evolved to offset dangers detected at different distances. Thus, while volatile organic compounds provide bacterial cells with a warning at the greatest distance, diffusible compounds like antibiotics or contact mediated killing systems, indicate a more pressing danger warranting highly-specific responses. In the competitive environments in which bacteria live, it is crucial that cells are able to detect real or potential dangers from other cells. By utilizing mechanisms of detection that can infer the distance from danger, bacteria can fine-tune aggressive interactions so that they can optimally respond to threats occurring with distinct levels of risk.
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Affiliation(s)
- Sanne Westhoff
- Institute of Biology, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2300 BE Leiden, The Netherlands.
| | - Gilles P van Wezel
- Institute of Biology, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2300 BE Leiden, The Netherlands
| | - Daniel E Rozen
- Institute of Biology, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2300 BE Leiden, The Netherlands
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34
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Ghoul M, Mitri S. The Ecology and Evolution of Microbial Competition. Trends Microbiol 2016; 24:833-845. [DOI: 10.1016/j.tim.2016.06.011] [Citation(s) in RCA: 378] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 06/15/2016] [Accepted: 06/28/2016] [Indexed: 01/23/2023]
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35
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Stylianidou S, Brennan C, Nissen SB, Kuwada NJ, Wiggins PA. SuperSegger: robust image segmentation, analysis and lineage tracking of bacterial cells. Mol Microbiol 2016; 102:690-700. [PMID: 27569113 DOI: 10.1111/mmi.13486] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2016] [Indexed: 11/29/2022]
Abstract
Many quantitative cell biology questions require fast yet reliable automated image segmentation to identify and link cells from frame-to-frame, and characterize the cell morphology and fluorescence. We present SuperSegger, an automated MATLAB-based image processing package well-suited to quantitative analysis of high-throughput live-cell fluorescence microscopy of bacterial cells. SuperSegger incorporates machine-learning algorithms to optimize cellular boundaries and automated error resolution to reliably link cells from frame-to-frame. Unlike existing packages, it can reliably segment microcolonies with many cells, facilitating the analysis of cell-cycle dynamics in bacteria as well as cell-contact mediated phenomena. This package has a range of built-in capabilities for characterizing bacterial cells, including the identification of cell division events, mother, daughter and neighbouring cells, and computing statistics on cellular fluorescence, the location and intensity of fluorescent foci. SuperSegger provides a variety of postprocessing data visualization tools for single cell and population level analysis, such as histograms, kymographs, frame mosaics, movies and consensus images. Finally, we demonstrate the power of the package by analyzing lag phase growth with single cell resolution.
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Affiliation(s)
- Stella Stylianidou
- Department of Physics, University of Washington, Seattle, WA, 98195, USA
| | - Connor Brennan
- Department of Physics, University of Washington, Seattle, WA, 98195, USA
| | - Silas B Nissen
- Department of StemPhys, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Nathan J Kuwada
- Department of Physics, Central Washington University, Ellensburg, WA, 98926, USA
| | - Paul A Wiggins
- Department of Physics, University of Washington, Seattle, WA, 98195, USA.,Department of Bioengineering, University of Washington, Seattle, WA, 98195, USA.,Department of Microbiology, University of Washington, Seattle, WA, 98195, USA
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36
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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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37
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38
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Interbacterial signaling via Burkholderia contact-dependent growth inhibition system proteins. Proc Natl Acad Sci U S A 2016; 113:8296-301. [PMID: 27335458 DOI: 10.1073/pnas.1606323113] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In prokaryotes and eukaryotes, cell-cell communication and recognition of self are critical to coordinate multicellular functions. Although kin and kind discrimination are increasingly appreciated to shape naturally occurring microbe populations, the underlying mechanisms that govern these interbacterial interactions are insufficiently understood. Here, we identify a mechanism of interbacterial signal transduction that is mediated by contact-dependent growth inhibition (CDI) system proteins. CDI systems have been characterized by their ability to deliver a polymorphic protein toxin into the cytoplasm of a neighboring bacterium, resulting in growth inhibition or death unless the recipient bacterium produces a corresponding immunity protein. Using the model organism Burkholderia thailandensis, we show that delivery of a catalytically active CDI system toxin to immune (self) bacteria results in gene expression and phenotypic changes within the recipient cells. Termed contact-dependent signaling (CDS), this response promotes biofilm formation and other community-associated behaviors. Engineered strains that are isogenic with B. thailandensis, except the DNA region encoding the toxin and immunity proteins, did not display CDS, whereas a strain of Burkholderia dolosa producing a nearly identical toxin-immunity pair induced signaling in B. thailandensis Our data indicate that bcpAIOB loci confer dual benefits; they direct antagonism toward non-self bacteria and promote cooperation between self bacteria, with self being defined by the bcpAIOB allele and not by genealogic relatedness.
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39
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Abstract
The ability of bacteria to recognize kin provides a means to form social groups. In turn these groups can lead to cooperative behaviors that surpass the ability of the individual. Kin recognition involves specific biochemical interactions between a receptor(s) and an identification molecule(s). Recognition specificity, ensuring that nonkin are excluded and kin are included, is critical and depends on the number of loci and polymorphisms involved. After recognition and biochemical perception, the common ensuing cooperative behaviors include biofilm formation, quorum responses, development, and swarming motility. Although kin recognition is a fundamental mechanism through which cells might interact, microbiologists are only beginning to explore the topic. This review considers both molecular and theoretical aspects of bacterial kin recognition. Consideration is also given to bacterial diversity, genetic relatedness, kin selection theory, and mechanisms of recognition.
