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Patz S, Becker Y, Richert-Pöggeler KR, Berger B, Ruppel S, Huson DH, Becker M. Phage tail-like particles are versatile bacterial nanomachines - A mini-review. J Adv Res 2019; 19:75-84. [PMID: 31341672 PMCID: PMC6629978 DOI: 10.1016/j.jare.2019.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 04/06/2019] [Accepted: 04/14/2019] [Indexed: 11/27/2022] Open
Abstract
Suggestion to simplify and unify the nomenclature of phage tail-like particles. Discovery of kosakonicin, a new bacteriocin and tailocin. Microscopy of kosakonicin from Kosakonia radicincitans DSM 16656. Discovery of multiple tail fiber genes in the kosakonicin gene cluster. Discovery of large genetic diversity in the kosakonicin tail fiber locus among ten Kosakonia strains.
Type VI secretion systems and tailocins, two bacterial phage tail-like particles, have been reported to foster interbacterial competition. Both nanostructures enable their producer to kill other bacteria competing for the same ecological niche. Previously, type VI secretion systems and particularly R-type tailocins were considered highly specific, attacking a rather small range of competitors. Their specificity is conferred by cell surface receptors of the target bacterium and receptor-binding proteins on tailocin tail fibers and tail fiber-like appendages of T6SS. Since many R-type tailocin gene clusters contain only one tail fiber gene it was appropriate to expect small R-type tailocin target ranges. However, recently up to three tail fiber genes and broader target ranges have been reported for one plant-associated Pseudomonas strain. Here, we show that having three tail fiber genes per R-type tailocin gene cluster is a common feature of several strains of Gram-negative (often plant-associated) bacteria of the genus Kosakonia. Knowledge about the specificity of type VI secretion systems binding to target bacteria is even lower than in R-type tailocins. Although the mode of operation implicated specific binding, it was only published recently that type VI secretion systems develop tail fiber-like appendages. Here again Kosakonia, exhibiting up to three different type VI secretion systems, may provide valuable insights into the antagonistic potential of plant-associated bacteria. Current understanding of the diversity and potential of phage tail-like particles is fragmentary due to various synonyms and misleading terminology. Consistency in technical terms is a precondition for concerted and purposeful research, which precedes a comprehensive understanding of the specific interaction between bacteria producing phage tail-like particles and their targets. This knowledge is fundamental for selecting and applying tailored, and possibly engineered, producer bacteria for antagonizing plant pathogenic microorganisms.
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Affiliation(s)
- Sascha Patz
- Algorithms in Bioinformatics, Center for Bioinformatics, University of Tübingen, 72074 Tübingen, Germany
| | - Yvonne Becker
- Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institute - Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany
| | - Katja R Richert-Pöggeler
- Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institute - Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany
| | - Beatrice Berger
- Institute for National and International Plant Health, Julius Kühn-Institute - Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany
| | - Silke Ruppel
- Leibniz Institute of Vegetable and Ornamental Crops, 14979 Grossbeeren, Germany
| | - Daniel H Huson
- Algorithms in Bioinformatics, Center for Bioinformatics, University of Tübingen, 72074 Tübingen, Germany
| | - Matthias Becker
- Institute for National and International Plant Health, Julius Kühn-Institute - Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany.,Leibniz Institute of Vegetable and Ornamental Crops, 14979 Grossbeeren, Germany
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102
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Bidirectional contraction of a type six secretion system. Nat Commun 2019; 10:1565. [PMID: 30952865 PMCID: PMC6450956 DOI: 10.1038/s41467-019-09603-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 03/20/2019] [Indexed: 12/31/2022] Open
Abstract
Contractile injection systems (CISs) mediate cell-cell interactions by a phage tail-like apparatus. Their conserved mechanism relies on the anchoring of the proximal end of a sheath-tube module to a membrane, followed by contraction of the sheath towards the attachment site and ejection of the inner tube. Here we reveal a major variation of the CIS mechanism in the type six secretion system (T6SS) of enteroaggregative Escherichia coli (EAEC). We show that both ends of the sheath-tube module are attached to opposite sides of the cell, enabling the structure to contract in two opposite directions. The protein TssA1 mediates the interaction of the distal end with the cell envelope, the termination of tail elongation, and non-canonical contraction towards the distal end. We provide a framework for the molecular processes at the T6SS distal end. Further research will address whether bidirectional contraction allows for bidirectional effector secretion. The unrecognized concept of non-canonical contractions could be relevant to biofilms of the human intestine.
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Jiang F, Li N, Wang X, Cheng J, Huang Y, Yang Y, Yang J, Cai B, Wang YP, Jin Q, Gao N. Cryo-EM Structure and Assembly of an Extracellular Contractile Injection System. Cell 2019; 177:370-383.e15. [PMID: 30905475 DOI: 10.1016/j.cell.2019.02.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/11/2019] [Accepted: 02/13/2019] [Indexed: 02/06/2023]
Abstract
Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC) represents one group of extracellular CISs that are present in both bacteria and archaea. Here, we report the cryo-EM structure of an intact PVC from P. asymbiotica. This over 10-MDa device resembles a simplified T4 phage tail, containing a hexagonal baseplate complex with six fibers and a capped 117-nanometer sheath-tube trunk. One distinct feature of the PVC is the presence of three variants for both tube and sheath proteins, indicating a functional specialization of them during evolution. The terminal hexameric cap docks onto the topmost layer of the inner tube and locks the outer sheath in pre-contraction state with six stretching arms. Our results on the PVC provide a framework for understanding the general mechanism of widespread CISs and pave the way for using them as delivery tools in biological or therapeutic applications.
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Affiliation(s)
- Feng Jiang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, PRC
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, PRC
| | - Xia Wang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, PRC
| | - Jiaxuan Cheng
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, PRC; Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, PRC
| | - Yaoguang Huang
- Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, PRC
| | - Yun Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, PRC
| | - Jianguo Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, PRC
| | - Bin Cai
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, PRC
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, PRC
| | - Qi Jin
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, PRC.
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, PRC.
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104
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Liang X, Peng LH, Zhang S, Zhou S, Yoshida A, Osatomi K, Bellou N, Guo XP, Dobretsov S, Yang JL. Polyurethane, epoxy resin and polydimethylsiloxane altered biofilm formation and mussel settlement. CHEMOSPHERE 2019; 218:599-608. [PMID: 30502698 DOI: 10.1016/j.chemosphere.2018.11.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 11/17/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
In many environments, biofilms are a major mode and an emergent form of microbial life. Biofilms play crucial roles in biogeochemical cycling and invertebrate recruitment in marine environments. However, relatively little is known about how marine biofilms form on different substrata and about how these biofilms impact invertebrate recruitment. Here, we performed a comparative analysis of a 28-day-old biofilm community on non-coated (a control glass) and coated substrata (polyurethane (PU), epoxy resin (EP) and polydimethylsiloxane (PDMS)) and examined the settlement of Mytilus coruscus plantigrades on these biofilms. PU, EP and PDMS deterred the development of marine biofilms by reducing the biofilm biomass including the biofilm dry weight, cell density of the bacteria and diatoms and chlorophyll a concentrations. Further analysis of bacterial community revealed that EP altered the bacterial community composition compared with that on the glass substrata by reducing the relative abundance of Ruegeria (Alphaproteobacteria) and by increasing the relative abundance of Methylotenera (Betaproteobacteria) and Cyanobacteria in the biofilms. However, bacterial communities developed on PU and PDMS, as well as glass and PU, EP and PDMS did not exhibit differences from each other. The M. coruscus settlement rates on biofilms on PU, EP and PDMS were reduced by 20-41% compared with those on the glass after 28 days. Thus, the tested coatings impacted the development of marine biofilms by altering the biofilm biomass and/or the bacterial community composition. The mussel settlements decreased in the biofilms that formed on the coatings compared with those on non-coated glass.
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Affiliation(s)
- Xiao Liang
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China; National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Li-Hua Peng
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China
| | - Shuo Zhang
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China
| | - Shuxue Zhou
- Department of Materials Science, State Key Laboratory of Molecular Engineering of Polymers, Advanced Coatings Research Center of Ministry of Education of China, Fudan University, Shanghai, China
| | - Asami Yoshida
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
| | - Kiyoshi Osatomi
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
| | - Nikoleta Bellou
- Hellenic Centre for Marine Research, Institute of Oceanography, Athens, Greece
| | - Xing-Pan Guo
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China.
| | - Sergey Dobretsov
- Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman; Center of Excellence in Marine Biotechnology, Sultan Qaboos University, Muscat, Oman.
| | - Jin-Long Yang
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China; National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China.
