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Gucwa K, Wons E, Wisniewska A, Jakalski M, Dubiak Z, Kozlowski LP, Mruk I. Lethal perturbation of an Escherichia coli regulatory network is triggered by a restriction-modification system's regulator and can be mitigated by excision of the cryptic prophage Rac. Nucleic Acids Res 2024; 52:2942-2960. [PMID: 38153127 PMCID: PMC11014345 DOI: 10.1093/nar/gkad1234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 12/29/2023] Open
Abstract
Bacterial gene regulatory networks orchestrate responses to environmental challenges. Horizontal gene transfer can bring in genes with regulatory potential, such as new transcription factors (TFs), and this can disrupt existing networks. Serious regulatory perturbations may even result in cell death. Here, we show the impact on Escherichia coli of importing a promiscuous TF that has adventitious transcriptional effects within the cryptic Rac prophage. A cascade of regulatory network perturbations occurred on a global level. The TF, a C regulatory protein, normally controls a Type II restriction-modification system, but in E. coli K-12 interferes with expression of the RacR repressor gene, resulting in de-repression of the normally-silent Rac ydaT gene. YdaT is a prophage-encoded TF with pleiotropic effects on E. coli physiology. In turn, YdaT alters expression of a variety of bacterial regulons normally controlled by the RcsA TF, resulting in deficient lipopolysaccharide biosynthesis and cell division. At the same time, insufficient RacR repressor results in Rac DNA excision, halting Rac gene expression due to loss of the replication-defective Rac prophage. Overall, Rac induction appears to counteract the lethal toxicity of YdaT. We show here that E. coli rewires its regulatory network, so as to minimize the adverse regulatory effects of the imported C TF. This complex set of interactions may reflect the ability of bacteria to protect themselves by having robust mechanisms to maintain their regulatory networks, and/or suggest that regulatory C proteins from mobile operons are under selection to manipulate their host's regulatory networks for their own benefit.
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Affiliation(s)
- Katarzyna Gucwa
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Ewa Wons
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Aleksandra Wisniewska
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Marcin Jakalski
- 3P-Medicine Laboratory, Medical University of Gdansk, Debinki 7, 80-211 Gdansk, Poland
| | - Zuzanna Dubiak
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Lukasz Pawel Kozlowski
- Institute of Informatics, Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Banacha 2, 02-097 Warsaw, Poland
| | - Iwona Mruk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
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Evolutionary Dynamics between Phages and Bacteria as a Possible Approach for Designing Effective Phage Therapies against Antibiotic-Resistant Bacteria. Antibiotics (Basel) 2022; 11:antibiotics11070915. [PMID: 35884169 PMCID: PMC9311878 DOI: 10.3390/antibiotics11070915] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 02/06/2023] Open
Abstract
With the increasing global threat of antibiotic resistance, there is an urgent need to develop new effective therapies to tackle antibiotic-resistant bacterial infections. Bacteriophage therapy is considered as a possible alternative over antibiotics to treat antibiotic-resistant bacteria. However, bacteria can evolve resistance towards bacteriophages through antiphage defense mechanisms, which is a major limitation of phage therapy. The antiphage mechanisms target the phage life cycle, including adsorption, the injection of DNA, synthesis, the assembly of phage particles, and the release of progeny virions. The non-specific bacterial defense mechanisms include adsorption inhibition, superinfection exclusion, restriction-modification, and abortive infection systems. The antiphage defense mechanism includes a clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated (Cas) system. At the same time, phages can execute a counterstrategy against antiphage defense mechanisms. However, the antibiotic susceptibility and antibiotic resistance in bacteriophage-resistant bacteria still remain unclear in terms of evolutionary trade-offs and trade-ups between phages and bacteria. Since phage resistance has been a major barrier in phage therapy, the trade-offs can be a possible approach to design effective bacteriophage-mediated intervention strategies. Specifically, the trade-offs between phage resistance and antibiotic resistance can be used as therapeutic models for promoting antibiotic susceptibility and reducing virulence traits, known as bacteriophage steering or evolutionary medicine. Therefore, this review highlights the synergistic application of bacteriophages and antibiotics in association with the pleiotropic trade-offs of bacteriophage resistance.
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Seniya SP, Jain V. Decoding phage resistance by mpr and its role in survivability of Mycobacterium smegmatis. Nucleic Acids Res 2022; 50:6938-6952. [PMID: 35713559 PMCID: PMC9262609 DOI: 10.1093/nar/gkac505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/09/2022] [Accepted: 06/14/2022] [Indexed: 12/24/2022] Open
Abstract
Bacteria and bacteriophages co-evolve in a constant arms race, wherein one tries and finds newer ways to overcome the other. Phage resistance poses a great threat to the development of phage therapy. Hence, it is both essential and important to understand the mechanism of phage resistance in bacteria. First identified in Mycobacterium smegmatis, the gene mpr, upon overexpression, confers resistance against D29 mycobacteriophage. Presently, the mechanism behind phage resistance by mpr is poorly understood. Here we show that Mpr is a membrane-bound DNA exonuclease, which digests DNA in a non-specific manner independent of the sequence, and shares no sequence or structural similarity with any known nuclease. Exonuclease activity of mpr provides resistance against phage infection, but the role of mpr may very well go beyond just phage resistance. Our experiments show that mpr plays a crucial role in the appearance of mutant colonies (phage resistant strains). However, the molecular mechanism behind the emergence of these mutant/resistant colonies is yet to be understood. Nevertheless, it appears that mpr is involved in the survival and evolution of M. smegmatis against phage. A similar mechanism may be present in other organisms, which requires further exploration.
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Affiliation(s)
- Surya Pratap Seniya
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal 462066, India
| | - Vikas Jain
- To whom correspondence should be addressed. Tel: +91 755 2691425; Fax: +91 755 2692392;
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4
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Boulias K, Greer EL. Means, mechanisms and consequences of adenine methylation in DNA. Nat Rev Genet 2022; 23:411-428. [PMID: 35256817 PMCID: PMC9354840 DOI: 10.1038/s41576-022-00456-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2022] [Indexed: 12/29/2022]
Abstract
N6-methyl-2'-deoxyadenosine (6mA or m6dA) has been reported in the DNA of prokaryotes and eukaryotes ranging from unicellular protozoa and algae to multicellular plants and mammals. It has been proposed to modulate DNA structure and transcription, transmit information across generations and have a role in disease, among other functions. However, its existence in more recently evolved eukaryotes remains a topic of debate. Recent technological advancements have facilitated the identification and quantification of 6mA even when the modification is exceptionally rare, but each approach has limitations. Critical assessment of existing data, rigorous design of future studies and further development of methods will be required to confirm the presence and biological functions of 6mA in multicellular eukaryotes.
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5
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O’Brown ZK, Greer EL. N6-methyladenine: A Rare and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1389:177-210. [DOI: 10.1007/978-3-031-11454-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Small RNA mediated gradual control of lipopolysaccharide biosynthesis affects antibiotic resistance in Helicobacter pylori. Nat Commun 2021; 12:4433. [PMID: 34290242 PMCID: PMC8295292 DOI: 10.1038/s41467-021-24689-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/28/2021] [Indexed: 01/19/2023] Open
Abstract
The small, regulatory RNA RepG (Regulator of polymeric G-repeats) regulates the expression of the chemotaxis receptor TlpB in Helicobacter pylori by targeting a variable G-repeat in the tlpB mRNA leader. Here, we show that RepG additionally controls lipopolysaccharide (LPS) phase variation by also modulating the expression of a gene (hp0102) that is co-transcribed with tlpB. The hp0102 gene encodes a glycosyltransferase required for LPS O-chain biosynthesis and in vivo colonization of the mouse stomach. The G-repeat length defines a gradual (rather than ON/OFF) control of LPS biosynthesis by RepG, and leads to gradual resistance to a membrane-targeting antibiotic. Thus, RepG-mediated modulation of LPS structure might impact host immune recognition and antibiotic sensitivity, thereby helping H. pylori to adapt and persist in the host. The small RNA RepG modulates expression of chemotaxis receptor TlpB in Helicobacter pylori by targeting a length-variable G-repeat in the tlpB mRNA. Here, Pernitzsch et al. show that RepG also gradually controls lipopolysaccharide biosynthesis, antibiotic susceptibility, and in-vivo colonization of the stomach, by regulating a gene that is co-transcribed with tlpB.
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Sørensen MCH, Vitt A, Neve H, Soverini M, Ahern SJ, Klumpp J, Brøndsted L. Campylobacter phages use hypermutable polyG tracts to create phenotypic diversity and evade bacterial resistance. Cell Rep 2021; 35:109214. [PMID: 34107245 DOI: 10.1016/j.celrep.2021.109214] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/15/2020] [Accepted: 05/12/2021] [Indexed: 12/16/2022] Open
Abstract
Phase variation is a common mechanism for creating phenotypic heterogeneity of surface structures in bacteria important for niche adaptation. In Campylobacter, phase variation occurs by random variation in hypermutable homonucleotide 7-11 G (polyG) tracts. To elucidate how phages adapt to phase-variable hosts, we study Fletchervirus phages infecting Campylobacter dependent on a phase-variable receptor. Our data demonstrate that Fletcherviruses mimic their host and encode hypermutable polyG tracts, leading to phase-variable expression of two of four receptor-binding proteins. This creates phenotypically diverse phage populations, including a sub-population that infects the bacterial host when the phase-variable receptor is not expressed. Such population dynamics of both phage and host promote co-existence in a shared niche. Strikingly, we identify polyG tracts in more than 100 phage genera, infecting more than 70 bacterial species. Future experimental work may confirm phase variation as a widespread strategy for creating phenotypically diverse phage populations.
