151
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Characterization of a Cryptic Rolling-Circle Replication Plasmid pMK8 from Enterococcus durans 1-8. Curr Microbiol 2018; 75:1198-1205. [PMID: 29777339 DOI: 10.1007/s00284-018-1509-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 05/12/2018] [Indexed: 10/16/2022]
Abstract
A novel cryptic plasmid from Enterococcus durans 1-8, designated as pMK8, was sequenced and analyzed in this study. It consists of 3337 bp with a G + C content of 33.11%. Sequence analysis of pMK8 revealed three putative open reading frames (ORFs). Based on homology, two of them were identified as genes encoding replication initiation (RepC) and mobilization (Mob) protein, respectively. Sequence analysis revealed a pT181 family double-strand origin (dso) and a putative single-strand origin (sso) located upstream of the repC gene. Sequence homology analysis indicated that the sso belongs to the ssoW family. Southern hybridization confirmed the presence of single-strand DNA (ssDNA) intermediates, suggesting that pMK8 replicates via the RCR mechanism. Furthermore, the relative copy number of pMK8 was estimated by real-time PCR to be 175 ± 14 copies in each cell.
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152
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Salto IP, Torres Tejerizo G, Wibberg D, Pühler A, Schlüter A, Pistorio M. Comparative genomic analysis of Acinetobacter spp. plasmids originating from clinical settings and environmental habitats. Sci Rep 2018; 8:7783. [PMID: 29773850 PMCID: PMC5958079 DOI: 10.1038/s41598-018-26180-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/27/2018] [Indexed: 12/20/2022] Open
Abstract
Bacteria belonging to the genus Acinetobacter have become of clinical importance over the last decade due to the development of a multi-resistant phenotype and their ability to survive under multiple environmental conditions. The development of these traits among Acinetobacter strains occurs frequently as a result of plasmid-mediated horizontal gene transfer. In this work, plasmids from nosocomial and environmental Acinetobacter spp. collections were separately sequenced and characterized. Assembly of the sequenced data resulted in 19 complete replicons in the nosocomial collection and 77 plasmid contigs in the environmental collection. Comparative genomic analysis showed that many of them had conserved backbones. Plasmid coding sequences corresponding to plasmid specific functions were bioinformatically and functionally analyzed. Replication initiation protein analysis revealed the predominance of the Rep_3 superfamily. The phylogenetic tree constructed from all Acinetobacter Rep_3 superfamily plasmids showed 16 intermingled clades originating from nosocomial and environmental habitats. Phylogenetic analysis of relaxase proteins revealed the presence of a new sub-clade named MOBQAci, composed exclusively of Acinetobacter relaxases. Functional analysis of proteins belonging to this group showed that they behaved differently when mobilized using helper plasmids belonging to different incompatibility groups.
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Affiliation(s)
- Ileana P Salto
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
| | - Gonzalo Torres Tejerizo
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Daniel Wibberg
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Alfred Pühler
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Andreas Schlüter
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Mariano Pistorio
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina.
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153
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Dynamics in Copy Numbers of Five Plasmids of a Dairy Lactococcus lactis Strain under Dairy-Related Conditions Including Near-Zero Growth Rates. Appl Environ Microbiol 2018; 84:AEM.00314-18. [PMID: 29572209 DOI: 10.1128/aem.00314-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 03/19/2018] [Indexed: 11/20/2022] Open
Abstract
Lactic acid bacteria can carry multiple plasmids affecting their performance in dairy fermentations. The expression of plasmid-borne genes and the activity of the corresponding proteins are severely affected by changes in the numbers of plasmid copies. We studied the impact of growth rate on the dynamics of plasmid copy numbers at high growth rates in chemostat cultures and down to near-zero growth rates in retentostat cultures. Five plasmids of the dairy strain Lactococcus lactis FM03-V1 were selected, and these varied in size (3 to 39 kb), in replication mechanism (theta or rolling circle), and in putative (dairy-associated) functions. The copy numbers ranged from 1.5 to 40.5, and the copy number of theta-type replicating plasmids was negatively correlated to the plasmid size. Despite the extremely wide range of growth rates (0.0003 h-1 to 0.6 h-1), the copy numbers of the five plasmids were stable and only slightly increased at near-zero growth rates, showing that the plasmid replication rate was strictly controlled. One low-copy-number plasmid, carrying a large exopolysaccharide gene cluster, was segregationally unstable during retentostat cultivations, reflected in a complete loss of the plasmid in one of the retentostat cultures. The copy number of the five plasmids was also hardly affected by varying the pH value, nutrient limitation, or the presence of citrate (maximum 2.2-fold), signifying the stability in copy number of the plasmids.IMPORTANCE Lactococcus lactis is extensively used in starter cultures for dairy fermentations. Important traits for the growth and survival of L. lactis in dairy fermentations are encoded by genes located on plasmids, such as genes involved in lactose and citrate metabolism, protein degradation, oligopeptide uptake, and bacteriophage resistance. Because the number of plasmid copies could affect the expression of plasmid-borne genes, it is important to know the factors that influence the plasmid copy numbers. We monitored the plasmid copy numbers of L. lactis at near-zero growth rates, characteristic for cheese ripening. Moreover, we analyzed the effects of pH, nutrient limitation, and the presence of citrate. This showed that the plasmid copy numbers were stable, giving insight into plasmid copy number dynamics in dairy fermentations.
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154
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Next-generation biocontainment systems for engineered organisms. Nat Chem Biol 2018; 14:530-537. [PMID: 29769737 DOI: 10.1038/s41589-018-0056-x] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 03/09/2018] [Indexed: 12/14/2022]
Abstract
The increasing use of engineered organisms for industrial, clinical, and environmental applications poses a growing risk of spreading hazardous biological entities into the environment. To address this biosafety issue, significant effort has been invested in creating ways to confine these organisms and transgenic materials. Emerging technologies in synthetic biology involving genetic circuit engineering, genome editing, and gene expression regulation have led to the development of novel biocontainment systems. In this perspective, we highlight recent advances in biocontainment and suggest a number of approaches for future development, which may be applied to overcome remaining challenges in safeguard implementation.
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155
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Abstract
Plasmids mediate the horizontal transmission of genetic information between bacteria, facilitating their adaptation to multiple environmental conditions. An especially important example of the ability of plasmids to catalyze bacterial adaptation and evolution is their instrumental role in the global spread of antibiotic resistance, which constitutes a major threat to public health. Plasmids provide bacteria with new adaptive tools, but they also entail a metabolic burden that, in the absence of selection for plasmid-encoded traits, reduces the competitiveness of the plasmid-carrying clone. Although this fitness reduction can be alleviated over time through compensatory evolution, the initial cost associated with plasmid carriage is the main constraint on the vertical and horizontal replication of these genetic elements. The fitness effects of plasmids therefore have a crucial influence on their ability to associate with new bacterial hosts and consequently on the evolution of plasmid-mediated antibiotic resistance. However, the molecular mechanisms underlying plasmid fitness cost remain poorly understood. Here, we analyze the literature in the field and examine the potential fitness effects produced by plasmids throughout their life cycle in the host bacterium. We also explore the various mechanisms evolved by plasmids and bacteria to minimize the cost entailed by these mobile genetic elements. Finally, we discuss potential future research directions in the field.
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156
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Mariat D, Robert V, Langella P, Chatel JM. Plasmid transfer efficiency using Lactoccocus lactis strains depends on invasiveness status but also on plasmid copy number. FEMS Microbiol Lett 2018; 364:3827360. [PMID: 28505315 DOI: 10.1093/femsle/fnx100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/12/2017] [Indexed: 12/19/2022] Open
Abstract
Lactic acid bacteria as Lactococcus lactis are used as vector for protein but also DNA delivery into intestinal cells in vitro and in vivo. For the plasmid delivery strategy, the plasmid copy number per bacteria (PCN) is thus of great importance. The aim of this paper is to determine the physiological conditions when PCN is the highest in the bacteria. PCN was characterized by qPCR in five different recombinant Lactococcus lactis strains, containing one (mono-) or two different plasmids (biplasmidic), at exponential or stationary phase. We showed that in all cases but one, PCN is higher at exponential than stationary phase. PCN seems to depend on (i) monoplasmidic or biplasmidic strain; (ii) origin of replication of the plasmid; and (iii) the DNA load of the bacteria. Then we studied plasmid transfer in vitro from recombinant L. lactis to eukaryotic COS-7 cells using culture at exponential or stationary phase. We showed that plasmid transfer can be improved in vitro by using bacteria at exponential phase.
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Affiliation(s)
- Denis Mariat
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Véronique Robert
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Philippe Langella
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Jean-Marc Chatel
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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157
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Liu F, Ma R, Tay CYA, Octavia S, Lan R, Chung HKL, Riordan SM, Grimm MC, Leong RW, Tanaka MM, Connor S, Zhang L. Genomic analysis of oral Campylobacter concisus strains identified a potential bacterial molecular marker associated with active Crohn's disease. Emerg Microbes Infect 2018; 7:64. [PMID: 29636463 PMCID: PMC5893538 DOI: 10.1038/s41426-018-0065-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/14/2018] [Accepted: 03/20/2018] [Indexed: 02/08/2023]
Abstract
Campylobacter concisus is an oral bacterium that is associated with inflammatory bowel disease (IBD) including Crohn’s disease (CD) and ulcerative colitis (UC). C. concisus consists of two genomospecies (GS) and diverse strains. This study aimed to identify molecular markers to differentiate commensal and IBD-associated C. concisus strains. The genomes of 63 oral C. concisus strains isolated from patients with IBD and healthy controls were examined, of which 38 genomes were sequenced in this study. We identified a novel secreted enterotoxin B homologue, Csep1. The csep1 gene was found in 56% of GS2 C. concisus strains, presented in the plasmid pICON or the chromosome. A six-nucleotide insertion at the position 654–659 bp in csep1 (csep1-6bpi) was found. The presence of csep1-6bpi in oral C. concisus strains isolated from patients with active CD (47%, 7/15) was significantly higher than that in strains from healthy controls (0/29, P = 0.0002), and the prevalence of csep1-6bpi positive C. concisus strains was significantly higher in patients with active CD (67%, 4/6) as compared to healthy controls (0/23, P = 0.0006). Proteomics analysis detected the Csep1 protein. A csep1 gene hot spot in the chromosome of different C. concisus strains was found. The pICON plasmid was only found in GS2 strains isolated from the two relapsed CD patients with small bowel complications. This study reports a C. concisus molecular marker (csep1-6bpi) that is associated with active CD.
