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Leavitt JC, Woodbury BM, Gilcrease EB, Bridges CM, Teschke CM, Casjens SR. Bacteriophage P22 SieA-mediated superinfection exclusion. mBio 2024; 15:e0216923. [PMID: 38236051 PMCID: PMC10883804 DOI: 10.1128/mbio.02169-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 11/10/2023] [Indexed: 01/19/2024] Open
Abstract
Many temperate phages encode prophage-expressed functions that interfere with superinfection of the host bacterium by external phages. Salmonella phage P22 has four such systems that are expressed from the prophage in a lysogen that are encoded by the c2 (repressor), gtrABC, sieA, and sieB genes. Here we report that the P22-encoded SieA protein is necessary and sufficient for exclusion by the SieA system and that it is an inner membrane protein that blocks DNA injection by P22 and its relatives, but has no effect on infection by other tailed phage types. The P22 virion injects its DNA through the host cell membranes and periplasm via a conduit assembled from three "ejection proteins" after their release from the virion. Phage P22 mutants that overcome the SieA block were isolated, and they have amino acid changes in the C-terminal regions of the gene 16 and 20 encoded ejection proteins. Three different single-amino acid changes in these proteins are required to obtain nearly full resistance to SieA. Hybrid P22 phages that have phage HK620 ejection protein genes are also partially resistant to SieA. There are three sequence types of extant phage-encoded SieA proteins that are less than 30% identical to one another, yet comparison of two of these types found no differences in phage target specificity. Our data strongly suggest a model in which the inner membrane protein SieA interferes with the assembly or function of the periplasmic gp20 and membrane-bound gp16 DNA delivery conduit.IMPORTANCEThe ongoing evolutionary battle between bacteria and the viruses that infect them is a critical feature of bacterial ecology on Earth. Viruses can kill bacteria by infecting them. However, when their chromosomes are integrated into a bacterial genome as a prophage, viruses can also protect the host bacterium by expressing genes whose products defend against infection by other viruses. This defense property is called "superinfection exclusion." A significant fraction of bacteria harbor prophages that encode such protective systems, and there are many different molecular strategies by which superinfection exclusion is mediated. This report is the first to describe the mechanism by which bacteriophage P22 SieA superinfection exclusion protein protects its host bacterium from infection by other P22-like phages. The P22 prophage-encoded inner membrane SieA protein prevents infection by blocking transport of superinfecting phage DNA across the inner membrane during injection.
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Affiliation(s)
- Justin C Leavitt
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Brianna M Woodbury
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Eddie B Gilcrease
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Charles M Bridges
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Carolyn M Teschke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
| | - Sherwood R Casjens
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah, USA
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2
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Van Cauwenberghe J, Simms EL. How might bacteriophages shape biological invasions? mBio 2023; 14:e0188623. [PMID: 37812005 PMCID: PMC10653932 DOI: 10.1128/mbio.01886-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023] Open
Abstract
Invasions by eukaryotes dependent on environmentally acquired bacterial mutualists are often limited by the ability of bacterial partners to survive and establish free-living populations. Focusing on the model legume-rhizobium mutualism, we apply invasion biology hypotheses to explain how bacteriophages can impact the competitiveness of introduced bacterial mutualists. Predicting how phage-bacteria interactions affect invading eukaryotic hosts requires knowing the eco-evolutionary constraints of introduced and native microbial communities, as well as their differences in abundance and diversity. By synthesizing research from invasion biology, as well as bacterial, viral, and community ecology, we create a conceptual framework for understanding and predicting how phages can affect biological invasions through their effects on bacterial mutualists.
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Affiliation(s)
- Jannick Van Cauwenberghe
- Institute of Biodiversity, Faculty of Biological Sciences, Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Ellen L. Simms
- Department of Integrative Biology, University of California, Berkeley, California, USA
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3
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Abstract
EMBL-EBI The European Bioinformatics Institute; E. coli Escherichia coli; E. faecalis Enterobacter faecalis; B. fragilis Bacteroides fragilis; B. vulgatus Bacteroides vulgatus; SaPIs Staphylococcus aureus pathogenicity islands; ARGs Antibiotic resistance genes; STEC Shiga toxigenic E. coli; Stx Shiga toxin; BLAST Basic Local Alignment Search Tool; TSST-1 Toxic shock toxin 1; RBPs Receptor-binding proteins; LPS lipopolysaccharide; OMVs Outer membrane vesicles; PT Phosphorothioate; BREX Bacteriophage exclusion; OCR Overcome classical restriction; Pgl Phage growth limitation; DISARM Defense island system associated with restrictionmodification; R-M system Restriction-modification system; BREX system Bacteriophage exclusion system; CRISPR Clustered regularly interspaced short palindromic repeats; Cas CRISPR-associated; PAMs Prospacer adjacent motifs; crRNA CRISPR RNA; SIE; OMPs; Superinfection exclusion; Outer membrane proteins; Abi Abortive infection; TA Toxin-antitoxin; TLR Toll-like receptor; APCs Antigen-presenting cells; DSS Dextran sulfate sodium; IELs Intraepithelial lymphocytes; FMT Fecal microbiota transfer; IFN-γ Interferon-gamma; IBD Inflammatory bowel disease; AgNPs Silver nanoparticles; MDSC Myeloid-derived suppressor cell; CRC Colorectal cancer; VLPs Virus-like particles; TMP Tape measure protein; PSMB4 Proteasome subunit beta type-4; ALD Alcohol-related liver disease; GVHD Graft-versus-host disease; ROS Reactive oxygen species; RA Rheumatoid arthritis; CCP Cyclic citrullinated protein; AMGs Accessory metabolic genes; T1DM Type 1 diabetes mellitus; T2DM Type 2 diabetes mellitus; SCFAs Short-chain fatty acids; GLP-1 Glucagon-like peptide-1; A. baumannii Acinetobacter baumannii; CpG Deoxycytidylinate-phosphodeoxyguanosine; PEG Polyethylene glycol; MetS Metabolic syndrome; OprM Outer membrane porin M.
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Affiliation(s)
- Han Shuwen
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China,Department of Medical Oncology, Huzhou Central Hospital, Huzhou, China
| | - Ding Kefeng
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China,Department of Colorectal Surgery and Oncology, Cancer Center Zhejiang University, Hangzhou, China,CONTACT Ding Kefeng Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Building 6 room 2018, Hangzhou, Zhejiang310009, China
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4
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Genetic Mining of Newly Isolated Salmophages for Phage Therapy. Int J Mol Sci 2022; 23:ijms23168917. [PMID: 36012174 PMCID: PMC9409062 DOI: 10.3390/ijms23168917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/29/2022] [Accepted: 08/07/2022] [Indexed: 11/16/2022] Open
Abstract
Salmonella enterica, a Gram-negative zoonotic bacterium, is mainly a food-borne pathogen and the main cause of diarrhea in humans worldwide. The main reservoirs are found in poultry farms, but they are also found in wild birds. The development of antibiotic resistance in S. enterica species raises concerns about the future of efficient therapies against this pathogen and revives the interest in bacteriophages as a useful therapy against bacterial infections. Here, we aimed to decipher and functionally annotate 10 new Salmonella phage genomes isolated in Spain in the light of phage therapy. We designed a bioinformatic pipeline using available building blocks to de novo assemble genomes and perform syntaxic annotation. We then used genome-wide analyses for taxonomic annotation enabled by vContact2 and VICTOR. We were also particularly interested in improving functional annotation using remote homologies detection and comparisons with the recently published phage-specific PHROG protein database. Finally, we searched for useful functions for phage therapy, such as systems encoded by the phage to circumvent cellular defenses with a particular focus on anti-CRISPR proteins. We, thus, were able to genetically characterize nine virulent phages and one temperate phage and identify putative functions relevant to the formulation of phage cocktails for Salmonella biocontrol.
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5
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Staes I, Bäcker LE, Simoens K, De Winter K, Marolt G, Cenens W, Wolput S, Vazquez AR, Goos P, Lavigne R, Bernaerts K, Aertsen A. Superinfection exclusion factors drive a history-dependent switch from vertical to horizontal phage transmission. Cell Rep 2022; 39:110804. [PMID: 35545039 DOI: 10.1016/j.celrep.2022.110804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/24/2022] [Accepted: 04/19/2022] [Indexed: 11/03/2022] Open
Abstract
Temperate bacterial viruses are commonly thought to favor vertical (lysogenic) transmission over horizontal (lytic) transmission when the virion-to-host-cell ratio is high and available host cells become scarce. In P22-infected Salmonella Typhimurium populations, however, we find that host subpopulations become lytically consumed despite high phage-to-host ratios that would normally favor lysogeny. These subpopulations originate from the proliferation of P22-free siblings that spawn off from P22-carrier cells from which they cytoplasmically inherit P22-borne superinfection exclusion factors (SEFs). In fact, we demonstrate that the gradual dilution of these SEFs in the growing subpopulation of P22-free siblings restricts the number of incoming phages, thereby imposing the perception of a low phage-to-host ratio that favors lytic development. Although their role has so far been neglected, our data indicate that phage-borne SEFs can spur complex infection dynamics and a history-dependent switch from vertical to horizontal transmission in the face of host-cell scarcity.
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Affiliation(s)
- Ines Staes
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Leonard E Bäcker
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Kenneth Simoens
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Kjerstin De Winter
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Gasper Marolt
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium; Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - William Cenens
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Sanne Wolput
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Alan R Vazquez
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Peter Goos
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium; Department of Engineering Management, University of Antwerp, Antwerp, Belgium
| | - Rob Lavigne
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Kristel Bernaerts
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium.
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6
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Correa AMS, Howard-Varona C, Coy SR, Buchan A, Sullivan MB, Weitz JS. Revisiting the rules of life for viruses of microorganisms. Nat Rev Microbiol 2021; 19:501-513. [PMID: 33762712 DOI: 10.1038/s41579-021-00530-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2021] [Indexed: 02/01/2023]
Abstract
Viruses that infect microbial hosts have traditionally been studied in laboratory settings with a focus on either obligate lysis or persistent lysogeny. In the environment, these infection archetypes are part of a continuum that spans antagonistic to beneficial modes. In this Review, we advance a framework to accommodate the context-dependent nature of virus-microorganism interactions in ecological communities by synthesizing knowledge from decades of virology research, eco-evolutionary theory and recent technological advances. We discuss that nuanced outcomes, rather than the extremes of the continuum, are particularly likely in natural communities given variability in abiotic factors, the availability of suboptimal hosts and the relevance of multitrophic partnerships. We revisit the 'rules of life' in terms of how long-term infections shape the fate of viruses and microbial cells, populations and ecosystems.
