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Alsaadi SE, Lu H, Zhang M, Dykes GF, Allison HE, Horsburgh MJ. Bacteriophages from human skin infecting coagulase-negative Staphylococcus: diversity, novelty and host resistance. Sci Rep 2024; 14:8245. [PMID: 38589670 PMCID: PMC11001980 DOI: 10.1038/s41598-024-59065-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 04/06/2024] [Indexed: 04/10/2024] Open
Abstract
The human skin microbiome comprises diverse populations that differ temporally between body sites and individuals. The virome is a less studied component of the skin microbiome and the study of bacteriophages is required to increase knowledge of the modulation and stability of bacterial communities. Staphylococcus species are among the most abundant colonisers of skin and are associated with both health and disease yet the bacteriophages infecting the most abundant species on skin are less well studied. Here, we report the isolation and genome sequencing of 40 bacteriophages from human skin swabs that infect coagulase-negative Staphylococcus (CoNS) species, which extends our knowledge of phage diversity. Six genetic clusters of phages were identified with two clusters representing novel phages, one of which we characterise and name Alsa phage. We identified that Alsa phages have a greater ability to infect the species S. hominis that was otherwise infected less than other CoNS species by the isolated phages, indicating an undescribed barrier to phage infection that could be in part due to numerous restriction-modification systems. The extended diversity of Staphylococcus phages here enables further research to define their contribution to skin microbiome research and the mechanisms that limit phage infection.
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Affiliation(s)
- Samah E Alsaadi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Hanshuo Lu
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Minxing Zhang
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Gregory F Dykes
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Heather E Allison
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Malcolm J Horsburgh
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
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2
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Stanojković A, Skoupý S, Škaloud P, Dvořák P. High genomic differentiation and limited gene flow indicate recent cryptic speciation within the genus Laspinema (cyanobacteria). Front Microbiol 2022; 13:977454. [PMID: 36160208 PMCID: PMC9500459 DOI: 10.3389/fmicb.2022.977454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022] Open
Abstract
The sympatric occurrence of closely related lineages displaying conserved morphological and ecological traits is often characteristic of free-living microbes. Gene flow, recombination, selection, and mutations govern the genetic variability between these cryptic lineages and drive their differentiation. However, sequencing conservative molecular markers (e.g., 16S rRNA) coupled with insufficient population-level sampling hindered the study of intra-species genetic diversity and speciation in cyanobacteria. We used phylogenomics and a population genomic approach to investigate the extent of local genomic diversity and the mechanisms underlying sympatric speciation of Laspinema thermale. We found two cryptic lineages of Laspinema. The lineages were highly genetically diverse, with recombination occurring more frequently within than between them. That suggests the existence of a barrier to gene flow, which further maintains divergence. Genomic regions of high population differentiation harbored genes associated with possible adaptations to high/low light conditions and stress stimuli, although with a weak diversifying selection. Overall, the diversification of Laspinema species might have been affected by both genomic and ecological processes.
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Affiliation(s)
| | - Svatopluk Skoupý
- Department of Botany, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
| | - Pavel Škaloud
- Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czechia
| | - Petr Dvořák
- Department of Botany, Faculty of Science, Palacký University Olomouc, Olomouc, Czechia
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3
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Sun H, Mu X, Zhang K, Lang H, Su Q, Li X, Zhou X, Zhang X, Zheng H. Geographical resistome profiling in the honeybee microbiome reveals resistance gene transfer conferred by mobilizable plasmids. MICROBIOME 2022; 10:69. [PMID: 35501925 PMCID: PMC9063374 DOI: 10.1186/s40168-022-01268-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 04/04/2022] [Indexed: 05/11/2023]
Abstract
BACKGROUND The spread of antibiotic resistance genes (ARGs) has been of global concern as one of the greatest environmental threats. The gut microbiome of animals has been found to be a large reservoir of ARGs, which is also an indicator of the environmental antibiotic spectrum. The conserved microbiota makes the honeybee a tractable and confined ecosystem for studying the maintenance and transfer of ARGs across gut bacteria. Although it has been found that honeybee gut bacteria harbor diverse sets of ARGs, the influences of environmental variables and the mechanism driving their distribution remain unclear. RESULTS We characterized the gut resistome of two closely related honeybee species, Apis cerana and Apis mellifera, domesticated in 14 geographic locations across China. The composition of the ARGs was more associated with host species rather than with geographical distribution, and A. mellifera had a higher content of ARGs in the gut. There was a moderate geographic pattern of resistome distribution, and several core ARG groups were found to be prevalent among A. cerana samples. These shared genes were mainly carried by the honeybee-specific gut members Gilliamella and Snodgrassella. Transferrable ARGs were frequently detected in honeybee guts, and the load was much higher in A. mellifera samples. Genomic loci of the bee gut symbionts containing a streptomycin resistance gene cluster were nearly identical to those of the broad-host-range IncQ plasmid, a proficient DNA delivery system in the environment. By in vitro conjugation experiments, we confirmed that the mobilizable plasmids could be transferred between honeybee gut symbionts by conjugation. Moreover, "satellite plasmids" with fragmented genes were identified in the integrated regions of different symbionts from multiple areas. CONCLUSIONS Our study illustrates that the gut microbiota of different honeybee hosts varied in their antibiotic resistance structure, highlighting the role of the bee microbiome as a potential bioindicator and disseminator of antibiotic resistance. The difference in domestication history is highly influential in the structuring of the bee gut resistome. Notably, the evolution of plasmid-mediated antibiotic resistance is likely to promote the probability of its persistence and dissemination. Video Abstract.
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Affiliation(s)
- Huihui Sun
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Xiaohuan Mu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Kexun Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Haoyu Lang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Qinzhi Su
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Xingan Li
- Key Laboratory for Bee Genetics and Breeding, Jilin Provincial Institute of Apicultural Sciences, Jilin, 132000, China
| | - Xin Zhou
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100083, China
| | - Xue Zhang
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100083, China.
| | - Hao Zheng
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
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4
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Birkholz N, Jackson SA, Fagerlund RD, Fineran P. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3348-3361. [PMID: 35286398 PMCID: PMC8989522 DOI: 10.1093/nar/gkac147] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 11/16/2022] Open
Abstract
Epigenetic DNA methylation plays an important role in bacteria by influencing gene expression and allowing discrimination between self-DNA and intruders such as phages and plasmids. Restriction–modification (RM) systems use a methyltransferase (MTase) to modify a specific sequence motif, thus protecting host DNA from cleavage by a cognate restriction endonuclease (REase) while leaving invading DNA vulnerable. Other REases occur solitarily and cleave methylated DNA. REases and RM systems are frequently mobile, influencing horizontal gene transfer by altering the compatibility of the host for foreign DNA uptake. However, whether mobile defence systems affect pre-existing host defences remains obscure. Here, we reveal an epigenetic conflict between an RM system (PcaRCI) and a methylation-dependent REase (PcaRCII) in the plant pathogen Pectobacterium carotovorum RC5297. The PcaRCI RM system provides potent protection against unmethylated plasmids and phages, but its methylation motif is targeted by the methylation-dependent PcaRCII. This potentially lethal co-existence is enabled through epigenetic silencing of the PcaRCII-encoding gene via promoter methylation by the PcaRCI MTase. Comparative genome analyses suggest that the PcaRCII-encoding gene was already present and was silenced upon establishment of the PcaRCI system. These findings provide a striking example for selfishness of RM systems and intracellular competition between different defences.
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Affiliation(s)
- Nils Birkholz
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Simon A Jackson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Peter C Fineran
- To whom correspondence should be addressed: Tel: +64 3 479 7735;
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6
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Randall SE, Martini MC, Zhou Y, Joubran SR, Shell SS. MamA essentiality in Mycobacterium smegmatis is explained by the presence of an apparent cognate restriction endonuclease. BMC Res Notes 2020; 13:462. [PMID: 32993774 PMCID: PMC7526240 DOI: 10.1186/s13104-020-05302-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/22/2020] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Restriction-Modification (R-M) systems are ubiquitous in bacteria and were considered for years as rudimentary immune systems that protect bacterial cells from foreign DNA. Currently, these R-M systems are recognized as important players in global gene expression and other cellular processes such us virulence and evolution of genomes. Here, we report the role of the unique DNA methyltransferase in Mycobacterium smegmatis, which shows a moderate degree of sequence similarity to MamA, a previously characterized methyltransferase that affects gene expression in Mycobacterium tuberculosis and is important for survival under hypoxic conditions. RESULTS We found that depletion of mamA levels impairs growth and produces elongated cell bodies. Microscopy revealed irregular septation and unevenly distributed DNA, with large areas devoid of DNA and small DNA-free cells. Deletion of MSMEG_3214, a predicted endonuclease-encoding gene co-transcribed with mamA, restored the WT growth phenotype in a mamA-depleted background. Our results suggest that the mamA-depletion phenotype can be explained by DNA cleavage by the apparent cognate restriction endonuclease MSMEG_3214. In addition, in silico analysis predicts that both MamA methyltransferase and MSMEG_3214 endonuclease recognize the same palindromic DNA sequence. We propose that MamA and MSMEG_3214 constitute a previously undescribed R-M system in M. smegmatis.
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Affiliation(s)
- Samantha E Randall
- Department of Biology & Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Maria Carla Martini
- Department of Biology & Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Ying Zhou
- Department of Biology & Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Samantha R Joubran
- Department of Biology & Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Scarlet S Shell
- Department of Biology & Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA. .,Program in Bioinformatics & Computational Biology, Worcester Polytechnic Institute, Worcester, MA, USA.
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Calder A, Menkiti CJ, Çağdaş A, Lisboa Santos J, Streich R, Wong A, Avini AH, Bojang E, Yogamanoharan K, Sivanesan N, Ali B, Ashrafi M, Issa A, Kaur T, Latif A, Mohamed HAS, Maqsood A, Tamang L, Swager E, Stringer AJ, Snyder LAS. Virulence genes and previously unexplored gene clusters in four commensal Neisseria spp. isolated from the human throat expand the neisserial gene repertoire. Microb Genom 2020; 6. [PMID: 32845827 PMCID: PMC7643975 DOI: 10.1099/mgen.0.000423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Commensal non-pathogenic Neisseria spp. live within the human host alongside the pathogenic Neisseria meningitidis and Neisseria gonorrhoeae and due to natural competence, horizontal gene transfer within the genus is possible and has been observed. Four distinct Neisseria spp. isolates taken from the throats of two human volunteers have been assessed here using a combination of microbiological and bioinformatics techniques. Three of the isolates have been identified as Neisseria subflava biovar perflava and one as Neisseria cinerea. Specific gene clusters have been identified within these commensal isolate genome sequences that are believed to encode a Type VI Secretion System, a newly identified CRISPR system, a Type IV Secretion System unlike that in other Neisseria spp., a hemin transporter, and a haem acquisition and utilization system. This investigation is the first to investigate these systems in either the non-pathogenic or pathogenic Neisseria spp. In addition, the N. subflava biovar perflava possess previously unreported capsule loci and sequences have been identified in all four isolates that are similar to genes seen within the pathogens that are associated with virulence. These data from the four commensal isolates provide further evidence for a Neisseria spp. gene pool and highlight the presence of systems within the commensals with functions still to be explored.
