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Ohdate K, Sakata M, Maeda K, Sakamaki Y, Nimura-Matsune K, Ohbayashi R, Hess WR, Watanabe S. Discovery of novel replication proteins for large plasmids in cyanobacteria and their potential applications in genetic engineering. Front Microbiol 2024; 15:1311290. [PMID: 38419637 PMCID: PMC10899382 DOI: 10.3389/fmicb.2024.1311290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/31/2024] [Indexed: 03/02/2024] Open
Abstract
Numerous cyanobacteria capable of oxygenic photosynthesis possess multiple large plasmids exceeding 100 kbp in size. These plasmids are believed to have distinct replication and distribution mechanisms, as they coexist within cells without causing incompatibilities between plasmids. However, information on plasmid replication proteins (Rep) in cyanobacteria is limited. Synechocystis sp. PCC 6803 hosts four large plasmids, pSYSM, pSYSX, pSYSA, and pSYSG, but Rep proteins for these plasmids, except for CyRepA1 on pSYSA, are unknown. Using Autonomous Replication sequencing (AR-seq), we identified two potential Rep genes in Synechocystis 6803, slr6031 and slr6090, both located on pSYSX. The corresponding Rep candidates, Slr6031 and Slr6090, share structural similarities with Rep-associated proteins of other bacteria and homologs were also identified in various cyanobacteria. We observed autonomous replication activity for Slr6031 and Slr6090 in Synechococcus elongatus PCC 7942 by fusing their genes with a construct expressing GFP and introducing them via transformation. The slr6031/slr6090-containing plasmids exhibited lower copy numbers and instability in Synechococcus 7942 cells compared to the expression vector pYS. While recombination occurred in the case of slr6090, the engineered plasmid with slr6031 coexisted with plasmids encoding CyRepA1 or Slr6090 in Synechococcus 7942 cells, indicating the compatibility of Slr6031 and Slr6090 with CyRepA1. Based on these results, we designated Slr6031 and Slr6090 as CyRepX1 (Cyanobacterial Rep-related protein encoded on pSYSX) and CyRepX2, respectively, demonstrating that pSYSX is a plasmid with "two Reps in one plasmid." Furthermore, we determined the copy number and stability of plasmids with cyanobacterial Reps in Synechococcus 7942 and Synechocystis 6803 to elucidate their potential applications. The novel properties of CyRepX1 and 2, as revealed by this study, hold promise for the development of innovative genetic engineering tools in cyanobacteria.
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Affiliation(s)
- Kazuma Ohdate
- Department of Bioscience, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
| | - Minori Sakata
- Department of Bioscience, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
| | - Kaisei Maeda
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Yutaka Sakamaki
- Department of Bioscience, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
| | - Kaori Nimura-Matsune
- Department of Bioscience, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
| | - Ryudo Ohbayashi
- Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Wolfgang R. Hess
- Genetics and Experimental Bioinformatics Group, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Satoru Watanabe
- Department of Bioscience, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
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Williams JG, Ly D, Geraghty NJ, McArthur JD, Vyas HKN, Gorman J, Tsatsaronis JA, Sluyter R, Sanderson-Smith ML. Streptococcus pyogenes M1T1 Variants Induce an Inflammatory Neutrophil Phenotype Including Activation of Inflammatory Caspases. Front Cell Infect Microbiol 2021; 10:596023. [PMID: 33585270 PMCID: PMC7876443 DOI: 10.3389/fcimb.2020.596023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
Invasive infections due to group A Streptococcus (GAS) advance rapidly causing tissue degradation and unregulated inflammation. Neutrophils are the primary immune cells that respond to GAS. The neutrophil response to GAS was characterised in response to two M1T1 isolates; 5448 and animal passaged variant 5448AP. Co-incubation of neutrophils with 5448AP resulted in proliferation of GAS and lowered the production of reactive oxygen species when compared with 5448. Infection with both strains invoked neutrophil death, however apoptosis was reduced in response to 5448AP. Both strains induced neutrophil caspase-1 and caspase-4 expression in vitro, with inflammatory caspase activation detected in vitro and in vivo. GAS infections involving strains such as 5448AP that promote an inflammatory neutrophil phenotype may contribute to increased inflammation yet ineffective bacterial eradication, contributing to the severity of invasive GAS infections.