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Affiliation(s)
| | | | - Samantha R Coy
- BioSciences Department, Rice University, Houston, TX, USA
| | - Alison Buchan
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA.
| | - Matthew B Sullivan
- Department of Microbiology, The Ohio State University, Columbus, OH, USA. .,Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, Columbus, OH, USA.
| | - Joshua S Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA. .,School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
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7
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Zaworski J, McClung C, Ruse C, Weigele PR, Hendrix RW, Ko CC, Edgar R, Hatfull GF, Casjens SR, Raleigh EA. Genome analysis of Salmonella enterica serovar Typhimurium bacteriophage L, indicator for StySA (StyLT2III) restriction-modification system action. G3-GENES GENOMES GENETICS 2021; 11:6044188. [PMID: 33561243 PMCID: PMC8022706 DOI: 10.1093/g3journal/jkaa037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/07/2020] [Indexed: 01/10/2023]
Abstract
Bacteriophage L, a P22-like phage of Salmonella enterica sv Typhimurium LT2, was important for definition of mosaic organization of the lambdoid phage family and for characterization of restriction-modification systems of Salmonella. We report the complete genome sequences of bacteriophage L cI–40 13–am43 and L cII–101; the deduced sequence of wildtype L is 40,633 bp long with a 47.5% GC content. We compare this sequence with those of P22 and ST64T, and predict 72 Coding Sequences, 2 tRNA genes and 14 intergenic rho-independent transcription terminators. The overall genome organization of L agrees with earlier genetic and physical evidence; for example, no secondary immunity region (immI: ant, arc) or known genes for superinfection exclusion (sieA and sieB) are present. Proteomic analysis confirmed identification of virion proteins, along with low levels of assembly intermediates and host cell envelope proteins. The genome of L is 99.9% identical at the nucleotide level to that reported for phage ST64T, despite isolation on different continents ∼35 years apart. DNA modification by the epigenetic regulator Dam is generally incomplete. Dam modification is also selectively missing in one location, corresponding to the P22 phase-variation-sensitive promoter region of the serotype-converting gtrABC operon. The number of sites for SenLTIII (StySA) action may account for stronger restriction of L (13 sites) than of P22 (3 sites).
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Affiliation(s)
- Julie Zaworski
- Research Department, New England Biolabs, Ipswich, MA 01938-2723, USA
| | - Colleen McClung
- Research Department, New England Biolabs, Ipswich, MA 01938-2723, USA
| | - Cristian Ruse
- Research Department, New England Biolabs, Ipswich, MA 01938-2723, USA
| | - Peter R Weigele
- Research Department, New England Biolabs, Ipswich, MA 01938-2723, USA
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Ching-Chung Ko
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Robert Edgar
- Bioengineering Department, University of Pittsburgh, USA
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Sherwood R Casjens
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.,School of Biological Science, University of Utah, Salt Lake City, UT 84112, USA
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8
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Doekes HM, Mulder GA, Hermsen R. Repeated outbreaks drive the evolution of bacteriophage communication. eLife 2021; 10:58410. [PMID: 33459590 PMCID: PMC7935489 DOI: 10.7554/elife.58410] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 01/15/2021] [Indexed: 12/25/2022] Open
Abstract
Recently, a small-molecule communication mechanism was discovered in a range of Bacillus-infecting bacteriophages, which these temperate phages use to inform their lysis-lysogeny decision. We present a mathematical model of the ecological and evolutionary dynamics of such viral communication and show that a communication strategy in which phages use the lytic cycle early in an outbreak (when susceptible host cells are abundant) but switch to the lysogenic cycle later (when susceptible cells become scarce) is favoured over a bet-hedging strategy in which cells are lysogenised with constant probability. However, such phage communication can evolve only if phage-bacteria populations are regularly perturbed away from their equilibrium state, so that acute outbreaks of phage infections in pools of susceptible cells continue to occur. Our model then predicts the selection of phages that switch infection strategy when half of the available susceptible cells have been infected. Bacteriophages, or phages for short, are viruses that need to infect bacteria to multiply. Once inside a cell, phages follow one of two strategies. They either start to replicate quickly, killing the host in the process; or they lay dormant, their genetic material slowly duplicating as the bacterium divides. These two strategies are respectively known as a ‘lytic’ or a ‘lysogenic’ infection. In 2017, scientists discovered that, during infection, some phages produce a signalling molecule that influences the strategy other phages will use. Generally, a high concentration of the signal triggers lysogenic infection, while a low level prompts the lytic type. However, it is still unclear what advantages this communication system brings to the viruses, and how it has evolved. Here, Doekes et al. used a mathematical model to explore how communication changes as phages infect a population of bacteria, rigorously testing earlier theories. The simulations showed that early in an outbreak, when only a few cells have yet been infected, the signalling molecule levels are low: lytic infections are therefore triggered and the phages quickly multiply, killing their hosts in the process. This is an advantageous strategy since many bacteria are available for the viruses to prey on. Later on, as more phages are being produced and available bacteria become few and far between, the levels of the signalling molecule increase. The viruses then switch to lysogenic infections, which allows them to survive dormant, inside their host. Doekes et al. also discovered that this communication system only evolves if phages regularly cause large outbreaks in new, uninfected bacterial populations. From there, the model was able to predict that phages switch from lytic to lysogenic infections when about half the available bacteria have been infected. As antibiotic resistance rises around the globe, phages are increasingly considered as a new way to fight off harmful bacteria. Deciphering the way these viruses communicate could help to understand how they could be harnessed to control the spread of bacteria.
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Affiliation(s)
- Hilje M Doekes
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, Netherlands.,Laboratory of Genetics, Department of Plant Sciences, Wageningen University, Wageningen, Netherlands
| | - Glenn A Mulder
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Rutger Hermsen
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, Netherlands
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9
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Storey N, Rabiey M, Neuman BW, Jackson RW, Mulley G. Genomic Characterisation of Mushroom Pathogenic Pseudomonads and Their Interaction with Bacteriophages. Viruses 2020; 12:E1286. [PMID: 33182769 PMCID: PMC7696170 DOI: 10.3390/v12111286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/02/2020] [Accepted: 11/05/2020] [Indexed: 01/16/2023] Open
Abstract
Bacterial diseases of the edible white button mushroom Agaricus bisporus caused by Pseudomonas species cause a reduction in crop yield, resulting in considerable economic loss. We examined bacterial pathogens of mushrooms and bacteriophages that target them to understand the disease and opportunities for control. The Pseudomonastolaasii genome encoded a single type III protein secretion system (T3SS), but contained the largest number of non-ribosomal peptide synthase (NRPS) genes, multimodular enzymes that can play a role in pathogenicity, including a putative tolaasin-producing gene cluster, a toxin causing blotch disease symptom. However, Pseudomonasagarici encoded the lowest number of NRPS and three putative T3SS while non-pathogenic Pseudomonas sp. NS1 had intermediate numbers. Potential bacteriophage resistance mechanisms were identified in all three strains, but only P. agarici NCPPB 2472 was observed to have a single Type I-F CRISPR/Cas system predicted to be involved in phage resistance. Three novel bacteriophages, NV1, ϕNV3, and NV6, were isolated from environmental samples. Bacteriophage NV1 and ϕNV3 had a narrow host range for specific mushroom pathogens, whereas phage NV6 was able to infect both mushroom pathogens. ϕNV3 and NV6 genomes were almost identical and differentiated within their T7-like tail fiber protein, indicating this is likely the major host specificity determinant. Our findings provide the foundations for future comparative analyses to study mushroom disease and phage resistance.
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Affiliation(s)
- Nathaniel Storey
- School of Biological Sciences, Whiteknights Campus, University of Reading, Reading RG6 6AJ, UK; (N.S.); (R.W.J.); (G.M.)
| | - Mojgan Rabiey
- School of Biological Sciences, Whiteknights Campus, University of Reading, Reading RG6 6AJ, UK; (N.S.); (R.W.J.); (G.M.)
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham B15 2TT, UK
| | - Benjamin W. Neuman
- Biology Department, College of Arts, Sciences and Education, TAMUT, Texarkana, TX 75503, USA;
| | - Robert W. Jackson
- School of Biological Sciences, Whiteknights Campus, University of Reading, Reading RG6 6AJ, UK; (N.S.); (R.W.J.); (G.M.)
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham B15 2TT, UK
| | - Geraldine Mulley
- School of Biological Sciences, Whiteknights Campus, University of Reading, Reading RG6 6AJ, UK; (N.S.); (R.W.J.); (G.M.)
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10
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Stephan MS, Broeker NK, Saragliadis A, Roos N, Linke D, Barbirz S. In vitro Analysis of O-Antigen-Specific Bacteriophage P22 Inactivation by Salmonella Outer Membrane Vesicles. Front Microbiol 2020; 11:510638. [PMID: 33072001 PMCID: PMC7541932 DOI: 10.3389/fmicb.2020.510638] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 08/26/2020] [Indexed: 11/23/2022] Open
Abstract
Bacteriophages use a large number of different bacterial cell envelope structures as receptors for surface attachment. As a consequence, bacterial surfaces represent a major control point for the defense against phage attack. One strategy for phage population control is the production of outer membrane vesicles (OMVs). In Gram-negative host bacteria, O-antigen-specific bacteriophages address lipopolysaccharide (LPS) to initiate infection, thus relying on an essential outer membrane glycan building block as receptor that is constantly present also in OMVs. In this work, we have analyzed interactions of Salmonella (S.) bacteriophage P22 with OMVs. For this, we isolated OMVs that were formed in large amounts during mechanical cell lysis of the P22 S. Typhimurium host. In vitro, these OMVs could efficiently reduce the number of infective phage particles. Fluorescence spectroscopy showed that upon interaction with OMVs, bacteriophage P22 released its DNA into the vesicle lumen. However, only about one third of the phage P22 particles actively ejected their genome. For the larger part, no genome release was observed, albeit the majority of phages in the system had lost infectivity towards their host. With OMVs, P22 ejected its DNA more rapidly and could release more DNA against elevated osmotic pressures compared to DNA release triggered with protein-free LPS aggregates. This emphasizes that OMV composition is a key feature for the regulation of infective bacteriophage particles in the system.