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Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Chukwuma Jude Menkiti
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Aylin Çağdaş
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Jefferson Lisboa Santos
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Ricarda Streich
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Alice Wong
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Amir H Avini
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Ebrima Bojang
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Karththeepan Yogamanoharan
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Nivetha Sivanesan
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Besma Ali
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Mariam Ashrafi
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Abdirizak Issa
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Tajinder Kaur
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Aisha Latif
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Hani A Sheik Mohamed
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Atifa Maqsood
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Laxmi Tamang
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Emily Swager
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Alex J Stringer
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Kingston upon Thames, KT1 2EE, UK
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8
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Oliveira PH, Fang G. Conserved DNA Methyltransferases: A Window into Fundamental Mechanisms of Epigenetic Regulation in Bacteria. Trends Microbiol 2020; 29:28-40. [PMID: 32417228 DOI: 10.1016/j.tim.2020.04.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 03/19/2020] [Accepted: 04/10/2020] [Indexed: 12/14/2022]
Abstract
An increasing number of studies have reported that bacterial DNA methylation has important functions beyond the roles in restriction-modification systems, including the ability of affecting clinically relevant phenotypes such as virulence, host colonization, sporulation, biofilm formation, among others. Although insightful, such studies have a largely ad hoc nature and would benefit from a systematic strategy enabling a joint functional characterization of bacterial methylomes by the microbiology community. In this opinion article, we propose that highly conserved DNA methyltransferases (MTases) represent a unique opportunity for bacterial epigenomic studies. These MTases are rather common in bacteria, span various taxonomic scales, and are present in multiple human pathogens. Apart from well-characterized core DNA MTases, like those from Vibrio cholerae, Salmonella enterica, Clostridioides difficile, or Streptococcus pyogenes, multiple highly conserved DNA MTases are also found in numerous human pathogens, including those belonging to the genera Burkholderia and Acinetobacter. We discuss why and how these MTases can be prioritized to enable a community-wide, integrative approach for functional epigenomic studies. Ultimately, we discuss how some highly conserved DNA MTases may emerge as promising targets for the development of novel epigenetic inhibitors for biomedical applications.
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Affiliation(s)
- Pedro H Oliveira
- Department of Genetics and Genomic Sciences, Institute for Genomics and Multiscale Biology, Mount Sinai School of Medicine, New York, NY, USA.
| | - Gang Fang
- Department of Genetics and Genomic Sciences, Institute for Genomics and Multiscale Biology, Mount Sinai School of Medicine, New York, NY, USA.
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9
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Negri A, Jąkalski M, Szczuka A, Pryszcz LP, Mruk I. Transcriptome analyses of cells carrying the Type II Csp231I restriction-modification system reveal cross-talk between two unrelated transcription factors: C protein and the Rac prophage repressor. Nucleic Acids Res 2019; 47:9542-9556. [PMID: 31372643 PMCID: PMC6765115 DOI: 10.1093/nar/gkz665] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 07/16/2019] [Accepted: 07/23/2019] [Indexed: 12/27/2022] Open
Abstract
Restriction-modification (R–M) systems represent an effective mechanism of defence against invading bacteriophages, and are widely spread among bacteria and archaea. In acquiring a Type II R–M system via horizontal gene transfer, the new hosts become more resistant to phage infection, through the action of a restriction endonuclease (REase), which recognizes and cleaves specific target DNAs. To protect the host cell's DNA, there is also a methyltransferase (MTase), which prevents DNA cleavage by the cognate REase. In some R–M systems, the host also accepts a cis-acting transcription factor (C protein), which regulates the counteracting activities of REase and MTase to avoid host self-restriction. Our study characterized the unexpected phenotype of Escherichia coli cells, which manifested as extensive cell filamentation triggered by acquiring the Csp231I R–M system from Citrobacter sp. Surprisingly, we found that the cell morphology defect was solely dependent on the C regulator. Our transcriptome analysis supported by in vivo and in vitro assays showed that C protein directly silenced the expression of the RacR repressor to affect the Rac prophage-related genes. The rac locus ydaST genes, when derepressed, exerted a toxicity indicated by cell filamentation through an unknown mechanism. These results provide an apparent example of transcription factor cross-talk, which can have significant consequences for the host, and may represent a constraint on lateral gene transfer.
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Affiliation(s)
- Alessandro Negri
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Marcin Jąkalski
- Department of Plant Taxonomy and Nature Conservation, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| | - Aleksandra Szczuka
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Leszek P Pryszcz
- Laboratory of Zebrafish Developmental Genomics, International Institute of Molecular and Cell Biology, Warsaw, ul. Trojdena 4, 02-109 Warsaw, Poland
| | - Iwona Mruk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
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Yang C, Pei X, Wu Y, Yan L, Yan Y, Song Y, Coyle NM, Martinez-Urtaza J, Quince C, Hu Q, Jiang M, Feil E, Yang D, Song Y, Zhou D, Yang R, Falush D, Cui Y. Recent mixing of Vibrio parahaemolyticus populations. THE ISME JOURNAL 2019; 13:2578-2588. [PMID: 31235840 PMCID: PMC6775990 DOI: 10.1038/s41396-019-0461-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 06/04/2019] [Accepted: 06/07/2019] [Indexed: 02/07/2023]
Abstract
Humans have profoundly affected the ocean environment but little is known about anthropogenic effects on the distribution of microbes. Vibrio parahaemolyticus is found in warm coastal waters and causes gastroenteritis in humans and economically significant disease in shrimps. Based on data from 1103 genomes of environmental and clinical isolates, we show that V. parahaemolyticus is divided into four diverse populations, VppUS1, VppUS2, VppX and VppAsia. The first two are largely restricted to the US and Northern Europe, while the others are found worldwide, with VppAsia making up the great majority of isolates in the seas around Asia. Patterns of diversity within and between the populations are consistent with them having arisen by progressive divergence via genetic drift during geographical isolation. However, we find that there is substantial overlap in their current distribution. These observations can be reconciled without requiring genetic barriers to exchange between populations if long-range dispersal has increased dramatically in the recent past. We found that VppAsia isolates from the US have an average of 1.01% more shared ancestry with VppUS1 and VppUS2 isolates than VppAsia isolates from Asia itself. Based on time calibrated trees of divergence within epidemic lineages, we estimate that recombination affects about 0.017% of the genome per year, implying that the genetic mixture has taken place within the last few decades. These results suggest that human activity, such as shipping, aquatic products trade and increased human migration between continents, are responsible for the change of distribution pattern of this species.
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Affiliation(s)
- Chao Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Xiaoyan Pei
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yarong Wu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Lin Yan
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Yuqin Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | | | | | | | - Qinghua Hu
- Shenzhen Centre for Disease Control and Prevention, Shenzhen, 518055, China
| | - Min Jiang
- Shenzhen Centre for Disease Control and Prevention, Shenzhen, 518055, China
| | | | - Dajin Yang
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
| | | | - Yujun Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
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11
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Zhu D, Wan J, Yang Z, Xu J, Wang M, Jia R, Chen S, Liu M, Zhao X, Yang Q, Wu Y, Zhang S, Liu Y, Zhang L, Yu Y, Chen X, Cheng A. First Report of Integrative Conjugative Elements in Riemerella anatipestifer Isolates From Ducks in China. Front Vet Sci 2019; 6:128. [PMID: 31069241 PMCID: PMC6491836 DOI: 10.3389/fvets.2019.00128] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 04/05/2019] [Indexed: 12/15/2022] Open
Abstract
We report for the first time the occurrence of integrative conjugative elements (ICEs) in Riemerella anatipestifer (R.anatipestifer) isolated from diseased ducks in China. For this purpose, a total of 48 genome sequences were investigated, which comprised 30 publicly available R. anatipestifer genome sequences, and 18 clinical isolates genomes sequences. Two ICEs, named ICERanRCAD0133-1 and ICERanRCAD0179-1 following the classic nomenclature system, were identified in R. anatipestifer through the use of bioinformatics tools. Comparative analysis revealed that three ICEs in Ornithobacterium rhinotracheale showed a high degree of conservation with the core genes of ICERanRCAD0133-1, while 13 ICEs with high similarity to ICERanRCAD0179-1 were found in Bacteroidetes. Based on the definition of ICE family, ICERanRCAD0179-1 was grouped in CTnDOT/ERL family; however, ICERanRCAD0133-1, which had no significant similarity with known ICEs, might be classified into a novel ICE family. The sequences of ICERanRCAD0133-1 and ICERanRCAD0179-1 were 70890 bp and 49166 bp in length, had 33.14 and 50.34% GC content, and contained 77 CDSs and 51 CDSs, respectively. Cargo genes carried by these two ICEs were predicted to encode: R-M systems, IS elements, a putative TonB-dependent receptor, a bacteriocin/lantibiotic efflux ABC transporter, a tetracycline resistance gene and more. In addition, phylogenetic analyses revealed that ICERanRCAD0179-1 and related ICEs were derived from a common ancestor, which may have undergone divergence prior to integartation into the host bacterial chromosome, and that the core genes co-evolved via a related evolutionary process or experienced only a low degree of recombination events during spread from a common CTnDOT/ERL family ancestor. Collectively, this study is the first identification and characterization of ICEs in R. anatipestifer; and provides new insights into the genetic diversity, evolution, adaptation, antimicrobial resistance, and virulence of R. anatipestifer.
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Affiliation(s)
- Dekang Zhu
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Jianbang Wan
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
| | - Zhishuang Yang
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Jinge Xu
- Guizhou Animal Husbandry and Veterinary Research Institute, Guiyang, China
| | - Mingshu Wang
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yunya Liu
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhang
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yanling Yu
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyue Chen
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Anchun Cheng
- Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.,Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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12
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Natural tuning of restriction endonuclease synthesis by cluster of rare arginine codons. Sci Rep 2019; 9:5808. [PMID: 30967604 PMCID: PMC6456624 DOI: 10.1038/s41598-019-42311-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/28/2019] [Indexed: 01/21/2023] Open
Abstract
Restriction–modification (R-M) systems are highly widespread among bacteria and archaea, and they appear to play a pivotal role in modulating horizontal gene transfer, as well as in protecting the host organism against viruses and other invasive DNA particles. Type II R-M systems specify two independent enzymes: a restriction endonuclease (REase) and protective DNA methyltransferase (MTase). If the cell is to survive, the counteracting activities as toxin and antitoxin, must be finely balanced in vivo. The molecular basis of this regulatory process remains unclear and current searches for regulatory elements in R-M modules are focused mainly at the transcription step. In this report, we show new aspects of REase control that are linked to translation. We used the EcoVIII R-M system as a model. Both, the REase and MTase genes for this R-M system contain an unusually high number of rare arginine codons (AGA and AGG) when compared to the rest of the E. coli K-12 genome. Clusters of these codons near the N-terminus of the REase greatly affect the translational efficiency. Changing these to higher frequency codons for E. coli (CGC) improves the REase synthesis, making the R-M system more potent to defend its host against bacteriophages. However, this improved efficiency in synthesis reduces host fitness due to increased autorestriction. We hypothesize that expression of the endonuclease gene can be modulated depending on the host genetic context and we propose a novel post-transcriptional mode of R–M system regulation that alleviates the potential lethal action of the restriction enzyme.