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Affiliation(s)
- Jonathan G. Williams
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Diane Ly
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Nicholas J. Geraghty
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Jason D. McArthur
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Heema K. N. Vyas
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Jody Gorman
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - James A. Tsatsaronis
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Martina L. Sanderson-Smith
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
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Abstract
The study of the genetics of enterococci has focused heavily on mobile genetic elements present in these organisms, the complex regulatory circuits used to control their mobility, and the antibiotic resistance genes they frequently carry. Recently, more focus has been placed on the regulation of genes involved in the virulence of the opportunistic pathogenic species Enterococcus faecalis and Enterococcus faecium. Little information is available concerning fundamental aspects of DNA replication, partition, and division; this article begins with a brief overview of what little is known about these issues, primarily by comparison with better-studied model organisms. A variety of transcriptional and posttranscriptional mechanisms of regulation of gene expression are then discussed, including a section on the genetics and regulation of vancomycin resistance in enterococci. The article then provides extensive coverage of the pheromone-responsive conjugation plasmids, including sections on regulation of the pheromone response, the conjugative apparatus, and replication and stable inheritance. The article then focuses on conjugative transposons, now referred to as integrated, conjugative elements, or ICEs, and concludes with several smaller sections covering emerging areas of interest concerning the enterococcal mobilome, including nonpheromone plasmids of particular interest, toxin-antitoxin systems, pathogenicity islands, bacteriophages, and genome defense.
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Kohler V, Vaishampayan A, Grohmann E. Broad-host-range Inc18 plasmids: Occurrence, spread and transfer mechanisms. Plasmid 2018; 99:11-21. [PMID: 29932966 DOI: 10.1016/j.plasmid.2018.06.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/17/2018] [Accepted: 06/18/2018] [Indexed: 11/18/2022]
Abstract
Conjugative plasmid transfer is one of the major mechanisms responsible for the spread of antibiotic resistance and virulence genes. The incompatibility (Inc) 18 group of plasmids is a family of plasmids replicating by the theta-mechanism, whose members have been detected frequently in enterococci and streptococci. Inc18 plasmids encode a variety of antibiotic resistances, including resistance to vancomycin, chloramphenicol and the macrolide-lincosamide-streptogramine (MLS) group of antibiotics. These plasmids comprising insertions of Tn1546 were demonstrated to be responsible for the transfer of vancomycin resistance encoded by the vanA gene from vancomycin resistant enterococci (VRE) to methicillin resistant Staphylococcus aureus (MRSA). Thereby vancomycin resistant S. aureus (VRSA) were generated, which are serious multi-resistant pathogens challenging the health care system. Inc18 plasmids are widespread in the clinic and frequently have been detected in the environment, especially in domestic animals and wastewater. pIP501 is one of the best-characterized conjugative Inc18 plasmids. It was originally isolated from a clinical Streptococcus agalactiae strain and is, due to its small size and simplicity, a model to study conjugative plasmid transfer in Gram-positive bacteria. Here, we report on the occurrence and spread of Inc18-type plasmids in the clinic and in different environments as well as on the exchange of the plasmids among them. In addition, we discuss molecular details on the transfer mechanism of Inc18 plasmids and its regulation, as exemplified by the model plasmid pIP501. We finish with an outlook on promising approaches on how to reduce the emerging spread of antibiotic resistances.
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Affiliation(s)
- Verena Kohler
- Institute of Molecular Biosciences, University of Graz, A-8010 Graz, Austria
| | - Ankita Vaishampayan
- Life Sciences and Technology, Beuth University of Applied Sciences Berlin, D-13347 Berlin, Germany
| | - Elisabeth Grohmann
- Life Sciences and Technology, Beuth University of Applied Sciences Berlin, D-13347 Berlin, Germany.
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5
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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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Paracchini V, Petrillo M, Reiting R, Angers-Loustau A, Wahler D, Stolz A, Schönig B, Matthies A, Bendiek J, Meinel DM, Pecoraro S, Busch U, Patak A, Kreysa J, Grohmann L. Molecular characterization of an unauthorized genetically modified Bacillus subtilis production strain identified in a vitamin B 2 feed additive. Food Chem 2017; 230:681-689. [PMID: 28407967 PMCID: PMC5399532 DOI: 10.1016/j.foodchem.2017.03.042] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/08/2017] [Accepted: 03/08/2017] [Indexed: 12/17/2022]
Abstract
Genetically modified Bacillus subtilis identified in a vitamin B2 product. Whole genome sequencing runs are performed for characterization of the isolated strain. Complex modifications of the genome are identified. Four putative recombinant plasmids are characterized. Real-time PCR methods are developed and available for testing vitamin B2 products.