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Affiliation(s)
- Fang Liu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Rena Ma
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Chin Yen Alfred Tay
- Helicobacter Research Laboratory, Marshall Centre for Infectious Diseases Research and Training, School of Pathology and Laboratory Medicine, University of Western Australia, Perth, WA, Australia
| | - Sophie Octavia
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Heung Kit Leslie Chung
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Stephen M Riordan
- Gastrointestinal and Liver Unit, Prince of Wales Hospital, University of New South Wales, Sydney, NSW, Australia
| | - Michael C Grimm
- St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Rupert W Leong
- Concord Hospital, University of New South Wales, Sydney, NSW, Australia
| | - Mark M Tanaka
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Susan Connor
- Liverpool Hospital, University of New South Wales, Sydney, NSW, Australia
| | - Li Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.
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158
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Dietel AK, Kaltenpoth M, Kost C. Convergent Evolution in Intracellular Elements: Plasmids as Model Endosymbionts. Trends Microbiol 2018; 26:755-768. [PMID: 29650391 DOI: 10.1016/j.tim.2018.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 11/29/2022]
Abstract
Endosymbionts are organisms that live inside the cells of other species. This lifestyle is ubiquitous across the tree of life and is featured by unicellular eukaryotes, prokaryotes, and by extrachromosomal genetic elements such as plasmids. Given that all of these elements dwell in the cytoplasm of their host cell, they should be subject to similar selection pressures. Here we show that strikingly similar features have evolved in both bacterial endosymbionts and plasmids. Since host and endosymbiont are often metabolically tightly intertwined, they are difficult to disentangle experimentally. We propose that using plasmids as tractable model systems can help to solve this problem, thus allowing fundamental questions to be experimentally addressed about the ecology and evolution of endosymbiotic interactions.
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Affiliation(s)
- Anne-Kathrin Dietel
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany
| | - Martin Kaltenpoth
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Christian Kost
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany; Current address: Department of Ecology, School of Biology/Chemistry, University of Osnabrück, 49069 Osnabrück, Germany.
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159
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Lavi B, Levy Karin E, Pupko T, Hazkani-Covo E. The Prevalence and Evolutionary Conservation of Inverted Repeats in Proteobacteria. Genome Biol Evol 2018; 10:918-927. [PMID: 29608719 PMCID: PMC5941160 DOI: 10.1093/gbe/evy044] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2018] [Indexed: 12/11/2022] Open
Abstract
Perfect short inverted repeats (IRs) are known to be enriched in a variety of bacterial and eukaryotic genomes. Currently, it is unclear whether perfect IRs are conserved over evolutionary time scales. In this study, we aimed to characterize the prevalence and evolutionary conservation of IRs across 20 proteobacterial strains. We first identified IRs in Escherichia coli K-12 substr MG1655 and showed that they are overabundant. We next aimed to test whether this overabundance is reflected in the conservation of IRs over evolutionary time scales. To this end, for each perfect IR identified in E. coli MG1655, we collected orthologous sequences from related proteobacterial genomes. We next quantified the evolutionary conservation of these IRs, that is, the presence of the exact same IR across orthologous regions. We observed high conservation of perfect IRs: out of the 234 examined orthologous regions, 145 were more conserved than expected, which is statistically significant even after correcting for multiple testing. Our results together with previous experimental findings support a model in which imperfect IRs are corrected to perfect IRs in a preferential manner via a template switching mechanism.
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Affiliation(s)
- Bar Lavi
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Eli Levy Karin
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
- Department of Molecular Biology & Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Tal Pupko
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Einat Hazkani-Covo
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
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160
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van Mastrigt O, Mager EE, Jamin C, Abee T, Smid EJ. Citrate, low pH and amino acid limitation induce citrate utilization in Lactococcus lactis biovar diacetylactis. Microb Biotechnol 2018; 11:369-380. [PMID: 29215194 PMCID: PMC5812246 DOI: 10.1111/1751-7915.13031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/07/2017] [Accepted: 11/05/2017] [Indexed: 11/27/2022] Open
Abstract
In Lactococcus lactis subsp. lactis biovar diacetylactis, citrate transport is facilitated by the plasmid-encoded citrate permease (CitP). In this work, we analysed regulation of citrate utilization by pH, nutrient limitation and the presence of citrate at four different levels: (i) plasmid copy number, (ii) citP transcription, (iii) citP mRNA processing and (iv) citrate utilization capacity. Citrate was supplied as cosubstrate together with lactose. The citP gene is known to be induced in cells grown at low pH. However, we demonstrated that transcription of citP was even higher in the presence of citrate (3.8-fold compared with 2.0-fold). The effect of citrate has been overlooked by other researchers because they determined the effect of citrate using M17 medium, which already contains 0.80 ± 0.07 mM citrate. The plasmid copy number increased in cells grown under amino acid limitation (1.6-fold) and/or at low pH (1.4-fold). No significant differences in citP mRNA processing were found. Citrate utilization rates increased from approximately 1 to 65 μmol min-1 gDW-1 from lowest to highest citP expression. Acetoin formation increased during growth in an acidic environment due to induction of the acetoin pathway. Quantification of the relative contributions allowed us to construct a model for regulation of citrate utilization in L. lactis biovar diacetylactis. This knowledge will help to select conditions to improve flavour formation from citrate.
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Affiliation(s)
- Oscar van Mastrigt
- Laboratory of Food MicrobiologyWageningen University and ResearchWageningenThe Netherlands
| | - Emma E. Mager
- Laboratory of Food MicrobiologyWageningen University and ResearchWageningenThe Netherlands
| | - Casper Jamin
- Laboratory of Food MicrobiologyWageningen University and ResearchWageningenThe Netherlands
| | - Tjakko Abee
- Laboratory of Food MicrobiologyWageningen University and ResearchWageningenThe Netherlands
| | - Eddy J. Smid
- Laboratory of Food MicrobiologyWageningen University and ResearchWageningenThe Netherlands
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161
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Butzin NC, Mather WH. Crosstalk between Diverse Synthetic Protein Degradation Tags in Escherichia coli. ACS Synth Biol 2018; 7:54-62. [PMID: 29193958 DOI: 10.1021/acssynbio.7b00122] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, a synthetic circuit in E. coli demonstrated that two proteins engineered with LAA tags targeted to the native protease ClpXP are susceptible to crosstalk due to competition for degradation between proteins. To understand proteolytic crosstalk beyond the single protease regime, we investigated in E. coli a set of synthetic circuits designed to probe the dynamics of existing and novel degradation tags fused to fluorescent proteins. These circuits were tested using both microplate reader and single-cell assays. We first quantified the degradation rates of each tag in isolation. We then tested if there was crosstalk between two distinguishable fluorescent proteins engineered with identical or different degradation tags. We demonstrated that proteolytic crosstalk was indeed not limited to the LAA degradation tag, but was also apparent between other diverse tags, supporting the complexity of the E. coli protein degradation system.
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Affiliation(s)
- Nicholas C. Butzin
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota 57007, United States
| | - William H. Mather
- Quantitative Biosciences, Inc., Solana Beach, California 92075, United States
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162
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Kwong SM, Ramsay JP, Jensen SO, Firth N. Replication of Staphylococcal Resistance Plasmids. Front Microbiol 2017; 8:2279. [PMID: 29218034 PMCID: PMC5703833 DOI: 10.3389/fmicb.2017.02279] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 11/06/2017] [Indexed: 11/16/2022] Open
Abstract
The currently widespread and increasing prevalence of resistant bacterial pathogens is a significant medical problem. In clinical strains of staphylococci, the genetic determinants that confer resistance to antimicrobial agents are often located on mobile elements, such as plasmids. Many of these resistance plasmids are capable of horizontal transmission to other bacteria in their surroundings, allowing extraordinarily rapid adaptation of bacterial populations. Once the resistance plasmids have been spread, they are often perpetually maintained in the new host, even in the absence of selective pressure. Plasmid persistence is accomplished by plasmid-encoded genetic systems that ensure efficient replication and segregational stability during cell division. Staphylococcal plasmids utilize proteins of evolutionarily diverse families to initiate replication from the plasmid origin of replication. Several distinctive plasmid copy number control mechanisms have been studied in detail and these appear conserved within plasmid classes. The initiators utilize various strategies and serve a multifunctional role in (i) recognition and processing of the cognate replication origin to an initiation active form and (ii) recruitment of host-encoded replication proteins that facilitate replisome assembly. Understanding the detailed molecular mechanisms that underpin plasmid replication may lead to novel approaches that could be used to reverse or slow the development of resistance.
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Affiliation(s)
- Stephen M Kwong
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Joshua P Ramsay
- School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Slade O Jensen
- Antimicrobial Resistance and Mobile Elements Group, Ingham Institute for Applied Medical Research, Sydney, NSW, Australia
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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163
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Werbowy O, Werbowy S, Kaczorowski T. Plasmid stability analysis based on a new theoretical model employing stochastic simulations. PLoS One 2017; 12:e0183512. [PMID: 28846713 PMCID: PMC5573283 DOI: 10.1371/journal.pone.0183512] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 08/05/2017] [Indexed: 12/03/2022] Open
Abstract
Here, we present a simple theoretical model to study plasmid stability, based on one input parameter which is the copy number of plasmids present in a host cell. The Monte Carlo approach was used to analyze random fluctuations affecting plasmid replication and segregation leading to gradual reduction in the plasmid population within the host cell. This model was employed to investigate maintenance of pEC156 derivatives, a high-copy number ColE1-type Escherichia coli plasmid that carries an EcoVIII restriction-modification system. Plasmid stability was examined in selected Escherichia coli strains (MG1655, wild-type; MG1655 pcnB, and hyper-recombinogenic JC8679 sbcA). We have compared the experimental data concerning plasmid maintenance with the simulations and found that the theoretical stability patterns exhibited an excellent agreement with those empirically tested. In our simulations, we have investigated the influence of replication fails (α parameter) and uneven partition as a consequence of multimer resolution fails (δ parameter), and the post-segregation killing factor (β parameter). All of these factors act at the same time and affect plasmid inheritance at different levels. In case of pEC156-derivatives we concluded that multimerization is a major determinant of plasmid stability. Our data indicate that even small changes in the fidelity of segregation can have serious effects on plasmid stability. Use of the proposed mathematical model can provide a valuable description of plasmid maintenance, as well as enable prediction of the probability of the plasmid loss.