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105
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Oikonomou CM, Jensen GJ. Electron Cryotomography of Bacterial Secretion Systems. Microbiol Spectr 2019; 7:10.1128/microbiolspec.PSIB-0019-2018. [PMID: 30953431 PMCID: PMC6452891 DOI: 10.1128/microbiolspec.psib-0019-2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Indexed: 02/08/2023] Open
Abstract
In biology, function arises from form. For bacterial secretion systems, which often span two membranes, avidly bind to the cell wall, and contain hundreds of individual proteins, studying form is a daunting task, made possible by electron cryotomography (ECT). ECT is the highest-resolution imaging technique currently available to visualize unique objects inside cells, providing a three-dimensional view of the shapes and locations of large macromolecular complexes in their native environment. Over the past 15 years, ECT has contributed to the study of bacterial secretion systems in two main ways: by revealing intact forms for the first time and by mapping components into these forms. Here we highlight some of these contributions, revealing structural convergence in type II secretion systems, structural divergence in type III secretion systems, unexpected structures in type IV secretion systems, and unexpected mechanisms in types V and VI secretion systems. Together, they offer a glimpse into a world of fantastic forms-nanoscale rotors, needles, pumps, and dart guns-much of which remains to be explored.
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Affiliation(s)
- Catherine M. Oikonomou
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Grant J. Jensen
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Howard Hughes Medical Institute, Pasadena, CA, USA
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106
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Ding W, Zhang W, Wang R, Sun Y, Pei B, Gao Z, Qian PY. Distribution, diversity and functional dissociation of the mac genes in marine biofilms. BIOFOULING 2019; 35:230-243. [PMID: 30950294 DOI: 10.1080/08927014.2019.1593384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Bacteria produce metamorphosis-associated contractile (MAC) structures to induce larval metamorphosis in Hydroides elegans. The distribution and diversity of mac gene homologs in marine environments are largely unexplored. In the present study mac genes were examined in marine environments by analyzing 101 biofilm and 91 seawater metagenomes. There were more mac genes in biofilms than in seawater, and substratum type, location, or sampling time did not affect the mac genes in biofilms. The mac gene clusters were highly diverse and often incomplete while the three MAC components co-occurred with other genes of different functions. Genomic analysis of four Pseudoalteromonas and two Streptomyces strains revealed the mac genes transfers among different microbial taxa. It is proposed that mac genes are more specific to biofilms; gene transfer among different microbial taxa has led to highly diverse mac gene clusters; and in most cases, the three MAC components function individually rather than forming a complex.
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Affiliation(s)
- Wei Ding
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
| | - Weipeng Zhang
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
| | - Ruojun Wang
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
| | - Yanan Sun
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
| | - Bite Pei
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
| | - Zhaoming Gao
- b Sanya Institute of Deep-sea Science and Engineering , Chinese Academy of Sciences , Hainan , PR China
| | - Pei-Yuan Qian
- a Department of Ocean Science and Division of Life Science , Hong Kong University of Science and Technology , Hong Kong , PR China
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107
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Schwab DB, Casasa S, Moczek AP. On the Reciprocally Causal and Constructive Nature of Developmental Plasticity and Robustness. Front Genet 2019; 9:735. [PMID: 30687394 PMCID: PMC6335315 DOI: 10.3389/fgene.2018.00735] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/22/2018] [Indexed: 01/29/2023] Open
Abstract
Exposure to environmental variation is a characteristic feature of normal development, one that organisms can respond to during their lifetimes by actively adjusting or maintaining their phenotype in order to maximize fitness. Plasticity and robustness have historically been studied by evolutionary biologists through quantitative genetic and reaction norm approaches, while more recent efforts emerging from evolutionary developmental biology have begun to characterize the molecular and developmental genetic underpinnings of both plastic and robust trait formation. In this review, we explore how our growing mechanistic understanding of plasticity and robustness is beginning to force a revision of our perception of both phenomena, away from our conventional view of plasticity and robustness as opposites along a continuum and toward a framework that emphasizes their reciprocal, constructive, and integrative nature. We do so in three sections. Following an introduction, the first section looks inward and reviews the genetic, epigenetic, and developmental mechanisms that enable organisms to sense and respond to environmental conditions, maintaining and adjusting trait formation in the process. In the second section, we change perspective and look outward, exploring the ways in which organisms reciprocally shape their environments in ways that influence trait formation, and do so through the lens of behavioral plasticity, niche construction, and host-microbiota interactions. In the final section, we revisit established plasticity and robustness concepts in light of these findings, and highlight research opportunities to further advance our understanding of the causes, mechanisms, and consequences of these ubiquitous, and interrelated, phenomena.
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108
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Biogenesis and structure of a type VI secretion baseplate. Nat Microbiol 2018; 3:1404-1416. [DOI: 10.1038/s41564-018-0260-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/31/2018] [Indexed: 12/20/2022]
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109
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Koehler S, Gaedeke R, Thompson C, Bongrand C, Visick K, Ruby E, McFall-Ngai M. The model squid-vibrio symbiosis provides a window into the impact of strain- and species-level differences during the initial stages of symbiont engagement. Environ Microbiol 2018; 21:10.1111/1462-2920.14392. [PMID: 30136358 PMCID: PMC6386636 DOI: 10.1111/1462-2920.14392] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 08/14/2018] [Accepted: 08/18/2018] [Indexed: 11/29/2022]
Abstract
Among horizontally acquired symbioses, the mechanisms underlying microbial strain- and species-level specificity remain poorly understood. Here, confocal-microscopy analyses and genetic manipulation of the squid-vibrio association revealed quantitative differences in a symbiont's capacity to interact with the host during initial engagement. Specifically, dominant strains of Vibrio fischeri, 'D-type', previously named for their dominant, single-strain colonization of the squid's bioluminescent organ, were compared with 'S-type', or 'sharing', strains, which can co-colonize the organ. These D-type strains typically: (i) formed aggregations of 100s-1000s of cells on the light-organ surface, up to 3 orders of magnitude larger than those of S-type strains; (ii) showed dominance in co-aggregation experiments, independent of inoculum size or strain proportion; (iii) perturbed larger areas of the organ's ciliated surface; and, (iv) appeared at the pore of the organ approximately 4×s more quickly than S-type strains. At least in part, genes responsible for biofilm synthesis control the hyperaggregation phenotype of a D-type strain. Other marine vibrios produced relatively small aggregations, while an array of marine Gram-positive and -negative species outside of the Vibrionaceae did not attach to the organ's surface. These studies provide insight into the impact of strain variation on early events leading to establishment of an environmentally acquired symbiosis.
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Affiliation(s)
- Sabrina Koehler
- Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Roxane Gaedeke
- Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Cecilia Thompson
- Department of Microbiology and Immunology, Loyola University Chicago, IL, USA
| | - Clotilde Bongrand
- Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Karen Visick
- Department of Microbiology and Immunology, Loyola University Chicago, IL, USA
| | - Edward Ruby
- Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Margaret McFall-Ngai
- Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
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110
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Role of Chemical Mediators in Aquatic Interactions across the Prokaryote-Eukaryote Boundary. J Chem Ecol 2018; 44:1008-1021. [PMID: 30105643 DOI: 10.1007/s10886-018-1004-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 10/28/2022]
Abstract
There is worldwide growing interest in the occurrence and diversity of metabolites used as chemical mediators in cross-kingdom interactions within aquatic systems. Bacteria produce metabolites to protect and influence the growth and life cycle of their eukaryotic hosts. In turn, the host provides a nutrient-enriched environment for the bacteria. Here, we discuss the role of waterborne chemical mediators that are responsible for such interactions in aquatic multi-partner systems, including algae or invertebrates and their associated bacteria. In particular, this review highlights recent advances in the chemical ecology of aquatic systems that support the overall ecological significance of signaling molecules across the prokaryote-eukaryote boundary (cross-kingdom interactions) for growth, development and morphogenesis of the host. We emphasize the value of establishing well-characterized model systems that provide the basis for the development of ecological principles that represent the natural lifestyle and dynamics of aquatic microbial communities and enable a better understanding of the consequences of environmental change and the most effective means of managing community interactions.
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111
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112
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Koonin EV, Krupovic M. The depths of virus exaptation. Curr Opin Virol 2018; 31:1-8. [PMID: 30071360 DOI: 10.1016/j.coviro.2018.07.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/13/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023]
Abstract
Viruses are ubiquitous parasites of cellular life forms and the most abundant biological entities on earth. The relationships between viruses and their hosts involve the continuous arms race but are by no account limited to it. Growing evidence shows that, in the course of evolution, viruses and their components are repeatedly recruited (exapted) for host functions. The functions of exapted viruses typically involve either defense from other viruses or cellular competitors or transfer of nucleic acids between cells, or storage functions. Virus exaptation can reach different depths, from recruitment of a fully functional virus to exploitation of defective, partially degraded viruses, to utilization of individual virus proteins.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, United States.
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France.
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113
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Renault MG, Zamarreno Beas J, Douzi B, Chabalier M, Zoued A, Brunet YR, Cambillau C, Journet L, Cascales E. The gp27-like Hub of VgrG Serves as Adaptor to Promote Hcp Tube Assembly. J Mol Biol 2018; 430:3143-3156. [PMID: 30031895 DOI: 10.1016/j.jmb.2018.07.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 07/06/2018] [Accepted: 07/12/2018] [Indexed: 12/25/2022]
Abstract
Contractile injection systems are multiprotein complexes that use a spring-like mechanism to deliver effectors into target cells. In addition to using a conserved mechanism, these complexes share a common core known as the tail. The tail comprises an inner tube tipped by a spike, wrapped by a contractile sheath, and assembled onto a baseplate. Here, using the type VI secretion system (T6SS) as a model of contractile injection systems, we provide molecular details on the interaction between the inner tube and the spike. Reconstitution into the Escherichia coli heterologous host in the absence of other T6SS components and in vitro experiments demonstrated that the Hcp tube component and the VgrG spike interact directly. VgrG deletion studies coupled to functional assays showed that the N-terminal domain of VgrG is sufficient to interact with Hcp, to initiate proper Hcp tube polymerization, and to promote sheath dynamics and Hcp release. The interaction interface between Hcp and VgrG was then mapped using docking simulations, mutagenesis, and cysteine-mediated cross-links. Based on these results, we propose a model in which the VgrG base serves as adaptor to recruit the first Hcp hexamer and initiates inner tube polymerization.