Many food and feed additives result from fermentation of genetically modified (GM) microorganisms. For vitamin B2 (riboflavin), GM Bacillus subtilis production strains have been developed and are often used. The presence of neither the GM strain nor its recombinant DNA is allowed for fermentation products placed on the EU market as food or feed additive. A vitamin B2 product (80% feed grade) imported from China was analysed. Viable B. subtilis cells were identified and DNAs of two bacterial isolates (LHL and LGL) were subjected to three whole genome sequencing (WGS) runs with different devices (MiSeq, 454 or HiSeq system). WGS data revealed the integration of a chloramphenicol resistance gene, the deletion of the endogenous riboflavin (rib) operon and presence of four putative plasmids harbouring rib operons. Event- and construct-specific real-time PCR methods for detection of the GM strain and its putative plasmids in food and feed products have been developed.
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Affiliation(s)
| | - Mauro Petrillo
- European Commission, Joint Research Centre, Ispra, Italy
| | - Ralf Reiting
- Hessian State Laboratory Kassel (LHL), Kassel, Germany
| | | | - Daniela Wahler
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany
| | - Andrea Stolz
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany
| | - Birgit Schönig
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany
| | - Anastasia Matthies
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany
| | - Joachim Bendiek
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany
| | - Dominik M Meinel
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
| | - Sven Pecoraro
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
| | - Ulrich Busch
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
| | - Alex Patak
- European Commission, Joint Research Centre, Ispra, Italy
| | - Joachim Kreysa
- European Commission, Joint Research Centre, Ispra, Italy
| | - Lutz Grohmann
- Federal Office of Consumer Protection and Food Safety (BVL), Genetic Engineering Department, Berlin, Germany.
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7
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The Interplay between Different Stability Systems Contributes to Faithful Segregation: Streptococcus pyogenes pSM19035 as a Model. Microbiol Spectr 2016; 2:PLAS-0007-2013. [PMID: 26104212 DOI: 10.1128/microbiolspec.plas-0007-2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The Streptococcus pyogenes pSM19035 low-copy-number θ-replicating plasmid encodes five segregation (seg) loci that contribute to plasmid maintenance. These loci map outside of the minimal replicon. The segA locus comprises β2 recombinase and two six sites, and segC includes segA and also the γ topoisomerase and two ssiA sites. Recombinase β2 plays a role both in maximizing random segregation by resolving plasmid dimers (segA) and in catalyzing inversion between two inversely oriented six sites. segA, in concert with segC, facilitates replication fork pausing at ssiA sites and overcomes the accumulation of "toxic" replication intermediates. The segB1 locus encodes ω, ε, and ζ genes. The short-lived ε2 antitoxin and the long-lived ζ toxin form an inactive ζε2ζ complex. Free ζ toxin halts cell proliferation upon decay of the ε2 antitoxin and enhances survival. If ε2 expression is not recovered, by loss of the plasmid, the toxin raises lethality. The segB2 locus comprises δ and ω genes and six parS sites. Proteins δ2 and ω2, by forming complexes with parS and chromosomal DNA, pair the plasmid copies at the nucleoid, leading to the formation of a dynamic δ2 gradient that separates the plasmids to ensure roughly equal distribution to daughter cells at cell division. The segD locus, which comprises ω2 (or ω2 plus ω22) and parS sites, coordinates expression of genes that control copy number, better-than-random segregation, faithful partition, and antibiotic resistance. The interplay of the seg loci and with the rep locus facilitates almost absolute plasmid stability.
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8
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Abstract
One of the disadvantages of circular plasmids and chromosomes is their high sensitivity to rearrangements caused by homologous recombination. Odd numbers of crossing-over occurring during or after replication of a circular replicon result in the formation of a dimeric molecule in which the two copies of the replicon are fused. If they are not converted back to monomers, the dimers of replicons may fail to correctly segregate at the time of cell division. Resolution of multimeric forms of circular plasmids and chromosomes is mediated by site-specific recombination, and the enzymes that catalyze this type of reaction fall into two families of proteins: the serine and tyrosine recombinase families. Here we give an overview of the variety of site-specific resolution systems found on circular plasmids and chromosomes.