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13
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Schmutzer M, Barraclough TG. The role of recombination, niche-specific gene pools and flexible genomes in the ecological speciation of bacteria. Ecol Evol 2019; 9:4544-4556. [PMID: 31031926 PMCID: PMC6476844 DOI: 10.1002/ece3.5052] [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: 01/18/2019] [Revised: 02/16/2019] [Accepted: 02/18/2019] [Indexed: 12/21/2022] Open
Abstract
Bacteria diversify into genetic clusters analogous to those observed in sexual eukaryotes, but the definition of bacterial species is an ongoing problem. Recent work has focused on adaptation to distinct ecological niches as the main driver of clustering, but there remains debate about the role of recombination in that process. One view is that homologous recombination occurs too rarely for gene flow to constrain divergent selection. Another view is that homologous recombination is frequent enough in many bacterial populations that barriers to gene flow are needed to permit divergence. Niche-specific gene pools have been proposed as a general mechanism to limit gene flow. We use theoretical models to evaluate additional hypotheses that evolving genetic architecture, specifically the effect sizes of genes and gene gain and loss, can limit gene flow between diverging populations. Our model predicts that (a) in the presence of gene flow and recombination, ecological divergence is concentrated in few loci of large effect and (b) high rates of gene flow plus recombination promote gene loss and favor the evolution of niche-specific genes. The results show that changing genetic architecture and gene loss can facilitate ecological divergence, even without niche-specific gene pools. We discuss these results in the context of recent studies of sympatric divergence in microbes.
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14
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Rendueles O, de Sousa JAM, Bernheim A, Touchon M, Rocha EPC. Genetic exchanges are more frequent in bacteria encoding capsules. PLoS Genet 2018; 14:e1007862. [PMID: 30576310 PMCID: PMC6322790 DOI: 10.1371/journal.pgen.1007862] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/07/2019] [Accepted: 11/29/2018] [Indexed: 12/12/2022] Open
Abstract
Capsules allow bacteria to colonize novel environments, to withstand numerous stresses, and to resist antibiotics. Yet, even though genetic exchanges with other cells should be adaptive under such circumstances, it has been suggested that capsules lower the rates of homologous recombination and horizontal gene transfer. We analysed over one hundred pan-genomes and thousands of bacterial genomes for the evidence of an association between genetic exchanges (or lack thereof) and the presence of a capsule system. We found that bacteria encoding capsules have larger pan-genomes, higher rates of horizontal gene transfer, and higher rates of homologous recombination in their core genomes. Accordingly, genomes encoding capsules have more plasmids, conjugative elements, transposases, prophages, and integrons. Furthermore, capsular loci are frequent in plasmids, and can be found in prophages. These results are valid for Bacteria, independently of their ability to be naturally transformable. Since we have shown previously that capsules are commonly present in nosocomial pathogens, we analysed their co-occurrence with antibiotic resistance genes. Genomes encoding capsules have more antibiotic resistance genes, especially those encoding efflux pumps, and they constitute the majority of the most worrisome nosocomial bacteria. We conclude that bacteria with capsule systems are more genetically diverse and have fast-evolving gene repertoires, which may further contribute to their success in colonizing novel niches such as humans under antibiotic therapy. Previous works showed that bacteria encoding capsules are better colonizers and are dominant in most environments suggesting a positive role for capsules in the genetic diversification of bacteria. Yet, it has been repeatedly suggested, based almost exclusively studies in few model species, that such bacteria are less diverse and engage in fewer genetic exchanges. Here, we reverse the current paradigm and show that bacteria encoding capsules have larger and more diverse gene repertoires, which change faster by horizontal gene transfer and recombination. Our study alters the traditional view of the capsule as a barrier to gene flow and raises novel questions about the role of capsules in bacterial adaptation.
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Affiliation(s)
- Olaya Rendueles
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- UMR 3525, CNRS, Paris, France
- * E-mail:
| | - Jorge A. Moura de Sousa
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- UMR 3525, CNRS, Paris, France
| | - Aude Bernheim
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- UMR 3525, CNRS, Paris, France
| | - Marie Touchon
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- UMR 3525, CNRS, Paris, France
| | - Eduardo P. C. Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- UMR 3525, CNRS, Paris, France
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15
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Mouammine A, Collier J. The impact of DNA methylation in Alphaproteobacteria. Mol Microbiol 2018; 110:1-10. [PMID: 29995343 DOI: 10.1111/mmi.14079] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2018] [Indexed: 02/02/2023]
Abstract
Alphaproteobacteria include bacteria with very different modes of life, from free-living to host-associated and pathogenic bacteria. Their genomes vary in size and organization from single circular chromosomes to multipartite genomes and are often methylated by one or more adenine or cytosine methyltransferases (MTases). These include MTases that are part of restriction/modification systems and so-called orphan MTases. The development of novel technologies accelerated the analysis of methylomes and revealed the existence of epigenetic patterns in several Alphaproteobacteria. This review describes the known functions of DNA methylation in Alphaproteobacteria and also discusses its potential drawbacks through the accidental deamination of methylated cytosines. Particular emphasis is given to the strong connection between the cell cycle-regulated orphan MTase CcrM and the complex network that controls gene expression and cell cycle progression in Alphaproteobacteria.
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Affiliation(s)
- Annabelle Mouammine
- Faculty of Biology and Medicine, Department of Fundamental Microbiology, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland
| | - Justine Collier
- Faculty of Biology and Medicine, Department of Fundamental Microbiology, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland
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16
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Sitaraman R. Prokaryotic horizontal gene transfer within the human holobiont: ecological-evolutionary inferences, implications and possibilities. MICROBIOME 2018; 6:163. [PMID: 30223892 PMCID: PMC6142633 DOI: 10.1186/s40168-018-0551-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 09/05/2018] [Indexed: 05/26/2023]
Abstract
The ubiquity of horizontal gene transfer in the living world, especially among prokaryotes, raises interesting and important scientific questions regarding its effects on the human holobiont i.e., the human and its resident bacterial communities considered together as a unit of selection. Specifically, it would be interesting to determine how particular gene transfer events have influenced holobiont phenotypes in particular ecological niches and, conversely, how specific holobiont phenotypes have influenced gene transfer events. In this synthetic review, we list some notable and recent discoveries of horizontal gene transfer among the prokaryotic component of the human microbiota, and analyze their potential impact on the holobiont from an ecological-evolutionary viewpoint. Finally, the human-Helicobacter pylori association is presented as an illustration of these considerations, followed by a delineation of unresolved questions and avenues for future research.
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Affiliation(s)
- Ramakrishnan Sitaraman
- Department of Biotechnology, TERI School of Advanced Studies, 10 Institutional Area, Vasant Kunj, New Delhi, 110070, India.
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17
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González-Torres P, Gabaldón T. Genome Variation in the Model Halophilic Bacterium Salinibacter ruber. Front Microbiol 2018; 9:1499. [PMID: 30072959 PMCID: PMC6060240 DOI: 10.3389/fmicb.2018.01499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/18/2018] [Indexed: 01/08/2023] Open
Abstract
The halophilic bacterium Salinibacter ruber is an abundant and ecologically important member of halophilic communities worldwide. Given its broad distribution and high intraspecific genetic diversity, S. ruber is considered one of the main models for ecological and evolutionary studies of bacterial adaptation to hypersaline environments. However, current insights on the genomic diversity of this species is limited to the comparison of the genomes of two co-isolated strains. Here, we present a comparative genomic analysis of eight S. ruber strains isolated at two different time points in each of two different Mediterranean solar salterns. Our results show an open pangenome with contrasting evolutionary patterns in the core and accessory genomes. We found that the core genome is shaped by extensive homologous recombination (HR), which results in limited sequence variation within population clusters. In contrast, the accessory genome is modulated by horizontal gene transfer (HGT), with genomic islands and plasmids acting as gateways to the rest of the genome. In addition, both types of genetic exchange are modulated by restriction and modification (RM) or CRISPR-Cas systems. Finally, genes differentially impacted by such processes reveal functional processes potentially relevant for environmental interactions and adaptation to extremophilic conditions. Altogether, our results support scenarios that conciliate “Neutral” and “Constant Diversity” models of bacterial evolution.
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Affiliation(s)
- Pedro González-Torres
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain.,Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Toni Gabaldón
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain.,Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
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18
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Kopčáková A, Dubíková K, Šuľák M, Javorský P, Kmeť V, Lauková A, Pristaš P. Restriction-modification systems and phage resistance of enterococci from ewe milk. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.03.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Freed E, Fenster J, Smolinski SL, Walker J, Henard CA, Gill R, Eckert CA. Building a genome engineering toolbox in nonmodel prokaryotic microbes. Biotechnol Bioeng 2018; 115:2120-2138. [PMID: 29750332 DOI: 10.1002/bit.26727] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/02/2018] [Accepted: 03/10/2018] [Indexed: 12/26/2022]
Abstract
The realization of a sustainable bioeconomy requires our ability to understand and engineer complex design principles for the development of platform organisms capable of efficient conversion of cheap and sustainable feedstocks (e.g., sunlight, CO2 , and nonfood biomass) into biofuels and bioproducts at sufficient titers and costs. For model microbes, such as Escherichia coli, advances in DNA reading and writing technologies are driving the adoption of new paradigms for engineering biological systems. Unfortunately, microbes with properties of interest for the utilization of cheap and renewable feedstocks, such as photosynthesis, autotrophic growth, and cellulose degradation, have very few, if any, genetic tools for metabolic engineering. Therefore, it is important to develop "design rules" for building a genetic toolbox for novel microbes. Here, we present an overview of our current understanding of these rules for the genetic manipulation of prokaryotic microbes and the available genetic tools to expand our ability to genetically engineer nonmodel systems.