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Affiliation(s)
- Olesia Werbowy
- Laboratory of Extremophiles Biology, Department of Microbiology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, Gdansk, Poland
| | - Sławomir Werbowy
- Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, ul. Wita Stwosza 57, Gdansk, Poland
| | - Tadeusz Kaczorowski
- Laboratory of Extremophiles Biology, Department of Microbiology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, Gdansk, Poland
- * E-mail:
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164
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Challacombe JF, Pillai S, Kuske CR. Shared features of cryptic plasmids from environmental and pathogenic Francisella species. PLoS One 2017; 12:e0183554. [PMID: 28837612 PMCID: PMC5570271 DOI: 10.1371/journal.pone.0183554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/07/2017] [Indexed: 12/17/2022] Open
Abstract
The Francisella genus includes several recognized species, additional potential species, and other representatives that inhabit a range of incredibly diverse ecological niches, but are not closely related to the named species. Francisella species have been obtained from a wide variety of clinical and environmental sources; documented species include highly virulent human and animal pathogens, fish pathogens, opportunistic human pathogens, tick endosymbionts, and free-living isolates inhabiting brackish water. While more than 120 Francisella genomes have been sequenced to date, only a few contain plasmids, and most of these appear to be cryptic, with unknown benefit to the host cell. We have identified several putative cryptic plasmids in the sequenced genomes of three Francisella novicida and F. novicida-like strains (TX07-6608, AZ06-7470, DPG_3A-IS) and two new Francisella species (F. frigiditurris CA97-1460 and F. opportunistica MA06-7296). These plasmids were compared to each other and to previously identified plasmids from other Francisella species. Some of the plasmids encoded functions potentially involved in replication, conjugal transfer and partitioning, environmental survival (transcriptional regulation, signaling, metabolism), and hypothetical proteins with no assignable functions. Genomic and phylogenetic comparisons of these new plasmids to the other known Francisella plasmids revealed some similarities that add to our understanding of the evolutionary relationships among the diverse Francisella species.
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Affiliation(s)
- Jean F. Challacombe
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Segaran Pillai
- Office of Laboratory Science and Safety, US Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Cheryl R. Kuske
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
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165
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Lauritsen I, Porse A, Sommer MOA, Nørholm MHH. A versatile one-step CRISPR-Cas9 based approach to plasmid-curing. Microb Cell Fact 2017; 16:135. [PMID: 28764701 PMCID: PMC5540278 DOI: 10.1186/s12934-017-0748-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/22/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Plasmids are widely used and essential tools in molecular biology. However, plasmids often impose a metabolic burden and are only temporarily useful for genetic engineering, bio-sensing and characterization purposes. While numerous techniques for genetic manipulation exist, a universal tool enabling rapid removal of plasmids from bacterial cells is lacking. RESULTS Based on replicon abundance and sequence conservation analysis, we show that the vast majority of bacterial cloning and expression vectors share sequence similarities that allow for broad CRISPR-Cas9 targeting. We have constructed a universal plasmid-curing system (pFREE) and developed a one-step protocol and PCR procedure that allow for identification of plasmid-free clones within 24 h. While the context of the targeted replicons affects efficiency, we obtained curing efficiencies between 40 and 100% for the plasmids most widely used for expression and engineering purposes. By virtue of the CRISPR-Cas9 targeting, our platform is highly expandable and can be applied in a broad host context. We exemplify the wide applicability of our system in Gram-negative bacteria by demonstrating the successful application in both Escherichia coli and the promising cell factory chassis Pseudomonas putida. CONCLUSION As a fast and freely available plasmid-curing system, targeting virtually all vectors used for cloning and expression purposes, we believe that pFREE has the potential to eliminate the need for individualized vector suicide solutions in molecular biology. We envision the application of pFREE to be especially useful in methodologies involving multiple plasmids, used sequentially or simultaneously, which are becoming increasingly popular for genome editing or combinatorial pathway engineering.
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Affiliation(s)
- Ida Lauritsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Andreas Porse
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Morten O. A. Sommer
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Morten H. H. Nørholm
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
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166
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167
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Lorenzo-Díaz F, Fernández-López C, Lurz R, Bravo A, Espinosa M. Crosstalk between vertical and horizontal gene transfer: plasmid replication control by a conjugative relaxase. Nucleic Acids Res 2017; 45:7774-7785. [PMID: 28525572 PMCID: PMC5737340 DOI: 10.1093/nar/gkx450] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/25/2017] [Accepted: 05/09/2017] [Indexed: 01/09/2023] Open
Abstract
Horizontal gene transfer is a key process in the evolution of bacteria and also represents a source of genetic variation in eukaryotes. Among elements participating in gene transfer, thousands of small (<10 kb) mobile bacterial plasmids that replicate by the rolling circle mechanism represent a driving force in the spread of antibiotic resistances. In general, these plasmids are built as genetic modules that encode a replicase, an antibiotic-resistance determinant, and a relaxase that participates in their conjugative mobilization. Further, they control their relatively high copy number (∼30 copies per genome equivalent) by antisense RNAs alone or combined with a repressor protein. We report here that the MobM conjugative relaxase encoded by the promiscuous plasmid pMV158 participates in regulation of the plasmid copy number by transcriptional repression of the antisense RNA, thus increasing the number of plasmid molecules ready to be horizontally transferred (mobilization) and/or vertically inherited (replication). This type of crosstalk between genetic modules involved in vertical and horizontal gene flow has not been reported before.
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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Binding Sites
- Conjugation, Genetic
- DNA Copy Number Variations
- DNA Replication
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Superhelical/chemistry
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- Drug Resistance, Bacterial/genetics
- Endodeoxyribonucleases/genetics
- Endodeoxyribonucleases/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Evolution, Molecular
- Gene Flow
- Gene Transfer, Horizontal
- Microscopy, Electron
- Models, Biological
- Plasmids/genetics
- Promoter Regions, Genetic
- Replicon
- Streptococcus pneumoniae/genetics
- Streptococcus pneumoniae/metabolism
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna. Av. Astrofísico Francisco Sánchez s/n, 38071 Santa Cruz de Tenerife, Spain
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
| | - Cris Fernández-López
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Rudi Lurz
- Max-Plank Institut für molekulare Genetik, Ihnestrasse 63-73, D-14195 Berlin, Germany
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
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168
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Jiang X, Liu X, Law COK, Wang Y, Lo WU, Weng X, Chan TF, Ho PL, Lau TCK. The CTX-M-14 plasmid pHK01 encodes novel small RNAs and influences host growth and motility. FEMS Microbiol Ecol 2017; 93:3940222. [DOI: 10.1093/femsec/fix090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 07/07/2017] [Indexed: 01/24/2023] Open
Affiliation(s)
- Xinlei Jiang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
| | - Xuan Liu
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
| | - Carmen O. K. Law
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
| | - Ya Wang
- Department of Microbiology, University of Hong Kong, Hong Kong, Hong Kong Special Administrative Region
| | - Wai U Lo
- Department of Microbiology, University of Hong Kong, Hong Kong, Hong Kong Special Administrative Region
| | - Xing Weng
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
| | - Ting Fung Chan
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region
| | - P. L. Ho
- Department of Microbiology, University of Hong Kong, Hong Kong, Hong Kong Special Administrative Region
| | - Terrence C. K. Lau
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
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169
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Song Y, Li J, Shin HD, Liu L, Du G, Chen J. Tuning the transcription and translation of L-amino acid deaminase in Escherichia coli improves α-ketoisocaproate production from L-leucine. PLoS One 2017; 12:e0179229. [PMID: 28662040 PMCID: PMC5491005 DOI: 10.1371/journal.pone.0179229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/25/2017] [Indexed: 11/19/2022] Open
Abstract
α-Ketoisocaproate (KIC) is used widely in the pharmaceutical and nutraceutical industries. In previous studies, we achieved a one-step biosynthesis of KIC from l-leucine, using an Escherichia coli whole-cell biocatalyst expressing an l-amino acid deaminase (l-AAD) from Proteus vulgaris. Herein, we report the fine-tuning of l-AAD gene expression in E. coli BL21 (DE3) at the transcriptional and translational levels to improve the KIC titer. By optimizing the plasmid origin with different copy numbers, modulating messenger RNA structure downstream of the initiation codon, and designing the sequences at the ribosome binding site, we increased biocatalyst activity to 31.77%, 24.89%, and 30.20%, respectively, above that achieved with BL21/pet28a-lad. The highest KIC titers reached 76.47 g·L-1, 80.29 g·L-1, and 81.41 g·L-1, respectively. Additionally, the integration of these three engineering strategies achieved an even higher KIC production of 86.55 g·L-1 and a higher l-leucine conversion rate of 94.25%. The enzyme-engineering strategies proposed herein may be generally applicable to the construction of other biocatalysts.
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Affiliation(s)
- Yang Song
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- Synergetic Innovation of Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- Synergetic Innovation of Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
| | - Hyun-dong Shin
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, United States of America
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- Synergetic Innovation of Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- Synergetic Innovation of Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
| | - Jian Chen
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- Synergetic Innovation of Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
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170
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Fate and Persistence of a Pathogenic NDM-1-Positive Escherichia coli Strain in Anaerobic and Aerobic Sludge Microcosms. Appl Environ Microbiol 2017; 83:AEM.00640-17. [PMID: 28411227 PMCID: PMC5479002 DOI: 10.1128/aem.00640-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 04/08/2017] [Indexed: 12/01/2022] Open
Abstract
The presence of emerging biological pollutants in treated wastewater effluents has gained attention due to increased interest in water reuse. To evaluate the effectiveness of the removal of such contaminants by the conventional wastewater treatment process, the fate and decay kinetics of NDM-1-positive Escherichia coli strain PI7 and its plasmid-encoded antibiotic resistance genes (ARGs) were assessed in microcosms of anaerobic and aerobic sludge. Results showed that E. coli PI7 decayed at a significantly lower rate under anaerobic conditions. Approximate half-lives were 32.4 ± 1.4 h and 5.9 ± 0.9 h in the anaerobic and aerobic microcosms, respectively. In the aerobic microcosms, after 72 h of operation, E. coli PI7 remained detectable, but no further decay was observed. Instead, 1 in every 10,000 E. coli cells was identified to be recalcitrant to decay and persist indefinitely in the sludge. ARGs associated with the E. coli PI7 strain were detected to have transferred to other native microorganisms in the sludge or were released to the liquid fraction upon host decay. Extracellular DNA quickly degraded in the liquid fraction of the aerobic sludge. In contrast, no DNA decay was detected in the anaerobic sludge water matrix throughout the 24-h sampling period. This study suggests an increased likelihood of environmental dispersion of ARGs associated with anaerobically treated wastewater effluents and highlights the potential importance of persister cells in the dissemination of E. coli in the environment during reuse events of treated wastewater. IMPORTANCE This study examines the decay kinetics of a pathogenic and antibiotic resistant strain of Escherichia coli in microcosms simulating biological treatment units of aerobic and anaerobic sludge. The results of this study point at a significantly prolonged persistence of the E. coli and the associated antibiotic resistance gene in the anaerobic sludge. However, horizontal transfer of the plasmid encoding the antibiotic resistance gene was detected in the aerobic sludge by a cultivation method. A subpopulation of persister E. coli cells was also detected in the aerobic sludge. The findings of this study suggest potential areas of concern arising from pathogenic and antibiotic-resistant E. coli during both anaerobic and aerobic sludge treatment processes.