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Affiliation(s)
- Mareike S Stephan
- Physical Biochemistry, Department for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Nina K Broeker
- Physical Biochemistry, Department for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | | | - Norbert Roos
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Stefanie Barbirz
- Physical Biochemistry, Department for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
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11
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The Concerted Action of Two B3-Like Prophage Genes Excludes Superinfecting Bacteriophages by Blocking DNA Entry into Pseudomonas aeruginosa. J Virol 2020; 94:JVI.00953-20. [PMID: 32461312 DOI: 10.1128/jvi.00953-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 05/15/2020] [Indexed: 12/15/2022] Open
Abstract
In this study, we describe seven vegetative phage genomes homologous to the historic phage B3 that infect Pseudomonas aeruginosa Like other phage groups, the B3-like group contains conserved (core) and variable (accessory) open reading frames (ORFs) grouped at fixed regions in their genomes; however, in either case, many ORFs remain without assigned functions. We constructed lysogens of the seven B3-like phages in strain Ps33 of P. aeruginosa, a novel clinical isolate, and assayed the exclusion phenotype against a variety of temperate and virulent superinfecting phages. In addition to the classic exclusion conferred by the phage immunity repressor, the phenotype observed in B3-like lysogens suggested the presence of other exclusion genes. We set out to identify the genes responsible for this exclusion phenotype. Phage Ps56 was chosen as the study subject since it excluded numerous temperate and virulent phages. Restriction of the Ps56 genome, cloning of several fragments, and resection of the fragments that retained the exclusion phenotype allowed us to identify two core ORFs, so far without any assigned function, as responsible for a type of exclusion. Neither gene expressed separately from plasmids showed activity, but the concurrent expression of both ORFs is needed for exclusion. Our data suggest that phage adsorption occurs but that phage genome translocation to the host's cytoplasm is defective. To our knowledge, this is the first report on this type of exclusion mediated by a prophage in P. aeruginosa IMPORTANCE Pseudomonas aeruginosa is a Gram-negative bacterium frequently isolated from infected immunocompromised patients, and the strains are resistant to a broad spectrum of antibiotics. Recently, the use of phages has been proposed as an alternative therapy against multidrug-resistant bacteria. However, this approach may present various hurdles. This work addresses the problem that pathogenic bacteria may be lysogenized by phages carrying genes encoding resistance against secondary infections, such as those used in phage therapy. Discovering phage genes that exclude superinfecting phages not only assigns novel functions to orphan genes in databases but also provides insight into selection of the proper phages for use in phage therapy.
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12
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Nurtay A, Hennessy MG, Alsedà L, Elena SF, Sardanyés J. Host-virus evolutionary dynamics with specialist and generalist infection strategies: Bifurcations, bistability, and chaos. CHAOS (WOODBURY, N.Y.) 2020; 30:053128. [PMID: 32491911 DOI: 10.1063/1.5144875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
In this work, we have investigated the evolutionary dynamics of a generalist pathogen, e.g., a virus population, that evolves toward specialization in an environment with multiple host types. We have particularly explored under which conditions generalist viral strains may rise in frequency and coexist with specialist strains or even dominate the population. By means of a nonlinear mathematical model and bifurcation analysis, we have determined the theoretical conditions for stability of nine identified equilibria and provided biological interpretation in terms of the infection rates for the viral specialist and generalist strains. By means of a stability diagram, we identified stable fixed points and stable periodic orbits, as well as regions of bistability. For arbitrary biologically feasible initial population sizes, the probability of evolving toward stable solutions is obtained for each point of the analyzed parameter space. This probability map shows combinations of infection rates of the generalist and specialist strains that might lead to equal chances for each type becoming the dominant strategy. Furthermore, we have identified infection rates for which the model predicts the onset of chaotic dynamics. Several degenerate Bogdanov-Takens and zero-Hopf bifurcations are detected along with generalized Hopf and zero-Hopf bifurcations. This manuscript provides additional insights into the dynamical complexity of host-pathogen evolution toward different infection strategies.
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Affiliation(s)
- Anel Nurtay
- Centre de Recerca Matemàtica (CRM), Campus de Bellaterra, Edifici C, 08193 Bellaterra, Spain
| | - Matthew G Hennessy
- Centre de Recerca Matemàtica (CRM), Campus de Bellaterra, Edifici C, 08193 Bellaterra, Spain
| | - Lluís Alsedà
- Centre de Recerca Matemàtica (CRM), Campus de Bellaterra, Edifici C, 08193 Bellaterra, Spain
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas (I2SysBio), CSIC-Universitat de València, Parc Científic UV, Paterna 46980 València, Spain
| | - Josep Sardanyés
- Centre de Recerca Matemàtica (CRM), Campus de Bellaterra, Edifici C, 08193 Bellaterra, Spain
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Cryptic-Prophage-Encoded Small Protein DicB Protects Escherichia coli from Phage Infection by Inhibiting Inner Membrane Receptor Proteins. J Bacteriol 2019; 201:JB.00475-19. [PMID: 31527115 PMCID: PMC6832061 DOI: 10.1128/jb.00475-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/12/2019] [Indexed: 02/06/2023] Open
Abstract
Temperate bacteriophages can integrate their genomes into the bacterial host chromosome and exist as prophages whose gene products play key roles in bacterial fitness and interactions with eukaryotic host organisms. Most bacterial chromosomes contain “cryptic” prophages that have lost genes required for production of phage progeny but retain genes of unknown function that may be important for regulating bacterial host physiology. This study provides such an example, where a cryptic-prophage-encoded product can perform multiple roles in the bacterial host and influence processes, including metabolism, cell division, and susceptibility to phage infection. Further functional characterization of cryptic-prophage-encoded functions will shed new light on host-phage interactions and their cellular physiological implications. Bacterial genomes harbor cryptic prophages that have lost genes required for induction, excision from host chromosomes, or production of phage progeny. Escherichia coli K-12 strains contain a cryptic prophage, Qin, that encodes a small RNA, DicF, and a small protein, DicB, that have been implicated in control of bacterial metabolism and cell division. Since DicB and DicF are encoded in the Qin immunity region, we tested whether these gene products could protect the E. coli host from bacteriophage infection. Transient expression of the dicBF operon yielded cells that were ∼100-fold more resistant to infection by λ phage than control cells, and the phenotype was DicB dependent. DicB specifically inhibited infection by λ and other phages that use ManYZ membrane proteins for cytoplasmic entry of phage DNA. In addition to blocking ManYZ-dependent phage infection, DicB also inhibited the canonical sugar transport activity of ManYZ. Previous studies demonstrated that DicB interacts with MinC, an FtsZ polymerization inhibitor, causing MinC localization to midcell and preventing Z ring formation and cell division. In strains producing mutant MinC proteins that do not interact with DicB, both DicB-dependent phenotypes involving ManYZ were lost. These results suggest that DicB is a pleiotropic regulator of bacterial physiology and cell division and that these effects are mediated by a key molecular interaction with the cell division protein MinC. IMPORTANCE Temperate bacteriophages can integrate their genomes into the bacterial host chromosome and exist as prophages whose gene products play key roles in bacterial fitness and interactions with eukaryotic host organisms. Most bacterial chromosomes contain “cryptic” prophages that have lost genes required for production of phage progeny but retain genes of unknown function that may be important for regulating bacterial host physiology. This study provides such an example, where a cryptic-prophage-encoded product can perform multiple roles in the bacterial host and influence processes, including metabolism, cell division, and susceptibility to phage infection. Further functional characterization of cryptic-prophage-encoded functions will shed new light on host-phage interactions and their cellular physiological implications.
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Sousa JAMD, Rocha EPC. Environmental structure drives resistance to phages and antibiotics during phage therapy and to invading lysogens during colonisation. Sci Rep 2019; 9:3149. [PMID: 30816246 PMCID: PMC6395636 DOI: 10.1038/s41598-019-39773-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/07/2019] [Indexed: 01/21/2023] Open
Abstract
Microbial communities are shaped by bacteriophages through predation and lysogeny. A better understanding of the interactions between these processes across different types of environments is key to elucidate how phages mediate microbial competition and to design efficient phage therapies. We introduce an individual-based model (eVIVALDI) to investigate the role of environmental structure in the elimination of a population with a combined treatment of antibiotics and virulent phages, and in the invasion of a population of phage-sensitive bacteria by lysogens. We show that structured environments facilitate the emergence of double resistance, to antibiotics and phages, due to limited diffusion of phage particles and increased nutrient availability from dead cells. They also hinder phage amplification, thus decreasing the generation of phage genetic diversity and increasing the unpredictability of phage-bacteria arms-races. We used a machine learning approach to determine the variables most important for the invasion of sensitive populations by lysogens. They revealed that phage-associated traits and environmental structure are the key drivers of the process. Structured environments hinder invasions, and accounting for their existence improves the fit of the model to published in vivo experimental data. Our results underline environmental structure as key to understand in vivo phage-bacteria interactions.
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Affiliation(s)
| | - Eduardo P C Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, Paris, 75015, France
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15
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Abstract
Mycobacteriophages are viruses that infect mycobacterial hosts. A large number of mycobacteriophages have been isolated and genomically characterized, providing insights into viral diversity and evolution, as well as fueling development of tools for mycobacterial genetics. Mycobacteriophages have intimate relationships with their hosts and provide insights into the genetics and physiology of the mycobacteria and tools for potential clinical applications such as drug development, diagnosis, vaccines, and potentially therapy.
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16
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Wahl A, Battesti A, Ansaldi M. Prophages in Salmonella enterica: a driving force in reshaping the genome and physiology of their bacterial host? Mol Microbiol 2018; 111:303-316. [PMID: 30466179 PMCID: PMC7380047 DOI: 10.1111/mmi.14167] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2018] [Indexed: 12/11/2022]
Abstract
Thanks to the exponentially increasing number of publicly available bacterial genome sequences, one can now estimate the important contribution of integrated viral sequences to the diversity of bacterial genomes. Indeed, temperate bacteriophages are able to stably integrate the genome of their host through site‐specific recombination and transmit vertically to the host siblings. Lysogenic conversion has been long acknowledged to provide additional functions to the host, and particularly to bacterial pathogen genomes where prophages contribute important virulence factors. This review aims particularly at highlighting the current knowledge and questions about lysogeny in Salmonella genomes where functional prophages are abundant, and where genetic interactions between host and prophages are of particular importance for human health considerations.