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9
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A stable luciferase reporter plasmid for in vivo imaging in murine models of Staphylococcus aureus infections. Appl Microbiol Biotechnol 2015; 100:3197-206. [PMID: 26685857 DOI: 10.1007/s00253-015-7229-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/03/2015] [Accepted: 12/05/2015] [Indexed: 11/27/2022]
Abstract
In vivo imaging of bioluminescent bacteria permits their visualization in infected mice, allowing spatial and temporal evaluation of infection progression. Most available bioluminescent strains were obtained by integration of the luciferase genes into the bacterial chromosome, a challenging and time-consuming approach. Recently, episomal plasmids were used, which were introduced in bacteria and expressed all genes required for bioluminescence emission. However, the plasmid was progressively lost in vitro and in vivo, if bacteria were not maintained under antibiotic selective pressure. Increased stability could be obtained inserting into the plasmid backbone sequences that assured plasmid partition between daughter bacterial cells, or caused death of bacteria that had lost the plasmid. So far, no detailed analysis was performed of either plasmid stability in vivo or contribution of different stabilizing sequence types. Here we report the construction of a plasmid, which includes the Photorhabdus luminescens lux cassette expressed under the control of a Staphylococcus aureus specific gene promoter, and toxin/antitoxin (T/A) and partition sequences (Par) conferring stability and transmissibility of the plasmid. Following infection of mice with S. aureus carrying this plasmid, we demonstrated that the promoter-lux fusion was functional in vivo, that the plasmid was retained by 70-100% of bacterial cells 7 days post-infection, and that both stabilizing sequence types were required to maximize plasmid retention. These data suggest that the plasmid can be a valuable tool to study gene expression and bacterial spread in small laboratory animals infected with S. aureus or possibly other Gram-positive human pathogens.
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10
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Loh JMS, Proft T. Stabilized plasmid-based system for bioluminescent labeling of multiple streptococcal species. Biotechnol Lett 2015; 38:139-43. [PMID: 26410784 DOI: 10.1007/s10529-015-1967-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 09/22/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To determine if multiple streptococcal species can be easily labeled for biophotonic imaging using a toxin-antitoxin stabilized reporter plasmid containing the native firefly luciferase gene, originally developed for use in Group A Streptococcus. RESULTS A number of streptococcal species including Group B Streptococcus, Group C Streptococcus, Group G Streptococcus, S. iniae, S. vestibularis, and S. salivarius were successfully transformed with the reporter plasmid. In absence of antibiotic selection, the plasmid had variable stability amongst the six strains. The expression of firefly luciferase was highest in Group B Streptococcus and S. iniae, as observed by the brightest signal and lowest detection limits in vitro. CONCLUSION Multiple streptococcal species can be easily transformed with our toxin-antitoxin stabilized bioluminescent reporter plasmid. However, this plasmid shows variable stability and signal in different species, restricting its use for certain applications.
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Affiliation(s)
- Jacelyn M S Loh
- Department of Molecular Medicine & Pathology, School of Medical Sciences and the Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand.
| | - Thomas Proft
- Department of Molecular Medicine & Pathology, School of Medical Sciences and the Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand.
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11
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Volante A, Carrasco B, Tabone M, Alonso JC. The interaction of ω2 with the RNA polymerase β' subunit functions as an activation to repression switch. Nucleic Acids Res 2015; 43:9249-61. [PMID: 26243774 PMCID: PMC4627068 DOI: 10.1093/nar/gkv788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/23/2015] [Indexed: 12/03/2022] Open
Abstract
The ω gene is encoded in broad-host range and low-copy plasmids. It is genetically linked to antibiotic resistance genes of the major human pathogens of phylum Firmicutes. The homodimeric forms of ω (ω2) coordinate the plasmid copy number control, faithful partition (ω2 and δ2) and better-than-random segregation (ζϵ2ζ) systems. The promoter (P) of the ωϵζ operon (Pω) transiently interacts with ω2. Adding δ2 facilitates the formation of stable ω2·Pω complexes. Here we show that limiting ω2 interacts with the N-terminal domain of the β’ subunit of the Bacillus subtilis RNA polymerase (RNAP-σA) vegetative holoenzyme. In this way ω2 recruits RNAP-σA onto Pω DNA. Partial Pω occupancy by ω2 increases the rate at which RNAP-σA complex shifts from its closed (RPC) to open (RPO) form. This shift increases transcription activation. Adding δ2 further increases the rate of Pω transcription initiation, perhaps by stabilizing the ω2·Pω complex. In contrast, full operator occupancy by ω2 facilitates RPC formation, but it blocks RPO isomerization and represses Pω utilization. The stimulation and inhibition of RPO formation is the mechanism whereby ω2 mediates copy number fluctuation and stable plasmid segregation. By this mechanism, ω2 also indirectly influences the acquisition of antibiotic resistance genes.
