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Borodovich T, Shkoporov AN, Ross RP, Hill C. OUP accepted manuscript. Gastroenterol Rep (Oxf) 2022; 10:goac012. [PMID: 35425613 PMCID: PMC9006064 DOI: 10.1093/gastro/goac012] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 02/08/2022] [Accepted: 03/04/2022] [Indexed: 11/26/2022] Open
Abstract
Horizontal gene transfer (HGT) in the microbiome has profound consequences for human health and disease. The spread of antibiotic resistance genes, virulence, and pathogenicity determinants predominantly occurs by way of HGT. Evidence exists of extensive horizontal transfer in the human gut microbiome. Phage transduction is a type of HGT event in which a bacteriophage transfers non-viral DNA from one bacterial host cell to another. The abundance of tailed bacteriophages in the human gut suggests that transduction could act as a significant mode of HGT in the gut microbiome. Here we review in detail the known mechanisms of phage-mediated HGT, namely specialized and generalized transduction, lateral transduction, gene-transfer agents, and molecular piracy, as well as methods used to detect phage-mediated HGT, and discuss its potential implications for the human gut microbiome.
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Affiliation(s)
- Tatiana Borodovich
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Corresponding author. APC Microbiome Ireland, Biosciences Institute, University College Cork, Room 3.63, College Road, Cork, T12 YT20, Ireland.
| | - Andrey N Shkoporov
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - R Paul Ross
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Colin Hill
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
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2
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Bacillus pumilus 15.1, a Strain Active against Ceratitis capitata, Contains a Novel Phage and a Phage-Related Particle with Bacteriocin Activity. Int J Mol Sci 2021; 22:ijms22158164. [PMID: 34360927 PMCID: PMC8347963 DOI: 10.3390/ijms22158164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
A 98.1 Kb genomic region from B. pumilus 15.1, a strain isolated as an entomopathogen toward C. capitata, the Mediterranean fruit fly, has been characterised in search of potential virulence factors. The 98.1 Kb region shows a high number of phage-related protein-coding ORFs. Two regions with different phylogenetic origins, one with 28.7 Kb in size, highly conserved in Bacillus strains, and one with 60.2 Kb in size, scarcely found in Bacillus genomes are differentiated. The content of each region is thoroughly characterised using comparative studies. This study demonstrates that these two regions are responsible for the production, after mitomycin induction, of a phage-like particle that packages DNA from the host bacterium and a novel phage for B. pumilus, respectively. Both the phage-like particles and the novel phage are observed and characterised by TEM, and some of their structural proteins are identified by protein fingerprinting. In addition, it is found that the phage-like particle shows bacteriocin activity toward other B. pumilus strains. The effect of the phage-like particles and the phage in the toxicity of the strain toward C. capitata is also evaluated.
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3
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Kuchina A, Brettner LM, Paleologu L, Roco CM, Rosenberg AB, Carignano A, Kibler R, Hirano M, DePaolo RW, Seelig G. Microbial single-cell RNA sequencing by split-pool barcoding. Science 2020; 371:science.aba5257. [PMID: 33335020 DOI: 10.1126/science.aba5257] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/08/2020] [Indexed: 12/16/2022]
Abstract
Single-cell RNA sequencing (scRNA-seq) has become an essential tool for characterizing gene expression in eukaryotes, but current methods are incompatible with bacteria. Here, we introduce microSPLiT (microbial split-pool ligation transcriptomics), a high-throughput scRNA-seq method for Gram-negative and Gram-positive bacteria that can resolve heterogeneous transcriptional states. We applied microSPLiT to >25,000 Bacillus subtilis cells sampled at different growth stages, creating an atlas of changes in metabolism and lifestyle. We retrieved detailed gene expression profiles associated with known, but rare, states such as competence and prophage induction and also identified unexpected gene expression states, including the heterogeneous activation of a niche metabolic pathway in a subpopulation of cells. MicroSPLiT paves the way to high-throughput analysis of gene expression in bacterial communities that are otherwise not amenable to single-cell analysis, such as natural microbiota.