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Affiliation(s)
- Daniel Wall
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071;
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40
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Metzger LC, Stutzmann S, Scrignari T, Van der Henst C, Matthey N, Blokesch M. Independent Regulation of Type VI Secretion in Vibrio cholerae by TfoX and TfoY. Cell Rep 2016; 15:951-958. [PMID: 27117415 PMCID: PMC4858559 DOI: 10.1016/j.celrep.2016.03.092] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/16/2016] [Accepted: 03/27/2016] [Indexed: 11/30/2022] Open
Abstract
Type VI secretion systems (T6SSs) are nanomachines used for interbacterial killing and intoxication of eukaryotes. Although Vibrio cholerae is a model organism for structural studies on T6SSs, the underlying regulatory network is less understood. A recent study showed that the T6SS is part of the natural competence regulon in V. cholerae and is activated by the regulator TfoX. Here, we identify the TfoX homolog TfoY as a second activator of the T6SS. Importantly, despite inducing the same T6SS core machinery, the overall regulons differ significantly for TfoX and TfoY. We show that TfoY does not contribute to competence induction. Instead, TfoY drives the production of T6SS-dependent and T6SS-independent toxins, together with an increased motility phenotype. Hence, we conclude that V. cholerae uses its sole T6SS in response to diverse cues and for distinctive outcomes: either to kill for the prey’s DNA, leading to horizontal gene transfer, or as part of a defensive escape reaction. The type VI secretion system (T6SS) of V. cholerae is activated by TfoX and TfoY Both regulators aim at different phenotypic outcomes TfoY drives the production of T6SS-dependent and T6SS-independent toxins The absence of TfoY severely impairs constitutive T6SS activity in strain V52
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Affiliation(s)
- Lisa C Metzger
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Sandrine Stutzmann
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Tiziana Scrignari
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Charles Van der Henst
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Noémie Matthey
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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41
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Hajishengallis G, Lamont RJ. Dancing with the Stars: How Choreographed Bacterial Interactions Dictate Nososymbiocity and Give Rise to Keystone Pathogens, Accessory Pathogens, and Pathobionts. Trends Microbiol 2016; 24:477-489. [PMID: 26968354 DOI: 10.1016/j.tim.2016.02.010] [Citation(s) in RCA: 205] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/06/2016] [Accepted: 02/19/2016] [Indexed: 12/25/2022]
Abstract
Many diseases that originate on mucosal membranes ensue from the action of polymicrobial communities of indigenous organisms working in concert to disrupt homeostatic mechanisms. Multilevel physical and chemical communication systems among constituent organisms underlie polymicrobial synergy and dictate the community's pathogenic potential or nososymbiocity, that is, disease arising from living together with a susceptible host. Functional specialization of community participants, often originating from metabolic codependence, has given rise to several newly appreciated designations within the commensal-to-pathogen spectrum. Accessory pathogens, while inherently commensal in a particular microenvironment, nonetheless enhance the colonization or metabolic activity of pathogens. Keystone pathogens (bacterial drivers or alpha-bugs) exert their influence at low abundance by modulating both the composition and levels of community participants and by manipulating host responses. Pathobionts (or bacterial passengers) exploit disrupted host homeostasis to flourish and promote inflammatory disease. In this review we discuss how commensal or pathogenic properties of organisms are not intrinsic features, and have to be considered within the context of both the microbial community in which they reside and the host immune status.
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Affiliation(s)
- George Hajishengallis
- Department of Microbiology, Penn Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, KY, USA.
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42
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Abstract
Microbes are now known to participate in an extensive repertoire of cooperative behaviors such as biofilm formation, production of extracellular public-goods, group motility, and higher-ordered multicellular structures. A fundamental question is how these cooperative tasks are maintained in the face of non-cooperating defector cells. Recently, a number of molecular mechanisms including facultative participation, spatial sorting, and policing have been discovered to stabilize cooperation. Often these different mechanisms work in concert to reinforce cooperation. In this review, we describe bacterial cooperation and the current understanding of the molecular mechanisms that maintain it.
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Affiliation(s)
- Eric Bruger
- Department of Microbiology and Molecular Genetics and the BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, 48824, USA
| | - Christopher Waters
- Department of Microbiology and Molecular Genetics and the BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, 48824, USA
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43
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Stanley-Wall NR, Coulthurst SJ, Holland IB. A Snapshot of the Extraordinary World of Social Microbiology. J Mol Biol 2015; 427:3625-7. [PMID: 26518741 DOI: 10.1016/j.jmb.2015.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Nicola R Stanley-Wall
- Division of Molecular Microbiology of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
| | - Sarah J Coulthurst
- Division of Molecular Microbiology of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
| | - Ian Barry Holland
- Institute of Genetics and Microbiology, CNRS UMR1354, University Paris XI, Building 409, Orsay 91400, France.
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