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Affiliation(s)
- Martine C Holst Sørensen
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark.
| | - Amira Vitt
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
| | - Horst Neve
- Department of Microbiology and Biotechnology, Max-Rubner Institut, 24103 Kiel, Germany
| | - Matteo Soverini
- COPSAC, Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, 2820 Gentofte, Denmark
| | - Stephen James Ahern
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
| | - Jochen Klumpp
- Institute for Food, Nutrition and Health, ETH Zurich, 8092 Zurich, Switzerland
| | - Lone Brøndsted
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
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8
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Guerin E, Shkoporov AN, Stockdale SR, Comas JC, Khokhlova EV, Clooney AG, Daly KM, Draper LA, Stephens N, Scholz D, Ross RP, Hill C. Isolation and characterisation of ΦcrAss002, a crAss-like phage from the human gut that infects Bacteroides xylanisolvens. MICROBIOME 2021; 9:89. [PMID: 33845877 PMCID: PMC8042965 DOI: 10.1186/s40168-021-01036-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/12/2021] [Indexed: 05/04/2023]
Abstract
BACKGROUND The gut phageome comprises a complex phage community of thousands of individual strains, with a few highly abundant bacteriophages. CrAss-like phages, which infect bacteria of the order Bacteroidales, are the most abundant bacteriophage family in the human gut and make an important contribution to an individual's core virome. Based on metagenomic data, crAss-like phages form a family, with four sub-families and ten candidate genera. To date, only three representatives isolated in pure culture have been reported: ΦcrAss001 and two closely related phages DAC15 and DAC17; all are members of the less abundant candidate genus VI. The persistence at high levels of both crAss-like phage and their Bacteroidales hosts in the human gut has not been explained mechanistically, and this phage-host relationship can only be properly studied with isolated phage-host pairs from as many genera as possible. RESULTS Faeces from a healthy donor with high levels of crAss-like phage was used to initiate a faecal fermentation in a chemostat, with selected antibiotics chosen to inhibit rapidly growing bacteria and selectively enrich for Gram-negative Bacteroidales. This had the objective of promoting the simultaneous expansion of crAss-like phages on their native hosts. The levels of seven different crAss-like phages expanded during the fermentation, indicating that their hosts were also present in the fermenter. The enriched supernatant was then tested against individual Bacteroidales strains isolated from the same faecal sample. This resulted in the isolation of a previously uncharacterised crAss-like phage of candidate genus IV of the proposed Alphacrassvirinae sub-family, ΦcrAss002, that infects the gut commensal Bacteroides xylanisolvens. ΦcrAss002 does not form plaques or spots on lawns of sensitive cells, nor does it lyse liquid cultures, even at high titres. In keeping with the co-abundance of phage and host in the human gut, ΦcrAss002 and Bacteroides xylanisolvens can also co-exist at high levels when co-cultured in laboratory media. CONCLUSIONS We report the isolation and characterisation of ΦcrAss002, the first representative of the proposed Alphacrassvirinae sub-family of crAss-like phages. ΦcrAss002 cannot form plaques or spots on bacterial lawns but can co-exist with its host, Bacteroides xylanisolvens, at very high levels in liquid culture without impacting on bacterial numbers. Video abstract.
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Affiliation(s)
- Emma Guerin
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | | | | | | | | | - Adam G Clooney
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Karen M Daly
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | | | - Niamh Stephens
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Dimitri Scholz
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - R Paul Ross
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
| | - Colin Hill
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
- School of Microbiology, University College Cork, Cork, Ireland.
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9
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Gor V, Ohniwa RL, Morikawa K. No Change, No Life? What We Know about Phase Variation in Staphylococcus aureus. Microorganisms 2021; 9:microorganisms9020244. [PMID: 33503998 PMCID: PMC7911514 DOI: 10.3390/microorganisms9020244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 12/13/2022] Open
Abstract
Phase variation (PV) is a well-known phenomenon of high-frequency reversible gene-expression switching. PV arises from genetic and epigenetic mechanisms and confers a range of benefits to bacteria, constituting both an innate immune strategy to infection from bacteriophages as well as an adaptation strategy within an infected host. PV has been well-characterized in numerous bacterial species; however, there is limited direct evidence of PV in the human opportunistic pathogen Staphylococcus aureus. This review provides an overview of the mechanisms that generate PV and focuses on earlier and recent findings of PV in S. aureus, with a brief look at the future of the field.
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Affiliation(s)
- Vishal Gor
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
- Correspondence: (V.G.); (K.M.)
| | - Ryosuke L. Ohniwa
- Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan;
| | - Kazuya Morikawa
- Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan;
- Correspondence: (V.G.); (K.M.)
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10
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Guerin E, Hill C. Shining Light on Human Gut Bacteriophages. Front Cell Infect Microbiol 2020; 10:481. [PMID: 33014897 PMCID: PMC7511551 DOI: 10.3389/fcimb.2020.00481] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/04/2020] [Indexed: 12/15/2022] Open
Abstract
The human gut is a complex environment that contains a multitude of microorganisms that are collectively termed the microbiome. Multiple factors have a role to play in driving the composition of human gut bacterial communities either toward homeostasis or the instability that is associated with many disease states. One of the most important forces are likely to be bacteriophages, bacteria-infecting viruses that constitute by far the largest portion of the human gut virome. Despite this, bacteriophages (phages) are the one of the least studied residents of the gut. This is largely due to the challenges associated with studying these difficult to culture entities. Modern high throughput sequencing technologies have played an important role in improving our understanding of the human gut phageome but much of the generated sequencing data remains uncharacterised. Overcoming this requires database-independent bioinformatic pipelines and even those phages that are successfully characterized only provide limited insight into their associated biological properties, and thus most viral sequences have been characterized as “viral dark matter.” Fundamental to understanding the role of phages in shaping the human gut microbiome, and in turn perhaps influencing human health, is how they interact with their bacterial hosts. An essential aspect is the isolation of novel phage-bacteria host pairs by direct isolation through various screening methods, which can transform in silico phages into a biological reality. However, this is also beset with multiple challenges including culturing difficulties and the use of traditional methods, such as plaquing, which may bias which phage-host pairs that can be successfully isolated. Phage-bacteria interactions may be influenced by many aspects of complex human gut biology which can be difficult to reproduce under laboratory conditions. Here we discuss some of the main findings associated with the human gut phageome to date including composition, our understanding of phage-host interactions, particularly the observed persistence of virulent phages and their hosts, as well as factors that may influence these highly intricate relationships. We also discuss current methodologies and bottlenecks hindering progression in this field and identify potential steps that may be useful in overcoming these hurdles.
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Affiliation(s)
- Emma Guerin
- 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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11
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Systematic Analysis of REBASE Identifies Numerous Type I Restriction-Modification Systems with Duplicated, Distinct hsdS Specificity Genes That Can Switch System Specificity by Recombination. mSystems 2020; 5:5/4/e00497-20. [PMID: 32723795 PMCID: PMC7394358 DOI: 10.1128/msystems.00497-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Many bacterial species contain DNA methyltransferases that have random on/off switching of expression. These systems, called phasevarions (phase-variable regulons), control the expression of multiple genes by global methylation changes. In every previously characterized phasevarion, genes involved in pathobiology, antibiotic resistance, and potential vaccine candidates are randomly varied in their expression, commensurate with methyltransferase switching. Our systematic study to determine the extent of phasevarions controlled by invertible Type I R-M systems will provide valuable information for understanding how bacteria regulate genes and is key to the study of physiology, virulence, and vaccine development; therefore, it is critical to identify and characterize phase-variable methyltransferases controlling phasevarions. N6-Adenine DNA methyltransferases associated with some Type I and Type III restriction-modification (R-M) systems are able to undergo phase variation, randomly switching expression ON or OFF by varying the length of locus-encoded simple sequence repeats (SSRs). This variation of methyltransferase expression results in genome-wide methylation differences and global changes in gene expression. These epigenetic regulatory systems are called phasevarions, phase-variable regulons, and are widespread in bacteria. A distinct switching system has also been described in Type I R-M systems, based on recombination-driven changes in hsdS genes, which dictate the DNA target site. In order to determine the prevalence of recombination-driven phasevarions, we generated a program called RecombinationRepeatSearch to interrogate REBASE and identify the presence and number of inverted repeats of hsdS downstream of Type I R-M loci. We report that 3.9% of Type I R-M systems have duplicated variable hsdS genes containing inverted repeats capable of phase variation. We report the presence of these systems in the major pathogens Enterococcus faecalis and Listeria monocytogenes, which could have important implications for pathogenesis and vaccine development. These data suggest that in addition to SSR-driven phasevarions, many bacteria have independently evolved phase-variable Type I R-M systems via recombination between multiple, variable hsdS genes. IMPORTANCE Many bacterial species contain DNA methyltransferases that have random on/off switching of expression. These systems, called phasevarions (phase-variable regulons), control the expression of multiple genes by global methylation changes. In every previously characterized phasevarion, genes involved in pathobiology, antibiotic resistance, and potential vaccine candidates are randomly varied in their expression, commensurate with methyltransferase switching. Our systematic study to determine the extent of phasevarions controlled by invertible Type I R-M systems will provide valuable information for understanding how bacteria regulate genes and is key to the study of physiology, virulence, and vaccine development; therefore, it is critical to identify and characterize phase-variable methyltransferases controlling phasevarions.
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12
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Mangalea MR, Duerkop BA. Fitness Trade-Offs Resulting from Bacteriophage Resistance Potentiate Synergistic Antibacterial Strategies. Infect Immun 2020; 88:e00926-19. [PMID: 32094257 PMCID: PMC7309606 DOI: 10.1128/iai.00926-19] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Bacteria that cause life-threatening infections in humans are becoming increasingly difficult to treat. In some instances, this is due to intrinsic and acquired antibiotic resistance, indicating that new therapeutic approaches are needed to combat bacterial pathogens. There is renewed interest in utilizing viruses of bacteria known as bacteriophages (phages) as potential antibacterial therapeutics. However, critics suggest that similar to antibiotics, the development of phage-resistant bacteria will halt clinical phage therapy. Although the emergence of phage-resistant bacteria is likely inevitable, there is a growing body of literature showing that phage selective pressure promotes mutations in bacteria that allow them to subvert phage infection, but with a cost to their fitness. Such fitness trade-offs include reduced virulence, resensitization to antibiotics, and colonization defects. Resistance to phage nucleic acid entry, primarily via cell surface modifications, compromises bacterial fitness during antibiotic and host immune system pressure. In this minireview, we explore the mechanisms behind phage resistance in bacterial pathogens and the physiological consequences of acquiring phage resistance phenotypes. With this knowledge, it may be possible to use phages to alter bacterial populations, making them more tractable to current therapeutic strategies.