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Affiliation(s)
- Anna Kuchina
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Leandra M Brettner
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA
| | - Luana Paleologu
- Department of Microbiology, University of Washington, Seattle, WA, USA.,Department of Biology, University of Washington, Seattle, WA, USA
| | - Charles M Roco
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Alexander B Rosenberg
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Alberto Carignano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Ryan Kibler
- Biological Physics, Structure, and Design, University of Washington, Seattle, WA, USA
| | - Matthew Hirano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - R William DePaolo
- Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Gastroenterology, School of Medicine, University of Washington, Seattle, WA, USA
| | - Georg Seelig
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA. .,Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.,Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA
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4
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Kleiner M, Bushnell B, Sanderson KE, Hooper LV, Duerkop BA. Transductomics: sequencing-based detection and analysis of transduced DNA in pure cultures and microbial communities. MICROBIOME 2020; 8:158. [PMID: 33190645 PMCID: PMC7667829 DOI: 10.1186/s40168-020-00935-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/08/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Horizontal gene transfer (HGT) plays a central role in microbial evolution. Our understanding of the mechanisms, frequency, and taxonomic range of HGT in polymicrobial environments is limited, as we currently rely on historical HGT events inferred from genome sequencing and studies involving cultured microorganisms. We lack approaches to observe ongoing HGT in microbial communities. RESULTS To address this knowledge gap, we developed a DNA sequencing-based "transductomics" approach that detects and characterizes microbial DNA transferred via transduction. We validated our approach using model systems representing a range of transduction modes and show that we can detect numerous classes of transducing DNA. Additionally, we show that we can use this methodology to obtain insights into DNA transduction among all major taxonomic groups of the intestinal microbiome. CONCLUSIONS The transductomics approach that we present here allows for the detection and characterization of genes that are potentially transferred between microbes in complex microbial communities at the time of measurement and thus provides insights into real-time ongoing horizontal gene transfer. This work extends the genomic toolkit for the broader study of mobile DNA within microbial communities and could be used to understand how phenotypes spread within microbiomes. Video Abstract.
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Affiliation(s)
- Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA.
| | - Brian Bushnell
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA
| | - Kenneth E Sanderson
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Lora V Hooper
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Breck A Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA.
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5
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Hryckowian AJ, Merrill BD, Porter NT, Van Treuren W, Nelson EJ, Garlena RA, Russell DA, Martens EC, Sonnenburg JL. Bacteroides thetaiotaomicron-Infecting Bacteriophage Isolates Inform Sequence-Based Host Range Predictions. Cell Host Microbe 2020; 28:371-379.e5. [PMID: 32652063 PMCID: PMC8045012 DOI: 10.1016/j.chom.2020.06.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/22/2020] [Accepted: 06/12/2020] [Indexed: 12/21/2022]
Abstract
Our emerging view of the gut microbiome largely focuses on bacteria, while less is known about other microbial components, such as bacteriophages (phages). Though phages are abundant in the gut, very few phages have been isolated from this ecosystem. Here, we report the genomes of 27 phages from the United States and Bangladesh that infect the prevalent human gut bacterium Bacteroides thetaiotaomicron. These phages are mostly distinct from previously sequenced phages with the exception of two, which are crAss-like phages. We compare these isolates to existing human gut metagenomes, revealing similarities to previously inferred phages and additional unexplored phage diversity. Finally, we use host tropisms of these phages to identify alleles of phage structural genes associated with infectivity. This work provides a detailed view of the gut's "viral dark matter" and a framework for future efforts to further integrate isolation- and sequencing-focused efforts to understand gut-resident phages.
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Affiliation(s)
- Andrew J Hryckowian
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Bryan D Merrill
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nathan T Porter
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - William Van Treuren
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Eric J Nelson
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA
| | - Rebecca A Garlena
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Daniel A Russell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Eric C Martens
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Justin L Sonnenburg
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Beyond the canonical strategies of horizontal gene transfer in prokaryotes. Curr Opin Microbiol 2017; 38:95-105. [PMID: 28600959 DOI: 10.1016/j.mib.2017.04.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/24/2017] [Accepted: 04/26/2017] [Indexed: 01/16/2023]
Abstract
Efforts to identify and characterize strategies for horizontal gene transfer (HGT) in prokaryotes could have overlooked some mechanisms that do not entirely fit in with the canonical ones most often described (conjugation of plasmids, phage transduction and transformation). The difficulty in distinguishing the different HGT strategies could have contributed to underestimate their real extent. Here we review non classical HGT strategies: some that require mobile genetic elements (MGEs) and others independent of MGE. Among those strategies that require MGEs, there is a range of newly reported, hybrid and intermediate MGEs mobilizing only their own DNA, others that mobilize preferentially bacterial DNA, or both. Considering HGT strategies independent of MGE, a few are even not restricted to DNA transfer, but can also mobilize other molecules. This review considers those HGT strategies that are less commonly dealt with in the literature. The real impact of these elements could, in some conditions, be more relevant than previously thought.