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Affiliation(s)
- Astrid Wahl
- Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Aurélia Battesti
- Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Mireille Ansaldi
- Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
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Arguijo-Hernández ES, Hernandez-Sanchez J, Briones-Peña SJ, Oviedo N, Mendoza-Hernández G, Guarneros G, Kameyama L. Cor interacts with outer membrane proteins to exclude FhuA-dependent phages. Arch Virol 2018; 163:2959-2969. [PMID: 30043202 DOI: 10.1007/s00705-018-3954-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 05/16/2018] [Indexed: 12/01/2022]
Abstract
Superinfection exclusion (Sie) of FhuA-dependent phages is carried out by Cor in the Escherichia coli mEp167 prophage lysogenic strain. In this work, we present evidence that Cor is an outer membrane (OM) lipoprotein that requires the participation of additional outer membrane proteins (OMPs) to exclude FhuA-dependent phages. Two Cor species of ~13 and ~8.5 kDa, corresponding to the preprolipoprotein/prolipoprotein and lipoprotein, were observed by Western blot. Cell mutants for CorC17F, CorA18D and CorA57E lost the Sie phenotype for FhuA-dependent phages. A copurification affinity binding assay combined with LC_ESI_MS/MS showed that Cor bound to OMPs: OmpA, OmpC, OmpF, OmpW, LamB, and Slp. Interestingly, Sie for FhuA-dependent phages was reduced on Cor overexpressing FhuA+ mutant strains, where ompA, ompC, ompF, ompW, lamB, fhuE, genes were knocked out. The exclusion was restored when these strains were supplemented with plasmids expressing these genes. Sie was not lost in other Cor overexpressing FhuA+ null mutant strains JW3938(btuB-), JW5100(tolB-), JW3474(slp-). These results indicate that Cor interacts and requires some OMPs to exclude FhuA-dependent phages.
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Affiliation(s)
- Emma S Arguijo-Hernández
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 07360, Mexico City (CDMX), México
| | - Javier Hernandez-Sanchez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 07360, Mexico City (CDMX), México
| | - Saida J Briones-Peña
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 07360, Mexico City (CDMX), México
| | - Norma Oviedo
- Unidad de Investigación Médica en Inmunología e Infectología, Centro Médico Nacional la Raza, IMSS, 02990, Mexico City (CDMX), México
| | - Guillermo Mendoza-Hernández
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico City (CDMX), México
| | - Gabriel Guarneros
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 07360, Mexico City (CDMX), México
| | - Luis Kameyama
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 07360, Mexico City (CDMX), México.
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18
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Ko CC, Hatfull GF. Mycobacteriophage Fruitloop gp52 inactivates Wag31 (DivIVA) to prevent heterotypic superinfection. Mol Microbiol 2018; 108:443-460. [PMID: 29488662 DOI: 10.1111/mmi.13946] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2018] [Indexed: 01/04/2023]
Abstract
Bacteriophages engage in complex dynamic interactions with their bacterial hosts and with each other. Bacteria have numerous mechanisms to resist phage infection, and phages must co-evolve by overcoming bacterial resistance or by choosing an alternative host. Phages also compete with each other, both during lysogeny by prophage-mediated defense against viral attack and by superinfection exclusion during lytic replication. Phages are enormously diverse genetically and are replete with small genes of unknown function, many of which are not required for lytic growth, but which may modulate these bacteria-phage and phage-phage dynamics. Using cellular toxicity of phage gene overexpression as an assay, we identified the 93-residue protein gp52 encoded by Cluster F mycobacteriophage Fruitloop. The toxicity of Fruitloop gp52 overexpression results from interaction with and inactivation of Wag31 (DivIVA), an essential Mycobacterium smegmatis protein organizing cell wall biosynthesis at the growing cellular poles. Fruitloop gene 52 is expressed early in lytic growth and is not required for normal Fruitloop lytic replication but interferes with Subcluster B2 phages such as Hedgerow and Rosebush. We conclude that Hedgerow and Rosebush are Wag31-dependent phages and that Fruitloop gp52 confers heterotypic superinfection exclusion by inactivating Wag31.
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Affiliation(s)
- Ching-Chung Ko
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
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Fagen JR, Collias D, Singh AK, Beisel CL. Advancing the design and delivery of CRISPR antimicrobials. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2017. [DOI: 10.1016/j.cobme.2017.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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20
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Gutiérrez-Fernández J, Saleh M, Alcorlo M, Gómez-Mejía A, Pantoja-Uceda D, Treviño MA, Voß F, Abdullah MR, Galán-Bartual S, Seinen J, Sánchez-Murcia PA, Gago F, Bruix M, Hammerschmidt S, Hermoso JA. Modular Architecture and Unique Teichoic Acid Recognition Features of Choline-Binding Protein L (CbpL) Contributing to Pneumococcal Pathogenesis. Sci Rep 2016; 6:38094. [PMID: 27917891 PMCID: PMC5137146 DOI: 10.1038/srep38094] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 11/04/2016] [Indexed: 12/27/2022] Open
Abstract
The human pathogen Streptococcus pneumoniae is decorated with a special class of surface-proteins known as choline-binding proteins (CBPs) attached to phosphorylcholine (PCho) moieties from cell-wall teichoic acids. By a combination of X-ray crystallography, NMR, molecular dynamics techniques and in vivo virulence and phagocytosis studies, we provide structural information of choline-binding protein L (CbpL) and demonstrate its impact on pneumococcal pathogenesis and immune evasion. CbpL is a very elongated three-module protein composed of (i) an Excalibur Ca2+-binding domain -reported in this work for the very first time-, (ii) an unprecedented anchorage module showing alternate disposition of canonical and non-canonical choline-binding sites that allows vine-like binding of fully-PCho-substituted teichoic acids (with two choline moieties per unit), and (iii) a Ltp_Lipoprotein domain. Our structural and infection assays indicate an important role of the whole multimodular protein allowing both to locate CbpL at specific places on the cell wall and to interact with host components in order to facilitate pneumococcal lung infection and transmigration from nasopharynx to the lungs and blood. CbpL implication in both resistance against killing by phagocytes and pneumococcal pathogenesis further postulate this surface-protein as relevant among the pathogenic arsenal of the pneumococcus.
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Affiliation(s)
- Javier Gutiérrez-Fernández
- Department of Crystallography and Structural Biology, "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Malek Saleh
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - Martín Alcorlo
- Department of Crystallography and Structural Biology, "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Alejandro Gómez-Mejía
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - David Pantoja-Uceda
- Department of Biological Physical Chemistry. "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Miguel A Treviño
- Department of Biological Physical Chemistry. "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Franziska Voß
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - Mohammed R Abdullah
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - Sergio Galán-Bartual
- Department of Crystallography and Structural Biology, "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Jolien Seinen
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - Pedro A Sánchez-Murcia
- Department of Biomedical Sciences, Unidad Asociada al IQM-CSIC, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid, Spain
| | - Federico Gago
- Department of Biomedical Sciences, Unidad Asociada al IQM-CSIC, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid, Spain
| | - Marta Bruix
- Department of Biological Physical Chemistry. "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
| | - Sven Hammerschmidt
- Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, D-17487 Greifswald, Germany
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, "Rocasolano" Institute of Physical-Chemistry, CSIC, Serrano 119, E-28006-Madrid, Spain
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Diverse Bacteriophage Roles in an Aphid-Bacterial Defensive Mutualism. ADVANCES IN ENVIRONMENTAL MICROBIOLOGY 2016. [DOI: 10.1007/978-3-319-28068-4_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Cenens W, Makumi A, Govers SK, Lavigne R, Aertsen A. Viral Transmission Dynamics at Single-Cell Resolution Reveal Transiently Immune Subpopulations Caused by a Carrier State Association. PLoS Genet 2015; 11:e1005770. [PMID: 26720743 PMCID: PMC4697819 DOI: 10.1371/journal.pgen.1005770] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/04/2015] [Indexed: 11/19/2022] Open
Abstract
Monitoring the complex transmission dynamics of a bacterial virus (temperate phage P22) throughout a population of its host (Salmonella Typhimurium) at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. More specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered P22 episome. Upon subsequent division, the daughter cell inheriting this episome became lysogenized by an integration event yielding a prophage, while the other daughter cell became P22-free. However, since the phage carrier cell was shown to overproduce immunity factors that are cytoplasmically inherited by the P22-free daughter cell and further passed down to its siblings, a transiently resistant subpopulation was generated that upon dilution of these immunity factors again became susceptible to P22 infection. The iterative emergence and infection of transiently resistant subpopulations suggests a new bet-hedging strategy by which viruses could manage to sustain both vertical and horizontal transmission routes throughout an infected population without compromising a stable co-existence with their host. Extensive co-evolution with their host has shaped bacterial viruses into the most abundant and sophisticated pathogens known to date. However, how these important viral pathogens manage to safely exploit their host without jeopardizing stable co-existence remains a central question, since horizontal (lytic) transmission can reduce the number of susceptible host cells and cause pathogen extinction, while vertical (lysogenic) transmission impairs pathogen abundance. Scrutinizing transmission of temperate phage P22 throughout a bacterial population at single cell resolution now revealed that this phage is able to disseminate immunity factors that allow the emergence of transiently resistant subpopulations of host cells. The continued fostering and consumption of such subpopulations points to an entirely new strategy by which viruses could manage to sustain an active infection with their host.
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Affiliation(s)
- William Cenens
- Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Angela Makumi
- Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Sander K. Govers
- Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Abram Aertsen
- Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
- * E-mail:
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Edwards RA, McNair K, Faust K, Raes J, Dutilh BE. Computational approaches to predict bacteriophage-host relationships. FEMS Microbiol Rev 2015; 40:258-72. [PMID: 26657537 PMCID: PMC5831537 DOI: 10.1093/femsre/fuv048] [Citation(s) in RCA: 274] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2015] [Indexed: 01/21/2023] Open
Abstract
Metagenomics has changed the face of virus discovery by enabling the accurate identification of viral genome sequences without requiring isolation of the viruses. As a result, metagenomic virus discovery leaves the first and most fundamental question about any novel virus unanswered: What host does the virus infect? The diversity of the global virosphere and the volumes of data obtained in metagenomic sequencing projects demand computational tools for virus–host prediction. We focus on bacteriophages (phages, viruses that infect bacteria), the most abundant and diverse group of viruses found in environmental metagenomes. By analyzing 820 phages with annotated hosts, we review and assess the predictive power of in silico phage–host signals. Sequence homology approaches are the most effective at identifying known phage–host pairs. Compositional and abundance-based methods contain significant signal for phage–host classification, providing opportunities for analyzing the unknowns in viral metagenomes. Together, these computational approaches further our knowledge of the interactions between phages and their hosts. Importantly, we find that all reviewed signals significantly link phages to their hosts, illustrating how current knowledge and insights about the interaction mechanisms and ecology of coevolving phages and bacteria can be exploited to predict phage–host relationships, with potential relevance for medical and industrial applications. New viruses infecting bacteria are increasingly being discovered in many environments through sequence-based explorations. To understand their role in microbial ecosystems, computational tools are indispensable to prioritize and guide experimental efforts. This review assesses and discusses a range of bioinformatic approaches to predict bacteriophage–host relationships when all that is known is their genome sequence.