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Affiliation(s)
- Melvin G Renault
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Jordi Zamarreno Beas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Badreddine Douzi
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex, 09, France
| | - Maïalène Chabalier
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Abdelrahim Zoued
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Yannick R Brunet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex, 09, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Univ-Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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La Marca EC, Catania V, Quatrini P, Milazzo M, Chemello R. Settlement performance of the Mediterranean reef-builders Dendropoma cristatum (Biondi 1859) in response to natural bacterial films. MARINE ENVIRONMENTAL RESEARCH 2018; 137:149-157. [PMID: 29571588 DOI: 10.1016/j.marenvres.2018.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/12/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
The gastropod Dendropoma cristatum is a biogenic engineer of the central Mediterranean, forming reefs along the lower rocky intertidal fringe with a remarkable ecological role. To understand whether reef-associated biofilm cultivable bacterial and biofilm ageing may trigger the settlement of the juvenile snails, a combination of laboratory techniques and field experiments was used. Reef-associated biofilm cultivable bacteria were isolated, and a settlement-choice experiment was performed in situ on artificial biofilms composed of i) a mixture of six biofilm-forming selected isolates, ii) all the cultivable bacteria, and iii) 13-, 23-, 32-day old biofilms formed under natural conditions. Overall, settlement rate significantly differed among biofilm treatments (p < 0.0001). A significant positive correlation between biofilm ageing and juvenile D. cristatum settlement was assessed (r = 0.69 (p < 0.001), whereas the biofilm bacterial composition (relatively to the cultivable fraction) did not show any effect on the vermetid's settlement rate.
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Affiliation(s)
- Emanuela Claudia La Marca
- Department of Earth and Marine Sciences, University of Palermo, Via Archirafi 22, 90123, Palermo, Italy; Consorzio Interuniversitario per le Scienze del Mare (CoNISMa), Piazzale Flaminio 9, 00196, Roma, Italy.
| | - Valentina Catania
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy.
| | - Paola Quatrini
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Viale delle Scienze, Ed.16, 90128, Palermo, Italy.
| | - Marco Milazzo
- Department of Earth and Marine Sciences, University of Palermo, Via Archirafi 22, 90123, Palermo, Italy; Consorzio Interuniversitario per le Scienze del Mare (CoNISMa), Piazzale Flaminio 9, 00196, Roma, Italy.
| | - Renato Chemello
- Department of Earth and Marine Sciences, University of Palermo, Via Archirafi 22, 90123, Palermo, Italy; Consorzio Interuniversitario per le Scienze del Mare (CoNISMa), Piazzale Flaminio 9, 00196, Roma, Italy.
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115
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Woznica A, King N. Lessons from simple marine models on the bacterial regulation of eukaryotic development. Curr Opin Microbiol 2018; 43:108-116. [PMID: 29331767 PMCID: PMC6051772 DOI: 10.1016/j.mib.2017.12.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/26/2017] [Accepted: 12/28/2017] [Indexed: 02/07/2023]
Abstract
Molecular cues from environmental bacteria influence important developmental decisions in diverse marine eukaryotes. Yet, relatively little is understood about the mechanisms underlying these interactions, in part because marine ecosystems are dynamic and complex. With the help of simple model systems, including the choanoflagellate Salpingoeca rosetta, we have begun to uncover the bacterial cues that shape eukaryotic development in the ocean. Here, we review how diverse bacterial cues-from lipids to macromolecules-regulate development in marine eukaryotes. It is becoming clear that there are networks of chemical information circulating in the ocean, with both eukaryotes and bacteria acting as nodes; one eukaryote can precisely respond to cues from several diverse environmental bacteria, and a single environmental bacterium can regulate the development of different eukaryotes.
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Affiliation(s)
- Arielle Woznica
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, United States
| | - Nicole King
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, United States.
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116
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Clemens DL, Lee BY, Horwitz MA. The Francisella Type VI Secretion System. Front Cell Infect Microbiol 2018; 8:121. [PMID: 29740542 PMCID: PMC5924787 DOI: 10.3389/fcimb.2018.00121] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/03/2018] [Indexed: 12/27/2022] Open
Abstract
Francisella tularensisis subsp. tularensis is an intracellular bacterial pathogen and the causative agent of the life-threatening zoonotic disease tularemia. The Francisella Pathogenicity Island encodes a large secretion apparatus, known as a Type VI Secretion System (T6SS), which is essential for Francisella to escape from its phagosome and multiply within host macrophages and to cause disease in animals. The T6SS, found in one-quarter of Gram-negative bacteria including many highly pathogenic ones, is a recently discovered secretion system that is not yet fully understood. Nevertheless, there have been remarkable advances in our understanding of the structure, composition, and function of T6SSs of several bacteria in the past few years. The system operates like an inside-out headless contractile phage that is anchored to the bacterial membrane via a baseplate and membrane complex. The system injects effector molecules across the inner and outer bacterial membrane and into host prokaryotic or eukaryotic targets to kill, intoxicate, or in the case of Francisella, hijack the target cell. Recent advances include an atomic model of the contractile sheath, insights into the mechanics of sheath contraction, the composition of the baseplate and membrane complex, the process of assembly of the apparatus, and identification of numerous effector molecules and activities. While Francisella T6SS appears to be an outlier among T6SSs, with limited or no sequence homology with other systems, its structure and organization are strikingly similar to other systems. Nevertheless, we have only scratched the surface in uncovering the mysteries of the Francisella T6SS, and there are numerous questions that remain to be answered.
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Affiliation(s)
- Daniel L. Clemens
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | | | - Marcus A. Horwitz
- Division of Infectious Diseases, Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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117
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Weiss GL, Medeiros JM, Pilhofer M. In Situ Imaging of Bacterial Secretion Systems by Electron Cryotomography. Methods Mol Biol 2018; 1615:353-375. [PMID: 28667625 DOI: 10.1007/978-1-4939-7033-9_27] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The unique property of electron cryotomography (ECT) is its capability to resolve the structure of macromolecular machines in their cellular context. The integration of ECT data with high-resolution structures of purified subcomplexes and live-cell fluorescence light microscopy can generate pseudo-atomic models that lead to a mechanistic understanding across size and time scales. Recent advances in electron detection, sample thinning, data acquisition, and data processing have significantly enhanced the applicability and performance of ECT. Here we describe a detailed workflow for an ECT experiment, including cell culture, vitrification, data acquisition, data reconstruction, tomogram analysis, and subtomogram averaging. This protocol provides an entry point to the technique for students and researchers and indicates the many possible variations arising from specific target properties and the available instrumentation.
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Affiliation(s)
- Gregor L Weiss
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - João M Medeiros
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Martin Pilhofer
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland.
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118
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Chemical Ecology of Chemosensation in Asteroidea: Insights Towards Management Strategies of Pest Species. J Chem Ecol 2018; 44:147-177. [PMID: 29362949 DOI: 10.1007/s10886-018-0926-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/03/2017] [Accepted: 01/09/2018] [Indexed: 12/11/2022]
Abstract
Within the Phylum Echinodermata, the class Asteroidea, commonly known as starfish and sea stars, encompasses a large number of benthos inhabiting genera and species with various feeding modalities including herbivores, carnivores, omnivores and detritivores. The Asteroidea rely on chemosensation throughout their life histories including hunting prey, avoiding or deterring predators, in the formation of spawning aggregations, synchronizing gamete release and targeting appropriate locations for larval settlement. The identities of many of the chemical stimuli that mediate these physiological and behavioural processes remain unresolved even though evidence indicates they play pivotal roles in the functionality of benthic communities. Aspects of chemosensation, as well as putative chemically-mediated behaviours and the molecular mechanisms of chemoreception, within the Asteroidea are reviewed here, with particular reference to the coral reef pest the Crown-of-Thorns starfish Acanthaster planci species complex, in the context of mitigation of population outbreaks.
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119
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Rochal SB, Roshal DS, Myasnikova AE, Lorman VL. Commensurability between protein nanotubes in contractile ejection nanomachines. NANOSCALE 2018; 10:758-764. [PMID: 29255816 DOI: 10.1039/c7nr06940e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Contractile ejection nanomachines being sheath-tube assemblies create an opening in the cell membrane to translocate molecules or ions across it. Here, on the most structurally investigated examples of the bacteriophage T4 tail and pyocin R2, we show that the rearrangement of the sheath structure resulting in its contraction and twist occurs in such a way that the contracted sheath becomes commensurate with the inner tube. This fact dictates the previously unknown simple geometrical relationship between the nanotube symmetries. Using the Frank and van der Merwe classical theory of commensurability, we study an interaction between two protein nanotubes forming such nanomachines and obtain an expression for the corresponding energy, which depends on the tube structures and their mutual arrangement. The appearance of commensurability between the contracted sheath and the inner tube decreases both the interaction energy and the total energy of the system. It improves the nanomachine efficiency, since the energy gain obtained increases the torque of the inner tube piercing the cell membrane.