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Biological and genomic analysis of a PBSX-like defective phage induced from Bacillus pumilus AB94180. Arch Virol 2013; 159:739-52. [PMID: 24154951 DOI: 10.1007/s00705-013-1898-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
Defective prophages, which are found in the genomes of many bacteria, are unable to complete a viral replication cycle and propagate in their hosts as healthy prophages. They package random DNA fragments derived from various sites of the host chromosome instead of their own genomes. In this study, we characterized a defective phage, PBP180, which was induced from Bacillus pumilus AB94180 by treatment with mitomycin C. Electron microscopy showed that the PBP180 particle has a head with a hexagonal outline of ~40 nm in diameter and a long tail. The DNA packaged in the PBP180 head consists of 8-kb DNA fragments from random portions of the host chromosome. The head and tail proteins of the PBP180 particle consist of four major proteins of approximately 49, 33, 16 and 14 kDa. The protein profile of PBP180 is different from that of PBSX, a well-known defective phage induced from Bacillus subtilis 168. A killing activity test against two susceptible strains each of B. subtilis and B. pumilus showed that the defective particles of PBP180 killed three strains other than its own host, B. pumilus AB94180, differing from the host-killing ranges of the defective phages PBSX, PBSZ (induced from B. subtilis W23), and PBSX4 (induced from B. pumilus AB94044). The genome of the PBP180 prophage, which is integrated in the B. pumilus AB94180 chromosome, is 28,205 bp in length, with 40 predicted open reading frames (ORFs). Further genomic comparison of prophages PBP180, PBSX, PBSZ and other PBSX-like prophage elements in B. pumilus strains revealed that their overall architectures are similar, but significant low homology exists in ORF29-ORF38, which presumably encode tail fiber proteins involved in recognition and killing of susceptible strains.
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8
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Lysogeny and sporulation in Bacillus isolates from the Gulf of Mexico. Appl Environ Microbiol 2009; 76:829-42. [PMID: 20008174 DOI: 10.1128/aem.01710-09] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Eleven Bacillus isolates from the surface and subsurface waters of the Gulf of Mexico were examined for their capacity to sporulate and harbor prophages. Occurrence of sporulation in each isolate was assessed through decoyinine induction, and putative lysogens were identified by prophage induction by mitomycin C treatment. No obvious correlation between ability to sporulate and prophage induction was found. Four strains that contained inducible virus-like particles (VLPs) were shown to sporulate. Four strains did not produce spores upon induction by decoyinine but contained inducible VLPs. Two of the strains did not produce virus-like particles or sporulate significantly upon induction. Isolate B14905 had a high level of virus-like particle production and a high occurrence of sporulation and was further examined by genomic sequencing in an attempt to shed light on the relationship between sporulation and lysogeny. In silico analysis of the B14905 genome revealed four prophage-like regions, one of which was independently sequenced from a mitomycin C-induced lysate. Based on PCR and transmission electron microscopy (TEM) analysis of an induced phage lysate, one is a noninducible phage remnant, one may be a defective phage-like bacteriocin, and two were inducible prophages. One of the inducible phages contained four putative transcriptional regulators, one of which was a SinR-like regulator that may be involved in the regulation of host sporulation. Isolates that both possess the capacity to sporulate and contain temperate phage may be well adapted for survival in the oligotrophic ocean.