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Affiliation(s)
- Robert A Edwards
- Department of Computer Science, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA Department of Marine Biology, Institute of Biology, Federal University of Rio de Janeiro, CEP 21941-902, Brazil Division of Mathematics and Computer Science, Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439, USA
| | - Katelyn McNair
- Department of Computer Science, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA
| | - Karoline Faust
- Department of Microbiology and Immunology, Rega Institute KU Leuven, Herestraat 49, 3000 Leuven, Belgium VIB Center for the Biology of Disease, VIB, Herestraat 49, 3000 Leuven, Belgium Laboratory of Microbiology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Jeroen Raes
- Department of Microbiology and Immunology, Rega Institute KU Leuven, Herestraat 49, 3000 Leuven, Belgium VIB Center for the Biology of Disease, VIB, Herestraat 49, 3000 Leuven, Belgium Laboratory of Microbiology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Bas E Dutilh
- Department of Marine Biology, Institute of Biology, Federal University of Rio de Janeiro, CEP 21941-902, Brazil Theoretical Biology and Bioinformatics, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Geert Grooteplein 28, 6525 GA, Nijmegen, the Netherlands
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RNA Silencing May Play a Role in but Is Not the Only Determinant of the Multiplicity of Infection. J Virol 2015; 90:553-61. [PMID: 26491166 DOI: 10.1128/jvi.02345-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/15/2015] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED The multiplicity of infection (MOI), i.e., the number of viral genomes that infect a cell, is an important parameter in virus evolution, which for each virus and environment may have an optimum value that maximizes virus fitness. Thus, the MOI might be controlled by virus functions, an underexplored hypothesis in eukaryote-infecting viruses. To analyze if the MOI is controlled by virus functions, we estimated the MOI in plants coinfected by two genetic variants of Tomato bushy stunt virus (TBSV); by TBSV and a TBSV-derived defective interfering RNA (DI-RNA); or by TBSV and a second tombusvirus, Cymbidium ringspot virus (CymRSV). The MOI was significantly larger in TBSV-CymRSV coinfections (~4.0) than in TBSV-TBSV or TBSV-DI-RNA coinfections (~1.7 to 2.2). Coinfections by CymRSV or TBSV with chimeras in which an open reading frame (ORF) of one virus species was replaced by that of the other identified a role of viral proteins in determining the MOI, which ranged from 1.6 to 3.9 depending on the coinfecting genotypes. However, no virus-encoded protein or genomic region was the sole MOI determinant. Coinfections by CymRSV and TBSV mutants in which the expression of the gene-silencing suppressor protein p19 was abolished also showed a possible role of gene silencing in MOI determination. Taken together, these results demonstrate that the MOI is a quantitative trait showing continuous variation and that as such it has a complex determination involving different virus-encoded functions. IMPORTANCE The number of viral genomes infecting a cell, or the multiplicity of infection (MOI), is an important parameter in virus evolution affecting recombination rates, selection intensity on viral genes, evolution of multipartite genomes, or hyperparasitism by satellites or defective interfering particles. For each virus and environment, the MOI may have an optimum value that maximizes virus fitness, but little is known about MOI control in eukaryote-infecting viruses. We show here that in plants coinfected by two genotypes of Tomato bushy stunt virus (TBSV), the MOI was lower than in plants coinfected by TBSV and Cymbidium ringspot virus (CymRSV). Coinfections by CymRSV or TBSV with TBSV-CymRSV chimeras showed a role of viral proteins in MOI determination. Coinfections by CymRSV and TBSV mutants not expressing the gene-silencing suppressor protein also showed a role of gene silencing in MOI determination. The results demonstrate that the MOI is a quantitative trait with a complex determination involving different viral functions.
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Casjens SR, Hendrix RW. Bacteriophage lambda: Early pioneer and still relevant. Virology 2015; 479-480:310-30. [PMID: 25742714 PMCID: PMC4424060 DOI: 10.1016/j.virol.2015.02.010] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/13/2015] [Accepted: 02/05/2015] [Indexed: 12/14/2022]
Abstract
Molecular genetic research on bacteriophage lambda carried out during its golden age from the mid-1950s to mid-1980s was critically important in the attainment of our current understanding of the sophisticated and complex mechanisms by which the expression of genes is controlled, of DNA virus assembly and of the molecular nature of lysogeny. The development of molecular cloning techniques, ironically instigated largely by phage lambda researchers, allowed many phage workers to switch their efforts to other biological systems. Nonetheless, since that time the ongoing study of lambda and its relatives has continued to give important new insights. In this review we give some relevant early history and describe recent developments in understanding the molecular biology of lambda's life cycle.
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Affiliation(s)
- Sherwood R Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Emma Eccles Jones Medical Research Building, 15 North Medical Drive East, Salt Lake City, UT 84112, USA; Biology Department, University of Utah, Salt Lake City, UT 84112, USA.
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Abstract
Prophage-encoded genes can provide a variety of benefits for their bacterial hosts. These beneficial genes are often contained within “moron” elements. Morons, thus termed as the insertion of the DNA encoding them adds “more on” the genome in which they are found, are independent transcriptional units disseminated among phage genomes through horizontal gene transfer. Morons have been identified in the majority of phage genomes and they have been found to play diverse roles in bacterial physiology. At present, we are only beginning to ascribe functions to the many proteins encoded within these ubiquitous genetic elements. Recently, we discovered that the first described moron-encoded protein, gp15 of phage HK97, is expressed from the HK97 prophage and functions as a superinfection exclusion protein, protecting its host from genome injection by other phages. This work and the growing body of data pertaining to other morons challenges the traditional view of phages as purely parasites of bacteria and emphasizes the symbiotic relationship between bacteria and prophages.
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Affiliation(s)
- Nichole Cumby
- Department of Molecular Genetics; University of Toronto; Toronto, ON Canada
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Chaturongakul S, Ounjai P. Phage-host interplay: examples from tailed phages and Gram-negative bacterial pathogens. Front Microbiol 2014; 5:442. [PMID: 25191318 PMCID: PMC4138488 DOI: 10.3389/fmicb.2014.00442] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/04/2014] [Indexed: 01/21/2023] Open
Abstract
Complex interactions between bacteriophages and their bacterial hosts play significant roles in shaping the structure of environmental microbial communities, not only by genetic transduction but also by modification of bacterial gene expression patterns. Survival of phages solely depends on their ability to infect their bacterial hosts, most importantly during phage entry. Successful dynamic adaptation of bacteriophages when facing selective pressures, such as host adaptation and resistance, dictates their abundance and diversification. Co-evolution of the phage tail fibers and bacterial receptors determine bacterial host ranges, mechanisms of phage entry, and other infection parameters. This review summarizes the current knowledge about the physical interactions between tailed bacteriophages and bacterial pathogens (e.g., Salmonella enterica and Pseudomonas aeruginosa) and the influences of the phage on host gene expression. Understanding these interactions can offer insights into phage-host dynamics and suggest novel strategies for the design of bacterial pathogen biological controls.
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Affiliation(s)
- Soraya Chaturongakul
- Department of Microbiology, Faculty of Science, Mahidol University Bangkok, Thailand ; Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University Bangkok, Thailand
| | - Puey Ounjai
- Department of Biology, Faculty of Science, Mahidol University Bangkok, Thailand
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Leavitt JC, Gogokhia L, Gilcrease EB, Bhardwaj A, Cingolani G, Casjens SR. The tip of the tail needle affects the rate of DNA delivery by bacteriophage P22. PLoS One 2013; 8:e70936. [PMID: 23951045 PMCID: PMC3741392 DOI: 10.1371/journal.pone.0070936] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 06/25/2013] [Indexed: 02/01/2023] Open
Abstract
The P22-like bacteriophages have short tails. Their virions bind to their polysaccharide receptors through six trimeric tailspike proteins that surround the tail tip. These short tails also have a trimeric needle protein that extends beyond the tailspikes from the center of the tail tip, in a position that suggests that it should make first contact with the host’s outer membrane during the infection process. The base of the needle serves as a plug that keeps the DNA in the virion, but role of the needle during adsorption and DNA injection is not well understood. Among the P22-like phages are needle types with two completely different C-terminal distal tip domains. In the phage Sf6-type needle, unlike the other P22-type needle, the distal tip folds into a “knob” with a TNF-like fold, similar to the fiber knobs of bacteriophage PRD1 and Adenovirus. The phage HS1 knob is very similar to that of Sf6, and we report here its crystal structure which, like the Sf6 knob, contains three bound L-glutamate molecules. A chimeric P22 phage with a tail needle that contains the HS1 terminal knob efficiently infects the P22 host, Salmonella enterica, suggesting the knob does not confer host specificity. Likewise, mutations that should abrogate the binding of L-glutamate to the needle do not appear to affect virion function, but several different other genetic changes to the tip of the needle slow down potassium release from the host during infection. These findings suggest that the needle plays a role in phage P22 DNA delivery by controlling the kinetics of DNA ejection into the host.
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Affiliation(s)
- Justin C. Leavitt
- Biology Department, University of Utah, Salt Lake City, Utah, United States of America
| | - Lasha Gogokhia
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Eddie B. Gilcrease
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Anshul Bhardwaj
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Sherwood R. Casjens
- Biology Department, University of Utah, Salt Lake City, Utah, United States of America
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
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Bebeacua C, Lorenzo Fajardo JC, Blangy S, Spinelli S, Bollmann S, Neve H, Cambillau C, Heller KJ. X-ray structure of a superinfection exclusion lipoprotein from phage TP-J34 and identification of the tape measure protein as its target. Mol Microbiol 2013; 89:152-65. [PMID: 23692331 DOI: 10.1111/mmi.12267] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2013] [Indexed: 11/29/2022]
Abstract
Lipoproteins of temperate phage are a broad family of membrane proteins encoded in the lysogeny module of temperate phages. Expression of the ltp(TP-J34) gene of temperate Streptococcus thermophilus phage TP-J34 interferes with phage infection at the stage of triggering DNA release and injection into the cell. Here, we report the first structure of a superinfection exclusion protein. We have expressed and determined the X-ray structure of Ltp(TP-J34). The soluble domain of Ltp(TP-J34) is composed of a tandem of three-helix helix-turn-helix (HTH) domains exhibiting a highly negatively charged surface. By isolating mutants of lactococcal phage P008wt with reduced sensitivities to Ltp(TP-J34) and by genome sequencing of such mutants we obtained evidence supporting the notion that Ltp(TP-J34) targets the phage's tape measure protein (TMP) and blocks its insertion into the cytoplasmic membrane.