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171
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Fernandez-Lopez R, Redondo S, Garcillan-Barcia MP, de la Cruz F. Towards a taxonomy of conjugative plasmids. Curr Opin Microbiol 2017; 38:106-113. [PMID: 28586714 DOI: 10.1016/j.mib.2017.05.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 05/10/2017] [Accepted: 05/17/2017] [Indexed: 01/14/2023]
Abstract
Conjugative plasmids are the keystone of horizontal gene transfer. Metagenomic research and clinical understanding of plasmid transmission beg for a taxonomical approach to conjugative plasmid classification. Up to now, a meaningful classification was difficult to achieve for lack of appropriate analytical tools. The advent of the genomic era revolutionized the landscape, offering a plethora of plasmid sequences as well as bioinformatic analytical tools. Given the need and the opportunity, in view of the available evidence, a taxonomy of conjugative plasmids is proposed in the hope that it will leverage plasmid studies.
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Affiliation(s)
- Raul Fernandez-Lopez
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - Santiago Redondo
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - M Pilar Garcillan-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - Fernando de la Cruz
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain.
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172
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Zheng X, Xing XH, Zhang C. Targeted mutagenesis: A sniper-like diversity generator in microbial engineering. Synth Syst Biotechnol 2017; 2:75-86. [PMID: 29062964 PMCID: PMC5636951 DOI: 10.1016/j.synbio.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/30/2017] [Accepted: 07/03/2017] [Indexed: 12/26/2022] Open
Abstract
Mutations, serving as the raw materials of evolution, have been extensively utilized to increase the chances of engineering molecules or microbes with tailor-made functions. Global and targeted mutagenesis are two main methods of obtaining various mutations, distinguished by the range of action they can cover. While the former one stresses the mining of novel genetic loci within the whole genomic background, targeted mutagenesis performs in a more straightforward manner, bringing evolutionary escape and error catastrophe under control. In this review, we classify the existing techniques of targeted mutagenesis into two categories in terms of whether the diversity is generated in vitro or in vivo, and briefly introduce the mechanisms and applications of them separately. The inherent connections and development trends of the two classes are also discussed to provide an insight into the next generation evolution research.
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Key Words
- 3′-LTR, 3’-long terminal repeat
- 5-FOA, 5-fluoro-orotic acid
- CRISPR/Cas9, clustered regularly interspaced short palindromic repeats and associated protein 9
- DNA Pol III, DNA polymerase III
- DNA PolI, DNA polymerase I
- DSB, double strand break
- Evolution
- FLASH, fast ligation-based automatable solid-phase high-throughput
- HDR, homology-directed repair
- HIV, human immunodeficiency virus
- ICE, in vivo continuous evolution
- LIC, ligation-independent cloning
- MAGE, multiplex automated genome engineering
- MMEJ, microhomology-mediated end-joining
- Mutations
- NHEJ, error-prone non-homologous end-joining
- ORF, open reading frame
- PAM, protospacer-adjacent motif
- RVD, repeat variable di-residue
- Synthetic biology
- TALE, transcription activator-like effector
- TALEN, transcription activator-like effector nuclease
- TP, terminal protein
- TP-DNAP, TP-DNA polymerase fusion
- TaGTEAM, targeting glycosylase to embedded arrays for mutagenesis
- Targeted mutagenesis
- YOGE, yeast oligo-mediated genome engineering
- ZF, zinc-finger protein
- ZFN, zinc-finger nuclease
- dCas9, catalytically dead Cas9
- dNTP, deoxy-ribonucleoside triphosphate
- dsDNA, double-stranded DNA
- error-prone PCR, error-prone polymerase chain reaction
- non-GMO, non-genetically modified organism
- pre-crRNA, pre-CRISPR RNA
- sctetR, single chain tetR
- sgRNA, single-guide RNA
- ssDNA, single-stranded DNA
- tracrRNA, trans-encoded RNA
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Affiliation(s)
| | | | - Chong Zhang
- Key Laboratory for Industrial Biocatalysis, Ministry of Education, Institute of Biochemical Engineering, Department of Chemical Engineering, Center for Synthetic & Systems Biology, Tsinghua University, Beijing 100084, China
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173
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Multi-platform analysis reveals a complex transcriptome architecture of a circovirus. Virus Res 2017; 237:37-46. [PMID: 28549855 DOI: 10.1016/j.virusres.2017.05.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 05/17/2017] [Accepted: 05/17/2017] [Indexed: 11/20/2022]
Abstract
In this study, we used Pacific Biosciences RS II long-read and Illumina HiScanSQ short-read sequencing technologies for the characterization of porcine circovirus type 1 (PCV-1) transcripts. Our aim was to identify novel RNA molecules and transcript isoforms, as well as to determine the exact 5'- and 3'-end sequences of previously described transcripts with single base-pair accuracy. We discovered a novel 3'-UTR length isoform of the Cap transcript, and a non-spliced Cap transcript variant. Additionally, our analysis has revealed a 3'-UTR isoform of Rep and two 5'-UTR isoforms of Rep' transcripts, and a novel splice variant of the longer Rep' transcript. We also explored two novel long transcripts, one with a previously identified splice site, and a formerly undetected mRNA of ORF3. Altogether, our methods have identified nine novel RNA molecules, doubling the size of PCV-1 transcriptome that had been known before. Additionally, our investigations revealed an intricate pattern of transcript overlapping, which might produce transcriptional interference between the transcriptional machineries of adjacent genes, and thereby may potentially play a role in the regulation of gene expression in circoviruses.
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174
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Cox KEL, Schildbach JF. Sequence of the R1 plasmid and comparison to F and R100. Plasmid 2017; 91:53-60. [PMID: 28359666 DOI: 10.1016/j.plasmid.2017.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/13/2017] [Accepted: 03/26/2017] [Indexed: 12/29/2022]
Abstract
The R1 antibiotic resistance plasmid, originally discovered in a clinical Salmonella isolate in London, 1963, has served for decades as a key model for understanding conjugative plasmids. Despite its scientific importance, a complete sequence of this plasmid has never been reported. We present the complete genome sequence of R1 along with a brief review of the current knowledge concerning its various genetic systems and a comparison to the F and R100 plasmids. R1 is 97,566 nucleotides long and contains 120 genes. The plasmid consists of a backbone largely similar to that of F and R100, a Tn21-like transposon that is nearly identical to that of R100, and a unique 9-kb sequence that bears some resemblance to sequences found in certain Klebsiella oxytoca strains. These three regions of R1 are separated by copies of the insertion sequence IS1. Overall, the structure of R1 and comparison to F and R100 suggest a fairly stable shared conjugative plasmid backbone into which a variety of mobile elements have inserted to form an "accessory" genome, containing multiple antibiotic resistance genes, transposons, remnants of phage genes, and genes whose functions remain unknown.
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Affiliation(s)
- Katherine E L Cox
- Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA.
| | - Joel F Schildbach
- Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA.
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175
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Rozhon W. The replication protein of pHW126 auto-controls its expression. Plasmid 2017; 90:38-43. [PMID: 28300545 DOI: 10.1016/j.plasmid.2017.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 10/20/2022]
Abstract
pHW126 belongs to a small group of rolling circle plasmids. So far, the region mediating autonomous replication has been identified and it was shown that the rep gene is required for replication. However, the regulation of rep expression remained elusive. Here evidence is presented that expression of the replication gene rep is auto-regulated. Sequence analysis revealed a conserved stretch in the rep promoter consisting of three imperfect direct repeats (DR2.1, DR2.2 and DR2.3). Assays for promoter activity showed that these direct repeats act as an enhancer of transcriptional activity. Interestingly, the activating effect was reduced in the presence of Rep protein. Electrophoretic mobility shift assays demonstrated that the Rep protein can directly bind to direct repeats DR2.1 and DR2.3 while DR2.2 is not bound but places DR2.1 and DR2.3 in an appropriate distance. These results show that the synthesis of Rep protein is auto-regulated. In the absence of Rep protein the promoter is, due to the presence of the direct repeats acting as a transcriptional enhancer, highly active. Binding of Rep to the direct repeats reduces the transcription rate significantly. Since this regulation mechanism is independent of a specialised regulator protein it is presumably a very economic strategy.
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Affiliation(s)
- Wilfried Rozhon
- Biotechnology of Horticultural Crops, TUM School for Life Sciences Weihenstephan, Technische Universität München, Liesel-Beckmann-Straße 1, 85354 Freising-Weihenstephan, Germany.
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176
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Orlek A, Phan H, Sheppard AE, Doumith M, Ellington M, Peto T, Crook D, Walker AS, Woodford N, Anjum MF, Stoesser N. Ordering the mob: Insights into replicon and MOB typing schemes from analysis of a curated dataset of publicly available plasmids. Plasmid 2017; 91:42-52. [PMID: 28286183 PMCID: PMC5466382 DOI: 10.1016/j.plasmid.2017.03.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/08/2017] [Indexed: 01/17/2023]
Abstract
Plasmid typing can provide insights into the epidemiology and transmission of plasmid-mediated antibiotic resistance. The principal plasmid typing schemes are replicon typing and MOB typing, which utilize variation in replication loci and relaxase proteins respectively. Previous studies investigating the proportion of plasmids assigned a type by these schemes (‘typeability’) have yielded conflicting results; moreover, thousands of plasmid sequences have been added to NCBI in recent years, without consistent annotation to indicate which sequences represent complete plasmids. Here, a curated dataset of complete Enterobacteriaceae plasmids from NCBI was compiled, and used to assess the typeability and concordance of in silico replicon and MOB typing schemes. Concordance was assessed at hierarchical replicon type resolutions, from replicon family-level to plasmid multilocus sequence type (pMLST)-level, where available. We found that 85% and 65% of the curated plasmids could be replicon and MOB typed, respectively. Overall, plasmid size and the number of resistance genes were significant independent predictors of replicon and MOB typing success. We found some degree of non-concordance between replicon families and MOB types, which was only partly resolved when partitioning plasmids into finer-resolution groups (replicon and pMLST types). In some cases, non-concordance was attributed to ambiguous boundaries between MOBP and MOBQ types; in other cases, backbone mosaicism was considered a more plausible explanation. β-lactamase resistance genes tended not to show fidelity to a particular plasmid type, though some previously reported associations were supported. Overall, replicon and MOB typing schemes are likely to continue playing an important role in plasmid analysis, but their performance is constrained by the diverse and dynamic nature of plasmid genomes. 92% of clinically-relevant plasmids could be replicon typed, compared with reports of 100% typeability in 2014. Replicon and MOB typing were partly concordant; partitioning plasmids into finer-resolution groups increased concordance. Overlap between MOBP and MOBQ relaxase families complicates assignment of MOBP and MOBQ types. Generally, resistance genes showed low fidelity towards particular plasmid backbones. PacBio sequencing has driven increased availability of complete plasmid sequences, but retrieved datasets require curation.