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9
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Berglund EC, Frank AC, Calteau A, Vinnere Pettersson O, Granberg F, Eriksson AS, Näslund K, Holmberg M, Lindroos H, Andersson SGE. Run-off replication of host-adaptability genes is associated with gene transfer agents in the genome of mouse-infecting Bartonella grahamii. PLoS Genet 2009; 5:e1000546. [PMID: 19578403 PMCID: PMC2697382 DOI: 10.1371/journal.pgen.1000546] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 06/01/2009] [Indexed: 11/20/2022] Open
Abstract
The genus Bartonella comprises facultative intracellular bacteria adapted to mammals, including previously recognized and emerging human pathogens. We report the 2,341,328 bp genome sequence of Bartonella grahamii, one of the most prevalent Bartonella species in wild rodents. Comparative genomics revealed that rodent-associated Bartonella species have higher copy numbers of genes for putative host-adaptability factors than the related human-specific pathogens. Many of these gene clusters are located in a highly dynamic region of 461 kb. Using hybridization to a microarray designed for the B. grahamii genome, we observed a massive, putatively phage-derived run-off replication of this region. We also identified a novel gene transfer agent, which packages the bacterial genome, with an over-representation of the amplified DNA, in 14 kb pieces. This is the first observation associating the products of run-off replication with a gene transfer agent. Because of the high concentration of gene clusters for host-adaptation proteins in the amplified region, and since the genes encoding the gene transfer agent and the phage origin are well conserved in Bartonella, we hypothesize that these systems are driven by selection. We propose that the coupling of run-off replication with gene transfer agents promotes diversification and rapid spread of host-adaptability factors, facilitating host shifts in Bartonella. Emerging infectious diseases represent an increasing human health problem with many examples of disease outbreaks caused by transmissions from animals to humans, such as, most recently, the bird flu virus. Genes involved in virulence and antibiotic resistance are often carried by mobile elements like plasmids and viruses, which mediate transfer between cells at an amazing speed. Rodents represent a major carrier of infectious agents, and it is therefore particularly important to study the gene transfer processes in bacteria that use rodents as their natural host reservoir. We have studied the genome of a bacterium that is naturally adapted to mice and identified many more putative host-interaction genes than were observed in previously recognized human pathogens. Furthermore, most of these genes are located in a segment of about 25% of the genome, which was massively amplified and packaged into viral particles. This is the first demonstration of targeted packaging of a portion of the bacterial chromosome into viral particles, and we propose that this is a novel strategy for increased exchange of genes involved in the infectious process.
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Affiliation(s)
- Eva C. Berglund
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - A. Carolin Frank
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Alexandra Calteau
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Olga Vinnere Pettersson
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Fredrik Granberg
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Ann-Sofie Eriksson
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Kristina Näslund
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Martin Holmberg
- Department of Medical Sciences, Section for Infectious Diseases, Uppsala University Hospital, Uppsala, Sweden
| | - Hillevi Lindroos
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Siv G. E. Andersson
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- * E-mail:
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10
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Williamson KE, Schnitker JB, Radosevich M, Smith DW, Wommack KE. Cultivation-based assessment of lysogeny among soil bacteria. MICROBIAL ECOLOGY 2008; 56:437-447. [PMID: 18322729 DOI: 10.1007/s00248-008-9362-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2007] [Revised: 11/21/2007] [Accepted: 01/07/2008] [Indexed: 05/26/2023]
Abstract
Lysogeny has long been proposed as an important long-term maintenance strategy for autochthonous soil bacteriophages (phages). Whole genome sequence data indicate that prophage-derived sequences pervade prokaryotic genomes, but the connection between inferred prophage sequence and an active temperate phage is tenuous. Thus, definitive evidence of phage production from lysogenic prokaryotes will be critical in determining the presence and extent of temperate phage diversity existing as prophage within bacterial genomes and within environmental contexts such as soils. This study optimized methods for systematic and definitive determination of lysogeny within a collection of autochthonous soil bacteria. Twenty bacterial isolates from a range of Delaware soil environments (five from each soil) were treated with the inducing agents mitomycin C (MC) or UV light. Six isolates (30%) carried inducible temperate phages as evidenced by an increase in virus direct counts. The magnitude of induction response was highly dependent upon specific induction conditions, and corresponding burst sizes ranged from 1 to 176. Treatment with MC for 30 min yielded the largest induction responses for three of the six lysogens. Morphological analysis revealed that four of the lysogens produced lambda-like Siphoviridae particles, whereas two produced Myoviridae particles. Additionally, pulsed-field gel electrophoresis data indicated that two of the six lysogens were polylysogens, producing more than one distinct type of phage particle. These results suggest that lysogeny is relatively common among soil bacteria.