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Affiliation(s)
- Mihnea R Mangalea
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Breck A Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
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13
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Tan D, Zhang Y, Qin J, Le S, Gu J, Chen LK, Guo X, Zhu T. A Frameshift Mutation in wcaJ Associated with Phage Resistance in Klebsiella pneumoniae. Microorganisms 2020; 8:microorganisms8030378. [PMID: 32156053 PMCID: PMC7142929 DOI: 10.3390/microorganisms8030378] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 01/21/2023] Open
Abstract
Phage therapy is a potential and promising avenue for controlling the emergence and spread of multidrug-resistant (MDR) Klebsiella pneumoniae, however, the rapid development of anti-phage resistance has been identified as an obstacle to the development of phage therapy. Little is known about the mechanism employed by MDR K. pneumoniae strains and how they protect themselves from lytic phage predation in vitro and in vivo. In this study, comparative genomic analysis shows undecaprenyl-phosphate glucose-1-phosphate transferase (WcaJ), the initial enzyme catalyzing the biosynthesis of colanic acid, is necessary for the adsorption of phage 117 (Podoviridae) to the host strain Kp36 to complete its lytic life cycle. In-frame deletion of wcaJ alone was sufficient to provide phage 117 resistance in the Kp36 wild-type strain. Complementation assays demonstrated the susceptibility of phage 117, and the mucoid phenotype could be restored in the resistant strain Kp36-117R by expressing the wild-type version of wcaJ. Remarkably, we found that bacterial mobile genetic elements (insA and insB) block phage 117 infections by disrupting the coding region of wcaJ, thus preventing phage adsorption to its phage receptor. Further, we revealed that the wcaJ mutation likely occurred spontaneously rather than adapted by phage 117 predation under unfavorable environments. Taken together, our results address a crucial evolutionary question around the mechanisms of phage-host interactions, increasing our current understandings of anti-phage defense mechanisms in this important MDR pathogen.
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Affiliation(s)
- Demeng Tan
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
- Correspondence: (D.T.); (T.Z.)
| | - Yiyuan Zhang
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Jinhong Qin
- Institutes of Medical Sciences, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Shuai Le
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Jingmin Gu
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Li-kuang Chen
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Xiaokui Guo
- Institutes of Medical Sciences, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Tongyu Zhu
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
- Correspondence: (D.T.); (T.Z.)
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14
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Atack JM, Guo C, Yang L, Zhou Y, Jennings MP. DNA sequence repeats identify numerous Type I restriction-modification systems that are potential epigenetic regulators controlling phase-variable regulons; phasevarions. FASEB J 2019; 34:1038-1051. [PMID: 31914596 PMCID: PMC7383803 DOI: 10.1096/fj.201901536rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/07/2019] [Accepted: 11/09/2019] [Indexed: 12/27/2022]
Abstract
Over recent years several examples of randomly switching methyltransferases, associated with Type III restriction‐modification (R‐M) systems, have been described in pathogenic bacteria. In every case examined, changes in simple DNA sequence repeats result in variable methyltransferase expression and result in global changes in gene expression, and differentiation of the bacterial cell into distinct phenotypes. These epigenetic regulatory systems are called phasevarions, phase‐variable regulons, and are widespread in bacteria, with 17.4% of Type III R‐M system containing simple DNA sequence repeats. A distinct, recombination‐driven random switching system has also been described in Streptococci in Type I R‐M systems that also regulate gene expression. Here, we interrogate the most extensive and well‐curated database of R‐M systems, REBASE, by searching for all possible simple DNA sequence repeats in the hsdRMS genes that encode Type I R‐M systems. We report that 7.9% of hsdS, 2% of hsdM, and of 4.3% of hsdR genes contain simple sequence repeats that are capable of mediating phase variation. Phase variation of both hsdM and hsdS genes will lead to differential methyltransferase expression or specificity, and thereby the potential to control phasevarions. These data suggest that in addition to well characterized phasevarions controlled by Type III mod genes, and the previously described Streptococcal Type I R‐M systems that switch via recombination, approximately 10% of all Type I R‐M systems surveyed herein have independently evolved the ability to randomly switch expression via simple DNA sequence repeats.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Chengying Guo
- College of Plant Protection, Shandong Agricultural University, Taian City, China
| | - Long Yang
- College of Plant Protection, Shandong Agricultural University, Taian City, China
| | - Yaoqi Zhou
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
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15
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Aziz A, Sarovich DS, Nosworthy E, Beissbarth J, Chang AB, Smith-Vaughan H, Price EP, Harris TM. Molecular Signatures of Non-typeable Haemophilus influenzae Lung Adaptation in Pediatric Chronic Lung Disease. Front Microbiol 2019; 10:1622. [PMID: 31379777 PMCID: PMC6646836 DOI: 10.3389/fmicb.2019.01622] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/01/2019] [Indexed: 12/03/2022] Open
Abstract
Non-typeable Haemophilus influenzae (NTHi), an opportunistic pathogen of the upper airways of healthy children, can infect the lower airways, driving chronic lung disease. However, the molecular basis underpinning NTHi transition from a commensal to a pathogen is not clearly understood. Here, we performed comparative genomic and transcriptomic analyses of 12 paired, isogenic NTHi strains, isolated from the nasopharynx (NP) and bronchoalveolar lavage (BAL) of 11 children with chronic lung disease, to identify convergent molecular signatures associated with lung adaptation. Comparative genomic analyses of the 12 NP-BAL pairs demonstrated that five were genetically identical, with the remaining seven differing by only 1 to 3 mutations. Within-patient transcriptomic analyses identified between 2 and 58 differentially expressed genes in 8 of the 12 NP-BAL pairs, including pairs with no observable genomic changes. Whilst no convergence was observed at the gene level, functional enrichment analysis revealed significant under-representation of differentially expressed genes belonging to Coenzyme metabolism, Function unknown, Translation, ribosomal structure, and biogenesis Cluster of Orthologous Groups categories. In contrast, Carbohydrate transport and metabolism, Cell motility and secretion, Intracellular trafficking and secretion, and Energy production categories were over-represented. This observed trend amongst genetically unrelated NTHi strains provides evidence of convergent transcriptional adaptation of NTHi to pediatric airways that deserves further exploration. Understanding the pathoadaptative mechanisms that NTHi employs to infect and persist in the lower pediatric airways is essential for devising targeted diagnostics and treatments aimed at minimizing disease severity, and ultimately, preventing NTHi lung infections and subsequent chronic lung disease in children.
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Affiliation(s)
- Ammar Aziz
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Derek S. Sarovich
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
- GeneCology Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Elizabeth Nosworthy
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Jemima Beissbarth
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Anne B. Chang
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
- Department of Respiratory and Sleep Medicine, Children’s Health Queensland, Queensland University of Technology, Brisbane, QLD, Australia
| | - Heidi Smith-Vaughan
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Erin P. Price
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
- GeneCology Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Tegan M. Harris
- Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
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16
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Beaulaurier J, Schadt EE, Fang G. Deciphering bacterial epigenomes using modern sequencing technologies. Nat Rev Genet 2019; 20:157-172. [PMID: 30546107 DOI: 10.1038/s41576-018-0081-3] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prokaryotic DNA contains three types of methylation: N6-methyladenine, N4-methylcytosine and 5-methylcytosine. The lack of tools to analyse the frequency and distribution of methylated residues in bacterial genomes has prevented a full understanding of their functions. Now, advances in DNA sequencing technology, including single-molecule, real-time sequencing and nanopore-based sequencing, have provided new opportunities for systematic detection of all three forms of methylated DNA at a genome-wide scale and offer unprecedented opportunities for achieving a more complete understanding of bacterial epigenomes. Indeed, as the number of mapped bacterial methylomes approaches 2,000, increasing evidence supports roles for methylation in regulation of gene expression, virulence and pathogen-host interactions.
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Affiliation(s)
- John Beaulaurier
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Eric E Schadt
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Gang Fang
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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17
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Turkington CJR, Morozov A, Clokie MRJ, Bayliss CD. Phage-Resistant Phase-Variant Sub-populations Mediate Herd Immunity Against Bacteriophage Invasion of Bacterial Meta-Populations. Front Microbiol 2019; 10:1473. [PMID: 31333609 PMCID: PMC6625227 DOI: 10.3389/fmicb.2019.01473] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 06/13/2019] [Indexed: 01/06/2023] Open
Abstract
Hypermutable loci are widespread in bacteria as mechanisms for rapid generation of phenotypic diversity within a population that enables survival of fluctuating, often antagonistic, selection pressures. Localized hypermutation can mediate phase variation and enable survival of bacteriophage predation due to high frequency, reversible alterations in the expression of phage receptors. As phase variation can also generate population-to-population heterogeneity, we hypothesized that this phenomenon may facilitate survival of spatially-separated bacterial populations from phage invasion in a manner analogous to herd immunity to infectious diseases in human populations. The lic2A gene of Haemophilus influenzae is subject to “ON” and “OFF” switches in expression mediated by mutations in a 5′CAAT repeat tract present within the reading frame. The enzyme encoded by lic2A mediates addition of a galactose moiety of the lipopolysaccharide. This moiety is required for attachment of the HP1C1 phage such that the ON state of the lic2A gene is associated with HP1c1 susceptibility while the OFF state is resistant to infection. We developed an “oscillating prey assay” to examine phage spread through a series of sub-populations of Haemophilus influenzae whose phage receptor is in an ON or OFF state. Phage extinction was frequently observed when the proportion of phage-resistant sub-populations exceeded 34%. In silico modeling indicated that phage extinction was interdependent on phage loss during transfer between sub-populations and the frequency of resistant sub-populations. In a fixed-area oscillating prey assay, heterogeneity in phage resistance was observed to generate vast differences in phage densities across a meta-population of multiple bacterial sub-populations resulting in protective quarantining of some sub-populations from phage attack. We conclude that phase-variable hypermutable loci produce bacterial “herd immunity” with resistant intermediary-populations acting as a barricade to reduce the viral load faced by phage-susceptible sub-populations. This paradigm of meta-population protection is applicable to evolution of hypermutable loci in multiple bacteria-phage and host-pathogen interactions.