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Affiliation(s)
- Sergey B Rochal
- Faculty of Physics, Southern Federal University, 5 Zorge str., 344090 Rostov-on-Don, Russia.
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120
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Böck D, Medeiros JM, Tsao HF, Penz T, Weiss GL, Aistleitner K, Horn M, Pilhofer M. In situ architecture, function, and evolution of a contractile injection system. Science 2017; 357:713-717. [PMID: 28818949 DOI: 10.1126/science.aan7904] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/17/2017] [Indexed: 12/27/2022]
Abstract
Contractile injection systems mediate bacterial cell-cell interactions by a bacteriophage tail-like structure. In contrast to extracellular systems, the type 6 secretion system (T6SS) is defined by intracellular localization and attachment to the cytoplasmic membrane. Here we used cryo-focused ion beam milling, electron cryotomography, and functional assays to study a T6SS in Amoebophilus asiaticus The in situ architecture revealed three modules, including a contractile sheath-tube, a baseplate, and an anchor. All modules showed conformational changes upon firing. Lateral baseplate interactions coordinated T6SSs in hexagonal arrays. The system mediated interactions with host membranes and may participate in phagosome escape. Evolutionary sequence analyses predicted that T6SSs are more widespread than previously thought. Our insights form the basis for understanding T6SS key concepts and exploring T6SS diversity.
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Affiliation(s)
- Désirée Böck
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - João M Medeiros
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Han-Fei Tsao
- Division of Microbial Ecology, University of Vienna, A-1090 Vienna, Austria
| | - Thomas Penz
- Division of Microbial Ecology, University of Vienna, A-1090 Vienna, Austria
| | - Gregor L Weiss
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Karin Aistleitner
- Division of Microbial Ecology, University of Vienna, A-1090 Vienna, Austria
| | - Matthias Horn
- Division of Microbial Ecology, University of Vienna, A-1090 Vienna, Austria.
| | - Martin Pilhofer
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland.
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121
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Nazarov S, Schneider JP, Brackmann M, Goldie KN, Stahlberg H, Basler M. Cryo-EM reconstruction of Type VI secretion system baseplate and sheath distal end. EMBO J 2017; 37:embj.201797103. [PMID: 29255010 PMCID: PMC5813253 DOI: 10.15252/embj.201797103] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 11/09/2017] [Accepted: 11/16/2017] [Indexed: 01/02/2023] Open
Abstract
The bacterial Type VI secretion system (T6SS) assembles from three major parts: a membrane complex that spans inner and outer membranes, a baseplate, and a sheath-tube polymer. The baseplate assembles around a tip complex with associated effectors and connects to the membrane complex by TssK. The baseplate assembly initiates sheath-tube polymerization, which in some organisms requires TssA. Here, we analyzed both ends of isolated non-contractile Vibrio cholerae sheaths by cryo-electron microscopy. Our analysis suggests that the baseplate, solved to an average 8.0 Å resolution, is composed of six subunits of TssE/F2/G and the baseplate periphery is decorated by six TssK trimers. The VgrG/PAAR tip complex in the center of the baseplate is surrounded by a cavity, which may accommodate up to ~450 kDa of effector proteins. The distal end of the sheath, resolved to an average 7.5 Å resolution, shows sixfold symmetry; however, its protein composition is unclear. Our structures provide an important step toward an atomic model of the complete T6SS assembly.
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Affiliation(s)
- Sergey Nazarov
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Maximilian Brackmann
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Kenneth N Goldie
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland.,Focal Area Structural Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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122
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Shakya M, Soucy SM, Zhaxybayeva O. Insights into origin and evolution of α-proteobacterial gene transfer agents. Virus Evol 2017; 3:vex036. [PMID: 29250433 PMCID: PMC5721377 DOI: 10.1093/ve/vex036] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Several bacterial and archaeal lineages produce nanostructures that morphologically resemble small tailed viruses, but, unlike most viruses, contain apparently random pieces of the host genome. Since these elements can deliver the packaged DNA to other cells, they were dubbed gene transfer agents (GTAs). Because many genes involved in GTA production have viral homologs, it has been hypothesized that the GTA ancestor was a virus. Whether GTAs represent an atypical virus, a defective virus, or a virus co-opted by the prokaryotes for some function, remains to be elucidated. To evaluate these possibilities, we examined the distribution and evolutionary histories of genes that encode a GTA in the α-proteobacterium Rhodobacter capsulatus (RcGTA). We report that although homologs of many individual RcGTA genes are abundant across bacteria and their viruses, RcGTA-like genomes are mainly found in one subclade of α-proteobacteria. When compared with the viral homologs, genes of the RcGTA-like genomes evolve significantly slower, and do not have higher %A+T nucleotides than their host chromosomes. Moreover, they appear to reside in stable regions of the bacterial chromosomes that are generally conserved across taxonomic orders. These findings argue against RcGTA being an atypical or a defective virus. Our phylogenetic analyses suggest that RcGTA ancestor likely originated in the lineage that gave rise to contemporary α-proteobacterial orders Rhizobiales, Rhodobacterales, Caulobacterales, Parvularculales, and Sphingomonadales, and since that time the RcGTA-like element has co-evolved with its host chromosomes. Such evolutionary history is compatible with maintenance of these elements by bacteria due to some selective advantage. As for many other prokaryotic traits, horizontal gene transfer played a substantial role in the evolution of RcGTA-like elements, not only in shaping its genome components within the orders, but also in occasional dissemination of RcGTA-like regions across the orders and even to different bacterial phyla.
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Affiliation(s)
- Migun Shakya
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Shannon M Soucy
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Olga Zhaxybayeva
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA.,Department of Computer Science, Dartmouth College, 6211 Sudikoff Lab, Hanover, NH 03755, USA
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123
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Transcriptome Sequencing Reveals Novel Candidate Genes for Cardinium hertigii-Caused Cytoplasmic Incompatibility and Host-Cell Interaction. mSystems 2017; 2:mSystems00141-17. [PMID: 29181449 PMCID: PMC5698495 DOI: 10.1128/msystems.00141-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 10/23/2017] [Indexed: 11/29/2022] Open
Abstract
The majority of insects carry maternally inherited intracellular bacteria that are important in their hosts’ biology, ecology, and evolution. Some of these bacterial symbionts cause a reproductive failure known as cytoplasmic incompatibility (CI). In CI, the mating of symbiont-infected males and uninfected females produces few or no daughters. The CI symbiont then spreads and can have a significant impact on the insect host population. Cardinium, a bacterial endosymbiont of the parasitoid wasp Encarsia in the Bacteroidetes, is the only bacterial lineage known to cause CI outside the Alphaproteobacteria, where Wolbachia and another recently discovered CI symbiont reside. Here, we sought insight into the gene expression of a CI-inducing Cardinium strain in its natural host, Encarsia suzannae. Our study provides the first insights into the Cardinium transcriptome and provides support for the hypothesis that Wolbachia and Cardinium target similar host pathways with distinct and largely unrelated sets of genes. Cytoplasmic incompatibility (CI) is an intriguing, widespread, symbiont-induced reproductive failure that decreases offspring production of arthropods through crossing incompatibility of infected males with uninfected females or with females infected with a distinct symbiont genotype. For years, the molecular mechanism of CI remained unknown. Recent genomic, proteomic, biochemical, and cell biological studies have contributed to understanding of CI in the alphaproteobacterium Wolbachia and implicate genes associated with the WO prophage. Besides a recently discovered additional lineage of alphaproteobacterial symbionts only moderately related to Wolbachia, Cardinium (Bacteroidetes) is the only other symbiont known to cause CI, and genomic evidence suggests that it has very little homology with Wolbachia and evolved this phenotype independently. Here, we present the first transcriptomic study of the CI Cardinium strain cEper1, in its natural host, Encarsia suzannae, to detect important CI candidates and genes involved in the insect-Cardinium symbiosis. Highly expressed transcripts included genes involved in manipulating ubiquitination, apoptosis, and host DNA. Female-biased genes encoding ribosomal proteins suggest an increase in general translational activity of Cardinium in female wasps. The results confirm previous genomic analyses that indicated that Wolbachia and Cardinium utilize different genes to induce CI, and transcriptome patterns further highlight expression of some common pathways that these bacteria use to interact with the host and potentially cause this enigmatic and fundamental manipulation of host reproduction. IMPORTANCE The majority of insects carry maternally inherited intracellular bacteria that are important in their hosts’ biology, ecology, and evolution. Some of these bacterial symbionts cause a reproductive failure known as cytoplasmic incompatibility (CI). In CI, the mating of symbiont-infected males and uninfected females produces few or no daughters. The CI symbiont then spreads and can have a significant impact on the insect host population. Cardinium, a bacterial endosymbiont of the parasitoid wasp Encarsia in the Bacteroidetes, is the only bacterial lineage known to cause CI outside the Alphaproteobacteria, where Wolbachia and another recently discovered CI symbiont reside. Here, we sought insight into the gene expression of a CI-inducing Cardinium strain in its natural host, Encarsia suzannae. Our study provides the first insights into the Cardinium transcriptome and provides support for the hypothesis that Wolbachia and Cardinium target similar host pathways with distinct and largely unrelated sets of genes.