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Affiliation(s)
- Kurt E Williamson
- Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA 92037, USA
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11
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Paul JH. Prophages in marine bacteria: dangerous molecular time bombs or the key to survival in the seas? ISME JOURNAL 2008; 2:579-89. [PMID: 18521076 DOI: 10.1038/ismej.2008.35] [Citation(s) in RCA: 265] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacteriophages are realized to be numerous and important components of oceanic food webs principally because of their lytic capabilities. The subtle changes that temperate phages impart to their hosts in the oceans are far less understood. Occurrences of lysogeny in the oceans correlate well with conditions unfavorable for rapid host growth. In coliphage lambda, phage encoded repressors have been shown to modulate host metabolic gene expression and phenotype, resulting in economizing host energy expenditure. Comparison of lysogenized marine bacteria to the uninfected hosts indicated that prophage acquisition is correlated with host metabolic gene suppression. Screening 113 marine bacterial genomes for prophages yielded 64 prophage-like elements, 21 of which strongly resembled gene transfer agents (GTAs). The remaining 39 putative prophages had a relatively high incidence of transcriptional regulatory and repressor-like proteins (approximately 2/40 kb prophage sequence) compared to lytic marine phages (approximately 0.25/40 kb phage sequence). Here, it has been hypothesized that marine prophages directly contribute to host survival in unfavorable environments by suppression of unneeded metabolic activities. It has been further suggested that such metabolic downshifts are the result of phage-encoded repressors and transcriptional regulators acting directly on host genes. Finally, the widespread occurrence of GTAs may be an efficient mechanism for horizontal gene transfer in the oceans.
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Affiliation(s)
- John H Paul
- College of Marine Science, University of South Florida, St Petersburg, FL 33701, USA.
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12
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Stanton TB. Prophage-like gene transfer agents-novel mechanisms of gene exchange for Methanococcus, Desulfovibrio, Brachyspira, and Rhodobacter species. Anaerobe 2007; 13:43-9. [PMID: 17513139 DOI: 10.1016/j.anaerobe.2007.03.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 03/04/2007] [Indexed: 11/29/2022]
Abstract
Gene transfer agents (GTAs) are novel mechanisms for bacterial gene transfer. They resemble small, tailed bacteriophages in ultrastructure and act like generalized transducing prophages. In contrast to functional prophages, GTAs package random fragments of bacterial genomes and incomplete copies of their own genomes. The packaged DNA content is characteristic of the GTA and ranges in size from 4.4 to 13.6kb. GTAs have been reported in species of Brachyspira, Methanococcus, Desulfovibrio, and Rhodobacter. The best studied GTAs are VSH-1 of the anaerobic, pathogenic spirochete Brachyspira hyodysenteriae and RcGTA of the nonsulfur, purple, photosynthetic bacterium Rhodobacter capsulatus. VSH-1 and RcGTA have likely contributed to the ecology and evolution of these bacteria. The existence of GTAs in phylogenetically diverse bacteria suggests GTAs may be more common in nature than is now appreciated.
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Affiliation(s)
- Thad B Stanton
- Enteric Diseases and Food Safety Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, 2300 Dayton Road, Ames, IA 50010, USA.
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13
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Shingaki R, Kasahara Y, Inoue T, Kokeguchi S, Fukui K. Chromosome DNA fragmentation and excretion caused by defective prophage gene expression in the early-exponential-phase culture of Bacillus subtilis. Can J Microbiol 2003; 49:313-25. [PMID: 12897825 DOI: 10.1139/w03-041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacillus subtilis 168 and its major autolysin mutant, AN8, were shown to excrete two size classes of DNA when cultured in Luria-Bertani medium. Pulsed-field gel electrophoresis of DNA harvested from the cell surface demonstrated the presence of 13-kb-long and circa 50-kb-long strands. Restriction digestion of both sizes of DNA resulted in a smearing pattern, as observed by agarose gel electrophoresis. Shotgun sequencing of DNase I partial digests of 50-kb DNA fragments revealed that the strands originate from various sites on the chromosome. SDS-PAGE analysis of cell surface fractions and culture supernatants demonstrated the presence of several proteins that were thought to be associated with the DNA. Of these, three major proteins were identified, i.e., XkdG, XkdK, and XkdM, by tandem mass spectrometry, all of which were proteins of a defective prophage PBSX residing in the Bacillus subtilis chromosome. Disruption of these PBSX genes resulted in a reduction of 13-kb fragment generation and excretion and also a great reduction of 50-kb fragment excretion. Electron microscopy showed that a few mature phages and numerous membrane vesicle-like particles existed in the cell surface fractions of strain 168. The present findings suggest that the spontaneous generation and excretion of chromosome DNA fragments in Bacillus subtilis are both closely related to the expression of defective prophage genes.