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Affiliation(s)
| | - Andrew Morozov
- Department of Mathematics, University of Leicester, Leicester, United Kingdom
| | - Martha R J Clokie
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Christopher D Bayliss
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
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18
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Phillips ZN, Husna AU, Jennings MP, Seib KL, Atack JM. Phasevarions of bacterial pathogens - phase-variable epigenetic regulators evolving from restriction-modification systems. MICROBIOLOGY-SGM 2019; 165:917-928. [PMID: 30994440 DOI: 10.1099/mic.0.000805] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Phase-variable DNA methyltransferases control the expression of multiple genes via epigenetic mechanisms in a wide variety of bacterial species. These systems are called phasevarions, for phase-variable regulons. Phasevarions regulate genes involved in pathogenesis, host adaptation and antibiotic resistance. Many human-adapted bacterial pathogens contain phasevarions. These include leading causes of morbidity and mortality worldwide, such as non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Neisseria spp. Phase-variable methyltransferases and phasevarions have also been discovered in environmental organisms and veterinary pathogens. The existence of many different examples suggests that phasevarions have evolved multiple times as a contingency strategy in the bacterial domain, controlling phenotypes that are important in adapting to environmental change. Many of the organisms that contain phasevarions have existing or emerging drug resistance. Vaccines may therefore represent the best and most cost-effective tool to prevent disease caused by these organisms. However, many phasevarions also control the expression of current and putative vaccine candidates; variable expression of antigens could lead to immune evasion, meaning that vaccines designed using these targets become ineffective. It is therefore essential to characterize phasevarions in order to determine an organism's stably expressed antigenic repertoire, and rationally design broadly effective vaccines.
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Affiliation(s)
- Zachary N Phillips
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Asma-Ul Husna
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Kate L Seib
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
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19
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Abstract
To survive unpredictable environmental change, many organisms adopt bet-hedging strategies that are initially costly but provide a long-term fitness benefit. The temporal extent of these deferred fitness benefits determines whether bet-hedging organisms can survive long enough to realize them. In this article, we examine a model of microbial bet hedging in which there are two paths to extinction: unpredictable environmental change and demographic stochasticity. In temporally correlated environments, these drivers of extinction select for different switching strategies. Rapid phenotype switching ensures survival in the face of unpredictable environmental change, while slower-switching organisms become extinct. However, when both switching strategies are present in the same population, then demographic stochasticity-enforced by a limited population size-leads to extinction of the faster-switching organism. As a result, we find a novel form of evolutionary suicide whereby selection in a fluctuating environment can favor bet-hedging strategies that ultimately increase the risk of extinction. Population structures with multiple subpopulations and dispersal can reduce the risk of extinction from unpredictable environmental change and shift the balance so as to facilitate the evolution of slower-switching organisms.
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20
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Role of phage ϕ1 in two strains of Salmonella Rissen, sensitive and resistant to phage ϕ1. BMC Microbiol 2018; 18:208. [PMID: 30526475 PMCID: PMC6286511 DOI: 10.1186/s12866-018-1360-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 11/28/2018] [Indexed: 01/21/2023] Open
Abstract
Background The study describes the Salmonella Rissen phage ϕ1 isolated from the ϕ1-sensitive Salmonella Rissen strain RW. The same phage was then used to select the resistant strain RRϕ1+, which can harbour or not ϕ1. Results Following this approach, we found that ϕ1, upon excision from RW cells with mitomycin, behaves as a temperate phage: lyses host cells and generates phage particles; instead, upon spontaneous excision from RRϕ1+ cells, it does not generate phage particles; causes loss of phage resistance; switches the O-antigen from the smooth to the rough phenotype, and favors the transition of Salmonella Rissen from the planktonic to the biofilm growth. The RW and RRϕ1+ strains differ by 10 genes; of these, only two (phosphomannomutase_1 and phosphomannomutase_2; both involved in the mannose synthesis pathway) display significant differences at the expression levels. This result suggests that phage resistance is associated with these two genes. Conclusions Phage ϕ1 displays the unusual property of behaving as template as well as lytic phage. This feature was used by the phage to modulate several phases of Salmonella Rissen lifestyle. Electronic supplementary material The online version of this article (10.1186/s12866-018-1360-z) contains supplementary material, which is available to authorized users.
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21
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Atack JM, Tan A, Bakaletz LO, Jennings MP, Seib KL. Phasevarions of Bacterial Pathogens: Methylomics Sheds New Light on Old Enemies. Trends Microbiol 2018; 26:715-726. [PMID: 29452952 PMCID: PMC6054543 DOI: 10.1016/j.tim.2018.01.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 01/06/2018] [Accepted: 01/26/2018] [Indexed: 01/04/2023]
Abstract
A wide variety of bacterial pathogens express phase-variable DNA methyltransferases that control expression of multiple genes via epigenetic mechanisms. These randomly switching regulons - phasevarions - regulate genes involved in pathogenesis, host adaptation, and antibiotic resistance. Individual phase-variable genes can be identified in silico as they contain easily recognized features such as simple sequence repeats (SSRs) or inverted repeats (IRs) that mediate the random switching of expression. Conversely, phasevarion-controlled genes do not contain any easily identifiable features. The study of DNA methyltransferase specificity using Single-Molecule, Real-Time (SMRT) sequencing and methylome analysis has rapidly advanced the analysis of phasevarions by allowing methylomics to be combined with whole-transcriptome/proteome analysis to comprehensively characterize these systems in a number of important bacterial pathogens.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, 4222, Australia.
| | - Aimee Tan
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, 4222, Australia
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH 43205, USA
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, 4222, Australia
| | - Kate L Seib
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, 4222, Australia.
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22
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Górski A, Międzybrodzki R, Łobocka M, Głowacka-Rutkowska A, Bednarek A, Borysowski J, Jończyk-Matysiak E, Łusiak-Szelachowska M, Weber-Dąbrowska B, Bagińska N, Letkiewicz S, Dąbrowska K, Scheres J. Phage Therapy: What Have We Learned? Viruses 2018; 10:E288. [PMID: 29843391 PMCID: PMC6024844 DOI: 10.3390/v10060288] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/11/2018] [Accepted: 05/22/2018] [Indexed: 02/07/2023] Open
Abstract
In this article we explain how current events in the field of phage therapy may positively influence its future development. We discuss the shift in position of the authorities, academia, media, non-governmental organizations, regulatory agencies, patients, and doctors which could enable further advances in the research and application of the therapy. In addition, we discuss methods to obtain optimal phage preparations and suggest the potential of novel applications of phage therapy extending beyond its anti-bacterial action.
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Affiliation(s)
- Andrzej Górski
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Phage Therapy Unit, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Department of Clinical Immunology, Transplantation Institute, Medical University of Warsaw, Nowogrodzka Street 59, 02-006 Warsaw, Poland.
| | - Ryszard Międzybrodzki
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Phage Therapy Unit, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Department of Clinical Immunology, Transplantation Institute, Medical University of Warsaw, Nowogrodzka Street 59, 02-006 Warsaw, Poland.
| | - Małgorzata Łobocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego Street 5 A, 02-106 Warsaw, Poland.
- Autonomous Department of Microbial Biology, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska Street 159, 02-776 Warsaw, Poland.
| | - Aleksandra Głowacka-Rutkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego Street 5 A, 02-106 Warsaw, Poland.
| | - Agnieszka Bednarek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego Street 5 A, 02-106 Warsaw, Poland.
| | - Jan Borysowski
- Department of Clinical Immunology, Transplantation Institute, Medical University of Warsaw, Nowogrodzka Street 59, 02-006 Warsaw, Poland.
| | - Ewa Jończyk-Matysiak
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
| | - Marzanna Łusiak-Szelachowska
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
| | - Beata Weber-Dąbrowska
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Phage Therapy Unit, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
| | - Natalia Bagińska
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
| | - Sławomir Letkiewicz
- Phage Therapy Unit, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Medical Sciences Institute, Katowice School of Economics, Harcerzy Września Street 3, 40-659 Katowice, Poland.
| | - Krystyna Dąbrowska
- Bacteriophage Laboratory, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla Street 12, 53-114 Wroclaw, Poland.
- Research and Development Center, Regional Specialized Hospital, Kamieńskiego 73a, 51-124 Wrocław, Poland.
| | - Jacques Scheres
- National Institute of Public Health NIZP, Chocimska Street 24, 00-971 Warsaw, Poland.
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23
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Zhu Q, Stöger R, Alberio R. A Lexicon of DNA Modifications: Their Roles in Embryo Development and the Germline. Front Cell Dev Biol 2018; 6:24. [PMID: 29637072 PMCID: PMC5880922 DOI: 10.3389/fcell.2018.00024] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/27/2018] [Indexed: 12/12/2022] Open
Abstract
5-methylcytosine (5mC) on CpG dinucleotides has been viewed as the major epigenetic modification in eukaryotes for a long time. Apart from 5mC, additional DNA modifications have been discovered in eukaryotic genomes. Many of these modifications are thought to be solely associated with DNA damage. However, growing evidence indicates that some base modifications, namely 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), 5-carboxylcytosine (5caC), and N6-methadenine (6mA), may be of biological relevance, particularly during early stages of embryo development. Although abundance of these DNA modifications in eukaryotic genomes can be low, there are suggestions that they cooperate with other epigenetic markers to affect DNA-protein interactions, gene expression, defense of genome stability and epigenetic inheritance. Little is still known about their distribution in different tissues and their functions during key stages of the animal lifecycle. This review discusses current knowledge and future perspectives of these novel DNA modifications in the mammalian genome with a focus on their dynamic distribution during early embryonic development and their potential function in epigenetic inheritance through the germ line.