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124
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Inaba H, Ueno T. Artificial bio-nanomachines based on protein needles derived from bacteriophage T4. Biophys Rev 2017; 10:641-658. [PMID: 29147941 DOI: 10.1007/s12551-017-0336-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/07/2017] [Indexed: 12/17/2022] Open
Abstract
Bacteriophage T4 is a natural bio-nanomachine which achieves efficient infection of host cells via cooperative motion of specific three-dimensional protein architectures. The relationships between the protein structures and their dynamic functions have recently been clarified. In this review we summarize the design principles for fabrication of nanomachines using the component proteins of bacteriophage T4 based on these recent advances. We focus on the protein needle known as gp5, which is located at the center of the baseplate at the end of the contractile tail of bacteriophage T4. This protein needle plays a critical role in directly puncturing host cells, and analysis has revealed that it contains a common motif used for cell puncture in other known injection systems, such as T6SS. Our artificial needle based on the β-helical domain of gp5 retains the ability to penetrate cells and can be engineered to deliver various cargos into living cells. Thus, the unique components of bacteriophage T4 and other natural nanomachines have great potential for use as molecular scaffolds in efforts to fabricate new bio-nanomachines.
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Affiliation(s)
- Hiroshi Inaba
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-Minami, Tottori, 680-8552, Japan
| | - Takafumi Ueno
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B55, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
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125
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Guo H, Rischer M, Sperfeld M, Weigel C, Menzel KD, Clardy J, Beemelmanns C. Natural products and morphogenic activity of γ-Proteobacteria associated with the marine hydroid polyp Hydractinia echinata. Bioorg Med Chem 2017; 25:6088-6097. [PMID: 28893599 PMCID: PMC5675742 DOI: 10.1016/j.bmc.2017.06.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/21/2017] [Accepted: 06/30/2017] [Indexed: 02/07/2023]
Abstract
Illumina 16S rRNA gene sequencing was used to profile the associated bacterial community of the marine hydroid Hydractinia echinata, a long-standing model system in developmental biology. 56 associated bacteria were isolated and evaluated for their antimicrobial activity. Three strains were selected for further in-depth chemical analysis leading to the identification of 17 natural products. Several γ-Proteobacteria were found to induce settlement of the motile larvae, but only six isolates induced the metamorphosis to the primary polyp stage within 24h. Our study paves the way to better understand how bacterial partners contribute to protection, homeostasis and propagation of the hydroid polyp.
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Affiliation(s)
- Huijuan Guo
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstraβe 11a, D-07745 Jena, Germany
| | - Maja Rischer
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstraβe 11a, D-07745 Jena, Germany
| | - Martin Sperfeld
- Department of Applied and Ecological Microbiology, Institute for Microbiology, Friedrich Schiller University Jena, Philosophenweg 12, D-07743 Jena, Germany
| | - Christiane Weigel
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstraβe 11a, D-07745 Jena, Germany
| | - Klaus Dieter Menzel
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstraβe 11a, D-07745 Jena, Germany
| | - Jon Clardy
- Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Harvard University, 240 Longwood Ave., Boston, MA 02115, USA
| | - Christine Beemelmanns
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstraβe 11a, D-07745 Jena, Germany.
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126
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Affiliation(s)
- Dean Scholl
- AvidBiotics Corp., South San Francisco, California 94080;,
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127
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Cryo-EM structure of the extended type VI secretion system sheath–tube complex. Nat Microbiol 2017; 2:1507-1512. [DOI: 10.1038/s41564-017-0020-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/02/2017] [Indexed: 11/08/2022]
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128
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Brackmann M, Nazarov S, Wang J, Basler M. Using Force to Punch Holes: Mechanics of Contractile Nanomachines. Trends Cell Biol 2017; 27:623-632. [DOI: 10.1016/j.tcb.2017.05.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 05/10/2017] [Accepted: 05/12/2017] [Indexed: 12/25/2022]
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129
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Refined Cryo-EM Structure of the T4 Tail Tube: Exploring the Lowest Dose Limit. Structure 2017; 25:1436-1441.e2. [PMID: 28757144 DOI: 10.1016/j.str.2017.06.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/16/2017] [Accepted: 06/27/2017] [Indexed: 11/20/2022]
Abstract
The bacteriophage T4 contractile tail (containing a tube and sheath) was the first biological assembly reconstructed in three dimensions by electron microscopy at a resolution of ∼35 Å in 1968. A single-particle reconstruction of the T4 baseplate was able to generate a 4.1 Å resolution map for the first two rings of the tube using the overall baseplate for alignment. We have now reconstructed the T4 tail tube at a resolution of 3.4 Å, more than a 1,000-fold increase in information content for the tube from 1968. We have used legacy software (Spider) to show that we can do better than the typical 2/3 Nyquist frequency. A reasonable map can be generated with only 1.5 electrons/Å2 using the higher dose images for alignment, but increasing the dose results in a better map, consistent with other reports that electron dose does not represent the main limitation on resolution in cryo-electron microscopy.
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130
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Borchert E, Knobloch S, Dwyer E, Flynn S, Jackson SA, Jóhannsson R, Marteinsson VT, O'Gara F, Dobson ADW. Biotechnological Potential of Cold Adapted Pseudoalteromonas spp. Isolated from 'Deep Sea' Sponges. Mar Drugs 2017. [PMID: 28629190 PMCID: PMC5484134 DOI: 10.3390/md15060184] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The marine genus Pseudoalteromonas is known for its versatile biotechnological potential with respect to the production of antimicrobials and enzymes of industrial interest. We have sequenced the genomes of three Pseudoalteromonas sp. strains isolated from different deep sea sponges on the Illumina MiSeq platform. The isolates have been screened for various industrially important enzymes and comparative genomics has been applied to investigate potential relationships between the isolates and their host organisms, while comparing them to free-living Pseudoalteromonas spp. from shallow and deep sea environments. The genomes of the sponge associated Pseudoalteromonas strains contained much lower levels of potential eukaryotic-like proteins which are known to be enriched in symbiotic sponge associated microorganisms, than might be expected for true sponge symbionts. While all the Pseudoalteromonas shared a large distinct subset of genes, nonetheless the number of unique and accessory genes is quite large and defines the pan-genome as open. Enzymatic screens indicate that a vast array of enzyme activities is expressed by the isolates, including β-galactosidase, β-glucosidase, and protease activities. A β-glucosidase gene from one of the Pseudoalteromonas isolates, strain EB27 was heterologously expressed in Escherichia coli and, following biochemical characterization, the recombinant enzyme was found to be cold-adapted, thermolabile, halotolerant, and alkaline active.
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Affiliation(s)
- Erik Borchert
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
| | - Stephen Knobloch
- Department of Research and Innovation, Matís ohf., Reykjavik 113, Iceland.
| | - Emilie Dwyer
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
| | - Sinéad Flynn
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
| | - Stephen A Jackson
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
| | - Ragnar Jóhannsson
- Department of Research and Innovation, Matís ohf., Reykjavik 113, Iceland.
| | | | - Fergal O'Gara
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
- Biomerit Research Centre, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth 6102, WA, Australia.
| | - Alan D W Dobson
- School of Microbiology, University College Cork, National University of Ireland, Cork T12 YN60, Ireland.
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131
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Burns R, Pechenik J. Transcriptomic Basis of Metamorphic Competence in the Salt-Marsh-Dwelling Polychaete Capitella teleta. THE BIOLOGICAL BULLETIN 2017; 232:158-170. [PMID: 28898599 DOI: 10.1086/692829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Marine invertebrate larvae typically take hours to weeks after being released into the plankton before becoming "competent" to metamorphose. The mechanisms that govern this transition between the precompetent and metamorphically competent states are unknown. We studied gene expression patterns in precompetent and competent larvae of the salt-marsh-dwelling polychaete worm Capitella teleta (Blake, Grassle & Eckelbarger, 2009)-a species in which precompetent larvae are unusually easy to distinguish from competent larvae-to determine differences in gene expression associated with the onset of metamorphic competence. More than 1530 genes were more highly expressed in precompetent larvae, while more than 1060 genes were more highly expressed in competent larvae. Competent larvae downregulated the expression of genes belonging to gene ontologies relating to growth and development and upregulated those associated with ligand-binding transmembrane channels with possible chemo- and mechanosensory functions. Most of these channels were annotated as being from the degenerin/epithelial sodium channel family or the G-protein-coupled receptor family; proteins from these families can have chemosensory functions. Serotonin and GABA (γ-aminobutyric acid) receptors are among the genes that were upregulated in competent larvae; both have been shown to induce larvae of C. teleta and other marine invertebrates to metamorphose and are thought to be components of the signal transduction pathway that leads to metamorphosis. Overall, it appears that once larvae of C. teleta have completed development of the internal structures and physiology required for juvenile life during the precompetent period, they then upregulate the expression of chemosensory proteins and neurotransmitter receptors that will enable them to detect and transduce a settlement cue signal.