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Affiliation(s)
- Ryuji Shingaki
- Department of Oral Microbiology, Okayama University Graduate School of Medicine and Dentistry, Shikata-cho, Okayama 700-8525, Japan.
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14
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Bertani G. Transduction-like gene transfer in the methanogen Methanococcus voltae. J Bacteriol 1999; 181:2992-3002. [PMID: 10321998 PMCID: PMC93752 DOI: 10.1128/jb.181.10.2992-3002.1999] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/1998] [Accepted: 03/01/1999] [Indexed: 11/20/2022] Open
Abstract
Strain PS of Methanococcus voltae (a methanogenic, anaerobic archaebacterium) was shown to generate spontaneously 4.4-kbp chromosomal DNA fragments that are fully protected from DNase and that, upon contact with a cell, transform it genetically. This activity, here called VTA (voltae transfer agent), affects all markers tested: three different auxotrophies (histidine, purine, and cobalamin) and resistance to BES (2-bromoethanesulfonate, an inhibitor of methanogenesis). VTA was most effectively prepared by culture filtration. This process disrupted a fraction of the M. voltae cells (which have only an S-layer covering their cytoplasmic membrane). VTA was rapidly inactivated upon storage. VTA particles were present in cultures at concentrations of approximately two per cell. Gene transfer activity varied from a minimum of 2 x 10(-5) (BES resistance) to a maximum of 10(-3) (histidine independence) per donor cell. Very little VTA was found free in culture supernatants. The phenomenon is functionally similar to generalized transduction, but there is no evidence, for the time being, of intrinsically viral (i.e., containing a complete viral genome) particles. Consideration of VTA DNA size makes the existence of such viral particles unlikely. If they exist, they must be relatively few in number;perhaps they differ from VTA particles in size and other properties and thus escaped detection. Digestion of VTA DNA with the AluI restriction enzyme suggests that it is a random sample of the bacterial DNA, except for a 0.9-kbp sequence which is amplified relative to the rest of the bacterial chromosome. A VTA-sized DNA fraction was demonstrated in a few other isolates of M. voltae.
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Affiliation(s)
- G Bertani
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.
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Humphrey SB, Stanton TB, Jensen NS, Zuerner RL. Purification and characterization of VSH-1, a generalized transducing bacteriophage of Serpulina hyodysenteriae. J Bacteriol 1997; 179:323-9. [PMID: 8990282 PMCID: PMC178700 DOI: 10.1128/jb.179.2.323-329.1997] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Serpulina hyodysenteriae B204 cells treated with mitomycin (20 microg of mitomycin/ml of culture broth) lysed and released bacteriophages. Bacteriophage particles, precipitated by using polyethylene glycol and purified by CsC1 density gradient ultracentrifugation, had a buoyant density of 1.375 g/cm3 and consisted of a head (45-nm diameter) and an ultrastructurally simple (noncontractile) tail (64 by 9 nm) composed of at least 13 proteins with molecular masses ranging between 13 and 101 kDa. The purified bacteriophage has been designated VSH-1 (VSH for virus of S. hyodysenteriae). VSH-1 was incapable of lytic growth on any of five intestinal spirochete strains, representing three Serpulina species. VSH-1 nucleic acid was determined to be approximately 7.5 kb in size and to be linear, double-stranded DNA based on differential staining with acridine orange, DNase I sensitivity, electrophoretic mobility, and contour length as measured by electron microscopy. Phage DNA digested by the restriction enzymes SspI, AseI, EcoRV, and AflII gave electrophoretic banding patterns nearly identical to those of digested chromosomal DNA from S. hyodysenteriae. Additionally, VSH-1 DNA fragments hybridized with probes complementary to S. hyodysenteriae chromosomal genes nox and flaA1. When purified bacteriophages induced from cultures of S. hyodysenteriae A203 (deltaflaA1 593-762::cat) were added to growing cells of strain A216 (deltanox 438-760::kan), transductants (Cmr Kmr) were obtained at a frequency of 1.5 x l0(-6) per phage particle (enumerated by electron microscopy). These findings indicate that induced VSH-1 virions package DNA of S. hyodysenteriae and are capable of transferring host genes between cells of that spirochete. To our knowledge, this is the first report of genetic transduction of a spirochete.