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Affiliation(s)
- Qifan Zhu
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Reinhard Stöger
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Ramiro Alberio
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
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24
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Gencay YE, Sørensen MCH, Wenzel CQ, Szymanski CM, Brøndsted L. Phase Variable Expression of a Single Phage Receptor in Campylobacter jejuni NCTC12662 Influences Sensitivity Toward Several Diverse CPS-Dependent Phages. Front Microbiol 2018; 9:82. [PMID: 29467727 PMCID: PMC5808241 DOI: 10.3389/fmicb.2018.00082] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 01/12/2018] [Indexed: 12/17/2022] Open
Abstract
Campylobacter jejuni NCTC12662 is sensitive to infection by many Campylobacter bacteriophages. Here we used this strain to investigate the molecular mechanism behind phage resistance development when exposed to a single phage and demonstrate how phase variable expression of one surface component influences phage sensitivity against many diverse C. jejuni phages. When C. jejuni NCTC12662 was exposed to phage F207 overnight, 25% of the bacterial cells were able to grow on a lawn of phage F207, suggesting that resistance develops at a high frequency. One resistant variant, 12662R, was further characterized and shown to be an adsorption mutant. Plaque assays using our large phage collection showed that seven out of 36 diverse capsular polysaccharide (CPS)-dependent phages could not infect 12662R, whereas the remaining phages formed plaques on 12662R with reduced efficiencies. Analysis of the CPS composition of 12662R by high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) showed a diminished signal for O-methyl phosphoramidate (MeOPN), a phase variable modification of the CPS. This suggested that the majority of the 12662R population did not express this phase variable modification in the CPS, indicating that MeOPN serves as a phage receptor in NCTC12662. Whole genome analysis of 12662R showed a switch in the length of the phase variable homopolymeric G tract of gene 06810, encoding a putative MeOPN-transferase located in the CPS locus, resulting in a non-functional protein. To confirm the role of 06810 in phage resistance development of NCTC12662, a 06810 knockout mutant in NCTC12662 was constructed and analyzed by HR-MAS NMR demonstrating the absence of MeOPN in the CPS of the mutant. Plaque assays using NCTC12662Δ06810 demonstrated that seven of our CPS-dependent Campylobacter phages are dependent on the presence of MeOPN for successful infection of C. jejuni, whereas the remaining 29 phages infect independently of MeOPN, although with reduced efficiencies. Our data indicate that CPS-dependent phages uses diverse mechanisms for their initial interaction with their C. jejuni host.
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Affiliation(s)
- Yilmaz Emre Gencay
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Martine C H Sørensen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Cory Q Wenzel
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
| | - Christine M Szymanski
- Department of Biological Sciences, University of Alberta, Edmonton, Canada.,Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia
| | - Lone Brøndsted
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
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25
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Reduction of Listeria monocytogenes on chicken breasts by combined treatment with UV-C light and bacteriophage ListShield. Lebensm Wiss Technol 2017. [DOI: 10.1016/j.lwt.2017.07.060] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Hille F, Charpentier E. CRISPR-Cas: biology, mechanisms and relevance. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0496. [PMID: 27672148 PMCID: PMC5052741 DOI: 10.1098/rstb.2015.0496] [Citation(s) in RCA: 226] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2016] [Indexed: 12/21/2022] Open
Abstract
Prokaryotes have evolved several defence mechanisms to protect themselves from viral predators. Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated proteins (Cas) display a prokaryotic adaptive immune system that memorizes previous infections by integrating short sequences of invading genomes—termed spacers—into the CRISPR locus. The spacers interspaced with repeats are expressed as small guide CRISPR RNAs (crRNAs) that are employed by Cas proteins to target invaders sequence-specifically upon a reoccurring infection. The ability of the minimal CRISPR-Cas9 system to target DNA sequences using programmable RNAs has opened new avenues in genome editing in a broad range of cells and organisms with high potential in therapeutical applications. While numerous scientific studies have shed light on the biochemical processes behind CRISPR-Cas systems, several aspects of the immunity steps, however, still lack sufficient understanding. This review summarizes major discoveries in the CRISPR-Cas field, discusses the role of CRISPR-Cas in prokaryotic immunity and other physiological properties, and describes applications of the system as a DNA editing technology and antimicrobial agent. This article is part of the themed issue ‘The new bacteriology’.
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Affiliation(s)
- Frank Hille
- Department of Regulation in Infection Biology, Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Emmanuelle Charpentier
- Department of Regulation in Infection Biology, Max Planck Institute for Infection Biology, Berlin 10117, Germany The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Department of Molecular Biology, Umeå University, Umeå 90187, Sweden
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27
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Sadekuzzaman M, Yang S, Mizan MFR, Kim HS, Ha SD. Effectiveness of a phage cocktail as a biocontrol agent against L. monocytogenes biofilms. Food Control 2017. [DOI: 10.1016/j.foodcont.2016.10.056] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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28
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Aidley J, Sørensen MCH, Bayliss CD, Brøndsted L. Phage exposure causes dynamic shifts in the expression states of specific phase-variable genes of Campylobacter jejuni. MICROBIOLOGY-SGM 2017; 163:911-919. [PMID: 28597819 DOI: 10.1099/mic.0.000470] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Phase variation (PV) creates phenotypic heterogeneity at high frequencies and in a reversible manner. This phenomenon allows bacteria to adapt to a variety of different environments and selective pressures. In Campylobacterjejuni this reversible adaptive process is mediated by mutations in homopolymeric G/C tracts. Many C. jejuni-specific phages are dependent on phase-variable surface structures for successful infection. We previously identified the capsular polysaccharide (CPS) moiety, MeOPN-GalfNAc, as a receptor for phage F336 and showed that phase-variable expression of the transferase for this CPS modification, cj1421, and two other phase-variable CPS genes generated phage resistance in C. jejuni. Here we investigate the population dynamics of C. jejuni NCTC11168 when exposed to phage F336 in vitro using a newly described method - the 28-locus-CJ11168 PV analysis. Dynamic switching was observed in the ON/OFF states of three phase-variable CPS genes, cj1421, cj1422 and cj1426, during phage F336 exposure, with the dominant phage-resistant phasotype differing between cultures. Although loss of the phage receptor was predominately observed, several other PV events also led to phage resistance, a phenomenon that increases the chance of phage-resistant subpopulations being present in any growing culture. No other PV genes were affected and exposure to phage F336 resulted in a highly specific response, only selecting for phase variants of cj1421, cj1422 and cj1426. In summary, C. jejuni may benefit from modification of the surface in multiple ways to inhibit or reduce phage binding, thereby ensuring the survival of the population when exposed to phages.
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Affiliation(s)
- Jack Aidley
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK.,Present address: Zoologisches Institut, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Martine C Holst Sørensen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark
| | | | - Lone Brøndsted
- Department of Veterinary and Animal Sciences, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark
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29
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van Houte S, Buckling A, Westra ER. Evolutionary Ecology of Prokaryotic Immune Mechanisms. Microbiol Mol Biol Rev 2016; 80:745-63. [PMID: 27412881 PMCID: PMC4981670 DOI: 10.1128/mmbr.00011-16] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Bacteria have a range of distinct immune strategies that provide protection against bacteriophage (phage) infections. While much has been learned about the mechanism of action of these defense strategies, it is less clear why such diversity in defense strategies has evolved. In this review, we discuss the short- and long-term costs and benefits of the different resistance strategies and, hence, the ecological conditions that are likely to favor the different strategies alone and in combination. Finally, we discuss some of the broader consequences, beyond resistance to phage and other genetic elements, resulting from the operation of different immune strategies.
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Affiliation(s)
- Stineke van Houte
- ESI and CEC, Department of Biosciences, University of Exeter, Exeter, United Kingdom
| | - Angus Buckling
- ESI and CEC, Department of Biosciences, University of Exeter, Exeter, United Kingdom
| | - Edze R Westra
- ESI and CEC, Department of Biosciences, University of Exeter, Exeter, United Kingdom
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30
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Shabbir MAB, Hao H, Shabbir MZ, Wu Q, Sattar A, Yuan Z. Bacteria vs. Bacteriophages: Parallel Evolution of Immune Arsenals. Front Microbiol 2016; 7:1292. [PMID: 27582740 PMCID: PMC4987407 DOI: 10.3389/fmicb.2016.01292] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/05/2016] [Indexed: 12/26/2022] Open
Abstract
Bacteriophages are the most common entities on earth and represent a constant challenge to bacterial populations. To fend off bacteriophage infection, bacteria evolved immune systems to avert phage adsorption and block invader DNA entry. They developed restriction–modification systems and mechanisms to abort infection and interfere with virion assembly, as well as newly recognized clustered regularly interspaced short palindromic repeats (CRISPR). In response to bacterial immune systems, bacteriophages synchronously evolved resistance mechanisms, such as the anti-CRISPR systems to counterattack bacterial CRISPR-cas systems, in a continuing evolutionary arms race between virus and host. In turn, it is fundamental to the survival of the bacterial cell to evolve a system to combat bacteriophage immune strategies.