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Affiliation(s)
- Emily Freed
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
| | - Jacob Fenster
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO.,Chemical and Biological Engineering, University of Colorado, Boulder, CO
| | | | - Julie Walker
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
| | - Calvin A Henard
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO
| | - Ryan Gill
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO.,Chemical and Biological Engineering, University of Colorado, Boulder, CO
| | - Carrie A Eckert
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
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20
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Muraille E. Diversity Generator Mechanisms Are Essential Components of Biological Systems: The Two Queen Hypothesis. Front Microbiol 2018; 9:223. [PMID: 29487592 PMCID: PMC5816788 DOI: 10.3389/fmicb.2018.00223] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 01/30/2018] [Indexed: 01/02/2023] Open
Abstract
Diversity is widely known to fuel adaptation and evolutionary processes and increase robustness at the population, species and ecosystem levels. The Neo-Darwinian paradigm proposes that the diversity of biological entities is the consequence of genetic changes arising spontaneously and randomly, without regard for their usefulness. However, a growing body of evidence demonstrates that the evolutionary process has shaped mechanisms, such as horizontal gene transfer mechanisms, meiosis and the adaptive immune system, which has resulted in the regulated generation of diversity among populations. Though their origins are unrelated, these diversity generator (DG) mechanisms share common functional properties. They (i) contribute to the great unpredictability of the composition and/or behavior of biological systems, (ii) favor robustness and collectivism among populations and (iii) operate mainly by manipulating the systems that control the interaction of living beings with their environment. The definition proposed here for DGs is based on these properties and can be used to identify them according to function. Interestingly, prokaryotic DGs appear to be mainly reactive, as they generate diversity in response to environmental stress. They are involved in the widely described Red Queen/arms race/Cairnsian dynamic. The emergence of multicellular organisms harboring K selection traits (longer reproductive life cycle and smaller population size) has led to the acquisition of a new class of DGs that act anticipatively to stress pressures and generate a distinct dynamic called the “White Queen” here. The existence of DGs leads to the view of evolution as a more “intelligent” and Lamarckian-like process. Their repeated selection during evolution could be a neglected example of convergent evolution and suggests that some parts of the evolutionary process are tightly constrained by ecological factors, such as the population size, the generation time and the intensity of selective pressure. The ubiquity of DGs also suggests that regulated auto-generation of diversity is a fundamental property of life.
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Affiliation(s)
- Eric Muraille
- Laboratoire de Parasitologie, Faculté de Médecine, Université Libre de Bruxelles, Brussels, Belgium
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21
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Ambur OH, Engelstädter J, Johnsen PJ, Miller EL, Rozen DE. Steady at the wheel: conservative sex and the benefits of bacterial transformation. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0528. [PMID: 27619692 PMCID: PMC5031613 DOI: 10.1098/rstb.2015.0528] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2016] [Indexed: 12/25/2022] Open
Abstract
Many bacteria are highly sexual, but the reasons for their promiscuity remain obscure. Did bacterial sex evolve to maximize diversity and facilitate adaptation in a changing world, or does it instead help to retain the bacterial functions that work right now? In other words, is bacterial sex innovative or conservative? Our aim in this review is to integrate experimental, bioinformatic and theoretical studies to critically evaluate these alternatives, with a main focus on natural genetic transformation, the bacterial equivalent of eukaryotic sexual reproduction. First, we provide a general overview of several hypotheses that have been put forward to explain the evolution of transformation. Next, we synthesize a large body of evidence highlighting the numerous passive and active barriers to transformation that have evolved to protect bacteria from foreign DNA, thereby increasing the likelihood that transformation takes place among clonemates. Our critical review of the existing literature provides support for the view that bacterial transformation is maintained as a means of genomic conservation that provides direct benefits to both individual bacterial cells and to transformable bacterial populations. We examine the generality of this view across bacteria and contrast this explanation with the different evolutionary roles proposed to maintain sex in eukaryotes. This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Ole Herman Ambur
- Department of Life Sciences and Health, Oslo and Akershus University College of Applied Sciences, 1478 Oslo, Norway
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Pål J Johnsen
- Faculty of Health Sciences, Department of Pharmacy, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
| | - Eric L Miller
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, UK
| | - Daniel E Rozen
- Institute of Biology, Leiden University, 2333 BE Leiden, The Netherlands
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22
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The restriction modification system of Bacillus licheniformis MS1 and generation of a readily transformable deletion mutant. Appl Microbiol Biotechnol 2017; 101:7933-7944. [PMID: 28942561 DOI: 10.1007/s00253-017-8532-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/12/2017] [Accepted: 09/13/2017] [Indexed: 01/19/2023]
Abstract
Restriction modification systems (R-M systems), consisting of a restriction endonuclease and a cognate methyltransferase, constitute an effective means of a cell to protect itself from foreign DNA. Identification, characterization, and deletion of the restriction modification system BliMSI, a putative isoschizomer of ClaI from Caryophanon latum, were performed in the wild isolate Bacillus licheniformis MS1. BliMSI was produced as recombinant protein in Escherichia coli, purified, and in vitro analysis demonstrated identical restriction endonuclease activity as for ClaI. A recombinant E. coli strain, expressing the heterologous bliMSIM gene, was constructed and used as the host for in vivo methylation of plasmids prior to their introduction into B. licheniformis to improve transformation efficiencies. The establishment of suicide plasmids in the latter was rendered possible. The subsequent deletion of the restriction endonuclease encoding gene, bliMSIR, caused doubled transformation efficiencies in the respective mutant B. licheniformis MS2 (∆bliMSIR). Along with above in vivo methylation, the establishment of further gene deletions (∆upp, ∆yqfD) was performed. The constructed triple mutant (∆bliMSIR, ∆upp, ∆yqfD) enables rapid genome manipulation, a requirement for genetic engineering of industrially important strains.
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23
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Lourenço J, Watkins ER, Obolski U, Peacock SJ, Morris C, Maiden MCJ, Gupta S. Lineage structure of Streptococcus pneumoniae may be driven by immune selection on the groEL heat-shock protein. Sci Rep 2017; 7:9023. [PMID: 28831154 PMCID: PMC5567354 DOI: 10.1038/s41598-017-08990-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/20/2017] [Indexed: 12/29/2022] Open
Abstract
Populations of Streptococcus pneumoniae (SP) are typically structured into groups of closely related organisms or lineages, but it is not clear whether they are maintained by selection or neutral processes. Here, we attempt to address this question by applying a machine learning technique to SP whole genomes. Our results indicate that lineages evolved through immune selection on the groEL chaperone protein. The groEL protein is part of the groESL operon and enables a large range of proteins to fold correctly within the physical environment of the nasopharynx, thereby explaining why lineage structure is so stable within SP despite high levels of genetic transfer. SP is also antigenically diverse, exhibiting a variety of distinct capsular serotypes. Associations exist between lineage and capsular serotype but these can be easily perturbed, such as by vaccination. Overall, our analyses indicate that the evolution of SP can be conceptualized as the rearrangement of modular functional units occurring on several different timescales under different pressures: some patterns have locked in early (such as the epistatic interactions between groESL and a constellation of other genes) and preserve the differentiation of lineages, while others (such as the associations between capsular serotype and lineage) remain in continuous flux.
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Affiliation(s)
- José Lourenço
- Department of Zoology, University of Oxford, Oxford, United Kingdom.
| | | | - Uri Obolski
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Samuel J Peacock
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | | | | | - Sunetra Gupta
- Department of Zoology, University of Oxford, Oxford, United Kingdom
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24
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Fu P, Ge Y, Wu Y, Zhao N, Yuan Z, Hu X. The LspC3-41I restriction-modification system is the major determinant for genetic manipulations of Lysinibacillus sphaericus C3-41. BMC Microbiol 2017; 17:116. [PMID: 28525986 PMCID: PMC5437673 DOI: 10.1186/s12866-017-1014-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/26/2017] [Indexed: 12/26/2022] Open
Abstract
Background Lysinibacillus sphaericus has been widely used in integrated mosquito control program and it is one of the minority bacterial species unable to metabolize carbohydrates. In consideration of the high genetic conservation at genomic level and difficulty of genetic horizontal transfer, it is hypothesized that effective restriction-modification (R-M) systems existed in mosquitocidal L. sphaericus. Results In this study, six type II R-M systems including LspC3–41I were predicted in L. sphaericus C3–41 genome. It was found that the cell free extracts (CFE) from this strain shown similar restriction and methylation activity on exogenous Bacillus/Escherichia coli shuttle vector pBU4 as the HaeIII, which is an isoschizomer of BspRI. The Bsph_0498 (encoding the predicted LspC3–41IR) knockout mutant Δ0498 and the complement strain RC0498 were constructed. It was found that the unmethylated pBU4 can be digested by the CFE of C3–41 and RC0498, but not by that of Δ0498. Furthermore, the exogenous plasmid pBU4 can be transformed at very high efficacy into Δ0498, low efficacy into RC0498, but no transformation into C3–41, indicating that LspC3–41I might be a major determinant for the genetic restriction barrier of strain C3–41. Besides, lspC3–41IR and lspC3–41IM genes are detected in other two strains besides C3–41 of the tested 16 L. sphaericus strains, which all belonging to serotype H5 and MLST sequence type (ST) 1. Furthermore, the three strains are not horizontal transferred, and this restriction could be overcome by in vitro methylation either by the host CFE or by commercial methytransferase M. HaeIII. The results provide an insight to further study the genetic restriction, modification and evolution of mosquitocidal L. sphaericus, also a theoretical basis and a method for the genetic manipulations of L. sphaericus. Conclusions LspC3–41I is identified as the major determinant for the restriction barrier of L. sphaericus C3–41. Only three strains of the tested 16 L. sphaericus strains, which all belonging to serotype H5 and ST1 by MLST scheme, contain LspC3–41I system. Two different methods can be used to overcome the restriction barrier of the three isolates to get transformants efficiently: 1) to methylate plasmid DNA prior to the electroporation; and 2) to delete the major restriction endonuclease encoding gene lspC3–41IR.
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Affiliation(s)
- Pan Fu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Yong Ge
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Yiming Wu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Ni Zhao
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Zhiming Yuan
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
| | - Xiaomin Hu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
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Robbins RJ, Krishtalka L, Wooley JC. Advances in biodiversity: metagenomics and the unveiling of biological dark matter. Stand Genomic Sci 2016; 11:69. [PMID: 27617059 PMCID: PMC5016886 DOI: 10.1186/s40793-016-0180-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 08/16/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Efforts to harmonize genomic data standards used by the biodiversity and metagenomic research communities have shown that prokaryotic data cannot be understood or represented in a traditional, classical biological context for conceptual reasons, not technical ones. RESULTS Biology, like physics, has a fundamental duality-the classical macroscale eukaryotic realm vs. the quantum microscale microbial realm-with the two realms differing profoundly, and counter-intuitively, from one another. Just as classical physics is emergent from and cannot explain the microscale realm of quantum physics, so classical biology is emergent from and cannot explain the microscale realm of prokaryotic life. Classical biology describes the familiar, macroscale realm of multi-cellular eukaryotic organisms, which constitute a highly derived and constrained evolutionary subset of the biosphere, unrepresentative of the vast, mostly unseen, microbial world of prokaryotic life that comprises at least half of the planet's biomass and most of its genetic diversity. The two realms occupy fundamentally different mega-niches: eukaryotes interact primarily mechanically with the environment, prokaryotes primarily physiologically. Further, many foundational tenets of classical biology simply do not apply to prokaryotic biology. CONCLUSIONS Classical genetics one held that genes, arranged on chromosomes like beads on a string, were the fundamental units of mutation, recombination, and heredity. Then, molecular analysis showed that there were no fundamental units, no beads, no string. Similarly, classical biology asserts that individual organisms and species are fundamental units of ecology, evolution, and biodiversity, composing an evolutionary history of objectively real, lineage-defined groups in a single-rooted tree of life. Now, metagenomic tools are forcing a recognition that there are no completely objective individuals, no unique lineages, and no one true tree. The newly revealed biosphere of microbial dark matter cannot be understood merely by extending the concepts and methods of eukaryotic macrobiology. The unveiling of biological dark matter is allowing us to see, for the first time, the diversity of the entire biosphere and, to paraphrase Darwin, is providing a new view of life. Advancing and understanding that view will require major revisions to some of the most fundamental concepts and theories in biology.