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Affiliation(s)
- Alex Orlek
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK.
| | - Hang Phan
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
| | - Anna E Sheppard
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
| | - Michel Doumith
- Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, National Infection Service, Public Health England, London, UK
| | - Matthew Ellington
- NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK; Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, National Infection Service, Public Health England, London, UK
| | - Tim Peto
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
| | - Derrick Crook
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
| | - A Sarah Walker
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
| | - Neil Woodford
- NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK; Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, National Infection Service, Public Health England, London, UK
| | - Muna F Anjum
- NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK; Department of Bacteriology, Animal and Plant Health Agency, Addlestone, UK
| | - Nicole Stoesser
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
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177
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Bardaji L, Añorga M, Ruiz-Masó JA, Del Solar G, Murillo J. Plasmid Replicons from Pseudomonas Are Natural Chimeras of Functional, Exchangeable Modules. Front Microbiol 2017; 8:190. [PMID: 28243228 PMCID: PMC5304414 DOI: 10.3389/fmicb.2017.00190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 01/25/2017] [Indexed: 01/05/2023] Open
Abstract
Plasmids are a main factor for the evolution of bacteria through horizontal gene exchange, including the dissemination of pathogenicity genes, resistance to antibiotics and degradation of pollutants. Their capacity to duplicate is dependent on their replication determinants (replicon), which also define their bacterial host range and the inability to coexist with related replicons. We characterize a second replicon from the virulence plasmid pPsv48C, from Pseudomonas syringae pv. savastanoi, which appears to be a natural chimera between the gene encoding a newly described replication protein and a putative replication control region present in the widespread family of PFP virulence plasmids. We present extensive evidence of this type of chimerism in structurally similar replicons from species of Pseudomonas, including environmental bacteria as well as plant, animal and human pathogens. We establish that these replicons consist of two functional modules corresponding to putative control (REx-C module) and replication (REx-R module) regions. These modules are functionally separable, do not show specificity for each other, and are dynamically exchanged among replicons of four distinct plasmid families. Only the REx-C module displays strong incompatibility, which is overcome by a few nucleotide changes clustered in a stem-and-loop structure of a putative antisense RNA. Additionally, a REx-C module from pPsv48C conferred replication ability to a non-replicative chromosomal DNA region containing features associated to replicons. Thus, the organization of plasmid replicons as independent and exchangeable functional modules is likely facilitating rapid replicon evolution, fostering their diversification and survival, besides allowing the potential co-option of appropriate genes into novel replicons and the artificial construction of new replicon specificities.
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Affiliation(s)
- Leire Bardaji
- Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra Pamplona, Spain
| | - Maite Añorga
- Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra Pamplona, Spain
| | - José A Ruiz-Masó
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Gloria Del Solar
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Jesús Murillo
- Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra Pamplona, Spain
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178
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Gnügge R, Rudolf F. Saccharomyces cerevisiaeShuttle vectors. Yeast 2017; 34:205-221. [DOI: 10.1002/yea.3228] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 01/25/2023] Open
Affiliation(s)
- Robert Gnügge
- D-BSSE; ETH Zurich and Swiss Institute of Bioinformatics; Zurich Switzerland
- Life Science Zurich PhD Program on Molecular and Translational Biomedicine; Zurich Switzerland
- Competence Centre for Personalized Medicine; Zurich Switzerland
| | - Fabian Rudolf
- D-BSSE; ETH Zurich and Swiss Institute of Bioinformatics; Zurich Switzerland
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Zawilak-Pawlik A, Zakrzewska-Czerwińska J. Recent Advances in Helicobacter pylori Replication: Possible Implications in Adaptation to a Pathogenic Lifestyle and Perspectives for Drug Design. Curr Top Microbiol Immunol 2017; 400:73-103. [PMID: 28124150 DOI: 10.1007/978-3-319-50520-6_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
DNA replication is an important step in the life cycle of every cell that ensures the continuous flow of genetic information from one generation to the next. In all organisms, chromosome replication must be coordinated with overall cell growth. Helicobacter pylori growth strongly depends on its interaction with the host, particularly with the gastric epithelium. Moreover, H. pylori actively searches for an optimal microniche within a stomach, and it has been shown that not every microniche equally supports growth of this bacterium. We postulate that besides nutrients, H. pylori senses different, unknown signals, which presumably also affect chromosome replication to maintain H. pylori propagation at optimal ratio allowing H. pylori to establish a chronic, lifelong infection. Thus, H. pylori chromosome replication and particularly the regulation of this process might be considered important for bacterial pathogenesis. Here, we summarize our current knowledge of chromosome and plasmid replication in H. pylori and discuss the mechanisms responsible for regulating this key cellular process. The results of extensive studies conducted thus far allow us to propose common and unique traits in H. pylori chromosome replication. Interestingly, the repertoire of proteins involved in replication in H. pylori is significantly different to that in E. coli, strongly suggesting that novel factors are engaged in H. pylori chromosome replication and could represent attractive drug targets.
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Affiliation(s)
- Anna Zawilak-Pawlik
- Department of Microbiology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Ul. Weigla 12, 53-114, Wrocław, Poland.
| | - Jolanta Zakrzewska-Czerwińska
- Department of Microbiology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Ul. Weigla 12, 53-114, Wrocław, Poland
- Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Ul. Joliot-Curie 14A, 50-383, Wrocław, Poland
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180
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Identification of IncA/C Plasmid Replication and Maintenance Genes and Development of a Plasmid Multilocus Sequence Typing Scheme. Antimicrob Agents Chemother 2017; 61:AAC.01740-16. [PMID: 27872077 DOI: 10.1128/aac.01740-16] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 11/08/2016] [Indexed: 12/26/2022] Open
Abstract
Plasmids of incompatibility group A/C (IncA/C) are becoming increasingly prevalent within pathogenic Enterobacteriaceae They are associated with the dissemination of multiple clinically relevant resistance genes, including blaCMY and blaNDM Current typing methods for IncA/C plasmids offer limited resolution. In this study, we present the complete sequence of a blaNDM-1-positive IncA/C plasmid, pMS6198A, isolated from a multidrug-resistant uropathogenic Escherichia coli strain. Hypersaturated transposon mutagenesis, coupled with transposon-directed insertion site sequencing (TraDIS), was employed to identify conserved genetic elements required for replication and maintenance of pMS6198A. Our analysis of TraDIS data identified roles for the replicon, including repA, a toxin-antitoxin system; two putative partitioning genes, parAB; and a putative gene, 053 Construction of mini-IncA/C plasmids and examination of their stability within E. coli confirmed that the region encompassing 053 contributes to the stable maintenance of IncA/C plasmids. Subsequently, the four major maintenance genes (repA, parAB, and 053) were used to construct a new plasmid multilocus sequence typing (PMLST) scheme for IncA/C plasmids. Application of this scheme to a database of 82 IncA/C plasmids identified 11 unique sequence types (STs), with two dominant STs. The majority of blaNDM-positive plasmids examined (15/17; 88%) fall into ST1, suggesting acquisition and subsequent expansion of this blaNDM-containing plasmid lineage. The IncA/C PMLST scheme represents a standardized tool to identify, track, and analyze the dissemination of important IncA/C plasmid lineages, particularly in the context of epidemiological studies.
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181
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López-Pérez M, Ramon-Marco N, Rodriguez-Valera F. Networking in microbes: conjugative elements and plasmids in the genus Alteromonas. BMC Genomics 2017; 18:36. [PMID: 28056800 PMCID: PMC5217437 DOI: 10.1186/s12864-016-3461-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/22/2016] [Indexed: 12/15/2022] Open
Abstract
Background To develop evolutionary models for the free living bacterium Alteromonas the genome sequences of isolates of the genus have been extensively analyzed. However, the main genetic exchange drivers in these microbes, conjugative elements (CEs), have not been considered in detail thus far. In this work, CEs have been searched in several complete Alteromonas genomes and their sequence studied to understand their role in the evolution of this genus. Six genomes are reported here for the first time. Results We have found nine different plasmids of sizes ranging from 85 to 600 Kb, most of them were found in a single strain. Networks of gene similarity could be established among six of the plasmids that were also connected with another cluster of plasmids found in Shewanella strains. The cargo genes found in these plasmids included cassettes found before in chromosome flexible genomic islands of Alteromonas strains. We describe also the plasmids pAMCP48-600 and pAMCP49-600, the largest found in Alteromonas thus far (ca. 600 Kb) and containing all the hallmarks to be classified as chromids. We found in them some housekeeping genes and a cluster that code for an exocellular polysaccharide. They could represent the transport vectors for the previously described replacement flexible genomic islands. Integrative and conjugative elements (ICEs) were more common than plasmids and showed similar patterns of variation with cargo genes coding for components of additive flexible genomic islands. A nearly identical ICE was found in A. mediterranea MED64 and Vibrio cholera AHV1003 isolated from a human pathogen, indicating the potential exchange of these genes across phylogenetic distances exceeding the family threshold. Conclusion We have seen evidence of how CEs can be vectors to transfer gene cassettes acquired in the chromosomal flexible genomic islands, both of the additive and replacement kind. These CEs showed evidence of how genetic material is exchanged among members of the same species but also (albeit less frequently) across genus and family barriers. These gradients of exchange frequency are probably one of the main drivers of species origin and maintenance in prokaryotes and also provide these taxa with large genetic diversity. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3461-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mario López-Pérez
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Nieves Ramon-Marco
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, San Juan de Alicante, Apartado 18, San Juan, 03550, Alicante, Spain.
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182
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Mancha-Agresti P, Drumond MM, Carmo FLRD, Santos MM, Santos JSCD, Venanzi F, Chatel JM, Leclercq SY, Azevedo V. A New Broad Range Plasmid for DNA Delivery in Eukaryotic Cells Using Lactic Acid Bacteria: In Vitro and In Vivo Assays. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2016; 4:83-91. [PMID: 28344994 PMCID: PMC5363290 DOI: 10.1016/j.omtm.2016.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/15/2016] [Indexed: 12/30/2022]
Abstract
Lactococcus lactis is well documented as a promising candidate for development of novel oral live vaccines. It has been broadly engineered for heterologous expression, as well as for plasmid expression vector delivery, directly inside eukaryotic cells, for DNA vaccine, or as therapeutic vehicle. This work describes the characteristics of a new plasmid, pExu (extra chromosomal unit), for DNA delivery using L. lactis and evaluates its functionality both by in vitro and in vivo assays. This plasmid exhibits the following features: (1) a theta origin of replication and (2) an expression cassette containing a multiple cloning site and a eukaryotic promoter, the cytomegalovirus (pCMV). The functionality of pExu:egfp was evaluated by fluorescence microscopy. The L. lactis MG1363 (pExu:egfp) strains were administered by gavage to Balb/C mice and the eGFP expression was monitored by fluorescence microscopy. The pExu vector has demonstrated an excellent stability either in L. lactis or in Escherichia coli. The eGFP expression at different times in in vitro assay showed that 15.8% of CHO cells were able to express the protein after transfection. The enterocytes of mice showed the expression of eGFP protein. Thus, L. lactis carrying the pExu is a good candidate to deliver genes into eukaryotic cells.