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Affiliation(s)
- Andrea Volante
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Mariangela Tabone
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
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12
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Lioy VS, Volante A, Soberón NE, Lurz R, Ayora S, Alonso JC. ParAB Partition Dynamics in Firmicutes: Nucleoid Bound ParA Captures and Tethers ParB-Plasmid Complexes. PLoS One 2015; 10:e0131943. [PMID: 26161642 PMCID: PMC4498918 DOI: 10.1371/journal.pone.0131943] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/08/2015] [Indexed: 11/17/2022] Open
Abstract
In Firmicutes, small homodimeric ParA-like (δ2) and ParB-like (ω2) proteins, in concert with cis-acting plasmid-borne parS and the host chromosome, secure stable plasmid inheritance in a growing bacterial population. This study shows that (ω:YFP)2 binding to parS facilitates plasmid clustering in the cytosol. (δ:GFP)2 requires ATP binding but not hydrolysis to localize onto the cell’s nucleoid as a fluorescent cloud. The interaction of (δ:CFP)2 or δ2 bound to the nucleoid with (ω:YFP)2 foci facilitates plasmid capture, from a very broad distribution, towards the nucleoid and plasmid pairing. parS-bound ω2 promotes redistribution of (δ:GFP)2, leading to the dynamic release of (δ:GFP)2 from the nucleoid, in a process favored by ATP hydrolysis and protein-protein interaction. (δD60A:GFP)2, which binds but cannot hydrolyze ATP, also forms unstable complexes on the nucleoid. In the presence of ω2, (δD60A:GFP)2 accumulates foci or patched structures on the nucleoid. We propose that (δ:GFP)2 binding to different nucleoid regions and to ω2-parS might generate (δ:GFP)2 gradients that could direct plasmid movement. The iterative pairing and unpairing cycles may tether plasmids equidistantly on the nucleoid to ensure faithful plasmid segregation by a mechanism compatible with the diffusion-ratchet mechanism as proposed from in vitro reconstituted systems.
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Affiliation(s)
- Virginia S Lioy
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
| | - Andrea Volante
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
| | - Nora E Soberón
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
| | - Rudi Lurz
- Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-1000 Berlin, Germany
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
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13
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Volante A, Alonso JC. Molecular Anatomy of ParA-ParA and ParA-ParB Interactions during Plasmid Partitioning. J Biol Chem 2015; 290:18782-95. [PMID: 26055701 DOI: 10.1074/jbc.m115.649632] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Indexed: 11/06/2022] Open
Abstract
Firmicutes multidrug resistance inc18 plasmids encode parS sites and two small homodimeric ParA-like (δ2) and ParB-like (ω2) proteins to ensure faithful segregation. Protein ω2 binds to parS DNA, forming a short left-handed helix wrapped around the full parS, and interacts with δ2. Protein δ2 interacts with ω2 and, in the ATP-bound form, binds to nonspecific DNA (nsDNA), forming small clusters. Here, we have mapped the ω2·δ2 and δ2·δ2 interacting domains in the δ2 that are adjacent to but distinct from each other. The δ2 nsDNA binding domain is essential for stimulation of ω2·parS-mediated ATP hydrolysis. From the data presented here, we propose that δ2 interacts with ATP, nsDNA, and with ω2 bound to parS at near equimolar concentrations, facilitating a δ2 structural transition. This δ2 "activated" state overcomes its impediment in ATP hydrolysis, with the subsequent release of both of the proteins from nsDNA (plasmid unpairing).