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Affiliation(s)
- Robert J. Robbins
- Biodiversity Institute, University of Kansas, 1345 Jayhawk Blvd., Lawrence, KS 66045 USA
- University of California, San Diego, USA
| | - Leonard Krishtalka
- Biodiversity Institute, University of Kansas, 1345 Jayhawk Blvd., Lawrence, KS 66045 USA
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Ershova AS, Rusinov IS, Spirin SA, Karyagina AS, Alexeevski AV. Role of Restriction-Modification Systems in Prokaryotic Evolution and Ecology. BIOCHEMISTRY (MOSCOW) 2016; 80:1373-86. [PMID: 26567582 DOI: 10.1134/s0006297915100193] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Restriction-modification (R-M) systems are able to methylate or cleave DNA depending on methylation status of their recognition site. It allows them to protect bacterial cells from invasion by foreign DNA. Comparative analysis of a large number of available bacterial genomes and methylomes clearly demonstrates that the role of R-M systems in bacteria is wider than only defense. R-M systems maintain heterogeneity of a bacterial population and are involved in adaptation of bacteria to change in their environmental conditions. R-M systems can be essential for host colonization by pathogenic bacteria. Phase variation and intragenomic recombinations are sources of the fast evolution of the specificity of R-M systems. This review focuses on the influence of R-M systems on evolution and ecology of prokaryotes.
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Affiliation(s)
- A S Ershova
- Belozerksy Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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Werbowy O, Kaczorowski T. Plasmid pEC156, a Naturally Occurring Escherichia coli Genetic Element That Carries Genes of the EcoVIII Restriction-Modification System, Is Mobilizable among Enterobacteria. PLoS One 2016; 11:e0148355. [PMID: 26848973 PMCID: PMC4743918 DOI: 10.1371/journal.pone.0148355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/19/2016] [Indexed: 11/30/2022] Open
Abstract
Type II restriction-modification systems are ubiquitous in prokaryotes. Some of them are present in naturally occurring plasmids, which may facilitate the spread of these systems in bacterial populations by horizontal gene transfer. However, little is known about the routes of their dissemination. As a model to study this, we have chosen an Escherichia coli natural plasmid pEC156 that carries the EcoVIII restriction modification system. The presence of this system as well as the cis-acting cer site involved in resolution of plasmid multimers determines the stable maintenance of pEC156 not only in Escherichia coli but also in other enterobacteria. We have shown that due to the presence of oriT-type F and oriT-type R64 loci it is possible to mobilize pEC156 by conjugative plasmids (F and R64, respectively). The highest mobilization frequency was observed when pEC156-derivatives were transferred between Escherichia coli strains, Enterobacter cloacae and Citrobacter freundii representing coliform bacteria. We found that a pEC156-derivative with a functional EcoVIII restriction-modification system was mobilized in enterobacteria at a frequency lower than a plasmid lacking this system. In addition, we found that bacteria that possess the EcoVIII restriction-modification system can efficiently release plasmid content to the environment. We have shown that E. coli cells can be naturally transformed with pEC156-derivatives, however, with low efficiency. The transformation protocol employed neither involved chemical agents (e.g. CaCl2) nor temperature shift which could induce plasmid DNA uptake.
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Affiliation(s)
- Olesia Werbowy
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk, Poland
| | - Tadeusz Kaczorowski
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk, Poland
- * E-mail:
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Sitaraman R. The Role of DNA Restriction-Modification Systems in the Biology of Bacillus anthracis. Front Microbiol 2016; 7:11. [PMID: 26834729 PMCID: PMC4722110 DOI: 10.3389/fmicb.2016.00011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/08/2016] [Indexed: 11/13/2022] Open
Abstract
Restriction-modification (R-M) systems are widespread among prokaryotes and, depending on their type, may be viewed as selfish genetic elements that persist as toxin-antitoxin modules, or as cellular defense systems against phage infection that confer a selective advantage to the host bacterium. Studies in the last decade have made it amply clear that these two options do not exhaust the list of possible biological roles for R-M systems. Their presence in a cell may also have a bearing on other processes such as horizontal gene transfer and gene regulation. From genome sequencing and experimental data, we know that Bacillus anthracis encodes at least three methylation-dependent (typeIV) restriction endonucleases (RE), and an orphan DNA methyltransferase. In this article, we first present an outline of our current knowledge of R-M systems in B. anthracis. Based on available DNA sequence data, and on our current understanding of the functions of similar genes in other systems, we conclude with hypotheses on the possible roles of the three REs and the orphan DNA methyltransferase.
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Frank J, Dingemanse C, Schmitz AM, Vossen RHAM, van Ommen GJB, den Dunnen JT, Robanus-Maandag EC, Anvar SY. The Complete Genome Sequence of the Murine Pathobiont Helicobacter typhlonius. Front Microbiol 2016; 6:1549. [PMID: 26779178 PMCID: PMC4705304 DOI: 10.3389/fmicb.2015.01549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/21/2015] [Indexed: 01/27/2023] Open
Abstract
Background: Immuno-compromised mice infected with Helicobacter typhlonius are used to model microbially inducted inflammatory bowel disease (IBD). The specific mechanism through which H. typhlonius induces and promotes IBD is not fully understood. Access to the genome sequence is essential to examine emergent properties of this organism, such as its pathogenicity. To this end, we present the complete genome sequence of H. typhlonius MIT 97-6810, obtained through single-molecule real-time sequencing. Results: The genome was assembled into a single circularized contig measuring 1.92 Mbp with an average GC content of 38.8%. In total 2,117 protein-encoding genes and 43 RNA genes were identified. Numerous pathogenic features were found, including a putative pathogenicity island (PAIs) containing components of type IV secretion system, virulence-associated proteins and cag PAI protein. We compared the genome of H. typhlonius to those of the murine pathobiont H. hepaticus and human pathobiont H. pylori. H. typhlonius resembles H. hepaticus most with 1,594 (75.3%) of its genes being orthologous to genes in H. hepaticus. Determination of the global methylation state revealed eight distinct recognition motifs for adenine and cytosine methylation. H. typhlonius shares four of its recognition motifs with H. pylori. Conclusion: The complete genome sequence of H. typhlonius MIT 97-6810 enabled us to identify many pathogenic features suggesting that H. typhlonius can act as a pathogen. Follow-up studies are necessary to evaluate the true nature of its pathogenic capabilities. We found many methylated sites and a plethora of restriction-modification systems. The genome, together with the methylome, will provide an essential resource for future studies investigating gene regulation, host interaction and pathogenicity of H. typhlonius. In turn, this work can contribute to unraveling the role of Helicobacter in enteric disease.
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Affiliation(s)
- Jeroen Frank
- Leiden Genome Technology Center, Leiden University Medical Center Leiden, Netherlands
| | - Celia Dingemanse
- Department of Human Genetics, Leiden University Medical Center Leiden, Netherlands
| | - Arnoud M Schmitz
- Leiden Genome Technology Center, Leiden University Medical Center Leiden, Netherlands
| | - Rolf H A M Vossen
- Leiden Genome Technology Center, Leiden University Medical Center Leiden, Netherlands
| | - Gert-Jan B van Ommen
- Department of Human Genetics, Leiden University Medical Center Leiden, Netherlands
| | - Johan T den Dunnen
- Leiden Genome Technology Center, Leiden University Medical CenterLeiden, Netherlands; Department of Human Genetics, Leiden University Medical CenterLeiden, Netherlands; Department of Clinical Genetics, Leiden University Medical CenterLeiden, Netherlands
| | | | - Seyed Yahya Anvar
- Leiden Genome Technology Center, Leiden University Medical CenterLeiden, Netherlands; Department of Human Genetics, Leiden University Medical CenterLeiden, Netherlands
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Casadesús J. Bacterial DNA Methylation and Methylomes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 945:35-61. [PMID: 27826834 DOI: 10.1007/978-3-319-43624-1_3] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Formation of C5-methylcytosine, N4-methylcytosine, and N6-methyladenine in bacterial genomes is postreplicative and involves transfer of a methyl group from S-adenosyl-methionine to a base embedded in a specific DNA sequence context. Most bacterial DNA methyltransferases belong to restriction-modification systems; in addition, "solitary" or "orphan" DNA methyltransferases are frequently found in the genomes of bacteria and phage. Base methylation can affect the interaction of DNA-binding proteins with their cognate sites, either by a direct effect (e.g., steric hindrance) or by changes in DNA topology. In both Alphaproteobacteria and Gammaproteobacteria, the roles of DNA base methylation are especially well known for N6-methyladenine, including control of chromosome replication, nucleoid segregation, postreplicative correction of DNA mismatches, cell cycle-coupled transcription, formation of bacterial cell lineages, and regulation of bacterial virulence. Technical procedures that permit genome-wide analysis of DNA methylation are nowadays expanding our knowledge of the extent, evolution, and physiological significance of bacterial DNA methylation.
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Affiliation(s)
- Josep Casadesús
- Departamento de Genética, Universidad de Sevilla, Apartado 1095, Seville, 41080, Spain.