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Key Words
- 5-HT6, 5-hydroxytryptamine 6
- ASW, artificial seawater
- DEG/ENaC, degenerin/epithelial sodium channel
- FDR, false discovery rate
- GABA, γ-aminobutyric acid
- GPCR, G-protein-coupled receptor
- HSP, heat-shock protein
- NCBI, National Center for Biotechnology Information
- NOS, nitric oxide synthase
- PKD, polycystic kidney disease
- UTR, untranslated region
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Abstract
Electron cryotomography (ECT) provides three-dimensional views of macromolecular complexes inside cells in a native frozen-hydrated state. Over the last two decades, ECT has revealed the ultrastructure of cells in unprecedented detail. It has also allowed us to visualize the structures of macromolecular machines in their native context inside intact cells. In many cases, such machines cannot be purified intact for in vitro study. In other cases, the function of a structure is lost outside the cell, so that the mechanism can be understood only by observation in situ. In this review, we describe the technique and its history and provide examples of its power when applied to cell biology. We also discuss the integration of ECT with other techniques, including lower-resolution fluorescence imaging and higher-resolution atomic structure determination, to cover the full scale of cellular processes.
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Affiliation(s)
- Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; ,
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; , .,Howard Hughes Medical Institute, Pasadena, California 91125
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133
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Lysogeny in nature: mechanisms, impact and ecology of temperate phages. ISME JOURNAL 2017; 11:1511-1520. [PMID: 28291233 DOI: 10.1038/ismej.2017.16] [Citation(s) in RCA: 403] [Impact Index Per Article: 57.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 12/04/2016] [Accepted: 01/19/2017] [Indexed: 01/07/2023]
Abstract
Viruses that infect bacteria (phages) can influence bacterial community dynamics, bacterial genome evolution and ecosystem biogeochemistry. These influences differ depending on whether phages establish lytic, chronic or lysogenic infections. Although the first two produce virion progeny, with lytic infections resulting in cell destruction, phages undergoing lysogenic infections replicate with cells without producing virions. The impacts of lysogeny are numerous and well-studied at the cellular level, but ecosystem-level consequences remain underexplored compared to those of lytic infections. Here, we review lysogeny from molecular mechanisms to ecological patterns to emerging approaches of investigation. Our goal is to highlight both its diversity and importance in complex communities. Altogether, using a combined viral ecology toolkit that is applied across broad model systems and environments will help us understand more of the diverse lifestyles and ecological impacts of lysogens in nature.
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134
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Peixoto RS, Rosado PM, Leite DCDA, Rosado AS, Bourne DG. Beneficial Microorganisms for Corals (BMC): Proposed Mechanisms for Coral Health and Resilience. Front Microbiol 2017; 8:341. [PMID: 28326066 PMCID: PMC5339234 DOI: 10.3389/fmicb.2017.00341] [Citation(s) in RCA: 241] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 02/17/2017] [Indexed: 12/21/2022] Open
Abstract
The symbiotic association between the coral animal and its endosymbiotic dinoflagellate partner Symbiodinium is central to the success of corals. However, an array of other microorganisms associated with coral (i.e., Bacteria, Archaea, Fungi, and viruses) have a complex and intricate role in maintaining homeostasis between corals and Symbiodinium. Corals are sensitive to shifts in the surrounding environmental conditions. One of the most widely reported responses of coral to stressful environmental conditions is bleaching. During this event, corals expel Symbiodinium cells from their gastrodermal tissues upon experiencing extended seawater temperatures above their thermal threshold. An array of other environmental stressors can also destabilize the coral microbiome, resulting in compromised health of the host, which may include disease and mortality in the worst scenario. However, the exact mechanisms by which the coral microbiome supports coral health and increases resilience are poorly understood. Earlier studies of coral microbiology proposed a coral probiotic hypothesis, wherein a dynamic relationship exists between corals and their symbiotic microorganisms, selecting for the coral holobiont that is best suited for the prevailing environmental conditions. Here, we discuss the microbial-host relationships within the coral holobiont, along with their potential roles in maintaining coral health. We propose the term BMC (Beneficial Microorganisms for Corals) to define (specific) symbionts that promote coral health. This term and concept are analogous to the term Plant Growth Promoting Rhizosphere (PGPR), which has been widely explored and manipulated in the agricultural industry for microorganisms that inhabit the rhizosphere and directly or indirectly promote plant growth and development through the production of regulatory signals, antibiotics and nutrients. Additionally, we propose and discuss the potential mechanisms of the effects of BMC on corals, suggesting strategies for the use of this knowledge to manipulate the microbiome, reversing dysbiosis to restore and protect coral reefs. This may include developing and using BMC consortia as environmental "probiotics" to improve coral resistance after bleaching events and/or the use of BMC with other strategies such as human-assisted acclimation/adaption to shifting environmental conditions.
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Affiliation(s)
- Raquel S. Peixoto
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de JaneiroRio de Janeiro, Brazil
- Instituto Museu Aquário Marinho do Rio de Janeiro-AquaRio (IMAM/AquaRio) – Rio de Janeiro Marine Aquarium Research CenterRio de Janeiro, Brazil
| | - Phillipe M. Rosado
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de JaneiroRio de Janeiro, Brazil
- Instituto Museu Aquário Marinho do Rio de Janeiro-AquaRio (IMAM/AquaRio) – Rio de Janeiro Marine Aquarium Research CenterRio de Janeiro, Brazil
| | | | - Alexandre S. Rosado
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de JaneiroRio de Janeiro, Brazil
- Instituto Museu Aquário Marinho do Rio de Janeiro-AquaRio (IMAM/AquaRio) – Rio de Janeiro Marine Aquarium Research CenterRio de Janeiro, Brazil
| | - David G. Bourne
- College of Science and Engineering, James Cook University, TownsvilleQLD, Australia
- Australian Institute of Marine Science, TownsvilleQLD, Australia
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135
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Induction of Invertebrate Larval Settlement; Different Bacteria, Different Mechanisms? Sci Rep 2017; 7:42557. [PMID: 28195220 PMCID: PMC5307369 DOI: 10.1038/srep42557] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 01/10/2017] [Indexed: 12/23/2022] Open
Abstract
Recruitment via settlement of pelagic larvae is critical for the persistence of benthic marine populations. For many benthic invertebrates, larval settlement occurs in response to surface microbial films. Larvae of the serpulid polychaete Hydroides elegans can be induced to settle by single bacterial species. Until now, only Pseudoalteromonas luteoviolacea had been subjected to detailed genetic and mechanistic studies. To determine if the complex structures, termed tailocins, derived from phage-tail gene assemblies and hypothesized to be the settlement cue in P. luteoviolacea were present in all inductive bacteria, genomic comparisons with inductive strains of Cellulophaga lytica, Bacillus aquimaris and Staphylococcus warneri were undertaken. They revealed that the gene assemblies for tailocins are lacking in these other bacteria. Negatively stained TEM images confirmed the absence of tailocins and revealed instead large numbers of extracellular vesicles in settlement-inductive fractions from all three bacteria. TEM imaging confirmed for C. lytica that the vesicles are budded from cell surfaces in a manner consistent with the production of outer membrane vesicles. Finding multiple bacteria settlement cues highlights the importance of further studies into the role of bacterial extracellular vesicles in eliciting settlement and metamorphosis of benthic marine larvae.
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136
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Mandel MJ, Dunn AK. Impact and Influence of the Natural Vibrio-Squid Symbiosis in Understanding Bacterial-Animal Interactions. Front Microbiol 2016; 7:1982. [PMID: 28018314 PMCID: PMC5156696 DOI: 10.3389/fmicb.2016.01982] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/25/2016] [Indexed: 11/13/2022] Open
Abstract
Animals are colonized by bacteria, and in many cases partners have co-evolved to perform mutually beneficial functions. An exciting and ongoing legacy of the past decade has been an expansion of technology to enable study of natural associations in situ/in vivo. As a result, more symbioses are being examined, and additional details are being revealed for well-studied systems with a focus on the interactions between partners in the native context. With this framing, we review recent literature from the Vibrio fischeri-Euprymna scolopes symbiosis and focus on key studies that have had an impact on understanding bacteria-animal interactions broadly. This is not intended to be a comprehensive review of the system, but rather to focus on particular studies that have excelled at moving from pattern to process in facilitating an understanding of the molecular basis to intriguing observations in the field of host-microbe interactions. In this review we discuss the following topics: processes regulating strain and species specificity; bacterial signaling to host morphogenesis; multiple roles for nitric oxide; flagellar motility and chemotaxis; and efforts to understand unannotated and poorly annotated genes. Overall these studies demonstrate how functional approaches in vivo in a tractable system have provided valuable insight into general principles of microbe-host interactions.