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Affiliation(s)
- S B Humphrey
- National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50010, USA
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Wood HE, Devine KM, McConnell DJ. Characterisation of a repressor gene (xre) and a temperature-sensitive allele from the Bacillus subtilis prophage, PBSX. Gene X 1990; 96:83-8. [PMID: 2125016 DOI: 10.1016/0378-1119(90)90344-q] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The defective prophage of Bacillus subtilis 168, PBSX, is a chromosomally based element which encodes a non-infectious phage-like particle with bactericidal activity. PBSX is induced by agents which elicit the SOS response. In a PBSX thermoinducible strain which carries the xhi1479 mutation, PBSX is induced by raising the growth temperature from 37 degrees C to 48 degrees C. A 1.2-kb fragment has been cloned which complements the xhi1479 mutation. The nucleotide sequence of this fragment contains an open reading frame (ORF) which encodes a protein of 113 amino acids (aa). This aa sequence resembles that of other bacteriophage repressors and suggests that the N-terminal region forms a helix-turn-helix motif, typical of the DNA-binding domain of many bacterial regulatory proteins. The ORF is preceded by four 15-bp direct repeats, each of which contains an internal palindromic sequence, and by sequences resembling a SigA-dependent promoter. The nt sequence of an equivalent fragment from the PBSX thermoinducible strain has also been determined. There are three aa differences within the ORF compared to the wild type, one of which lies within the helix-turn-helix segment. This ORF encodes a repressor protein of PBSX.
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Affiliation(s)
- H E Wood
- Department of Genetics, Trinity College, Dublin, Ireland
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Tsutsumi Y, Hirokawa H, Shishido K. A new defective phage containing a randomly selected 8 kilobase-pairs fragment of host chromosomal DNA inducible in a strain ofBacillus natto. FEMS Microbiol Lett 1990. [DOI: 10.1111/j.1574-6968.1990.tb03858.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Wood HE, Dawson MT, Devine KM, McConnell DJ. Characterization of PBSX, a defective prophage of Bacillus subtilis. J Bacteriol 1990; 172:2667-74. [PMID: 2110147 PMCID: PMC208911 DOI: 10.1128/jb.172.5.2667-2674.1990] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PBSX, a defective Bacillus subtilis prophage, maps to the metA-metC region of the chromosome. DNA (33 kilobases) from this region of the chromosome was cloned and analyzed by insertional mutagenesis with the integrating plasmid pWD3. This plasmid had a promoterless alpha-amylase gene (amyL) that provided information on the direction and level of transcription at the site of integration. Transcription under the control of the PBSX repressor proceeded in the direction metA to metC over a distance of at least 18 kilobases. Electrophoretic analysis of proteins produced by different integrant strains upon PBSX induction and by fragments subcloned in Escherichia coli allowed the identification of early and late regions of the prophage. A set of contiguous fragments directing mutagenic integration suggested that the minimum size of an operon that encodes phage structural proteins is 19 kilobases. The adaptation of PBSX transcriptional and replicational functions to a chromosomally based, thermoinducible expression system is discussed.
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Affiliation(s)
- H E Wood
- Department of Genetics, Trinity College, Dublin, Ireland
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Abstract
The T1 pac site has been cloned into a plasmid vector. This recombinant plasmid was tested for T1-mediated transduction efficiency in comparison with a plasmid containing the phage lambda T1-pac-like site esp-lambda, plasmids containing T1 sequences other than the pac site, and plasmids containing neither T1 sequences nor known pac sites. The data obtained indicate that there are at least two distinct mechanisms of T1-mediated plasmid transduction. One requires the presence of any T1 sequence on the plasmid and probably takes place via cointegrate formation with the homologous region of an infecting T1 genome. The other is specifically dependent on the presence of a pac site on the plasmid. Plasmids are packaged as head-to-tail multimers that have one heterogeneous molecular end and the other terminated at pac, and the direction of packaging with respect to the pac site is the same for plasmids as for T1. Possible roles of pac in plasmid packaging and their implications with regard to the packaging of phage DNA are discussed.
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