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Kwiatek A, Mrozek A, Bacal P, Piekarowicz A, Adamczyk-Popławska M. Type III Methyltransferase M.NgoAX from Neisseria gonorrhoeae FA1090 Regulates Biofilm Formation and Interactions with Human Cells. Front Microbiol 2015; 6:1426. [PMID: 26733970 PMCID: PMC4685087 DOI: 10.3389/fmicb.2015.01426] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/30/2015] [Indexed: 11/24/2022] Open
Abstract
Neisseria gonorrhoeae is the etiological factor of the sexually transmitted gonorrhea disease that may lead, under specific conditions, to systemic infections. The gonococcal genome encodes many restriction modification (RM) systems, which main biological role is to defend the pathogen from potentially harmful foreign DNA. However, RM systems seem also to be involved in several other functions. In this study, we examined the effect of inactivation the N. gonorrhoeae FA1090 ngoAXmod gene encoding M.NgoAX methyltransferase on the global gene expression, biofilm formation, interactions with human epithelial host cells and overall bacterial growth. Expression microarrays showed at least a twofold deregulation of a total of 121 genes in the NgoAX knock-out mutant compared to the wild-type (wt) strain under standard grow conditions. Genes with changed expression levels encoded mostly proteins involved in cell metabolism, DNA replication and repair or regulating cellular processes and signaling (such as cell wall/envelop biogenesis). As determined by the assay with crystal violet, the NgoAX knock-out strain formed a slightly larger biofilm biomass per cell than the wt strain. Live biofilm observations showed that the biofilm formed by the gonococcal ngoAXmod gene mutant is more relaxed, dispersed and thicker than the one formed by the wt strain. This more relaxed feature of the biofilm, in respect to adhesion and bacterial interactions, can be involved in pathogenesis. Moreover, the overall adhesion of mutant bacterial cells to human cells was lower than adhesion of the wt gonococci [adhesion index = 0.672 (±0.2) and 2.15 (±1.53), respectively]; yet, a higher number of mutant than wt bacteria were found inside the Hec-1-B epithelial cells [invasion index = 3.38 (±0.93) × 105 for mutant and 4.67 (±3.09) × 104 for the wt strain]. These results indicate that NgoAX knock-out cells have lower ability to attach to human cells, but more easily penetrate inside the host cells. All these data suggest that the NgoAX methyltransferase, may be implicated in N. gonorrhoeae pathogenicity, involving regulation of biofilm formation, adhesion to host cells and epithelial cell invasion.
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Affiliation(s)
- Agnieszka Kwiatek
- Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
| | - Agnieszka Mrozek
- 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
| | - Andrzej Piekarowicz
- Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
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Lineage-Specific Methyltransferases Define the Methylome of the Globally Disseminated Escherichia coli ST131 Clone. mBio 2015; 6:e01602-15. [PMID: 26578678 PMCID: PMC4659465 DOI: 10.1128/mbio.01602-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Escherichia coli sequence type 131 (ST131) is a clone of uropathogenic E. coli that has emerged rapidly and disseminated globally in both clinical and community settings. Members of the ST131 lineage from across the globe have been comprehensively characterized in terms of antibiotic resistance, virulence potential, and pathogenicity, but to date nothing is known about the methylome of these important human pathogens. Here we used single-molecule real-time (SMRT) PacBio sequencing to determine the methylome of E. coli EC958, the most-well-characterized completely sequenced ST131 strain. Our analysis of 52,081 methylated adenines in the genome of EC958 discovered three (m6)A methylation motifs that have not been described previously. Subsequent SMRT sequencing of isogenic knockout mutants identified the two type I methyltransferases (MTases) and one type IIG MTase responsible for (m6)A methylation of novel recognition sites. Although both type I sites were rare, the type IIG sites accounted for more than 12% of all methylated adenines in EC958. Analysis of the distribution of MTase genes across 95 ST131 genomes revealed their prevalence is highly conserved within the ST131 lineage, with most variation due to the presence or absence of mobile genetic elements on which individual MTase genes are located. IMPORTANCE DNA modification plays a crucial role in bacterial regulation. Despite several examples demonstrating the role of methyltransferase (MTase) enzymes in bacterial virulence, investigation of this phenomenon on a whole-genome scale has remained elusive until now. Here we used single-molecule real-time (SMRT) sequencing to determine the first complete methylome of a strain from the multidrug-resistant E. coli sequence type 131 (ST131) lineage. By interrogating the methylome computationally and with further SMRT sequencing of isogenic mutants representing previously uncharacterized MTase genes, we defined the target sequences of three novel ST131-specific MTases and determined the genomic distribution of all MTase target sequences. Using a large collection of 95 previously sequenced ST131 genomes, we identified mobile genetic elements as a major factor driving diversity in DNA methylation patterns. Overall, our analysis highlights the potential for DNA methylation to dramatically influence gene regulation at the transcriptional level within a well-defined E. coli clone.
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Genetic Stabilization of the Drug-Resistant PMEN1 Pneumococcus Lineage by Its Distinctive DpnIII Restriction-Modification System. mBio 2015; 6:e00173. [PMID: 26081630 PMCID: PMC4471560 DOI: 10.1128/mbio.00173-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The human pathogen Streptococcus pneumoniae (pneumococcus) exhibits a high degree of genomic diversity and plasticity. Isolates with high genomic similarity are grouped into lineages that undergo homologous recombination at variable rates. PMEN1 is a pandemic, multidrug-resistant lineage. Heterologous gene exchange between PMEN1 and non-PMEN1 isolates is directional, with extensive gene transfer from PMEN1 strains and only modest transfer into PMEN1 strains. Restriction-modification (R-M) systems can restrict horizontal gene transfer, yet most pneumococcal strains code for either the DpnI or DpnII R-M system and neither limits homologous recombination. Our comparative genomic analysis revealed that PMEN1 isolates code for DpnIII, a third R-M system syntenic to the other Dpn systems. Characterization of DpnIII demonstrated that the endonuclease cleaves unmethylated double-stranded DNA at the tetramer sequence 5′ GATC 3′, and the cognate methylase is a C5 cytosine-specific DNA methylase. We show that DpnIII decreases the frequency of recombination under in vitro conditions, such that the number of transformants is lower for strains transformed with unmethylated DNA than in those transformed with cognately methylated DNA. Furthermore, we have identified two PMEN1 isolates where the DpnIII endonuclease is disrupted, and phylogenetic work by Croucher and colleagues suggests that these strains have accumulated genomic differences at a higher rate than other PMEN1 strains. We propose that the R-M locus is a major determinant of genetic acquisition; the resident R-M system governs the extent of genome plasticity. Pneumococcus is one of the most important community-acquired bacterial pathogens. Pneumococcal strains can develop resistance to antibiotics and to serotype vaccines by acquiring genes from other strains or species. Thus, genomic plasticity is associated with strain adaptability and pneumococcal success. PMEN1 is a widespread and multidrug-resistant highly pathogenic pneumococcal lineage, which has evolved over the past century and displays a relatively stable genome. In this study, we characterize DpnIII, a restriction-modification (R-M) system that limits recombination. DpnIII is encountered in the PMEN1 lineage, where it replaces other R-M systems that do not decrease plasticity. Our hypothesis is that this genomic region, where different pneumococcal lineages code for variable R-M systems, plays a role in the fine-tuning of the extent of genomic plasticity. It is possible that well-adapted lineages such as PMEN1 have a mechanism to increase genomic stability, rather than foster genomic plasticity.
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Ouellette M, Jackson L, Chimileski S, Papke RT. Genome-wide DNA methylation analysis of Haloferax volcanii H26 and identification of DNA methyltransferase related PD-(D/E)XK nuclease family protein HVO_A0006. Front Microbiol 2015; 6:251. [PMID: 25904898 PMCID: PMC4389544 DOI: 10.3389/fmicb.2015.00251] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 03/13/2015] [Indexed: 01/16/2023] Open
Abstract
Restriction-modification (RM) systems have evolved to protect the cell from invading DNAs and are composed of two enzymes: a DNA methyltransferase and a restriction endonuclease. Although RM systems are present in both archaeal and bacterial genomes, DNA methylation in archaea has not been well defined. In order to characterize the function of RM systems in archaeal species, we have made use of the model haloarchaeon Haloferax volcanii. A genomic DNA methylation analysis of H. volcanii strain H26 was performed using PacBio single molecule real-time (SMRT) sequencing. This analysis was also performed on a strain of H. volcanii in which an annotated DNA methyltransferase gene HVO_A0006 was deleted from the genome. Sequence analysis of H26 revealed two motifs which are modified in the genome: C(m4)TAG and GCA(m6)BN6VTGC. Analysis of the ΔHVO_A0006 strain indicated that it exhibited reduced adenine methylation compared to the parental strain and altered the detected adenine motif. However, protein domain architecture analysis and amino acid alignments revealed that HVO_A0006 is homologous only to the N-terminal endonuclease region of Type IIG RM proteins and contains a PD-(D/E)XK nuclease motif, suggesting that HVO_A0006 is a PD-(D/E)XK nuclease family protein. Further bioinformatic analysis of the HVO_A0006 gene demonstrated that the gene is rare among the Halobacteria. It is surrounded by two transposition genes suggesting that HVO_A0006 is a fragment of a Type IIG RM gene, which has likely been acquired through gene transfer, and affects restriction-modification activity by interacting with another RM system component(s). Here, we present the first genome-wide characterization of DNA methylation in an archaeal species and examine the function of a DNA methyltransferase related gene HVO_A0006.
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Affiliation(s)
- Matthew Ouellette
- Department of Molecular and Cell Biology, University of Connecticut Storrs, CT, USA
| | - Laura Jackson
- Department of Molecular and Cell Biology, University of Connecticut Storrs, CT, USA
| | - Scott Chimileski
- Department of Molecular and Cell Biology, University of Connecticut Storrs, CT, USA
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut Storrs, CT, USA
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Sánchez-Romero MA, Cota I, Casadesús J. DNA methylation in bacteria: from the methyl group to the methylome. Curr Opin Microbiol 2015; 25:9-16. [PMID: 25818841 DOI: 10.1016/j.mib.2015.03.004] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 10/23/2022]
Abstract
Formation of C(5)-methyl-cytosine, N(4)-methyl-cytosine, and N(6)-methyl-adenine in bacterial genomes is postreplicative, and occurs at specific targets. Base methylation can modulate the interaction of DNA-binding proteins with their cognate sites, and controls chromosome replication, correction of DNA mismatches, cell cycle-coupled transcription, and formation of epigenetic lineages by phase variation. During four decades, the roles of DNA methylation in bacterial physiology have been investigated by analyzing the contribution of individual methyl groups or small methyl group clusters to the control of DNA-protein interactions. Nowadays, single-molecule real-time sequencing can analyze the DNA methylation of the entire genome (the 'methylome'). Bacterial methylomes provide a wealth of information on the methylation marks present in bacterial genomes, and may open a new era in bacterial epigenomics.
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Affiliation(s)
| | - Ignacio Cota
- Departamento de Genética, Universidad de Sevilla, Apartado 1095, 41080 Seville, Spain
| | - Josep Casadesús
- Departamento de Genética, Universidad de Sevilla, Apartado 1095, 41080 Seville, Spain.