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Affiliation(s)
- Muhammad A B Shabbir
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural UniversityWuhan, China; Department of Basic Veterinary Medicine, Huazhong Agricultural UniversityWuhan, China
| | - Haihong Hao
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural UniversityWuhan, China; Department of Basic Veterinary Medicine, Huazhong Agricultural UniversityWuhan, China
| | - Muhammad Z Shabbir
- Quality Operations Laboratory, University of Veterinary and Animal Sciences Lahore, Pakistan
| | - Qin Wu
- Department of Basic Veterinary Medicine, Huazhong Agricultural UniversityWuhan, China; National Reference Laboratory of Veterinary Drug Residues and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural UniversityWuhan, China
| | - Adeel Sattar
- Department of Basic Veterinary Medicine, Huazhong Agricultural UniversityWuhan, China; National Reference Laboratory of Veterinary Drug Residues and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural UniversityWuhan, China
| | - Zonghui Yuan
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural UniversityWuhan, China; Department of Basic Veterinary Medicine, Huazhong Agricultural UniversityWuhan, China; National Reference Laboratory of Veterinary Drug Residues and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural UniversityWuhan, China
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31
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O'Brown ZK, Greer EL. N6-Methyladenine: A Conserved and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 945:213-246. [PMID: 27826841 DOI: 10.1007/978-3-319-43624-1_10] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Chromatin, consisting of deoxyribonucleic acid (DNA) wrapped around histone proteins, facilitates DNA compaction and allows identical DNA codes to confer many different cellular phenotypes. This biological versatility is accomplished in large part by posttranslational modifications to histones and chemical modifications to DNA. These modifications direct the cellular machinery to expand or compact specific chromatin regions and mark regions of the DNA as important for cellular functions. While each of the four bases that make up DNA can be modified (Iyer et al. 2011), this chapter will focus on methylation of the sixth position on adenines (6mA), as this modification has been poorly characterized in recently evolved eukaryotes, but shows promise as a new conserved layer of epigenetic regulation. 6mA was previously thought to be restricted to unicellular organisms, but recent work has revealed its presence in metazoa. Here, we will briefly describe the history of 6mA, examine its evolutionary conservation, and evaluate the current methods for detecting 6mA. We will discuss the enzymes that bind and regulate this mark and finally examine known and potential functions of 6mA in eukaryotes.
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Affiliation(s)
- Zach Klapholz O'Brown
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA. .,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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32
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Cota I, Sánchez-Romero MA, Hernández SB, Pucciarelli MG, García-del Portillo F, Casadesús J. Epigenetic Control of Salmonella enterica O-Antigen Chain Length: A Tradeoff between Virulence and Bacteriophage Resistance. PLoS Genet 2015; 11:e1005667. [PMID: 26583926 PMCID: PMC4652898 DOI: 10.1371/journal.pgen.1005667] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/25/2015] [Indexed: 12/21/2022] Open
Abstract
The Salmonella enterica opvAB operon is a horizontally-acquired locus that undergoes phase variation under Dam methylation control. The OpvA and OpvB proteins form intertwining ribbons in the inner membrane. Synthesis of OpvA and OpvB alters lipopolysaccharide O-antigen chain length and confers resistance to bacteriophages 9NA (Siphoviridae), Det7 (Myoviridae), and P22 (Podoviridae). These phages use the O-antigen as receptor. Because opvAB undergoes phase variation, S. enterica cultures contain subpopulations of opvABOFF and opvABON cells. In the presence of a bacteriophage that uses the O-antigen as receptor, the opvABOFF subpopulation is killed and the opvABON subpopulation is selected. Acquisition of phage resistance by phase variation of O-antigen chain length requires a payoff: opvAB expression reduces Salmonella virulence. However, phase variation permits resuscitation of the opvABOFF subpopulation as soon as phage challenge ceases. Phenotypic heterogeneity generated by opvAB phase variation thus preadapts Salmonella to survive phage challenge with a fitness cost that is transient only.
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Affiliation(s)
- Ignacio Cota
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | | | - Sara B. Hernández
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - M. Graciela Pucciarelli
- Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Centro de Biología Molecular Severo Ochoa (CBMSO-CSIC), Madrid, Spain
| | | | - Josep Casadesús
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
- * E-mail:
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33
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Marraffini LA. CRISPR-Cas immunity in prokaryotes. Nature 2015; 526:55-61. [PMID: 26432244 DOI: 10.1038/nature15386] [Citation(s) in RCA: 513] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/07/2015] [Indexed: 12/12/2022]
Abstract
Prokaryotic organisms are threatened by a large array of viruses and have developed numerous defence strategies. Among these, only clustered, regularly interspaced short palindromic repeat (CRISPR)-Cas systems provide adaptive immunity against foreign elements. Upon viral injection, a small sequence of the viral genome, known as a spacer, is integrated into the CRISPR locus to immunize the host cell. Spacers are transcribed into small RNA guides that direct the cleavage of the viral DNA by Cas nucleases. Immunization through spacer acquisition enables a unique form of evolution whereby a population not only rapidly acquires resistance to its predators but also passes this resistance mechanism vertically to its progeny.
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Affiliation(s)
- Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
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34
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Denes T, den Bakker HC, Tokman JI, Guldimann C, Wiedmann M. Selection and Characterization of Phage-Resistant Mutant Strains of Listeria monocytogenes Reveal Host Genes Linked to Phage Adsorption. Appl Environ Microbiol 2015; 81:4295-305. [PMID: 25888172 PMCID: PMC4475870 DOI: 10.1128/aem.00087-15] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/12/2015] [Indexed: 02/06/2023] Open
Abstract
Listeria-infecting phages are readily isolated from Listeria-containing environments, yet little is known about the selective forces they exert on their host. Here, we identified that two virulent phages, LP-048 and LP-125, adsorb to the surface of Listeria monocytogenes strain 10403S through different mechanisms. We isolated and sequenced, using whole-genome sequencing, 69 spontaneous mutant strains of 10403S that were resistant to either one or both phages. Mutations from 56 phage-resistant mutant strains with only a single mutation mapped to 10 genes representing five loci on the 10403S chromosome. An additional 12 mutant strains showed two mutations, and one mutant strain showed three mutations. Two of the loci, containing seven of the genes, accumulated the majority (n = 64) of the mutations. A representative mutant strain for each of the 10 genes was shown to resist phage infection through mechanisms of adsorption inhibition. Complementation of mutant strains with the associated wild-type allele was able to rescue phage susceptibility for 6 out of the 10 representative mutant strains. Wheat germ agglutinin, which specifically binds to N-acetylglucosamine, bound to 10403S and mutant strains resistant to LP-048 but did not bind to mutant strains resistant to only LP-125. We conclude that mutant strains resistant to only LP-125 lack terminal N-acetylglucosamine in their wall teichoic acid (WTA), whereas mutant strains resistant to both phages have disruptive mutations in their rhamnose biosynthesis operon but still possess N-acetylglucosamine in their WTA.
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Affiliation(s)
- Thomas Denes
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Henk C den Bakker
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Jeffrey I Tokman
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Claudia Guldimann
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York, USA
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35
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Tang F, Xing XW, Chu JM, Yuan Q, Zhou X, Feng YQ, Yuan BF. A highly sensitive fluorescence assay for methyltransferase activity by exonuclease-aided signal amplification. Analyst 2015; 140:4636-41. [DOI: 10.1039/c5an00732a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A highly sensitive fluorescence assay for DNA adenine methyltransferase activity was developed using exonuclease-aided signal amplification.
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Affiliation(s)
- Feng Tang
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Xi-Wen Xing
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Jie-Mei Chu
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Quan Yuan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Xiang Zhou
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Yu-Qi Feng
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
| | - Bi-Feng Yuan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)
- Department of Chemistry
- Wuhan University
- Wuhan 430072
- P. R. China
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36
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Ratcliff WC, Hawthorne P, Libby E. Courting disaster: How diversification rate affects fitness under risk. Evolution 2014; 69:126-35. [PMID: 25410817 PMCID: PMC4312886 DOI: 10.1111/evo.12568] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 10/26/2014] [Indexed: 01/21/2023]
Abstract
Life is full of risk. To deal with this uncertainty, many organisms have evolved bet-hedging strategies that spread risk through phenotypic diversification. These rates of diversification can vary by orders of magnitude in different species. Here we examine how key characteristics of risk and organismal ecology affect the fitness consequences of variation in diversification rate. We find that rapid diversification is strongly favored when the risk faced has a wide spatial extent, with a single disaster affecting a large fraction of the population. This advantage is especially great in small populations subject to frequent disaster. In contrast, when risk is correlated through time, slow diversification is favored because it allows adaptive tracking of disasters that tend to occur in series. Naturally evolved diversification mechanisms in diverse organisms facing a broad array of environmental risks largely support these results. The theory presented in this article provides a testable ecological hypothesis to explain the prevalence of slow stochastic switching among microbes and rapid, within-clutch diversification strategies among plants and animals.
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Affiliation(s)
- William C Ratcliff
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332.
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37
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Kwiatek A, Bacal P, Wasiluk A, Trybunko A, Adamczyk-Poplawska M. The dam replacing gene product enhances Neisseria gonorrhoeae FA1090 viability and biofilm formation. Front Microbiol 2014; 5:712. [PMID: 25566225 PMCID: PMC4269198 DOI: 10.3389/fmicb.2014.00712] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 11/29/2014] [Indexed: 12/23/2022] Open
Abstract
Many Neisseriaceae do not exhibit Dam methyltransferase activity and, instead of the dam gene, possess drg (dam replacing gene) inserted in the leuS/dam locus. The drg locus in Neisseria gonorrhoeae FA1090 has a lower GC-pairs content (40.5%) compared to the whole genome of N. gonorrhoeae FA1090 (52%). The gonococcal drg gene encodes a DNA endonuclease Drg, with GmeATC specificity. Disruption of drg or insertion of the dam gene in gonococcal genome changes the level of expression of genes as shown by transcriptome analysis. For the drg-deficient N. gonorrhoeae mutant, a total of 195 (8.94% of the total gene pool) genes exhibited an altered expression compared to the wt strain by at least 1.5 fold. In dam-expressing N. gonorrhoeae mutant, the expression of 240 genes (11% of total genes) was deregulated. Most of these deregulated genes were involved in translation, DNA repair, membrane biogenesis and energy production as shown by cluster of orthologous group analysis. In vivo, the inactivation of drg gene causes the decrease of the number of live neisserial cells and long lag phase of growth. The insertion of dam gene instead of drg locus restores cell viability. We have also shown that presence of the drg gene product is important for N. gonorrhoeae FA1090 in adhesion, including human epithelial cells, and biofilm formation. Biofilm produced by drg-deficient strain is formed by more dispersed cells, compared to this one formed by parental strain as shown by scanning electron and confocal microscopy. Also adherence assays show a significantly smaller biomass of formed biofilm (OD570 = 0.242 ± 0.038) for drg-deficient strain, compared to wild-type strain (OD570 = 0.378 ± 0.057). Dam-expressing gonococcal cells produce slightly weaker biofilm with cells embedded in an extracellular matrix. This strain has also a five times reduced ability for adhesion to human epithelial cells. In this context, the presence of Drg is more advantageous for N. gonorrhoeae biology than Dam presence.