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Affiliation(s)
- Mark J Mandel
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine Chicago, IL, USA
| | - Anne K Dunn
- Department of Microbiology and Plant Biology, University of Oklahoma Norman, OK, USA
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137
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Yang JL, Li YF, Liang X, Guo XP, Ding DW, Zhang D, Zhou S, Bao WY, Bellou N, Dobretsov S. Silver Nanoparticles Impact Biofilm Communities and Mussel Settlement. Sci Rep 2016; 6:37406. [PMID: 27869180 PMCID: PMC5116650 DOI: 10.1038/srep37406] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/28/2016] [Indexed: 02/07/2023] Open
Abstract
Silver nanoparticles (AgNPs) demonstrating good antimicrobial activity are widely used in many fields. However, the impact of AgNPs on the community structures of marine biofilms that drive biogeochemical cycling processes and the recruitment of marine invertebrate larvae remains unknown. Here, we employed MiSeq sequencing technology to evaluate the bacterial communities of 28-day-old marine biofilms formed on glass, polydimethylsiloxane (PDMS), and PDMS filled with AgNPs and subsequently tested the influence of these marine biofilms on plantigrade settlement by the mussel Mytilus coruscus. AgNP-filled PDMS significantly reduced the dry weight and bacterial density of biofilms compared with the glass and PDMS controls. AgNP incorporation impacted bacterial communities by reducing the relative abundance of Flavobacteriaceae (phylum: Bacteroidetes) and increasing the relative abundance of Vibrionaceae (phylum: Proteobacteria) in 28-day-old biofilms compared to PDMS. The settlement rate of M. coruscus on 28-day-old biofilms developed on AgNPs was lower by >30% compared to settlement on control biofilms. Thus, the incorporation of AgNPs influences biofilm bacterial communities in the marine environment and subsequently inhibits mussel settlement.
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Affiliation(s)
- Jin-Long Yang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, China.,Marine Ecology Research Center, The First Institute of Oceanography, State Oceanic Administration, Qingdao, China.,Collaborative Innovation Center for Zhejiang Marine High-efficiency and Healthy Aquaculture, Ningbo, China
| | - Yi-Feng Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, China
| | - Xiao Liang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, China
| | - Xing-Pan Guo
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, China
| | - De-Wen Ding
- Marine Ecology Research Center, The First Institute of Oceanography, State Oceanic Administration, Qingdao, China
| | - Demin Zhang
- Collaborative Innovation Center for Zhejiang Marine High-efficiency and Healthy Aquaculture, Ningbo, China
| | - Shuxue Zhou
- Department of Materials Science, State Key Laboratory of Molecular Engineering of Polymers, Advanced Coatings Research Center of Ministry of Education of China, Fudan University, Shanghai, China
| | - Wei-Yang Bao
- Institute of Marine Science and Technology, Yangzhou University, Yangzhou, China
| | - Nikoleta Bellou
- Hellenic Centre for Marine Research, Institute of Oceanography, Athens, Greece
| | - Sergey Dobretsov
- Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman.,Center of Excellence in Marine Biotechnology, Sultan Qaboos University, Muscat, Oman
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138
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Schwab DB, Riggs HE, Newton ILG, Moczek AP. Developmental and Ecological Benefits of the Maternally Transmitted Microbiota in a Dung Beetle. Am Nat 2016; 188:679-692. [PMID: 27860508 DOI: 10.1086/688926] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
To complete their development, diverse animal species rely on the presence of communities of symbiotic microbiota that are vertically transmitted from mother to offspring. In the dung beetle genus Onthophagus, newly hatched larvae acquire maternal gut symbionts by the consumption of a maternal fecal secretion known as the pedestal. Here, we investigate the role of pedestal symbionts in mediating the normal development of Onthophagus gazella. Through the stepwise removal of environmental and maternal sources of microbial inoculation, we find that pedestal microbiota can enhance both overall growth and developmental rate in O. gazella. Further, we find that the beneficial effects of symbionts on developmental outcomes are amplified in the presence of ecologically relevant temperature and desiccation stressors. Collectively, our results suggest that the pedestal may provide an adaptive function by transmitting beneficial microbiota to developing dung beetle larvae and that the importance of microbiota for developmental and fitness outcomes may be context dependent.
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139
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F-Type Bacteriocins of Listeria monocytogenes: a New Class of Phage Tail-Like Structures Reveals Broad Parallel Coevolution between Tailed Bacteriophages and High-Molecular-Weight Bacteriocins. J Bacteriol 2016; 198:2784-93. [PMID: 27457717 DOI: 10.1128/jb.00489-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 07/19/2016] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED Listeria monocytogenes is a significant foodborne human pathogen that can cause severe disease in certain high-risk individuals. L. monocytogenes is known to produce high-molecular-weight, phage tail-like bacteriocins, or "monocins," upon induction of the SOS system. In this work, we purified and characterized monocins and found them to be a new class of F-type bacteriocins. The L. monocytogenes monocin genetic locus was cloned and expressed in Bacillus subtilis, producing specifically targeted bactericidal particles. The receptor binding protein, which determines target cell specificity, was identified and engineered to change the bactericidal spectrum. Unlike the F-type pyocins of Pseudomonas aeruginosa, which are related to lambda-like phage tails, monocins are more closely related to TP901-1-like phage tails, structures not previously known to function as bacteriocins. Monocins therefore represent a new class of phage tail-like bacteriocins. It appears that multiple classes of phage tails and their related bacteriocins have coevolved separately in parallel. IMPORTANCE Phage tail-like bacteriocins (PTLBs) are structures widespread among the members of the bacterial kingdom that are evolutionarily related to the DNA delivery organelles of phages (tails). We identified and characterized "monocins" of Listeria monocytogenes and showed that they are related to the tail structures of TP901-1-like phages, structures not previously known to function as bacteriocins. Our results show that multiple types of envelope-penetrating machines have coevolved in parallel to function either for DNA delivery (phages) or as membrane-disrupting bacteriocins. While it has commonly been assumed that these structures were coopted from phages, we cannot rule out the opposite possibility, that ancient phages coopted complex bacteriocins from the cell, which then underwent adaptations to become efficient at translocating DNA.
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140
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Jékely G, Keijzer F, Godfrey-Smith P. An option space for early neural evolution. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0181. [PMID: 26554049 DOI: 10.1098/rstb.2015.0181] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The origin of nervous systems has traditionally been discussed within two conceptual frameworks. Input-output models stress the sensory-motor aspects of nervous systems, while internal coordination models emphasize the role of nervous systems in coordinating multicellular activity, especially muscle-based motility. Here we consider both frameworks and apply them to describe aspects of each of three main groups of phenomena that nervous systems control: behaviour, physiology and development. We argue that both frameworks and all three aspects of nervous system function need to be considered for a comprehensive discussion of nervous system origins. This broad mapping of the option space enables an overview of the many influences and constraints that may have played a role in the evolution of the first nervous systems.
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Affiliation(s)
- Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, Tübingen 72076, Germany
| | - Fred Keijzer
- Department of Theoretical Philosophy, University of Groningen, Oude Boteringestraat 52, Groningen 9712 GL, The Netherlands
| | - Peter Godfrey-Smith
- Philosophy Program, The Graduate Center, City University of New York, New York, NY 10016, USA History and Philosophy of Science Unit, University of Sydney, Sydney, New South Wales 2006, Australia
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141
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Baseplate assembly of phage Mu: Defining the conserved core components of contractile-tailed phages and related bacterial systems. Proc Natl Acad Sci U S A 2016; 113:10174-9. [PMID: 27555589 DOI: 10.1073/pnas.1607966113] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Contractile phage tails are powerful cell puncturing nanomachines that have been co-opted by bacteria for self-defense against both bacteria and eukaryotic cells. The tail of phage T4 has long served as the paradigm for understanding contractile tail-like systems despite its greater complexity compared with other contractile-tailed phages. Here, we present a detailed investigation of the assembly of a "simple" contractile-tailed phage baseplate, that of Escherichia coli phage Mu. By coexpressing various combinations of putative Mu baseplate proteins, we defined the required components of this baseplate and delineated its assembly pathway. We show that the Mu baseplate is constructed through the independent assembly of wedges that are organized around a central hub complex. The Mu wedges are comprised of only three protein subunits rather than the seven found in the equivalent structure in T4. Through extensive bioinformatic analyses, we found that homologs of the essential components of the Mu baseplate can be identified in the majority of contractile-tailed phages and prophages. No T4-like prophages were identified. The conserved simple baseplate components were also found in contractile tail-derived bacterial apparatuses, such as type VI secretion systems, Photorhabdus virulence cassettes, and R-type tailocins. Our work highlights the evolutionary connections and similarities in the biochemical behavior of phage Mu wedge components and the TssF and TssG proteins of the type VI secretion system. In addition, we demonstrate the importance of the Mu baseplate as a model system for understanding bacterial phage tail-derived systems.