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Werbowy O, Boratynski R, Dekowska A, Kaczorowski T. Genetic analysis of maintenance of pEC156, a naturally occurring Escherichia coli plasmid that carries genes of the EcoVIII restriction-modification system. Plasmid 2014; 77:39-50. [PMID: 25500017 DOI: 10.1016/j.plasmid.2014.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/24/2014] [Accepted: 12/01/2014] [Indexed: 11/16/2022]
Abstract
In the present study the role of the mechanisms responsible for maintenance of a natural plasmid pEC156, that carries genes of the EcoVIII restriction-modification system was investigated. Analysis of this plasmid's genetic content revealed the presence of genetic determinants suggesting two such mechanisms. The first of them relies on site specific recombination utilizing the Xer/cer molecular machinery, while the second involves a restriction-modification system as an addiction module. Our analysis indicated that three factors affect the maintenance of pEC156: (i) a cis-acting cer site involved in resolution of plasmid multimers, (ii) a gene coding for EcoVIII endonuclease, and (iii) plasmid copy number control. The lowest stability was observed with pEC156 derivatives deprived of the cer site. Decreased stability of pEC156 derivatives was also observed in E.coli strains deficient in genes coding for proteins involved in plasmid multimer resolution (XerC, XerD, ArgR and PepA). A similar effect, but to a much lesser extent was observed for the pEC156 derivative without a functional gene coding for EcoVIII endonuclease. Our results indicate that the presence of the cer site is more important for pEC156 stable maintenance than the presence of a functional gene coding for EcoVIII endonuclease. In our work we also tested maintenance of pEC156 possessing a ColE1-type replicon in bacteria belonging to Enterobacteriaceae family. We have found that pEC156 was most stably maintained in Enterobacter cloacae and Klebsiella oxytoca representing coli-type enterobacteria. We have found that in all enterobacteria tested pEC156 derivatives deficient in the cer site were significantly less stably maintained than cer(+) variants.
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Affiliation(s)
- Olesia Werbowy
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Robert Boratynski
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Agnieszka Dekowska
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Tadeusz Kaczorowski
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland.
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Cinelli T, Moscetti I, Marchi G. PsasM2I, a type II restriction-modification system in Pseudomonas savastanoi pv. savastanoi: differential distribution of carrier strains in the environment and the evolutionary history of homologous RM systems in the Pseudomonas syringae complex. MICROBIAL ECOLOGY 2014; 68:842-858. [PMID: 25008981 DOI: 10.1007/s00248-014-0451-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/19/2014] [Indexed: 06/03/2023]
Abstract
A type II restriction-modification system was found in a native plasmid of Pseudomonas savastanoi pv. savastanoi MLLI2. Functional analysis of the methyltransferase showed that the enzyme acts by protecting the DNA sequence CTGCAG from cleavage. Restriction endonuclease expression in recombinant Escherichia coli cells resulted in mutations in the REase sequence or transposition of insertion sequence 1A in the coding sequence, preventing lethal gene expression. Population screening detected homologous RM systems in other P. savastanoi strains and in the Pseudomonas syringae complex. An epidemiological survey carried out by sampling olive and oleander knots in two Italian regions showed an uneven diffusion of carrier strains, whose presence could be related to a selective advantage in maintaining the RM system in particular environments or subpopulations. Moreover, carrier strains can coexist in the same orchards, plants, and knot tissues with non-carriers, revealing unexpected genetic variability on a very small spatial scale. Phylogenetic analysis of the RM system and housekeeping gene sequences in the P. syringae complex demonstrated the ancient acquisition of the RM systems. However, the evolutionary history of the gene complex also showed the involvement of horizontal gene transfer between related strains and recombination events.
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Affiliation(s)
- Tamara Cinelli
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell'Ambiente (DISPAA), Sezione di Patologia Vegetale ed Entomologia, Università degli Studi di Firenze, Piazzale delle Cascine 28, 50144, Firenze, Italy,
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Anvar SY, Frank J, Pol A, Schmitz A, Kraaijeveld K, den Dunnen JT, Op den Camp HJ. The genomic landscape of the verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV. BMC Genomics 2014; 15:914. [PMID: 25331649 PMCID: PMC4210602 DOI: 10.1186/1471-2164-15-914] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 10/06/2014] [Indexed: 01/01/2023] Open
Abstract
Background Aerobic methanotrophs can grow in hostile volcanic environments and use methane as their sole source of energy. The discovery of three verrucomicrobial Methylacidiphilum strains has revealed diverse metabolic pathways used by these methanotrophs, including mechanisms through which methane is oxidized. The basis of a complete understanding of these processes and of how these bacteria evolved and are able to thrive in such extreme environments partially resides in the complete characterization of their genome and its architecture. Results In this study, we present the complete genome sequence of Methylacidiphilum fumariolicum SolV, obtained using Pacific Biosciences single-molecule real-time (SMRT) sequencing technology. The genome assembles to a single 2.5 Mbp chromosome with an average GC content of 41.5%. The genome contains 2,741 annotated genes and 314 functional subsystems including all key metabolic pathways that are associated with Methylacidiphilum strains, including the CBB pathway for CO2 fixation. However, it does not encode the serine cycle and ribulose monophosphate pathways for carbon fixation. Phylogenetic analysis of the particulate methane mono-oxygenase operon separates the Methylacidiphilum strains from other verrucomicrobial methanotrophs. RNA-Seq analysis of cell cultures growing in three different conditions revealed the deregulation of two out of three pmoCAB operons. In addition, genes involved in nitrogen fixation were upregulated in cell cultures growing in nitrogen fixing conditions, indicating the presence of active nitrogenase. Characterization of the global methylation state of M. fumariolicum SolV revealed methylation of adenines and cytosines mainly in the coding regions of the genome. Methylation of adenines was predominantly associated with 5′-m6ACN4GT-3′ and 5′-CCm6AN5CTC-3′ methyltransferase recognition motifs whereas methylated cytosines were not associated with any specific motif. Conclusions Our findings provide novel insights into the global methylation state of verrucomicrobial methanotroph M. fumariolicum SolV. However, partial conservation of methyltransferases between M. fumariolicum SolV and M. infernorum V4 indicates potential differences in the global methylation state of Methylacidiphilum strains. Unravelling the M. fumariolicum SolV genome and its epigenetic regulation allow for robust characterization of biological processes that are involved in oxidizing methane. In turn, they offer a better understanding of the evolution, the underlying physiological and ecological properties of SolV and other Methylacidiphilum strains. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-914) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Seyed Yahya Anvar
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Gonzalez D, Kozdon JB, McAdams HH, Shapiro L, Collier J. The functions of DNA methylation by CcrM in Caulobacter crescentus: a global approach. Nucleic Acids Res 2014; 42:3720-35. [PMID: 24398711 PMCID: PMC3973325 DOI: 10.1093/nar/gkt1352] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
DNA methylation is involved in a diversity of processes in bacteria, including maintenance of genome integrity and regulation of gene expression. Here, using Caulobacter crescentus as a model, we exploit genome-wide experimental methods to uncover the functions of CcrM, a DNA methyltransferase conserved in most Alphaproteobacteria. Using single molecule sequencing, we provide evidence that most CcrM target motifs (GANTC) switch from a fully methylated to a hemi-methylated state when they are replicated, and back to a fully methylated state at the onset of cell division. We show that DNA methylation by CcrM is not required for the control of the initiation of chromosome replication or for DNA mismatch repair. By contrast, our transcriptome analysis shows that >10% of the genes are misexpressed in cells lacking or constitutively over-expressing CcrM. Strikingly, GANTC methylation is needed for the efficient transcription of dozens of genes that are essential for cell cycle progression, in particular for DNA metabolism and cell division. Many of them are controlled by promoters methylated by CcrM and co-regulated by other global cell cycle regulators, demonstrating an extensive cross talk between DNA methylation and the complex regulatory network that controls the cell cycle of C. crescentus and, presumably, of many other Alphaproteobacteria.
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Affiliation(s)
- Diego Gonzalez
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, CH 1015, Switzerland, Department of Developmental Biology, Stanford University, CA 94305, USA and Department of Chemistry, Stanford University, CA 94305, USA
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Vasu K, Nagaraja V. Diverse functions of restriction-modification systems in addition to cellular defense. Microbiol Mol Biol Rev 2013; 77:53-72. [PMID: 23471617 PMCID: PMC3591985 DOI: 10.1128/mmbr.00044-12] [Citation(s) in RCA: 383] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Restriction-modification (R-M) systems are ubiquitous and are often considered primitive immune systems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population.
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Affiliation(s)
- Kommireddy Vasu
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Mebrhatu MT, Cenens W, Aertsen A. An overview of the domestication and impact of the Salmonella mobilome. Crit Rev Microbiol 2013; 40:63-75. [PMID: 23356413 DOI: 10.3109/1040841x.2012.755949] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Salmonella spp. are accountable for a large fraction of the global infectious disease burden, with most of their infections being food- or water-borne. The phenotypic features and adaptive potential of Salmonella spp. appear to be driven to a large extent by mobile or laterally acquired genetic elements. A better understanding of the conduct and diversification of these important pathogens consequently requires a more profound insight into the different mechanisms by which these pivotal elements establish themselves in the cell and affect its behavior. This review, therefore, provides an overview of the physiological impact and domestication of the Salmonella mobilome.
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Affiliation(s)
- Mehari Tesfazgi Mebrhatu
- Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, KU Leuven , Leuven , Belgium
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Abstract
In prokaryotes, alteration in gene expression was observed with the modification of DNA, especially DNA methylation. Such changes are inherited from generation to generation with no alterations in the DNA sequence and represent the epigenetic signal in prokaryotes. DNA methyltransferases are enzymes involved in DNA modification and thus in epigenetic regulation of gene expression. DNA methylation not only affects the thermodynamic stability of DNA, but also changes its curvature. Methylation of specific residues on DNA can affect the protein-DNA interactions. DNA methylation in prokaryotes regulates a number of physiological processes in the bacterial cell including transcription, DNA mismatch repair and replication initiation. Significantly, many reports have suggested a role of DNA methylation in regulating the expression of a number of genes in virulence and pathogenesis thus, making DNA methlytransferases novel targets for the designing of therapeutics. Here, we summarize the current knowledge about the influence of DNA methylation on gene regulation in different bacteria, and on bacterial virulence.
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Affiliation(s)
- Ritesh Kumar
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India,
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Kong Y, Ma JH, Warren K, Tsang RS, Low DE, Jamieson FB, Alexander DC, Hao W. Homologous recombination drives both sequence diversity and gene content variation in Neisseria meningitidis. Genome Biol Evol 2013; 5:1611-27. [PMID: 23902748 PMCID: PMC3787668 DOI: 10.1093/gbe/evt116] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2013] [Indexed: 01/13/2023] Open
Abstract
The study of genetic and phenotypic variation is fundamental for understanding the dynamics of bacterial genome evolution and untangling the evolution and epidemiology of bacterial pathogens. Neisseria meningitidis (Nm) is among the most intriguing bacterial pathogens in genomic studies due to its dynamic population structure and complex forms of pathogenicity. Extensive genomic variation within identical clonal complexes (CCs) in Nm has been recently reported and suggested to be the result of homologous recombination, but the extent to which recombination contributes to genomic variation within identical CCs has remained unclear. In this study, we sequenced two Nm strains of identical serogroup (C) and multi-locus sequence type (ST60), and conducted a systematic analysis with an additional 34 Nm genomes. Our results revealed that all gene content variation between the two ST60 genomes was introduced by homologous recombination at the conserved flanking genes, and 94.25% or more of sequence divergence was caused by homologous recombination. Recombination was found in genes associated with virulence factors, antigenic outer membrane proteins, and vaccine targets, suggesting an important role of homologous recombination in rapidly altering the pathogenicity and antigenicity of Nm. Recombination was also evident in genes of the restriction and modification systems, which may undermine barriers to DNA exchange. In conclusion, homologous recombination can drive both gene content variation and sequence divergence in Nm. These findings shed new light on the understanding of the rapid pathoadaptive evolution of Nm and other recombinogenic bacterial pathogens.