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Affiliation(s)
- Pamela Mancha-Agresti
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | - Mariana Martins Drumond
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil; CEFET - Centro Federal de Educação Tecnológica de Minas Gerais, Coordenação de Ciências, Campus I, 30421-169 Belo Horizonte, Brazil
| | - Fillipe Luiz Rosa do Carmo
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | - Monica Morais Santos
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | | | - Franco Venanzi
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy
| | - Jean-Marc Chatel
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Sophie Yvette Leclercq
- Laboratório de Inovação Biotecnológica, Fundação Ezequiel Dias (FUNED), Belo Horizonte, 30510-010 Minas Gerais, Brazil
| | - Vasco Azevedo
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
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183
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Jahn M, Vorpahl C, Hübschmann T, Harms H, Müller S. Copy number variability of expression plasmids determined by cell sorting and Droplet Digital PCR. Microb Cell Fact 2016; 15:211. [PMID: 27993152 PMCID: PMC5168713 DOI: 10.1186/s12934-016-0610-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Accepted: 12/02/2016] [Indexed: 12/31/2022] Open
Abstract
Background Plasmids are widely used for molecular cloning or production of proteins in laboratory and industrial settings. Constant modification has brought forth countless plasmid vectors whose characteristics in terms of average plasmid copy number (PCN) and stability are rarely known. The crucial factor determining the PCN is the replication system; most replication systems in use today belong to a small number of different classes and are available through repositories like the Standard European Vector Architecture (SEVA). Results In this study, the PCN was determined in a set of seven SEVA-based expression plasmids only differing in the replication system. The average PCN for all constructs was determined by Droplet Digital PCR and ranged between 2 and 40 per chromosome in the host organism Escherichia coli. Furthermore, a plasmid-encoded EGFP reporter protein served as a means to assess variability in reporter gene expression on the single cell level. Only cells with one type of plasmid (RSF1010 replication system) showed a high degree of heterogeneity with a clear bimodal distribution of EGFP intensity while the others showed a normal distribution. The heterogeneous RSF1010-carrying cell population and one normally distributed population (ColE1 replication system) were further analyzed by sorting cells of sub-populations selected according to EGFP intensity. For both plasmids, low and highly fluorescent sub-populations showed a remarkable difference in PCN, ranging from 9.2 to 123.4 for ColE1 and from 0.5 to 11.8 for RSF1010, respectively. Conclusions The average PCN determined here for a set of standardized plasmids was generally at the lower end of previously reported ranges and not related to the degree of heterogeneity. Further characterization of a heterogeneous and a homogeneous population demonstrated considerable differences in the PCN of sub-populations. We therefore present direct molecular evidence that the average PCN does not represent the true number of plasmid molecules in individual cells. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0610-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael Jahn
- Helmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.,School of Biotechnology, Science for Life Laboratory, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Carsten Vorpahl
- Helmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Thomas Hübschmann
- Helmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Hauke Harms
- Helmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Susann Müller
- Helmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.
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184
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Krute CN, Krausz KL, Markiewicz MA, Joyner JA, Pokhrel S, Hall PR, Bose JL. Generation of a Stable Plasmid for In Vitro and In Vivo Studies of Staphylococcus Species. Appl Environ Microbiol 2016; 82:6859-6869. [PMID: 27637878 PMCID: PMC5103085 DOI: 10.1128/aem.02370-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 09/10/2016] [Indexed: 12/31/2022] Open
Abstract
A major shortcoming to plasmid-based genetic tools is the necessity of using antibiotics to ensure plasmid maintenance. While selectable markers are very powerful, their use is not always practical, such as during in vivo models of bacterial infection. During previous studies, it was noted that the uncharacterized LAC-p01 plasmid in Staphylococcus aureus USA300 isolates was stable in the absence of a known selection and therefore could serve as a platform for new genetic tools for Staphylococcus species. LAC-p01 was genetically manipulated into an Escherichia coli-S. aureus shuttle vector that remained stable for at least 100 generations without antibiotic selection. The double- and single-stranded (dso and sso) origins were identified and found to be essential for plasmid replication and maintenance, respectively. In contrast, deletion analyses revealed that none of the four LAC-p01 predicted open reading frames were necessary for stability. Subsequent to this, the shuttle vector was used as a platform to generate two plasmids. The first plasmid, pKK22, contains all genes native to the plasmid for use in S. aureus USA300 strains, while the second, pKK30, lacks the four predicted open reading frames for use in non-USA300 isolates. pKK30 was also determined to be stable in Staphylococcus epidermidis Moreover, pKK22 was maintained for 7 days postinoculation during a murine model of S. aureus systemic infection and successfully complemented an hla mutant in a dermonecrosis model. These plasmids that eliminate the need for antibiotics during both in vitro and in vivo experiments are powerful new tools for studies of StaphylococcusIMPORTANCE Plasmid stability has been problematic in bacterial studies, and historically antibiotics have been used to ensure plasmid maintenance. This has been a major limitation during in vivo studies, where providing antibiotics for plasmid maintenance is difficult and has confounding effects. Here, we have utilized the naturally occurring plasmid LAC-p01 from an S. aureus USA300 strain to construct stable plasmids that obviate antibiotic usage. These newly modified plasmids retain stability over a multitude of generations in vitro and in vivo without antibiotic selection. With these plasmids, studies requiring genetic complementation, protein expression, or genetic reporter systems would not only overcome the burden of antibiotic usage but also eliminate the side effects of these antibiotics. Thus, our plasmids can be used as a powerful genetic tool for studies of Staphylococcus species.
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Affiliation(s)
- Christina N Krute
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Kelsey L Krausz
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mary A Markiewicz
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Jason A Joyner
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, New Mexico, USA
| | - Srijana Pokhrel
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, New Mexico, USA
| | - Pamela R Hall
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, New Mexico, USA
| | - Jeffrey L Bose
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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185
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Abstract
Object-oriented combinator chemistry (OOCC) is an artificial chemistry with composition devices borrowed from object-oriented and functional programming languages. Actors in OOCC are embedded in space and subject to diffusion; since they are neither created nor destroyed, their mass is conserved. Actors use programs constructed from combinators to asynchronously update their own states and the states of other actors in their neighborhoods. The fact that programs and combinators are themselves reified as actors makes it possible to build programs that build programs from combinators of a few primitive types using asynchronous spatial processes that resemble chemistry as much as computation. To demonstrate this, OOCC is used to define a parallel, asynchronous, spatially distributed self-replicating system modeled in part on the living cell. Since interactions among its parts result in the construction of more of these same parts, the system is strongly constructive. The system's high normalized complexity is contrasted with that of a simple composome.
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186
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Yong D, Tee KK, Yin WF, Chan KG. Characterization and Comparative Overview of Complete Sequences of the First Plasmids of Pandoraea across Clinical and Non-clinical Strains. Front Microbiol 2016; 7:1606. [PMID: 27790203 PMCID: PMC5064223 DOI: 10.3389/fmicb.2016.01606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/26/2016] [Indexed: 11/25/2022] Open
Abstract
To date, information on plasmid analysis in Pandoraea spp. is scarce. To address the gap of knowledge on this, the complete sequences of eight plasmids from Pandoraea spp. namely Pandoraea faecigallinarum DSM 23572T (pPF72-1, pPF72-2), Pandoraea oxalativorans DSM 23570T (pPO70-1, pPO70-2, pPO70-3, pPO70-4), Pandoraea vervacti NS15 (pPV15) and Pandoraea apista DSM 16535T (pPA35) were studied for the first time in this study. The information on plasmid sequences in Pandoraea spp. is useful as the sequences did not match any known plasmid sequence deposited in public databases. Replication genes were not identified in some plasmids, a situation that has led to the possibility of host interaction involvement. Some plasmids were also void of par genes and intriguingly, repA gene was also not discovered in these plasmids. This further leads to the hypothesis of host-plasmid interaction. Plasmid stabilization/stability protein-encoding genes were observed in some plasmids but were not established for participating in plasmid segregation. Toxin-antitoxin systems MazEF, VapBC, RelBE, YgiT-MqsR, HigBA, and ParDE were identified across the plasmids and their presence would improve plasmid maintenance. Conjugation genes were identified portraying the conjugation ability amongst Pandoraea plasmids. Additionally, we found a shared region amongst some of the plasmids that consists of conjugation genes. The identification of genes involved in replication, segregation, toxin-antitoxin systems and conjugation, would aid the design of drugs to prevent the survival or transmission of plasmids carrying pathogenic properties. Additionally, genes conferring virulence and antibiotic resistance were identified amongst the plasmids. The observed features in the plasmids shed light on the Pandoraea spp. as opportunistic pathogens.
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Affiliation(s)
- Delicia Yong
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Kok Keng Tee
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Faculty of Science, Institute of Biological Sciences, University of Malaya Kuala Lumpur, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Faculty of Science, Institute of Biological Sciences, University of Malaya Kuala Lumpur, Malaysia
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187
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Wang S, Zhang MN, Bai NL, Ding HT, Zhu XF, Zhao YH. Construction, properties, and application of the pCB5 plasmid, a novel conjugative shuttle vector with a Cupriavidus basilensis origin of replication. Appl Microbiol Biotechnol 2016; 101:1217-1226. [DOI: 10.1007/s00253-016-7936-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/05/2016] [Accepted: 10/12/2016] [Indexed: 10/20/2022]
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188
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Martínez-Alvarez L, Bell SD, Peng X. Multiple consecutive initiation of replication producing novel brush-like intermediates at the termini of linear viral dsDNA genomes with hairpin ends. Nucleic Acids Res 2016; 44:8799-8809. [PMID: 27407114 PMCID: PMC5062984 DOI: 10.1093/nar/gkw636] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/05/2016] [Accepted: 07/05/2016] [Indexed: 11/14/2022] Open
Abstract
Linear dsDNA replicons with hairpin ends are found in the three domains of life, mainly associated with plasmids and viruses including the poxviruses, some phages and archaeal rudiviruses. However, their replication mechanism is not clearly understood. In this study, we find that the rudivirus SIRV2 undergoes multiple consecutive replication reinitiation events at the genomic termini. Using a strand-displacement replication strategy, the multiple reinitiation events from one parental template yield highly branched intermediates corresponding to about 30 genome units which generate exceptional 'brush-like' structures. Moreover, our data support the occurrence of an additional strand-coupled bidirectional replication from a circular dimeric intermediate. The multiple reinitiation process ensures rapid copying of the parental viral genome and will enable protein factors involved in viral genome replication to be specifically localised intracellularly, thereby helping the virus to avoid host defence mechanisms.