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142
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Stepwise metamorphosis of the tubeworm Hydroides elegans is mediated by a bacterial inducer and MAPK signaling. Proc Natl Acad Sci U S A 2016; 113:10097-102. [PMID: 27551098 DOI: 10.1073/pnas.1603142113] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Diverse animal taxa metamorphose between larval and juvenile phases in response to bacteria. Although bacteria-induced metamorphosis is widespread among metazoans, little is known about the molecular changes that occur in the animal upon stimulation by bacteria. Larvae of the tubeworm Hydroides elegans metamorphose in response to surface-bound Pseudoalteromonas luteoviolacea bacteria, producing ordered arrays of phage tail-like metamorphosis-associated contractile structures (MACs). Sequencing the Hydroides genome and transcripts during five developmental stages revealed that MACs induce the regulation of groups of genes important for tissue remodeling, innate immunity, and mitogen-activated protein kinase (MAPK) signaling. Using two MAC mutations that block P. luteoviolacea from inducing settlement or metamorphosis and three MAPK inhibitors, we established a sequence of bacteria-induced metamorphic events: MACs induce larval settlement; then, particular properties of MACs encoded by a specific locus in P. luteoviolacea initiate cilia loss and activate metamorphosis-associated transcription; finally, signaling through p38 and c-Jun N-terminal kinase (JNK) MAPK pathways alters gene expression and leads to morphological changes upon initiation of metamorphosis. Our results reveal that the intricate interaction between Hydroides and P. luteoviolacea can be dissected using genomic, genetic, and pharmacological tools. Hydroides' dependency on bacteria for metamorphosis highlights the importance of external stimuli to orchestrate animal development. The conservation of Hydroides genome content with distantly related deuterostomes (urchins, sea squirts, and humans) suggests that mechanisms of bacteria-induced metamorphosis in Hydroides may have conserved features in diverse animals. As a major biofouling agent, insight into the triggers of Hydroides metamorphosis might lead to practical strategies for fouling control.
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143
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Basler M. Type VI secretion system: secretion by a contractile nanomachine. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0021. [PMID: 26370934 PMCID: PMC4632598 DOI: 10.1098/rstb.2015.0021] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action.
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Affiliation(s)
- Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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144
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Bacterial lipids activate, synergize, and inhibit a developmental switch in choanoflagellates. Proc Natl Acad Sci U S A 2016; 113:7894-9. [PMID: 27354530 DOI: 10.1073/pnas.1605015113] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In choanoflagellates, the closest living relatives of animals, multicellular rosette development is regulated by environmental bacteria. The simplicity of this evolutionarily relevant interaction provides an opportunity to identify the molecules and regulatory logic underpinning bacterial regulation of development. We find that the rosette-inducing bacterium Algoriphagus machipongonensis produces three structurally divergent classes of bioactive lipids that, together, activate, enhance, and inhibit rosette development in the choanoflagellate Salpingoeca rosetta. One class of molecules, the lysophosphatidylethanolamines (LPEs), elicits no response on its own but synergizes with activating sulfonolipid rosette-inducing factors (RIFs) to recapitulate the full bioactivity of live Algoriphagus. LPEs, although ubiquitous in bacteria and eukaryotes, have not previously been implicated in the regulation of a host-microbe interaction. This study reveals that multiple bacterially produced lipids converge to activate, enhance, and inhibit multicellular development in a choanoflagellate.
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145
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Hynes AP, Shakya M, Mercer RG, Grüll MP, Bown L, Davidson F, Steffen E, Matchem H, Peach ME, Berger T, Grebe K, Zhaxybayeva O, Lang AS. Functional and Evolutionary Characterization of a Gene Transfer Agent's Multilocus "Genome". Mol Biol Evol 2016; 33:2530-43. [PMID: 27343288 PMCID: PMC5026251 DOI: 10.1093/molbev/msw125] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Gene transfer agents (GTAs) are phage-like particles that can package and transfer a random piece of the producing cell’s genome, but are unable to transfer all the genes required for their own production. As such, GTAs represent an evolutionary conundrum: are they selfish genetic elements propagating through an unknown mechanism, defective viruses, or viral structures “repurposed” by cells for gene exchange, as their name implies? In Rhodobacter capsulatus, production of the R. capsulatus GTA (RcGTA) particles is associated with a cluster of genes resembling a small prophage. Utilizing transcriptomic, genetic and biochemical approaches, we report that the RcGTA “genome” consists of at least 24 genes distributed across five distinct loci. We demonstrate that, of these additional loci, two are involved in cell recognition and binding and one in the production and maturation of RcGTA particles. The five RcGTA “genome” loci are widespread within Rhodobacterales, but not all loci have the same evolutionary histories. Specifically, two of the loci have been subject to frequent, probably virus-mediated, gene transfer events. We argue that it is unlikely that RcGTA is a selfish genetic element. Instead, our findings are compatible with the scenario that RcGTA is a virus-derived element maintained by the producing organism due to a selective advantage of within-population gene exchange. The modularity of the RcGTA “genome” is presumably a result of selection on the host organism to retain GTA functionality.
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Affiliation(s)
- Alexander P Hynes
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Migun Shakya
- Department of Biological Sciences, Dartmouth College
| | - Ryan G Mercer
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Marc P Grüll
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Luke Bown
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Fraser Davidson
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Ekaterina Steffen
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Heidi Matchem
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Mandy E Peach
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Tim Berger
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Katherine Grebe
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
| | - Olga Zhaxybayeva
- Department of Biological Sciences, Dartmouth College Department of Computer Science, Dartmouth College
| | - Andrew S Lang
- Department of Biology, Memorial University of Newfoundland, St John's, NL, Canada
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146
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Taylor NMI, Prokhorov NS, Guerrero-Ferreira RC, Shneider MM, Browning C, Goldie KN, Stahlberg H, Leiman PG. Structure of the T4 baseplate and its function in triggering sheath contraction. Nature 2016; 533:346-52. [DOI: 10.1038/nature17971] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/05/2016] [Indexed: 12/12/2022]
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147
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Oikonomou CM, Chang YW, Jensen GJ. A new view into prokaryotic cell biology from electron cryotomography. Nat Rev Microbiol 2016; 14:205-20. [PMID: 26923112 PMCID: PMC5551487 DOI: 10.1038/nrmicro.2016.7] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electron cryotomography (ECT) enables intact cells to be visualized in 3D in an essentially native state to 'macromolecular' (∼4 nm) resolution, revealing the basic architectures of complete nanomachines and their arrangements in situ. Since its inception, ECT has advanced our understanding of many aspects of prokaryotic cell biology, from morphogenesis to subcellular compartmentalization and from metabolism to complex interspecies interactions. In this Review, we highlight how ECT has provided structural and mechanistic insights into the physiology of bacteria and archaea and discuss prospects for the future.
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Affiliation(s)
- Catherine M Oikonomou
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Yi-Wei Chang
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Grant J Jensen
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
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148
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Verbon EH, Liberman LM. Beneficial Microbes Affect Endogenous Mechanisms Controlling Root Development. TRENDS IN PLANT SCIENCE 2016; 21:218-229. [PMID: 26875056 PMCID: PMC4772406 DOI: 10.1016/j.tplants.2016.01.013] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 01/08/2016] [Accepted: 01/11/2016] [Indexed: 05/18/2023]
Abstract
Plants have incredible developmental plasticity, enabling them to respond to a wide range of environmental conditions. Among these conditions is the presence of plant growth-promoting rhizobacteria (PGPR) in the soil. Recent studies show that PGPR affect Arabidopsis thaliana root growth and development by modulating cell division and differentiation in the primary root and influencing lateral root development. These effects lead to dramatic changes in root system architecture that significantly impact aboveground plant growth. Thus, PGPR may promote shoot growth via their effect on root developmental programs. This review focuses on contextualizing root developmental changes elicited by PGPR in light of our understanding of plant-microbe interactions and root developmental biology.
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Affiliation(s)
- Eline H Verbon
- Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
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149
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Priming and polymerization of a bacterial contractile tail structure. Nature 2016; 531:59-63. [DOI: 10.1038/nature17182] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 02/01/2016] [Indexed: 12/20/2022]
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150
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Mushegian AA, Burcklen E, Schär TMM, Ebert D. Temperature-dependent benefits of bacterial exposure in embryonic development of Daphnia magna resting eggs. J Exp Biol 2016; 219:897-904. [DOI: 10.1242/jeb.134759] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/12/2016] [Indexed: 11/20/2022]
Abstract
The environments in which animals develop and evolve are profoundly shaped by bacteria, which affect animals both indirectly through their roles in biogeochemical processes and also through direct antagonistic or beneficial interactions. The outcomes of these activities can differ according to environmental context. In a series of laboratory experiments with diapausing eggs of the water flea Daphnia magna, we manipulated two environmental parameters, temperature and presence of bacteria, and examined their effect on development. At elevated temperatures (≥26 °C), resting eggs developing without live bacteria had reduced hatching success and correspondingly higher rates of severe morphological abnormalities compared to eggs with bacteria in their environment. The beneficial effect of bacteria was strongly reduced at 20 °C. Neither temperature nor presence of bacteria affected directly developing parthenogenetic eggs. The mechanistic basis of this effect of bacteria on development is unclear, but these results highlight the complex interplay of biotic and abiotic factors influencing animal development after diapause.
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Affiliation(s)
| | | | | | - Dieter Ebert
- Zoological Institute, Universität Basel, Basel, Switzerland
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