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Affiliation(s)
- Andrea Volante
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
| | - Juan C Alonso
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Darwin Str. 3, 28049 Madrid, Spain
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14
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Saeed S, Jowitt TA, Warwicker J, Hayes F. Breaking and restoring the hydrophobic core of a centromere-binding protein. J Biol Chem 2015; 290:9273-83. [PMID: 25713077 DOI: 10.1074/jbc.m115.638148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Indexed: 11/06/2022] Open
Abstract
The ribbon-helix-helix (RHH) superfamily of DNA-binding proteins is dispersed widely in procaryotes. The dimeric RHH fold is generated by interlocking of two monomers into a 2-fold symmetrical structure that comprises four α-helices enwrapping a pair of antiparallel β-strands (ribbon). Residues in the ribbon region are the principal determinants of DNA binding, whereas the RHH hydrophobic core is assembled from amino acids in both the α-helices and ribbon element. The ParG protein encoded by multiresistance plasmid TP228 is a RHH protein that functions dually as a centromere binding factor during segrosome assembly and as a transcriptional repressor. Here we identify residues in the α-helices of ParG that are critical for DNA segregation and in organization of the protein hydrophobic core. A key hydrophobic aromatic amino acid at one position was functionally substitutable by other aromatic residues, but not by non-aromatic hydrophobic amino acids. Nevertheless, intramolecular suppression of the latter by complementary change of a residue that approaches nearby from the partner monomer fully restored activity in vivo and in vitro. The interactions involved in assembling the ParG core may be highly malleable and suggest that RHH proteins are tractable platforms for the rational design of diverse DNA binding factors useful for synthetic biology and other purposes.
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Affiliation(s)
- Sadia Saeed
- From the Faculty of Life Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Thomas A Jowitt
- From the Faculty of Life Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Jim Warwicker
- From the Faculty of Life Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Finbarr Hayes
- From the Faculty of Life Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
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15
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Coupling between the basic replicon and the Kis-Kid maintenance system of plasmid R1: modulation by Kis antitoxin levels and involvement in control of plasmid replication. Toxins (Basel) 2015; 7:478-92. [PMID: 25664511 PMCID: PMC4344636 DOI: 10.3390/toxins7020478] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/29/2015] [Indexed: 01/14/2023] Open
Abstract
kis-kid, the auxiliary maintenance system of plasmid R1 and copB, the auxiliary copy number control gene of this plasmid, contribute to increase plasmid replication efficiency in cells with lower than average copy number. It is thought that Kis antitoxin levels decrease in these cells and that this acts as the switch that activates the Kid toxin; activated Kid toxin reduces copB-mRNA levels and this increases RepA levels that increases plasmid copy number. In support of this model we now report that: (i) the Kis antitoxin levels do decrease in cells containing a mini-R1 plasmid carrying a repA mutation that reduces plasmid copy number; (ii) kid-dependent replication rescue is abolished in cells in which the Kis antitoxin levels or the CopB levels are increased. Unexpectedly we found that this coordination significantly increases both the copy number of the repA mutant and of the wt mini-R1 plasmid. This indicates that the coordination between plasmid replication functions and kis-kid system contributes significantly to control plasmid R1 replication.
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16
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Miller EW, Cao TN, Pflughoeft KJ, Sumby P. RNA-mediated regulation in Gram-positive pathogens: an overview punctuated with examples from the group A Streptococcus. Mol Microbiol 2014; 94:9-20. [PMID: 25091277 DOI: 10.1111/mmi.12742] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2014] [Indexed: 11/29/2022]
Abstract
RNA-based mechanisms of regulation represent a ubiquitous class of regulators that are associated with diverse processes including nutrient sensing, stress response, modulation of horizontal gene transfer, and virulence factor expression. While better studied in Gram-negative bacteria, the literature is replete with examples of the importance of RNA-mediated regulatory mechanisms to the virulence and fitness of Gram-positives. Regulatory RNAs are classified as cis-acting, e.g. riboswitches, which modulate the transcription, translation, or stability of co-transcribed RNA, or trans-acting, e.g. small regulatory RNAs, which target separate mRNAs or proteins. The group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive bacterial pathogen from which several regulatory RNA mechanisms have been characterized. The study of RNA-mediated regulation in GAS has uncovered novel concepts with respect to how small regulatory RNAs may positively regulate target mRNA stability, and to how CRISPR RNAs are processed from longer precursors. This review provides an overview of RNA-mediated regulation in Gram-positive bacteria, and is highlighted with specific examples from GAS research. The key roles that these systems play in regulating bacterial virulence are discussed and future perspectives outlined.