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Affiliation(s)
- Cecilia Bebeacua
- Architecture et Fonction des Macromolecules Biologiques, UMR 7257, CNRS and Aix-Marseille University, Case 932, 163 Avenue de Luminy, 13288, Marseille, Cedex 09, France
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Differential infection properties of three inducible prophages from an epidemic strain of Pseudomonas aeruginosa. BMC Microbiol 2012; 12:216. [PMID: 22998633 PMCID: PMC3544612 DOI: 10.1186/1471-2180-12-216] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 09/19/2012] [Indexed: 12/16/2022] Open
Abstract
Background Pseudomonas aeruginosa is the most common bacterial pathogen infecting the lungs of patients with cystic fibrosis (CF). The Liverpool Epidemic Strain (LES) is transmissible, capable of superseding other P. aeruginosa populations and is associated with increased morbidity. Previously, multiple inducible prophages have been found to coexist in the LES chromosome and to constitute a major component of the accessory genome not found in other sequenced P. aerugionosa strains. LES phages confer a competitive advantage in a rat model of chronic lung infection and may, therefore underpin LES prevalence. Here the infective properties of three LES phages were characterised. Results This study focuses on three of the five active prophages (LESφ2, LESφ3 and LESφ4) that are members of the Siphoviridae. All were induced from LESB58 by norfloxacin. Lytic production of LESφ2 was considerably higher than that of LESφ3 and LESφ4. Each phage was capable of both lytic and lysogenic infection of the susceptible P. aeruginosa host, PAO1, producing phage-specific plaque morphologies. In the PAO1 host background, the LESφ2 prophage conferred immunity against LESφ3 infection and reduced susceptibility to LESφ4 infection. Each prophage was less stable in the PAO1 chromosome with substantially higher rates of spontaneous phage production than when residing in the native LESB58 host. We show that LES phages are capable of horizontal gene transfer by infecting P. aeruginosa strains from different sources and that type IV pili are required for infection by all three phages. Conclusions Multiple inducible prophages with diverse infection properties have been maintained in the LES genome. Our data suggest that LESφ2 is more sensitive to induction into the lytic cycle or has a more efficient replicative cycle than the other LES phages.
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The bacteriophage HK97 gp15 moron element encodes a novel superinfection exclusion protein. J Bacteriol 2012; 194:5012-9. [PMID: 22797755 DOI: 10.1128/jb.00843-12] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
A phage moron is a DNA element inserted between a pair of genes in one phage genome that are adjacent in other related phage genomes. Phage morons are commonly found within phage genomes, and in a number of cases, they have been shown to mediate phenotypic changes in the bacterial host. The temperate phage HK97 encodes a moron element, gp15, within its tail morphogenesis region that is absent in most closely related phages. We show that gp15 is actively expressed from the HK97 prophage and is responsible for providing the host cell with resistance to infection by phages HK97 and HK75, independent of repressor immunity. To identify the target(s) of this gp15-mediated resistance, we created a hybrid of HK97 and the related phage HK022. This hybrid phage revealed that the tail tube or tape measure proteins likely mediate the susceptibility of HK97 to inhibition by gp15. The N terminus of gp15 is predicted with high probability to contain a single membrane-spanning helix by several transmembrane prediction programs. Consistent with this putative membrane localization, gp15 acts to prevent the entry of phage DNA into the cytoplasm, acting in a manner reminiscent of those of several previously characterized superinfection exclusion proteins. The N terminus of gp15 and its phage homologues bear sequence similarity to YebO proteins, a family of proteins of unknown function found ubiquitously in enterobacteria. The divergence of their C termini suggests that phages have co-opted this bacterial protein and subverted its activity to their advantage.
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Sardanyés J, Elena SF. Quasispecies spatial models for RNA viruses with different replication modes and infection strategies. PLoS One 2011; 6:e24884. [PMID: 21949777 PMCID: PMC3176287 DOI: 10.1371/journal.pone.0024884] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 08/23/2011] [Indexed: 02/04/2023] Open
Abstract
Empirical observations and theoretical studies suggest that viruses may use different replication strategies to amplify their genomes, which impact the dynamics of mutation accumulation in viral populations and therefore, their fitness and virulence. Similarly, during natural infections, viruses replicate and infect cells that are rarely in suspension but spatially organized. Surprisingly, most quasispecies models of virus replication have ignored these two phenomena. In order to study these two viral characteristics, we have developed stochastic cellular automata models that simulate two different modes of replication (geometric vs stamping machine) for quasispecies replicating and spreading on a two-dimensional space. Furthermore, we explored these two replication models considering epistatic fitness landscapes (antagonistic vs synergistic) and different scenarios for cell-to-cell spread, one with free superinfection and another with superinfection inhibition. We found that the master sequences for populations replicating geometrically and with antagonistic fitness effects vanished at low critical mutation rates. By contrast, the highest critical mutation rate was observed for populations replicating geometrically but with a synergistic fitness landscape. Our simulations also showed that for stamping machine replication and antagonistic epistasis, a combination that appears to be common among plant viruses, populations further increased their robustness by inhibiting superinfection. We have also shown that the mode of replication strongly influenced the linkage between viral loci, which rapidly reached linkage equilibrium at increasing mutations for geometric replication. We also found that the strategy that minimized the time required to spread over the whole space was the stamping machine with antagonistic epistasis among mutations. Finally, our simulations revealed that the multiplicity of infection fluctuated but generically increased along time.
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Affiliation(s)
- Josep Sardanyés
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, València, Spain.
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33
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Berngruber TW, Weissing FJ, Gandon S. Inhibition of superinfection and the evolution of viral latency. J Virol 2010; 84:10200-8. [PMID: 20660193 PMCID: PMC2937782 DOI: 10.1128/jvi.00865-10] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/12/2010] [Indexed: 01/21/2023] Open
Abstract
Latent viruses generally defend their host cell against superinfection by nonlatent virulent mutants that could destroy the host cell. Superinfection inhibition thus seems to be a prerequisite for the maintenance of viral latency. Yet viral latency can break down when resistance to superinfection inhibition, known as ultravirulence, occurs. To understand the evolution of viral latency, we have developed a model that analyzes the epidemiology of latent infection in the face of ultravirulence. We show that latency can be maintained when superinfection inhibition and resistance against it coevolve in an arms race, which can result in large fluctuations in virulence. An example is the coevolution of the virulence and superinfection repressor protein of phage lambda (cI) and its binding target, the lambda oLoR operator. We show that this repressor/operator coevolution is the driving force for the evolution of superinfection immunity groups. Beyond latent phages, we predict analogous dynamics for any latent virus that uses a single repressor for the simultaneous control of virulence and superinfection.
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Affiliation(s)
- Thomas W Berngruber
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Route de Mende 1919, Montpellier, France.
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34
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Andres D, Hanke C, Baxa U, Seul A, Barbirz S, Seckler R. Tailspike interactions with lipopolysaccharide effect DNA ejection from phage P22 particles in vitro. J Biol Chem 2010; 285:36768-75. [PMID: 20817910 DOI: 10.1074/jbc.m110.169003] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Initial attachment of bacteriophage P22 to the Salmonella host cell is known to be mediated by interactions between lipopolysaccharide (LPS) and the phage tailspike proteins (TSP), but the events that subsequently lead to DNA injection into the bacterium are unknown. We used the binding of a fluorescent dye and DNA accessibility to DNase and restriction enzymes to analyze DNA ejection from phage particles in vitro. Ejection was specifically triggered by aggregates of purified Salmonella LPS but not by LPS with different O-antigen structure, by lipid A, phospholipids, or soluble O-antigen polysaccharide. This suggests that P22 does not use a secondary receptor at the bacterial outer membrane surface. Using phage particles reconstituted with purified mutant TSP in vitro, we found that the endorhamnosidase activity of TSP degrading the O-antigen polysaccharide was required prior to DNA ejection in vitro and DNA replication in vivo. If, however, LPS was pre-digested with soluble TSP, it was no longer able to trigger DNA ejection, even though it still contained five O-antigen oligosaccharide repeats. Together with known data on the structure of LPS and phage P22, our results suggest a molecular model. In this model, tailspikes position the phage particles on the outer membrane surface for DNA ejection. They force gp26, the central needle and plug protein of the phage tail machine, through the core oligosaccharide layer and into the hydrophobic portion of the outer membrane, leading to refolding of the gp26 lazo-domain, release of the plug, and ejection of DNA and pilot proteins.
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Affiliation(s)
- Dorothee Andres
- Department of Biochemistry and Biology, Laboratory of Physical Biochemistry, University of Potsdam, 14476 Potsdam-Golm, Germany
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González-Jara P, Fraile A, Canto T, García-Arenal F. The multiplicity of infection of a plant virus varies during colonization of its eukaryotic host. J Virol 2009; 83:7487-94. [PMID: 19474097 PMCID: PMC2708614 DOI: 10.1128/jvi.00636-09] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 05/19/2009] [Indexed: 11/20/2022] Open
Abstract
The multiplicity of infection (MOI), i.e., the number of virus genomes that infect a cell, is a key parameter in virus evolution, as it determines processes such as genetic exchange among genomes, selection intensity on viral genes, epistatic interactions, and the evolution of multipartite viruses. In fact, the MOI level is equivalent to the virus ploidy during genome expression. Nevertheless, there are few experimental estimates of MOI, particularly for viruses with eukaryotic hosts. Here we estimate the MOI of Tobacco mosaic virus (TMV) in its systemic host, Nicotiana benthamiana. The progress of infection of two TMV genotypes, differently tagged with the green or red fluorescent proteins GFP and RFP, was monitored by determining the number of leaf cell protoplasts that showed GFP, RFP, or GFP and RFP fluorescence at different times postinoculation. This approach allowed the quantitative analysis of the kinetics of infection and estimation of the generation time and the number of infection cycles required for leaf colonization. MOI levels were estimated from the frequency of cells infected by only TMV-GFP or TMV-RFP. The MOI was high, but it changed during the infection process, decreasing from an initial level of about 6 to a final one of 1 to 2, with most infection cycles occurring at the higher MOI levels. The decreasing MOI can be explained by mechanisms limiting superinfection and/or by genotype competition within double-infected cells, which was shown to occur in coinfected tobacco protoplasts. To our knowledge, this is the first estimate of MOI during virus colonization of a eukaryotic host.