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Affiliation(s)
- Ying Kong
- Department of Biological Sciences, Wayne State University
| | - Jennifer H. Ma
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
| | - Keisha Warren
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Raymond S.W. Tsang
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Donald E. Low
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Frances B. Jamieson
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - David C. Alexander
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
- Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Weilong Hao
- Department of Biological Sciences, Wayne State University
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Rockah-Shmuel L, Tawfik DS. Evolutionary transitions to new DNA methyltransferases through target site expansion and shrinkage. Nucleic Acids Res 2012; 40:11627-37. [PMID: 23074188 PMCID: PMC3526282 DOI: 10.1093/nar/gks944] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
DNA-binding and modifying proteins show high specificity but also exhibit a certain level of promiscuity. Such latent promiscuous activities comprise the starting points for new protein functions, but this hypothesis presents a paradox: a new activity can only evolve if it already exists. How then, do novel activities evolve? DNA methyltransferases, for example, are highly divergent in their target sites, but how transitions toward novel sites occur remains unknown. We performed laboratory evolution of the DNA methyltransferase M.HaeIII. We found that new target sites emerged primarily through expansion of the original site, GGCC, and the subsequent shrinkage of evolved expanded sites. Variants evolved for sites that are promiscuously methylated by M.HaeIII [GG(A/T)CC and GGCGCC] carried mutations in ‘gate-keeper’ residues. They could thereby methylate novel target sites such as GCGC and GGATCC that were neither selected for nor present in M.HaeIII. These ‘generalist’ intermediates were further evolved to obtain variants with novel target specificities. Our results demonstrate the ease by which new DNA-binding and modifying specificities evolve and the mechanism by which they occur at both the protein and DNA levels.
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Affiliation(s)
- Liat Rockah-Shmuel
- Department of Biological chemistry, Weizmann Institute of Science, Hertzel St, Rehovot 76100, Israel
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Ball NJ, McGeehan JE, Streeter SD, Thresh SJ, Kneale GG. The structural basis of differential DNA sequence recognition by restriction-modification controller proteins. Nucleic Acids Res 2012; 40:10532-42. [PMID: 22941636 PMCID: PMC3488213 DOI: 10.1093/nar/gks718] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Controller (C) proteins regulate the expression of restriction-modification (RM) genes in a wide variety of RM systems. However, the RM system Esp1396I is of particular interest as the C protein regulates both the restriction endonuclease (R) gene and the methyltransferase (M) gene. The mechanism of this finely tuned genetic switch depends on differential binding affinities for the promoters controlling the R and M genes, which in turn depends on differential DNA sequence recognition and the ability to recognize dual symmetries. We report here the crystal structure of the C protein bound to the M promoter, and compare the binding affinities for each operator sequence by surface plasmon resonance. Comparison of the structure of the transcriptional repression complex at the M promoter with that of the transcriptional activation complex at the R promoter shows how subtle changes in protein-DNA interactions, underpinned by small conformational changes in the protein, can explain the molecular basis of differential regulation of gene expression.
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Affiliation(s)
- N J Ball
- Biomolecular Structure Group, Institute of Biomedical and Biomolecular Sciences, School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
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Identification of Cj1051c as a major determinant for the restriction barrier of Campylobacter jejuni strain NCTC11168. Appl Environ Microbiol 2012; 78:7841-8. [PMID: 22923403 DOI: 10.1128/aem.01799-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Campylobacter jejuni is a leading cause of human diarrheal illness in the world, and research on it has benefitted greatly by the completion of several genome sequences and the development of molecular biology tools. However, many hurdles remain for a full understanding of this unique bacterial pathogen. One of the most commonly used strains for genetic work with C. jejuni is NCTC11168. While this strain is readily transformable with DNA for genomic recombination, transformation with plasmids is problematic. In this study, we have identified a determinant of this to be cj1051c, predicted to encode a restriction-modification type IIG enzyme. Knockout mutagenesis of this gene resulted in a strain with a 1,000-fold-enhanced transformation efficiency with a plasmid purified from a C. jejuni host. Additionally, this mutation conferred the ability to be transformed by plasmids isolated from an Escherichia coli host. Sequence analysis suggested a high level of variability of the specificity domain between strains and that this gene may be subject to phase variation. We provide evidence that cj1051c is active in NCTC11168 and behaves as expected for a type IIG enzyme. The identification of this determinant provides a greater understanding of the molecular biology of C. jejuni as well as a tool for plasmid work with strain NCTC11168.
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Vandžurová A, Hrašková I, Júdová J, Javorský P, Pristaš P. Antibiotic resistance and restriction endonucleases in fecal enterococci of chamois (Rupicapra rupicapra Linnaeus, 1758). Folia Microbiol (Praha) 2012; 57:355-8. [DOI: 10.1007/s12223-012-0141-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 01/04/2012] [Indexed: 11/28/2022]
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Diaz L, Kiratisin P, Mendes RE, Panesso D, Singh KV, Arias CA. Transferable plasmid-mediated resistance to linezolid due to cfr in a human clinical isolate of Enterococcus faecalis. Antimicrob Agents Chemother 2012; 56:3917-22. [PMID: 22491691 PMCID: PMC3393385 DOI: 10.1128/aac.00419-12] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 04/01/2012] [Indexed: 12/26/2022] Open
Abstract
Nonmutational resistance to linezolid is due to the presence of cfr, which encodes a methyltransferase responsible for methylation of A2503 in the 23S rRNA. The cfr gene was first described in animal isolates of staphylococci, and more recently, it has been identified in Staphylococcus aureus from human clinical infections, including in an outbreak of methicillin-resistant S. aureus. In enterococci, cfr has been described in an animal isolate of Enterococcus faecalis from China. Here, we report an isolate of linezolid-resistant E. faecalis (603-50427X) recovered from a patient in Thailand who received prolonged therapy with the antibiotic for the treatment of atypical mycobacterial disease. The isolate lacked mutations in the genes coding for 23S rRNA and L3 and L4 ribosomal proteins and belonged to the multilocus sequence type (MLST) 16 (ST16), which is commonly found in enterococcal isolates from animal sources. Resistance to linezolid was associated with the presence of cfr on an ~97-kb transferable plasmid. The cfr gene environment exhibited DNA sequences similar to those of other cfr-carrying plasmids previously identified in staphylococci (nucleotide identity, 99 to 100%). The cfr-carrying plasmid was transferable by conjugation to a laboratory strain of E. faecalis (OG1RF) but not to Enterococcus faecium or S. aureus. The cfr gene was flanked by IS256-like sequences both upstream and downstream. This is the first characterization of the potential horizontal transferability of the cfr gene from a human linezolid-resistant isolate of E. faecalis.
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Affiliation(s)
- Lorena Diaz
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas
- Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
| | - Pattarachai Kiratisin
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | | | - Diana Panesso
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas
- Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
| | - Kavindra V. Singh
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas
| | - Cesar A. Arias
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas
- Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
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Wiedenbeck J, Cohan FM. Origins of bacterial diversity through horizontal genetic transfer and adaptation to new ecological niches. FEMS Microbiol Rev 2011; 35:957-76. [PMID: 21711367 DOI: 10.1111/j.1574-6976.2011.00292.x] [Citation(s) in RCA: 380] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Horizontal genetic transfer (HGT) has played an important role in bacterial evolution at least since the origins of the bacterial divisions, and HGT still facilitates the origins of bacterial diversity, including diversity based on antibiotic resistance. Adaptive HGT is aided by unique features of genetic exchange in bacteria such as the promiscuity of genetic exchange and the shortness of segments transferred. Genetic exchange rates are limited by the genetic and ecological similarity of organisms. Adaptive transfer of genes is limited to those that can be transferred as a functional unit, provide a niche-transcending adaptation, and are compatible with the architecture and physiology of other organisms. Horizontally transferred adaptations may bring about fitness costs, and natural selection may ameliorate these costs. The origins of ecological diversity can be analyzed by comparing the genomes of recently divergent, ecologically distinct populations, which can be discovered as sequence clusters. Such genome comparisons demonstrate the importance of HGT in ecological diversification. Newly divergent populations cannot be discovered as sequence clusters when their ecological differences are coded by plasmids, as is often the case for antibiotic resistance; the discovery of such populations requires a screen for plasmid-coded functions. This paper reviews the features of bacterial genetics that allow HGT, the similarities between organisms that foster HGT between them, the limits to the kinds of adaptations that can be transferred, and amelioration of fitness costs associated with HGT; the paper also reviews approaches to discover the origins of new, ecologically distinct bacterial populations and the role that HGT plays in their founding.
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Affiliation(s)
- Jane Wiedenbeck
- Department of Biology, Wesleyan University, Middletown, CT 06459, USA
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Neisseria meningitidis is structured in clades associated with restriction modification systems that modulate homologous recombination. Proc Natl Acad Sci U S A 2011; 108:4494-9. [PMID: 21368196 DOI: 10.1073/pnas.1019751108] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molecular data on a limited number of chromosomal loci have shown that the population of Neisseria meningitidis (Nm), a deadly human pathogen, is structured in distinct lineages. Given that the Nm population undergoes substantial recombination, the mechanisms resulting in the evolution of these lineages, their persistence in time, and the implications for the pathogenicity of the bacterium are not yet completely understood. Based on whole-genome sequencing, we show that Nm is structured in phylogenetic clades. Through acquisition of specific genes and through insertions and rearrangements, each clade has acquired and remodeled specific genomic tracts, with the potential to impact on the commensal and virulence behavior of Nm. Despite this clear evidence of a structured population, we confirm high rates of detectable recombination throughout the whole Nm chromosome. However, gene conversion events were found to be longer within clades than between clades, suggesting a DNA cleavage mechanism associated with the phylogeny of the species. We identify 22 restriction modification systems, probably acquired by horizontal gene transfer from outside of the species/genus, whose distribution in the different strains coincides with the phylogenetic clade structure. We provide evidence that these clade-associated restriction modification systems generate a differential barrier to DNA exchange consistent with the observed population structure. These findings have general implications for the emergence of lineage structure and virulence in recombining bacterial populations, and they could provide an evolutionary framework for the population biology of a number of other bacterial species that show contradictory population structure and dynamics.
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