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Affiliation(s)
- Agnieszka Kwiatek
- Department of Virology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
| | - Pawel Bacal
- Laboratory of Theory and Applications of Electrodes, Faculty of Chemistry, University of Warsaw Warsaw, Poland
| | - Adrian Wasiluk
- Department of Virology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
| | - Anastasiya Trybunko
- Department of Virology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
| | - Monika Adamczyk-Poplawska
- Department of Virology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
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38
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Xing XW, Tang F, Wu J, Chu JM, Feng YQ, Zhou X, Yuan BF. Sensitive Detection of DNA Methyltransferase Activity Based on Exonuclease-Mediated Target Recycling. Anal Chem 2014; 86:11269-74. [DOI: 10.1021/ac502845b] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Xi-Wen Xing
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Feng Tang
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Jun Wu
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Jie-Mei Chu
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Yu-Qi Feng
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Xiang Zhou
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
| | - Bi-Feng Yuan
- Key Laboratory of Analytical
Chemistry for Biology and Medicine (Ministry of Education), Department
of Chemistry, Wuhan University, Wuhan, Hubei 430072, P.R. China
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39
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Are bacteriophage defence and virulence two sides of the same coin in Campylobacter jejuni? Biochem Soc Trans 2014; 41:1475-81. [PMID: 24256240 DOI: 10.1042/bst20130127] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The continuous battle for survival in the environment has led to the development or acquisition of sophisticated defence systems in bacteria. These defence systems have contributed to the survival of the bacterial species in the environment for millions of years. Some systems appear to have evolved in a number of pathogenic bacteria towards a role in virulence and host immune evasion. Recently, different bacterial cell envelope components from diverse bacterial species have been linked not only to bacteriophage defence, but also to virulence features. In the present review we focus specifically on the bacterial cell envelope-expressed sialic-acid-containing LOS (lipo-oligosaccharide) structures and Type II CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) genes that both occur in specific Gram-negative pathogens. In Campylobacter jejuni circumstantial evidence points at a potential intertwined dual function between sialylated LOS structures and subtype II-C CRISPR-Cas, i.e. in phage defence and virulence. In the present review we discuss whether a dual functionality of sialylated LOS and subtype II-C CRISPR-Cas is exclusive to C. jejuni only or could be more widespread within the group of Type II CRISPR-Cas-harbouring bacteria. We conclude from the literature that, at least in C. jejuni, circumstantial evidence exists for a complex intertwined dual functionality between sialylated LOS and Type II CRISPR-Cas, and that other bacteria show similar genomic signatures.
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40
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Rivière G. Epigenetic features in the oyster Crassostrea gigas suggestive of functionally relevant promoter DNA methylation in invertebrates. Front Physiol 2014; 5:129. [PMID: 24778620 PMCID: PMC3985014 DOI: 10.3389/fphys.2014.00129] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 03/14/2014] [Indexed: 12/22/2022] Open
Abstract
DNA methylation is evolutionarily conserved. Vertebrates exhibit high, widespread DNA methylation whereas invertebrate genomes are less methylated, predominantly within gene bodies. DNA methylation in invertebrates is associated with transcription level, alternative splicing, and genome evolution, but functional outcomes of DNA methylation remain poorly described in lophotrochozoans. Recent genome-wide approaches improve understanding in distant taxa such as molluscs, where the phylogenetic position, and life traits of Crassostrea gigas make this bivalve an ideal model to study the physiological and evolutionary implications of DNA methylation. We review the literature about DNA methylation in invertebrates and focus on DNA methylation features in the oyster. Indeed, though our MeDIP-seq results confirm predominant intragenic methylation, the profiles depend on the oyster's developmental and reproductive stage. We discuss the perspective that oyster DNA methylation could be biased toward the 5'-end of some genes, depending on physiological status, suggesting important functional outcomes of putative promoter methylation from cell differentiation during early development to sustained adaptation of the species to the environment.
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Affiliation(s)
- Guillaume Rivière
- Institute for Fundamental and Applied Biology, Normandy UniversityCaen, France
- UMR BOREA ‘Biologie des Organismes et Ecosystèmes Aquatiques’ Université de Caen Basse-Normandie, MNHN, UPMC, CNRS-7208, IRD-207Caen, France
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41
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Genomic and global approaches to unravelling how hypermutable sequences influence bacterial pathogenesis. Pathogens 2014; 3:164-84. [PMID: 25437613 PMCID: PMC4235727 DOI: 10.3390/pathogens3010164] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/06/2014] [Accepted: 02/13/2014] [Indexed: 12/23/2022] Open
Abstract
Rapid adaptation to fluctuations in the host milieu contributes to the host persistence and virulence of bacterial pathogens. Adaptation is frequently mediated by hypermutable sequences in bacterial pathogens. Early bacterial genomic studies identified the multiplicity and virulence-associated functions of these hypermutable sequences. Thus, simple sequence repeat tracts (SSRs) and site-specific recombination were found to control capsular type, lipopolysaccharide structure, pilin diversity and the expression of outer membrane proteins. We review how the population diversity inherent in the SSR-mediated mechanism of localised hypermutation is being unlocked by the investigation of whole genome sequences of disease isolates, analysis of clinical samples and use of model systems. A contrast is presented between the problematical nature of analysing simple sequence repeats in next generation sequencing data and in simpler, pragmatic PCR-based approaches. Specific examples are presented of the potential relevance of this localized hypermutation to meningococcal pathogenesis. This leads us to speculate on the future prospects for unravelling how hypermutable mechanisms may contribute to the transmission, spread and persistence of bacterial pathogens.
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42
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Danne C, Dubrac S, Trieu-Cuot P, Dramsi S. Single cell stochastic regulation of pilus phase variation by an attenuation-like mechanism. PLoS Pathog 2014; 10:e1003860. [PMID: 24453966 PMCID: PMC3894217 DOI: 10.1371/journal.ppat.1003860] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Accepted: 11/18/2013] [Indexed: 12/17/2022] Open
Abstract
The molecular triggers leading to virulence of a number of human-adapted commensal bacteria such as Streptococcus gallolyticus are largely unknown. This opportunistic pathogen is responsible for endocarditis in the elderly and associated with colorectal cancer. Colonization of damaged host tissues with exposed collagen, such as cardiac valves and pre-cancerous polyps, is mediated by appendages referred to as Pil1 pili. Populations of S. gallolyticus are heterogeneous with the majority of cells weakly piliated while a smaller fraction is hyper piliated. We provide genetic evidences that heterogeneous pil1 expression depends on a phase variation mechanism involving addition/deletion of GCAGA repeats that modifies the length of an upstream leader peptide. Synthesis of longer leader peptides potentiates the transcription of the pil1 genes through ribosome-induced destabilization of a premature stem-loop transcription terminator. This study describes, at the molecular level, a new regulatory mechanism combining phase variation in a leader peptide-encoding gene and transcription attenuation. This simple and robust mechanism controls a stochastic heterogeneous pilus expression, which is important for evading the host immune system while ensuring optimal tissue colonization. Streptococcus gallolyticus (formely known as S. bovis biotype I) is an emerging cause of septicemia and endocarditis in the elderly. Intriguingly, epidemiological studies revealed a strong association, up to 65%, between endocarditis due to S. gallolyticus and colorectal malignancies. Whether S. gallolyticus infection is a cause or a consequence of colon cancer remains to be investigated. We previously showed that colonization of damaged cardiac valves with exposed collagen is mediated by the Pil1 pilus in S. gallolyticus. In the present work, we report that Pil1 is heterogeneously expressed at the single cell level, giving rise to two distinct bacterial subpopulations, a majority of weakly piliated cells and a minority of hyper-piliated cells. We have characterized, at the molecular level, a novel regulatory mechanism responsible for Pil1 heterogeneous expression combining phase variation in the leader peptide and transcriptional attenuation. Pili are highly immunogenic proteins proposed as vaccine candidate in pathogenic streptococci whose expression involves a fitness cost due to the selective pressure of host immune responses. Hence, this robust and simple system mitigates susceptibility to immune defenses while ensuring optimal colonization of host tissues.
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Affiliation(s)
- Camille Danne
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
- Université Paris Diderot-Sorbonne Paris Cité, Paris, France
| | - Sarah Dubrac
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
- * E-mail:
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Bühlmann A, Dreo T, Rezzonico F, Pothier JF, Smits THM, Ravnikar M, Frey JE, Duffy B. Phylogeography and population structure of the biologically invasive phytopathogen Erwinia amylovora inferred using minisatellites. Environ Microbiol 2013; 16:2112-25. [PMID: 24112873 DOI: 10.1111/1462-2920.12289] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/14/2013] [Indexed: 01/08/2023]
Abstract
Erwinia amylovora causes a major disease of pome fruit trees worldwide, and is regulated as a quarantine organism in many countries. While some diversity of isolates has been observed, molecular epidemiology of this bacterium is hindered by a lack of simple molecular typing techniques with sufficiently high resolution. We report a molecular typing system of E. amylovora based on variable number of tandem repeats (VNTR) analysis. Repeats in the E. amylovora genome were identified with comparative genomic tools, and VNTR markers were developed and validated. A Multiple-Locus VNTR Analysis (MLVA) was applied to E. amylovora isolates from bacterial collections representing global and regional distribution of the pathogen. Based on six repeats, MLVA allowed the distinction of 227 haplotypes among a collection of 833 isolates of worldwide origin. Three geographically separated groups were recognized among global isolates using Bayesian clustering methods. Analysis of regional outbreaks confirmed presence of diverse haplotypes but also high representation of certain haplotypes during outbreaks. MLVA analysis is a practical method for epidemiological studies of E. amylovora, identifying previously unresolved population structure within outbreaks. Knowledge of such structure can increase our understanding on how plant diseases emerge and spread over a given geographical region.