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Affiliation(s)
- Pablo González-Jara
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Campus de Montegancedo, 28223 Pozuelo de Alarcón, Madrid, Spain
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Villafane R, Zayas M, Gilcrease EB, Kropinski AM, Casjens SR. Genomic analysis of bacteriophage epsilon 34 of Salmonella enterica serovar Anatum (15+). BMC Microbiol 2008; 8:227. [PMID: 19091116 PMCID: PMC2629481 DOI: 10.1186/1471-2180-8-227] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 12/17/2008] [Indexed: 12/21/2022] Open
Abstract
Background The presence of prophages has been an important variable in genetic exchange and divergence in most bacteria. This study reports the determination of the genomic sequence of Salmonella phage ε34, a temperate bacteriophage that was important in the early study of prophages that modify their hosts' cell surface and is of a type (P22-like) that is common in Salmonella genomes. Results The sequence shows that ε34 is a mosaically related member of the P22 branch of the lambdoid phages. Its sequence is compared with the known P22-like phages and several related but previously unanalyzed prophage sequences in reported bacterial genome sequences. Conclusion These comparisons indicate that there has been little if any genetic exchange within the procapsid assembly gene cluster with P22-like E. coli/Shigella phages that are have orthologous but divergent genes in this region. Presumably this observation reflects the fact that virion assembly proteins interact intimately and divergent proteins can no longer interact. On the other hand, non-assembly genes in the "ant moron" appear to be in a state of rapid flux, and regulatory genes outside the assembly gene cluster have clearly enjoyed numerous and recent horizontal exchanges with phages outside the P22-like group. The present analysis also shows that ε34 harbors a gtrABC gene cluster which should encode the enzymatic machinery to chemically modify the host O antigen polysaccharide, thus explaining its ability to alter its host's serotype. A comprehensive comparative analysis of the known phage gtrABC gene clusters shows that they are highly mobile, having been exchanged even between phage types, and that most "bacterial" gtrABC genes lie in prophages that vary from being largely intact to highly degraded. Clearly, temperate phages are very major contributors to the O-antigen serotype of their Salmonella hosts.
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Affiliation(s)
- Robert Villafane
- Ponce School of Medicine, Department of Microbiology, Ponce, Puerto Rico 00732, USA
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37
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Abstract
Although a great deal is known about the life cycle of bacteriophage P22, the mechanism of phage DNA transport into Salmonella is poorly understood. P22 DNA is initially ejected into the periplasmic space and subsequently transported into the host cytoplasm. Three phage-encoded proteins (gp16, gp20, and gp7) are coejected with the DNA. To test the hypothesis that one or more of these proteins mediate transport of the DNA across the cytoplasmic membrane, we purified gp16, gp20, and gp7 and analyzed their ability to associate with membranes and to facilitate DNA uptake into membrane vesicles in vitro. Membrane association experiments revealed that gp16 partitioned into the membrane fraction, while gp20 and gp7 remained in the soluble fraction. Moreover, the addition of gp16, but not gp7 or gp20, to liposomes preloaded with a fluorescent dye promoted release of the dye. Transport of (32)P-labeled DNA into liposomes occurred only in the presence of gp16 and an artificially created membrane potential. Taken together, these results suggest that gp16 partitions into the cytoplasmic membrane and mediates the active transport of P22 DNA across the cytoplasmic membrane of Salmonella.
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Roberts F, Allison GE, Verma NK. Transcription-termination-mediated immunity and its prevention in bacteriophage SfV of Shigella flexneri. J Gen Virol 2007; 88:3187-3197. [PMID: 17947546 DOI: 10.1099/vir.0.83062-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The temperate phage SfV encodes the genes responsible for the serotype conversion of Shigella flexneri strains from serotype Y to 5a. Bacteriophages often encode proteins that prevent subsequent infection by homologous phages; the mechanism by which this is accomplished is referred to as superinfection immunity. The serotype conversion mediated following lysogenization of SfV is one such mechanism. Another mechanism is the putative lambda-like CI protein within SfV. This study reports the characterization of a third superinfection mechanism, transcription termination, in SfV. The presence of a small immunity-mediating RNA molecule, called CI RNA, and its essential role in the establishment of immunity, is shown. The novel role of the gene orf77, located immediately downstream from the transcription termination region, in inhibiting the establishment of CI RNA-mediated immunity is also presented.
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Affiliation(s)
- Fleur Roberts
- School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia
| | - Gwen E Allison
- Australian National University Medical School, The Australian National University, Canberra, ACT 0200, Australia.,School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia
| | - Naresh K Verma
- School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia
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Uc-Mass A, Loeza EJ, de la Garza M, Guarneros G, Hernández-Sánchez J, Kameyama L. An orthologue of the cor gene is involved in the exclusion of temperate lambdoid phages. Evidence that Cor inactivates FhuA receptor functions. Virology 2005; 329:425-33. [PMID: 15518820 DOI: 10.1016/j.virol.2004.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2004] [Revised: 08/08/2004] [Accepted: 09/02/2004] [Indexed: 10/26/2022]
Abstract
A new set of lambdoid phages (mEp) classified into different immunity groups was previously described. Phages mEp213, mEp237, and mEp410 were unable to grow in mEp167 lysogenic cells, presumably due to an exclusion mechanism expressed constitutively by the mEp167 repressed prophage. In this work, to analyze the exclusion phenomenon, we constructed a genomic library from mEp167 phage in a pPROEX derivative plasmid. A DNA fragment containing an open reading frame for a 77 amino acid polypeptide was selected by its ability to confer resistance to heteroimmune phage infection. This ORF shows high amino acid sequence identity with putative Cor proteins of phages HK022, phi80 and N15. Cells expressing the mEp167 cor gene from a plasmid (Cor(+) phenotype) excluded 13 of 20 phages from different infection immunity groups. This exclusion was observed in both tonB(-) and tonB(+) cells. Lambdoid mEp phages that were excluded in these cells were unable to infect cells defective in the outer membrane FhuA receptor (fhuA(-)). Thus, Cor-mediated exclusion was only observed in fhuA(+) cells. Phage production after DNA transfection or the spontaneous induction of mEp prophage in Cor(+) cells was not blocked. In addition, ferrichrome uptake, which is mediated by FhuA, was inhibited in Cor(+) cells. Our results show that not only phage infection via FhuA but also a FhuA transport activity (ferrichrome uptake) are inhibited by Cor, presumably by inactivation of FhuA.
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Affiliation(s)
- Augusto Uc-Mass
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México D. F. 07000, México
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40
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Abstract
Bacterial genome nucleotide sequences are being completed at a rapid and increasing rate. Integrated virus genomes (prophages) are common in such genomes. Fifty-one of the 82 such genomes published to date carry prophages, and these contain 230 recognizable putative prophages. Prophages can constitute as much as 10-20% of a bacterium's genome and are major contributors to differences between individuals within species. Many of these prophages appear to be defective and are in a state of mutational decay. Prophages, including defective ones, can contribute important biological properties to their bacterial hosts. Therefore, if we are to comprehend bacterial genomes fully, it is essential that we are able to recognize accurately and understand their prophages from nucleotide sequence analysis. Analysis of the evolution of prophages can shed light on the evolution of both bacteriophages and their hosts. Comparison of the Rac prophages in the sequenced genomes of three Escherichia coli strains and the Pnm prophages in two Neisseria meningitidis strains suggests that some prophages can lie in residence for very long times, perhaps millions of years, and that recombination events have occurred between related prophages that reside at different locations in a bacterium's genome. In addition, many genes in defective prophages remain functional, so a significant portion of the temperate bacteriophage gene pool resides in prophages.
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Affiliation(s)
- Sherwood Casjens
- Department of Pathology, University of Utah Medical School, Salt Lake City, UT 84132-2501, USA.
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41
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Wu H, Sampson L, Parr R, Casjens S. The DNA site utilized by bacteriophage P22 for initiation of DNA packaging. Mol Microbiol 2002; 45:1631-46. [PMID: 12354230 DOI: 10.1046/j.1365-2958.2002.03114.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Virion proteins recognize their cognate nucleic acid for encapsidation into virions through recognition of a specific nucleotide sequence contained within that nucleic acid. Viruses like bacteriophage P22, which have partially circularly permuted, double-stranded virion DNAs, encapsidate DNA through processive series of packaging events in which DNA is recognized for packaging only once at the beginning of the series. Thus a single DNA recognition event programmes the encapsidation of multiple virion chromosomes. The protein product of P22 gene 3, a terminase component, is thought to be responsible for this recognition. The site on the P22 genome that is recognized by the gene 3 protein to initiate packaging series is called the pac site. We report here a strategy for assaying pac site activity in vivo, and the utilization of this system to identify and characterize the site genetically. It is an asymmetric site that spans 22 basepairs and is located near the centre of P22 gene 3.
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Affiliation(s)
- Hongyu Wu
- Department of Pathology, University of Utah Medical Center, Salt Lake City 84132, USA
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42
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Abstract
Bacteriophage with double-stranded, linear DNA genomes package DNA into pre-assembled icosahedral procapsids through a unique vertex. The packaging vertex contains an oligomeric ring of a portal protein that serves as a recognition site for the packaging enzymes, a conduit for DNA translocation, and the site of tail attachment. Previous studies have suggested that the portal protein of bacteriophage P22 is not essential for shell assembly; however, when assembled in the absence of functional portal protein, the assembled heads are not active in vitro packaging assays. In terms of head assembly, this raises an interesting question: how are portal vertices defined during morphogenesis if their incorporation is not a requirement for head assembly? To address this, the P22 portal gene was cloned into an inducible expression vector and transformed into the P22 host Salmonella typhimurium to allow control of the dosage of portal protein during infections. Using pulse-chase radiolabeling, it was determined that the portal protein is recruited into virion during head assembly. Surprisingly, over-expression of the portal protein during wild-type P22 infection caused a dramatic reduction in the yield of infectious virus. The cause of this reduction was traced to two potentially related phenomena. First, excess portal protein caused aberrant head assembly resulting in the formation of T=7 procapsid-like particles (PLPs) with twice the normal amount of portal protein. Second, maturation of the PLPs was blocked during DNA packaging resulting in the accumulation of empty PLPs within the host. In addition to PLPs with normal morphology, smaller heads (apparently T=4) and aberrant spirals were also produced. Interestingly, maturation of the small heads was relatively efficient resulting in the formation of small mature particles that were tailed and contained a head full of DNA. These data suggest that incorporation of portal vertices into heads occurs during growth of the coat lattice at decision points that dictate head assembly fidelity.