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Affiliation(s)
- Eric W Miller
- Center for Molecular Medicine, Department of Microbiology & Immunology, University of Nevada, School of Medicine, Reno, NV, USA
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17
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Brzozowska I, Zielenkiewicz U. The ClpXP protease is responsible for the degradation of the Epsilon antidote to the Zeta toxin of the streptococcal pSM19035 plasmid. J Biol Chem 2014; 289:7514-23. [PMID: 24492616 DOI: 10.1074/jbc.m113.519488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most bacterial genomes contain different types of toxin-antitoxin (TA) systems. The ω-ε-ζ proteinaceous type II TA cassette from the streptococcal pSM19035 plasmid is a member of the ε/ζ family, which is commonly found in multiresistance plasmids and chromosomes of various human pathogens. Regulation of type II TA systems relies on the proteolysis of antitoxin proteins. Under normal conditions, the Epsilon antidote neutralizes the Zeta toxin through the formation of a tight complex. In this study, we show, using both in vivo and in vitro analyses, that the ClpXP protease is responsible for Epsilon antitoxin degradation. Using in vivo studies, we examined the stability of the plasmids with active or inactive ω-ε-ζ TA cassettes in B. subtilis mutants that were defective for different proteases. Using in vitro assays, the degradation of purified His6-Epsilon by the His6-LonBs, ClpPBs, and ClpXBs proteases from B. subtilis was analyzed. Additionally, we showed that purified Zeta toxin protects the Epsilon protein from rapid ClpXP-catalyzed degradation.
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Affiliation(s)
- Iwona Brzozowska
- From the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
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18
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Loh JMS, Proft T. Comparison of firefly luciferase and NanoLuc luciferase for biophotonic labeling of group A Streptococcus. Biotechnol Lett 2013; 36:829-34. [DOI: 10.1007/s10529-013-1423-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 11/18/2013] [Indexed: 02/02/2023]
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19
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Loh JMS, Proft T. Toxin-antitoxin-stabilized reporter plasmids for biophotonic imaging of Group A streptococcus. Appl Microbiol Biotechnol 2013; 97:9737-45. [PMID: 24061415 DOI: 10.1007/s00253-013-5200-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/11/2013] [Accepted: 08/14/2013] [Indexed: 01/19/2023]
Abstract
Bioluminescence is a rapid and cost-efficient optical imaging technology that allows the detection of bacteria in real-time during disease development. Here, we report a novel strategy to generate a wide range of bioluminescent group A streptococcus (GAS) strains by using a toxin-antitoxin-stabilized plasmid. The bacterial luciferin-luciferase operon (lux) or the firefly luciferase gene (ffluc) was introduced into GAS via a stabilized plasmid. The FFluc reporter gave significantly stronger bioluminescent signals than the Lux reporter, and was generally more stable. Plasmid-based luciferase reporters could easily be introduced into a variety of GAS strains and the signals correlated linearly with viable cell counts. Co-expression of the streptococcal ω-ε-ζ toxin-antitoxin operon provided segregational stability in the absence of antibiotics for at least 17 passages in vitro and up to 7 days in a mouse infection model. In addition, genome-integrated reporter constructs were also generated by site-specific recombination, but were found to be technically more challenging. The quick and efficient generation of various M-type GAS strains expressing plasmid-based luciferase reporters with comparable and quantifiable bioluminescence signals allows for comparative analysis of different GAS strains in vitro and in vivo.
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Affiliation(s)
- Jacelyn M S Loh
- Department of Molecular Medicine and Pathology, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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20
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Regulation of toxin–antitoxin systems by proteolysis. Plasmid 2013; 70:33-41. [DOI: 10.1016/j.plasmid.2013.01.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 11/19/2022]
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21
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Rupakula A, Kruse T, Boeren S, Holliger C, Smidt H, Maillard J. The restricted metabolism of the obligate organohalide respiring bacterium Dehalobacter restrictus: lessons from tiered functional genomics. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120325. [PMID: 23479754 DOI: 10.1098/rstb.2012.0325] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Dehalobacter restrictus strain PER-K23 is an obligate organohalide respiring bacterium, which displays extremely narrow metabolic capabilities. It grows only via coupling energy conservation to anaerobic respiration of tetra- and trichloroethene with hydrogen as sole electron donor. Dehalobacter restrictus represents the paradigmatic member of the genus Dehalobacter, which in recent years has turned out to be a major player in the bioremediation of an increasing number of organohalides, both in situ and in laboratory studies. The recent elucidation of the D. restrictus genome revealed a rather elaborate genome with predicted pathways that were not suspected from its restricted metabolism, such as a complete corrinoid biosynthetic pathway, the Wood-Ljungdahl (WL) pathway for CO2 fixation, abundant transcriptional regulators and several types of hydrogenases. However, one important feature of the genome is the presence of 25 reductive dehalogenase genes, from which so far only one, pceA, has been characterized on genetic and biochemical levels. This study describes a multi-level functional genomics approach on D. restrictus across three different growth phases. A global proteomic analysis allowed consideration of general metabolic pathways relevant to organohalide respiration, whereas the dedicated genomic and transcriptomic analysis focused on the diversity, composition and expression of genes associated with reductive dehalogenases.