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Affiliation(s)
- Laura Martínez-Alvarez
- Archaea Centre, Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Stephen D Bell
- Department of Molecular and Cellular Biochemistry, Department of Biology, Indiana University, Simon Hall MSB, IN 47405, USA
| | - Xu Peng
- Archaea Centre, Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark
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189
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Interference-driven spacer acquisition is dominant over naive and primed adaptation in a native CRISPR-Cas system. Nat Commun 2016; 7:12853. [PMID: 27694798 PMCID: PMC5059440 DOI: 10.1038/ncomms12853] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 08/08/2016] [Indexed: 12/20/2022] Open
Abstract
CRISPR–Cas systems provide bacteria with adaptive immunity against foreign nucleic acids by acquiring short, invader-derived sequences called spacers. Here, we use high-throughput sequencing to analyse millions of spacer acquisition events in wild-type populations of Pectobacterium atrosepticum. Plasmids not previously encountered, or plasmids that had escaped CRISPR–Cas targeting via point mutation, are used to provoke naive or primed spacer acquisition, respectively. The origin, location and order of spacer acquisition show that spacer selection through priming initiates near the site of CRISPR–Cas recognition (the protospacer), but on the displaced strand, and is consistent with 3′–5′ translocation of the Cas1:Cas2-3 acquisition machinery. Newly acquired spacers determine the location and strand specificity of subsequent spacers and demonstrate that interference-driven spacer acquisition (‘targeted acquisition') is a major contributor to adaptation in type I-F CRISPR–Cas systems. Finally, we show that acquisition of self-targeting spacers is occurring at a constant rate in wild-type cells and can be triggered by foreign DNA with similarity to the bacterial chromosome. Prokaryotic CRISPR-Cas systems provide adaptive immunity against foreign nucleic acids by acquiring short, invader-derived sequences called spacers. Here, Staals et al. analyse millions of such events in a native CRISPR-Cas system, showing that newly acquired spacers provoke additional rounds of spacer acquisition.
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190
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Wassenaar TM, Ussery DW, Ingmer H. The qacC Gene Has Recently Spread between Rolling Circle Plasmids of Staphylococcus, Indicative of a Novel Gene Transfer Mechanism. Front Microbiol 2016; 7:1528. [PMID: 27729906 PMCID: PMC5037232 DOI: 10.3389/fmicb.2016.01528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/12/2016] [Indexed: 11/13/2022] Open
Abstract
Resistance of Staphylococcus species to quaternary ammonium compounds, frequently used as disinfectants and biocides, can be attributed to qac genes. Most qac gene products belong to the Small Multidrug Resistant (SMR) protein family, and are often encoded by rolling-circle (RC) replicating plasmids. Four classes of SMR-type qac gene families have been described in Staphylococcus species: qacC, qacG, qacJ, and qacH. Within their class, these genes are highly conserved, but qacC genes are extremely conserved, although they are found in variable plasmid backgrounds. The lower degree of sequence identity of these plasmids compared to the strict nucleotide conservation of their qacC means that this gene has recently spread. In the absence of insertion sequences or other genetic elements explaining the mobility, we sought for an explanation of mobilization by sequence comparison. Publically available sequences of qac genes, their flanking genes and the replication gene that is invariably present in RC-plasmids were compared to reconstruct the evolutionary history of these plasmids and to explain the recent spread of qacC. Here we propose a new model that explains how qacC is mobilized and transferred to acceptor RC-plasmids without assistance of other genes, by means of its location in between the Double Strand replication Origin (DSO) and the Single-Strand replication Origin (SSO). The proposed mobilization model of this DSO-qacC-SSO element represents a novel mechanism of gene mobilization in RC-plasmids, which has also been employed by other genes, such as lnuA (conferring lincomycin resistance). The proposed gene mobility has aided to the wide spread of clinically relevant resistance genes in Staphylococcus populations.
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Affiliation(s)
| | - David W Ussery
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
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Ruiz-Masó JA, Bordanaba-Ruiseco L, Sanz M, Menéndez M, Del Solar G. Metal-Induced Stabilization and Activation of Plasmid Replication Initiator RepB. Front Mol Biosci 2016; 3:56. [PMID: 27709114 PMCID: PMC5030251 DOI: 10.3389/fmolb.2016.00056] [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: 08/03/2016] [Accepted: 09/02/2016] [Indexed: 02/02/2023] Open
Abstract
Initiation of plasmid rolling circle replication (RCR) is catalyzed by a plasmid-encoded Rep protein that performs a Tyr- and metal-dependent site-specific cleavage of one DNA strand within the double-strand origin (dso) of replication. The crystal structure of RepB, the initiator protein of the streptococcal plasmid pMV158, constitutes the first example of a Rep protein structure from RCR plasmids. It forms a toroidal homohexameric ring where each RepB protomer consists of two domains: the C-terminal domain involved in oligomerization and the N-terminal domain containing the DNA-binding and endonuclease activities. Binding of Mn2+ to the active site is essential for the catalytic activity of RepB. In this work, we have studied the effects of metal binding on the structure and thermostability of full-length hexameric RepB and each of its separate domains by using different biophysical approaches. The analysis of the temperature-induced changes in RepB shows that the first thermal transition, which occurs at a range of temperatures physiologically relevant for the pMV158 pneumococcal host, represents an irreversible conformational change that affects the secondary and tertiary structure of the protein, which becomes prone to self-associate. This transition, which is also shown to result in loss of DNA binding capacity and catalytic activity of RepB, is confined to its N-terminal domain. Mn2+ protects the protein from undergoing this detrimental conformational change and the observed protection correlates well with the high-affinity binding of the cation to the active site, as substituting one of the metal-ligands at this site impairs both the protein affinity for Mn2+and the Mn2+-driven thermostabilization effect. The level of catalytic activity of the protein, especially in the case of full-length RepB, cannot be explained based only on the high-affinity binding of Mn2+ at the active site and suggests the existence of additional, lower-affinity metal binding site(s), missing in the separate catalytic domain, that must also be saturated for maximal activity. The molecular bases of the thermostabilizing effect of Mn2+ on the N-terminal domain of the protein as well as the potential location of additional metal binding sites in the entire RepB are discussed.
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Affiliation(s)
- José A Ruiz-Masó
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Lorena Bordanaba-Ruiseco
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Marta Sanz
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Margarita Menéndez
- Biological Physical Chemistry, Protein Structure and Thermodynamics, Instituto de Química-Física Rocasolano (Consejo Superior de Investigaciones Científicas)Madrid, Spain; CIBER of Respiratory DiseasesMadrid, Spain
| | - Gloria Del Solar
- Molecular Biology of Gram-Positive Bacteria, Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas (Consejo Superior de Investigaciones Científicas) Madrid, Spain
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192
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Characterization of a Rolling-Circle Replication Plasmid pM411 from Lactobacillus plantarum 1-3. Curr Microbiol 2016; 73:820-826. [PMID: 27592105 DOI: 10.1007/s00284-016-1124-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/13/2016] [Indexed: 10/21/2022]
Abstract
A cryptic plasmid pM411 isolated from Lactobacillus plantarum 1-3 consisted of a 2303-bp circular molecule with a G + C content 32.96 %. Sequence analysis of pM411 revealed four putative open reading frames (ORFs). ORF1 shared 99 and 94 % similarities, respectively, with the Rep proteins of plasmids pLC2 and pYC2, which belong to the rolling-circle replication pMV158 family. A typical pMV158 family double-strand origin (dso) and a putative single-strand origin (sso) located upstream of the rep gene. Southern hybridization confirmed the presence of single-strand DNA (ssDNA) intermediates, suggesting that pM411 belongs to the RCR pMV158 family. Sequence homology analysis indicated that the sso belongs to the ssoW family. Furthermore, the relative copy number of pM411 was about 88 copies in each cell by real-time PCR.
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193
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Tabata M, Ohhata S, Nikawadori Y, Kishida K, Sato T, Kawasumi T, Kato H, Ohtsubo Y, Tsuda M, Nagata Y. Comparison of the complete genome sequences of four γ-hexachlorocyclohexane-degrading bacterial strains: insights into the evolution of bacteria able to degrade a recalcitrant man-made pesticide. DNA Res 2016; 23:581-599. [PMID: 27581378 PMCID: PMC5144681 DOI: 10.1093/dnares/dsw041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/09/2016] [Indexed: 11/20/2022] Open
Abstract
γ-Hexachlorocyclohexane (γ-HCH) is a recalcitrant man-made chlorinated pesticide. Here, the complete genome sequences of four γ-HCH-degrading sphingomonad strains, which are most unlikely to have been derived from one ancestral γ-HCH degrader, were compared. Together with several experimental data, we showed that (i) all the four strains carry almost identical linA to linE genes for the conversion of γ-HCH to maleylacetate (designated “specific” lin genes), (ii) considerably different genes are used for the metabolism of maleylacetate in one of the four strains, and (iii) the linKLMN genes for the putative ABC transporter necessary for γ-HCH utilization exhibit structural divergence, which reflects the phylogenetic relationship of their hosts. Replicon organization and location of the lin genes in the four genomes are significantly different with one another, and that most of the specific lin genes are located on multiple sphingomonad-unique plasmids. Copies of IS6100, the most abundant insertion sequence in the four strains, are often located in close proximity to the specific lin genes. Analysis of the footprints of target duplication upon IS6100 transposition and the experimental detection of IS6100 transposition strongly suggested that the IS6100 transposition has caused dynamic genome rearrangements and the diversification of lin-flanking regions in the four strains.
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Affiliation(s)
- Michiro Tabata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Satoshi Ohhata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yuki Nikawadori
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Kouhei Kishida
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Takuya Sato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Toru Kawasumi
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Hiromi Kato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yoshiyuki Ohtsubo
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Masataka Tsuda
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yuji Nagata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
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194
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Abstract
The omnipresence of Arthrobacter species in polluted and toxic soils indicates their great potential in environmental biotechnologies, but practical applications of these bacteria are scarce mainly due to the availability of useful genetic engineering tools. Although many fully sequenced Arthrobacter genomes have been deposited in GenBank, little is known about the biology of their plasmids, especially the core functions: replication and partition. In this study the available Arthrobacter plasmid sequences were analyzed in order to identify their putative replication origin. At least the oris from the cryptic plasmids pXZ10142, pCG1, and pBL1 appear to work in this genus. Based on ParA homolog sequences, the Arthrobacter specific plasmids were classified into 4 clades. Iteron-like sequences were identified on most of the plasmids, indicating the position of the putative Arthrobacter specific oris. Although attempts were made to identify the core gene set required for plasmid replication in this genus, it was not possible. The plasmid proteomes showed a rather low similarity.