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Affiliation(s)
- Sean D Moore
- Department of Microbiology BBRB 416/6, University of Alabama at Birmingham, 845 19th St. South, Birmingham, AL 35294, USA
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43
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McGrath S, Fitzgerald GF, van Sinderen D. Identification and characterization of phage-resistance genes in temperate lactococcal bacteriophages. Mol Microbiol 2002; 43:509-20. [PMID: 11985726 DOI: 10.1046/j.1365-2958.2002.02763.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The sie2009 gene, which is situated between the genes encoding the repressor and integrase, on the lysogeny module of the temperate lactococcal bacteriophage Tuc2009, was shown to mediate a phage-resistance phenotype in Lactococcus lactis against a number of bacteriophages. The Sie2009 protein is associated with the cell membrane and its expression leaves phage adsorption, transfection and plasmid transformation unaffected, but interferes with plasmid transduction, as well as phage replication. These observations indicate that this resistance is as a result of DNA injection blocking, thus representing a novel superinfection exclusion system. A polymerase chain reaction (PCR)-based strategy was used to screen a number of lactococcal strains for the presence of other prophage-encoded phage-resistance systems. This screening resulted in the identification of two such systems, without homology to sie2009, which were shown to mediate a phage-resistance phenotype similar to that conferred by sie2009. To our knowledge, this is the first description of a phage-encoded super-infection exclusion/injection blocking mechanism in the genus Lactococcus.
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Affiliation(s)
- Stephen McGrath
- National Food Biotechnology Centre, University College Cork, Ireland
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44
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RamıÌrez E, Schmidt M, Rinas U, Villaverde A. RecA-dependent viral burst in bacterial colonies during the entry into stationary phase. FEMS Microbiol Lett 1999. [DOI: 10.1111/j.1574-6968.1999.tb13389.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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45
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Garvey P, Hill C, Fitzgerald GF. The Lactococcal Plasmid pNP40 Encodes a Third Bacteriophage Resistance Mechanism, One Which Affects Phage DNA Penetration. Appl Environ Microbiol 1996; 62:676-9. [PMID: 16535245 PMCID: PMC1388783 DOI: 10.1128/aem.62.2.676-679.1996] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lactococcal plasmid pNP40 mediates insensitivity to (phi)c2 by an early-acting phage resistance mechanism in addition to the previously identified abortive infection system, AbiF, in the Lactococcus lactis subsp. lactis MG1614 background. A second abortive infection determinant on pNP40, AbiE, does not confer resistance to (phi)c2. The early-acting mechanism on pNP40 does not prevent phage adsorption nor does it appear to operate by restriction/modification. Phage DNA was not detected in pNP40-containing cells until 30 min following exposure to (phi)c2 compared with 5 min in a sensitive host; however, electroporation of phage DNA into resistant hosts resulted in the release of phage progeny from a dramatically elevated number of cells compared with conventionally infected hosts. It appears therefore that pNP40 encodes a novel phage resistance mechanism which blocks DNA penetration specifically for (phi)c2.
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46
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Hofer B, Ruge M, Dreiseikelmann B. The superinfection exclusion gene (sieA) of bacteriophage P22: identification and overexpression of the gene and localization of the gene product. J Bacteriol 1995; 177:3080-6. [PMID: 7768804 PMCID: PMC176996 DOI: 10.1128/jb.177.11.3080-3086.1995] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Previous work has shown that the sieA gene of Salmonella bacteriophage P22 is located between the genes mnt and 16. We cloned DNA fragments of the region into multicopy vectors and tested the transformants for mediating superinfection exclusion. Subcloning, phenotypical tests, and DNA sequencing resulted in the identification of the sieA gene. There are two possible initiation codons within one open reading frame of 492 or 480 bp. The deduced amino acid sequence leads to a hypothetical polypeptide with a calculated molecular mass of 18.8 or 18.3 kDa, respectively. According to three hydrophobic regions, all of which are long enough to span the membrane, the product of sieA should be a protein of the inner membrane of a P22-lysogenic cell of Salmonella typhimurium. The SieA protein was moderately overproduced from an expression vector in cultures of Escherichia coli and could be recovered from the membrane fraction.
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Affiliation(s)
- B Hofer
- Universität Bielefeld, Fakultät für Biologie, Lehrstuhl für Mikrobiologie/Gentechnologie, Germany
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47
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Decker K, Krauel V, Meesmann A, Heller KJ. Lytic conversion of Escherichia coli by bacteriophage T5: blocking of the FhuA receptor protein by a lipoprotein expressed early during infection. Mol Microbiol 1994; 12:321-32. [PMID: 8057856 DOI: 10.1111/j.1365-2958.1994.tb01020.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The nucleotide sequence of the region between the oad gene, encoding the host specificity protein, and the right-terminal repetition of bacteriophage T5 DNA was determined. Five small open reading frames, the first of which was called llp, were detected, which apparently formed an operon transcribed from a promoter that overlapped the oad promoter. Both promoters were confirmed by primer extension assays. Using mRNA isolated at different times after T5 infection, the llp and oad promoters were identified as early and late promoters, respectively. The N-terminus of the llp gene product possess a signal sequence and a processing site characteristic of lipoproteins. After subcloning and expression of llp, its product Llp was identified as a 7.8 kDa polypeptide. Acylation of Llp was confirmed by addition of globomycin, which resulted in the accumulation of the unprocessed precursor form. FhuA+ cells synthesizing Llp were resistant to phage T5. Resistance was caused by inhibition of adsorption of T5 to its FhuA receptor protein. Resistance could be overcome by derepression of fhuA transcription, suggesting a blocking of FhuA by direct interaction with Llp. Since Llp-mediated T5 resistance has several aspects in common with the phenomenon of lysogenic conversion, we suggest that it should be called lytic conversion.
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Affiliation(s)
- K Decker
- University of Constance, Faculty of Biology, Germany
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48
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Abstract
The superinfection exclusion gene (sieB) of Salmonella phage P22 was mapped with phage deletion mutants. The DNA sequence in the region was reexamined in order to find an open reading frame consistent with the deletion mapping. Several discrepancies with the previously published sequence were discovered. The revised sequence revealed a single open reading frame of 242 codons with six likely translation initiation codons. On the basis of deletion and amber mutant phenotypes, the second of these six sites was inferred to be the translation initiation site of the sieB gene. The sieB gene encodes a polypeptide with 192 amino acid residues with a calculated molecular weight of 22,442, which is in reasonable agreement with that estimated from polyacrylamide gels. The transcription start site of sieB was identified by the use of an RNase protection assay. The sieB promoter thus identified was inactivated by a 2-base substitution in its -10 hexamer. The sieB gene of coliphage lambda was also identified. The promoter for lambda sieB was identified by homology to that of P22 sieB.
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Affiliation(s)
- K Ranade
- Department of Molecular Genetics and Microbiology, University of Massachusetts, Worcester 01655
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49
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Eppler K, Wyckoff E, Goates J, Parr R, Casjens S. Nucleotide sequence of the bacteriophage P22 genes required for DNA packaging. Virology 1991; 183:519-38. [PMID: 1853558 DOI: 10.1016/0042-6822(91)90981-g] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The mechanism of DNA packaging by dsDNA viruses is not well understood in any system. In bacteriophage P22 only five genes are required for successful condensation of DNA within the capsid. The products of three of these genes, the portal, scaffolding, and coat proteins, are structural components of the precursor particle, and two, the products of genes 2 and 3, are not. The scaffolding protein is lost from the structure during packaging, and only the portal and coat proteins are present in the mature virus particle. These five genes map in a contiguous cluster at the left end of the P22 genetic map. Three additional genes, 4, 10, and 26, are required for stabilizing of the condensed DNA within the capsid. In this report we present the nucleotide sequence of 7461 bp of P22 DNA that contains the five genes required for DNA condensation, as well as a nonessential open reading frame (ORF109), gene 4, and a portion of gene 10. N-terminal amino acid sequencing of the encoded proteins accurately located the translation starts of six genes in the sequence. Despite the fact that most of these proteins have striking analogs in the other dsDNA bacteriophage groups, which perform highly analogous functions, no amino acid sequence similarity between these analogous proteins has been found, indicating either that they diverged a very long time ago or that they are the products of spectacular convergent evolution.
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Affiliation(s)
- K Eppler
- Department of Cellular, Viral, and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132
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50
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Xu SY, Feiss M. The last duplex base-pair of the phage lambda chromosome. Involvement in packaging, ejection and routing of lambda DNA. J Mol Biol 1991; 220:293-306. [PMID: 1830344 DOI: 10.1016/0022-2836(91)90014-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
cosN is the site at which the bacteriophage lambda DNA packaging enzyme, terminase, introduces staggered nicks to generate the cohesive ends of mature lambda chromosomes. Genetic and molecular studies show that cosN is recognized specifically by terminase and that effects of cosN mutations on lambda DNA packaging and cosN cleavage are well correlated. Mutations affecting a particular base-pair of cosN are unusual in being lethal in spite of causing only a moderate defect in cosN cleavage and DNA packaging. The particular base-pair is the rightmost duplex base-pair in mature chromosomes, at position 48,502 in the numbering system of Daniels et al; herein called position - 1. A G.C to T.A transversion mutation at position - 1, called cosN - 1T, reduces the particle yield of lambda fivefold, and the particles formed are not infectious. lambda cosN - 1T particles have wild-type morphology, and contain chromosomes that have normal cohesive ends. The chromosomes of lambda cosN - 1T particles, like the chromosomes of lambda + particles, are associated with the tail. lambda cosN - 1T particles, in spite of being normal structurally, are defective in injection of DNA into a host cell. Only approximately 25% of lambda cosN - 1T particles are able to eject DNA from the capsid in contrast to 100% for lambda +. Furthermore, for the 25% that do eject, there is a further injection defect because the ejected lambda cosN - 1T chromosomes fail to cyclize, in contrast to the efficient cyclization found for wild-type chromosomes following injection. The cosN - 1T mutation has no effect on Ca2+ mediated transformation by lambda DNA, indicating that the effect of the mutation on DNA fate is specific to the process of DNA injection. Models in which specific DNA : protein interactions necessary for DNA injection, and involving the rightmost base-pair of the lambda chromosome, are considered.
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Affiliation(s)
- S Y Xu
- Department of Microbiology, University of Iowa, Iowa City 52242
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