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Affiliation(s)
- Andreas Bühlmann
- Plant Protection Division, Agroscope Changins-Wädenswil Research Station ACW, CH-8820, Wädenswil, Switzerland
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Chibeu A, Agius L, Gao A, Sabour PM, Kropinski AM, Balamurugan S. Efficacy of bacteriophage LISTEX™P100 combined with chemical antimicrobials in reducing Listeria monocytogenes in cooked turkey and roast beef. Int J Food Microbiol 2013; 167:208-14. [DOI: 10.1016/j.ijfoodmicro.2013.08.018] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/22/2013] [Accepted: 08/23/2013] [Indexed: 11/24/2022]
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Zhou K, Aertsen A, Michiels CW. The role of variable DNA tandem repeats in bacterial adaptation. FEMS Microbiol Rev 2013; 38:119-41. [PMID: 23927439 DOI: 10.1111/1574-6976.12036] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/13/2013] [Accepted: 07/26/2013] [Indexed: 01/05/2023] Open
Abstract
DNA tandem repeats (TRs), also designated as satellite DNA, are inter- or intragenic nucleotide sequences that are repeated two or more times in a head-to-tail manner. Because TR tracts are prone to strand-slippage replication and recombination events that cause the TR copy number to increase or decrease, loci containing TRs are hypermutable. An increasing number of examples illustrate that bacteria can exploit this instability of TRs to reversibly shut down or modulate the function of specific genes, allowing them to adapt to changing environments on short evolutionary time scales without an increased overall mutation rate. In this review, we discuss the prevalence and distribution of inter- and intragenic TRs in bacteria and the mechanisms of their instability. In addition, we review evidence demonstrating a role of TR variations in bacterial adaptation strategies, ranging from immune evasion and tissue tropism to the modulation of environmental stress tolerance. Nevertheless, while bioinformatic analysis reveals that most bacterial genomes contain a few up to several dozens of intra- and intergenic TRs, only a small fraction of these have been functionally studied to date.
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Affiliation(s)
- Kai Zhou
- Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
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Clark SE, Eichelberger KR, Weiser JN. Evasion of killing by human antibody and complement through multiple variations in the surface oligosaccharide of Haemophilus influenzae. Mol Microbiol 2013; 88:603-18. [PMID: 23577840 DOI: 10.1111/mmi.12214] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2013] [Indexed: 11/29/2022]
Abstract
The lipopolysaccharide (LPS) of H. influenzae is highly variable. Much of the structural diversity is derived from phase variation, or high frequency on-off switching, of molecules attached during LPS biosynthesis. In this study, we examined the dynamics of LPS phase variation following exposure to human serum as a source of antibody and complement in multiple H. influenzae isolates. We show that lic2A, lgtC and lex2A switch from phase-off to phase-on following serial passage in human serum. These genes, which control attachment of a galα1-4gal di-galactoside structure (lic2A and lgtC phase-on) or an alternative glucose extension (lex2A phase-on) from the same hexose moiety, reduce binding of bactericidal antibody to conserved inner core LPS structures. The effects of the di-galactoside and alternative glucose extension were also examined in the context of the additional LPS phase variable structures phosphorylcholine (ChoP) and sialic acid. We found that di-galactoside, the alternative glucose extension, ChoP, and sialic acid each contribute independently to bacterial survival in the presence of human complement, and have an additive effect in combination. We propose that LPS phase variable extensions serve to shield conserved inner core structures from recognition by host immune components encountered during infection.
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Affiliation(s)
- Sarah E Clark
- Department of Microbiology, University of Pennsylvania, Philadelphia, PA, USA
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Kęsik-Szeloch A, Drulis-Kawa Z, Weber-Dąbrowska B, Kassner J, Majkowska-Skrobek G, Augustyniak D, Lusiak-Szelachowska M, Zaczek M, Górski A, Kropinski AM. Characterising the biology of novel lytic bacteriophages infecting multidrug resistant Klebsiella pneumoniae. Virol J 2013; 10:100. [PMID: 23537199 PMCID: PMC3620542 DOI: 10.1186/1743-422x-10-100] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/25/2013] [Indexed: 01/21/2023] Open
Abstract
Background Members of the genus Klebsiella are among the leading microbial pathogens associated with nosocomial infection. The increased incidence of antimicrobial resistance in these species has propelled the need for alternate/combination therapeutic regimens to aid clinical treatment. Bacteriophage therapy forms one of these alternate strategies. Methods Electron microscopy, burst size, host range, sensitivity of phage particles to temperature, chloroform, pH, and restriction digestion of phage DNA were used to characterize Klebsiella phages. Results and conclusions Of the 32 isolated phages eight belonged to the family Myoviridae, eight to the Siphoviridae whilst the remaining 16 belonged to the Podoviridae. The host range of these phages was characterised against 254 clinical Enterobacteriaceae strains including multidrug resistant Klebsiella isolates producing extended-spectrum beta-lactamases (ESBLs). Based on their lytic potential, six of the phages were further characterised for burst size, physicochemical properties and sensitivity to restriction endonuclease digestion. In addition, five were fully sequenced. Multiple phage-encoded host resistance mechanisms were identified. The Siphoviridae phage genomes (KP16 and KP36) contained low numbers of host restriction sites similar to the strategy found in T7-like phages (KP32). In addition, phage KP36 encoded its own DNA adenine methyltransferase. The φKMV-like KP34 phage was sensitive to all endonucleases used in this study. Dam methylation of KP34 DNA was detected although this was in the absence of an identifiable phage encoded methyltransferase. The Myoviridae phages KP15 and KP27 both carried Dam and Dcm methyltransferase genes and other anti-restriction mechanisms elucidated in previous studies. No other anti-restriction mechanisms were found, e.g. atypical nucleotides (hmC or glucosyl hmC), although Myoviridae phage KP27 encodes an unknown anti-restriction mechanism that needs further investigation.
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Affiliation(s)
- Agata Kęsik-Szeloch
- Institute of Genetics and Microbiology, University of Wroclaw, Przybyszewskiego 63/77, Wroclaw, Poland
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Bayliss CD, Palmer ME. Evolution of simple sequence repeat-mediated phase variation in bacterial genomes. Ann N Y Acad Sci 2012; 1267:39-44. [PMID: 22954215 DOI: 10.1111/j.1749-6632.2012.06584.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mutability as mechanism for rapid adaptation to environmental challenge is an alluringly simple concept whose apotheosis is realized in simple sequence repeats (SSR). Bacterial genomes of several species contain SSRs with a proven role in adaptation to environmental fluctuations. SSRs are hypermutable and generate reversible mutations in localized regions of bacterial genomes, leading to phase variable ON/OFF switches in gene expression. The application of genetic, bioinformatic, and mathematical/computational modeling approaches are revolutionizing our current understanding of how genomic molecular forces and environmental factors influence SSR-mediated adaptation and led to evolution of this mechanism of localized hypermutation in bacterial genomes.
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Kim M, Ryu S. Spontaneous and transient defence against bacteriophage by phase-variable glucosylation of O-antigen in Salmonella enterica serovar Typhimurium. Mol Microbiol 2012; 86:411-25. [PMID: 22928771 DOI: 10.1111/j.1365-2958.2012.08202.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2012] [Indexed: 01/21/2023]
Abstract
As natural killers of bacteria, bacteriophages have forced bacteria to develop a variety of defence mechanisms. The alteration of host receptors is one of the most common bacterial defence strategies against phage infection, which completely blocks phage attachment but comes at a potential fitness cost to the bacteria. Here, we report the cost-free, transient emergence of phage resistance in Salmonella enterica subspecies enterica serovar Typhimurium through a phase-variable modification of the O-antigen. Phage SPC35 typically requires BtuB as a host receptor but also uses the Salmonella O12-antigen as an adsorption-assisting apparatus for the successful infection of S. Typhimurium. The α-1,4-glucosylation of galactose residues in the O12-antigen by phase variably expressed O-antigen glucosylating genes, designated the (LT) (2) gtrABC1 cluster, blocks the adsorption-assisting function of the O12-antigen. Consequently, it confers transient SPC35 resistance to Salmonella without any mutations to the btuB gene. This temporal switch-off of phage adsorption through phase-variable antigenic modification may be widespread among Gram-negative bacteria-phage systems.
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Affiliation(s)
- Minsik Kim
- Department of Food and Animal Biotechnology, Seoul, Korea
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50
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Bikard D, Marraffini LA. Innate and adaptive immunity in bacteria: mechanisms of programmed genetic variation to fight bacteriophages. Curr Opin Immunol 2011; 24:15-20. [PMID: 22079134 DOI: 10.1016/j.coi.2011.10.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 10/21/2011] [Indexed: 12/26/2022]
Abstract
Bacteria are constantly challenged by bacteriophages (viruses that infect bacteria), the most abundant microorganism on earth. Bacteria have evolved a variety of immunity mechanisms to resist bacteriophage infection. In response, bacteriophages can evolve counter-resistance mechanisms and launch a 'virus versus host' evolutionary arms race. In this context, rapid evolution is fundamental for the survival of the bacterial cell. Programmed genetic variation mechanisms at loci involved in immunity against bacteriophages generate diversity at a much faster rate than random point mutation and enable bacteria to quickly adapt and repel infection. Diversity-generating retroelements (DGRs) and phase variation mechanisms enhance the generic (innate) immune response against bacteriophages. On the other hand, the integration of small bacteriophage sequences in CRISPR loci provide bacteria with a virus-specific and sequence-specific adaptive immune response. Therefore, although using different molecular mechanisms, both prokaryotes and higher organisms rely on programmed genetic variation to increase genetic diversity and fight rapidly evolving infectious agents.
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Affiliation(s)
- David Bikard
- Laboratory of Bacteriology, The Rockefeller University, 10065 New York, NY, USA
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