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195
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Diner RE, Bielinski VA, Dupont CL, Allen AE, Weyman PD. Refinement of the Diatom Episome Maintenance Sequence and Improvement of Conjugation-Based DNA Delivery Methods. Front Bioeng Biotechnol 2016; 4:65. [PMID: 27551676 PMCID: PMC4976089 DOI: 10.3389/fbioe.2016.00065] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/21/2016] [Indexed: 11/13/2022] Open
Abstract
Conjugation of episomal plasmids from bacteria to diatoms advances diatom genetic manipulation by simplifying transgene delivery and providing a stable and consistent gene expression platform. To reach its full potential, this nascent technology requires new optimized expression vectors and a deeper understanding of episome maintenance. Here, we present the development of an additional diatom vector (pPtPBR1), based on the parent plasmid pBR322, to add a plasmid maintained at medium copy number in Escherichia coli to the diatom genetic toolkit. Using this new vector, we evaluated the contribution of individual yeast DNA elements comprising the 1.4-kb tripartite CEN6-ARSH4-HIS3 sequence that enables episome maintenance in Phaeodactylum tricornutum. While various combinations of these individual elements enable efficient conjugation and high exconjugant yield in P. tricornutum, individual elements alone do not. Conjugation of episomes containing CEN6-ARSH4 and a small sequence from the low GC content 3' end of HIS3 produced the highest number of diatom exconjugant colonies, resulting in a smaller and more efficient vector design. Our findings suggest that the CEN6 and ARSH4 sequences function differently in yeast and diatoms, and that low GC content regions of greater than ~500 bp are a potential indicator of a functional diatom episome maintenance sequence. Additionally, we have developed improvements to the conjugation protocol including a high-throughput option utilizing 12-well plates and plating methods that improve exconjugant yield and reduce time and materials required for the conjugation protocol. The data presented offer additional information regarding the mechanism by which the yeast-derived sequence enables diatom episome maintenance and demonstrate options for flexible vector design.
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Affiliation(s)
- Rachel E Diner
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA; Integrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Vincent A Bielinski
- Synthetic Biology and Bioenergy Group, J. Craig Venter Institute , La Jolla, CA , USA
| | - Christopher L Dupont
- Microbial and Environmental Genomics Group, J. Craig Venter Institute , La Jolla, CA , USA
| | - Andrew E Allen
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA; Integrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Philip D Weyman
- Synthetic Biology and Bioenergy Group, J. Craig Venter Institute , La Jolla, CA , USA
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196
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Pastrana CL, Carrasco C, Akhtar P, Leuba SH, Khan SA, Moreno-Herrero F. Force and twist dependence of RepC nicking activity on torsionally-constrained DNA molecules. Nucleic Acids Res 2016; 44:8885-8896. [PMID: 27488190 PMCID: PMC5062986 DOI: 10.1093/nar/gkw689] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/22/2016] [Indexed: 11/14/2022] Open
Abstract
Many bacterial plasmids replicate by an asymmetric rolling-circle mechanism that requires sequence-specific recognition for initiation, nicking of one of the template DNA strands and unwinding of the duplex prior to subsequent leading strand DNA synthesis. Nicking is performed by a replication-initiation protein (Rep) that directly binds to the plasmid double-stranded origin and remains covalently bound to its substrate 5′-end via a phosphotyrosine linkage. It has been proposed that the inverted DNA sequences at the nick site form a cruciform structure that facilitates DNA cleavage. However, the role of Rep proteins in the formation of this cruciform and the implication for its nicking and religation functions is unclear. Here, we have used magnetic tweezers to directly measure the DNA nicking and religation activities of RepC, the replication initiator protein of plasmid pT181, in plasmid sized and torsionally-constrained linear DNA molecules. Nicking by RepC occurred only in negatively supercoiled DNA and was force- and twist-dependent. Comparison with a type IB topoisomerase in similar experiments highlighted a relatively inefficient religation activity of RepC. Based on the structural modeling of RepC and on our experimental evidence, we propose a model where RepC nicking activity is passive and dependent upon the supercoiling degree of the DNA substrate.
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Affiliation(s)
- Cesar L Pastrana
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, CSIC, Darwin 3, 28049 Cantoblanco, Madrid, Spain
| | - Carolina Carrasco
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, CSIC, Darwin 3, 28049 Cantoblanco, Madrid, Spain
| | - Parvez Akhtar
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219, USA
| | - Sanford H Leuba
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Saleem A Khan
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219, USA
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, CSIC, Darwin 3, 28049 Cantoblanco, Madrid, Spain
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197
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Kim NH, Lee G, Sherer NA, Martini KM, Goldenfeld N, Kuhlman TE. Real-time transposable element activity in individual live cells. Proc Natl Acad Sci U S A 2016; 113:7278-83. [PMID: 27298350 PMCID: PMC4932956 DOI: 10.1073/pnas.1601833113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The excision and reintegration of transposable elements (TEs) restructure their host genomes, generating cellular diversity involved in evolution, development, and the etiology of human diseases. Our current knowledge of TE behavior primarily results from bulk techniques that generate time and cell ensemble averages, but cannot capture cell-to-cell variation or local environmental and temporal variability. We have developed an experimental system based on the bacterial TE IS608 that uses fluorescent reporters to directly observe single TE excision events in individual cells in real time. We find that TE activity depends upon the TE's orientation in the genome and the amount of transposase protein in the cell. We also find that TE activity is highly variable throughout the lifetime of the cell. Upon entering stationary phase, TE activity increases in cells hereditarily predisposed to TE activity. These direct observations demonstrate that real-time live-cell imaging of evolution at the molecular and individual event level is a powerful tool for the exploration of genome plasticity in stressed cells.
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Affiliation(s)
- Neil H Kim
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Gloria Lee
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Nicholas A Sherer
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - K Michael Martini
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Nigel Goldenfeld
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Institute for Universal Biology NASA Astrobiology Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
| | - Thomas E Kuhlman
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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198
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Karlowicz A, Wegrzyn K, Dubiel A, Ropelewska M, Konieczny I. Proteolysis in plasmid DNA stable maintenance in bacterial cells. Plasmid 2016; 86:7-13. [PMID: 27252071 DOI: 10.1016/j.plasmid.2016.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/25/2016] [Accepted: 05/26/2016] [Indexed: 01/12/2023]
Abstract
Plasmids, as extrachromosomal genetic elements, need to work out strategies that promote independent replication and stable maintenance in host bacterial cells. Their maintenance depends on constant formation and dissociation of nucleoprotein complexes formed on plasmid DNA. Plasmid replication initiation proteins (Rep) form specific complexes on direct repeats (iterons) localized within the plasmid replication origin. Formation of these complexes along with a strict control of Rep protein cellular concentration, quaternary structure, and activity, is essential for plasmid maintenance. Another important mechanism for maintenance of low-copy-number plasmids are the toxin-antitoxin (TA) post-segregational killing (psk) systems, which prevent plasmid loss from the bacterial cell population. In this mini review we discuss the importance of nucleoprotein complex processing by energy-dependent host proteases in plasmid DNA replication and plasmid type II toxin-antitoxin psk systems, and draw attention to the elusive role of DNA in this process.
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Affiliation(s)
- Anna Karlowicz
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Katarzyna Wegrzyn
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Andrzej Dubiel
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Malgorzata Ropelewska
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Igor Konieczny
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland.
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199
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Frage B, Döhlemann J, Robledo M, Lucena D, Sobetzko P, Graumann PL, Becker A. Spatiotemporal choreography of chromosome and megaplasmids in theSinorhizobium meliloticell cycle. Mol Microbiol 2016; 100:808-23. [DOI: 10.1111/mmi.13351] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Benjamin Frage
- LOEWE Center for Synthetic Microbiology and Faculty of Biology; Philipps-Universität Marburg; 35032 Marburg Germany
| | - Johannes Döhlemann
- LOEWE Center for Synthetic Microbiology and Faculty of Biology; Philipps-Universität Marburg; 35032 Marburg Germany
| | - Marta Robledo
- LOEWE Center for Synthetic Microbiology and Faculty of Biology; Philipps-Universität Marburg; 35032 Marburg Germany
| | - Daniella Lucena
- LOEWE Center for Synthetic Microbiology and Faculty of Chemistry, Philipps-Universität Marburg, 35032; Marburg Germany
| | - Patrick Sobetzko
- LOEWE Center for Synthetic Microbiology and Faculty of Biology; Philipps-Universität Marburg; 35032 Marburg Germany
| | - Peter L. Graumann
- LOEWE Center for Synthetic Microbiology and Faculty of Chemistry, Philipps-Universität Marburg, 35032; Marburg Germany
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology and Faculty of Biology; Philipps-Universität Marburg; 35032 Marburg Germany
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200
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Loftie-Eaton W, Yano H, Burleigh S, Simmons RS, Hughes JM, Rogers LM, Hunter SS, Settles ML, Forney LJ, Ponciano JM, Top EM. Evolutionary Paths That Expand Plasmid Host-Range: Implications for Spread of Antibiotic Resistance. Mol Biol Evol 2016; 33:885-97. [PMID: 26668183 PMCID: PMC4840908 DOI: 10.1093/molbev/msv339] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The World Health Organization has declared the emergence of antibiotic resistance to be a global threat to human health. Broad-host-range plasmids have a key role in causing this health crisis because they transfer multiple resistance genes to a wide range of bacteria. To limit the spread of antibiotic resistance, we need to gain insight into the mechanisms by which the host range of plasmids evolves. Although initially unstable plasmids have been shown to improve their persistence through evolution of the plasmid, the host, or both, the means by which this occurs are poorly understood. Here, we sought to identify the underlying genetic basis of expanded plasmid host-range and increased persistence of an antibiotic resistance plasmid using a combined experimental-modeling approach that included whole-genome resequencing, molecular genetics and a plasmid population dynamics model. In nine of the ten previously evolved clones, changes in host and plasmid each slightly improved plasmid persistence, but their combination resulted in a much larger improvement, which indicated positive epistasis. The only genetic change in the plasmid was the acquisition of a transposable element from a plasmid native to the Pseudomonas host used in these studies. The analysis of genetic deletions showed that the critical genes on this transposon encode a putative toxin-antitoxin (TA) and a cointegrate resolution system. As evolved plasmids were able to persist longer in multiple naïve hosts, acquisition of this transposon also expanded the plasmid's host range, which has important implications for the spread of antibiotic resistance.
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Affiliation(s)
- Wesley Loftie-Eaton
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | - Hirokazu Yano
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | | | | | - Julie M Hughes
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | - Linda M Rogers
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | - Samuel S Hunter
- Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | - Matthew L Settles
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | - Larry J Forney
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
| | | | - Eva M Top
- Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho
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