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Affiliation(s)
- Aamani Rupakula
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Laboratory for Environmental Biotechnology, Station 6, 1015 Lausanne, Switzerland
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22
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Modular evolution of TnGBSs, a new family of integrative and conjugative elements associating insertion sequence transposition, plasmid replication, and conjugation for their spreading. J Bacteriol 2013; 195:1979-90. [PMID: 23435978 DOI: 10.1128/jb.01745-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Integrative and conjugative elements (ICEs) have a major impact on gene flow and genome dynamics in bacteria. The ICEs TnGBS1 and TnGBS2, first identified in Streptococcus agalactiae, use a DDE transposase, unlike most characterized ICEs, which depend on a phage-like integrase for their mobility. Here we identified 56 additional TnGBS-related ICEs by systematic genome analysis. Interestingly, all except one are inserted in streptococcal genomes. Sequence comparison of the proteins conserved among these ICEs defined two subtypes related to TnGBS1 or TnGBS2. We showed that both types encode different conjugation modules: a type IV secretion system, a VirD4 coupling protein, and a relaxase and its cognate oriT site, shared with distinct lineages of conjugative elements of Firmicutes. Phylogenetic analysis suggested that TnGBSs evolved from two conjugative elements of different origins by the successive recruitment of a transposition module derived from insertion sequences (ISs). Furthermore, TnGBSs share replication modules with different plasmids. Mutational analyses and conjugation experiments showed that TnGBS1 and TnGBS2 combine replication and transposition upstream promoters for their transfer and stabilization. Despite an evolutionarily successful horizontal dissemination within the genus Streptococcus, these ICEs have a restricted host range. However, we reveal that for TnGBS1 and TnGBS2, this host restriction is not due to a transfer incompatibility linked to the conjugation machineries but most likely to their ability for transient maintenance through replication after their transfer.
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23
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Singh PK, Ramachandran G, Durán-Alcalde L, Alonso C, Wu LJ, Meijer WJJ. Inhibition of Bacillus subtilis natural competence by a native, conjugative plasmid-encoded comK repressor protein. Environ Microbiol 2012; 14:2812-25. [PMID: 22779408 DOI: 10.1111/j.1462-2920.2012.02819.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Under certain growth conditions, Bacillus subtilis can develop natural competence, the state in which it is able to bind, adsorb and incorporate exogenous DNA. Development of competence is a bistable process and is subject to complex regulation. Rok is a repressor of the key transcriptional activator of competence genes, comK, and limits the size of the subpopulation that develops competence. Here we report the finding that the large conjugative B. subtilis plasmid pLS20 harbours a rok homologue rok(LS20). Although the deduced product of rok(LS20) is considerably shorter than the chromosomally encoded Rok protein, we show that ectopic expression of the plasmid-encoded Rok(LS20) leads to inhibition of competence by repressing comK, and that the effects of the plasmid and chromosomally encoded Rok proteins are additive. We also show that pLS20 inhibits competence in a rok(LS20) -dependent manner and that purified Rok(LS20) preferentially binds to the comK promoter. By analysing the available databases we identified several additional rok-like genes. These putative rok genes can be divided into two groups and we propose that rok(LS20) is the prototype of a newly identified subgroup of nine rok genes. Finally, we discuss the possible role of the plasmid-located rok and its relatedness with other rok genes.
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Affiliation(s)
- Praveen K Singh
- Centro de Biología Molecular Severo Ochoa, Instituto de Biología Molecular Eladio Viñuela, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
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24
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Brzozowska I, Brzozowska K, Zielenkiewicz U. Functioning of the TA cassette of streptococcal plasmid pSM19035 in various Gram-positive bacteria. Plasmid 2012; 68:51-60. [PMID: 22309878 DOI: 10.1016/j.plasmid.2012.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 01/19/2012] [Accepted: 01/20/2012] [Indexed: 12/17/2022]
Abstract
Toxin-antitoxin (TA) systems are common in microorganisms and are frequently found in the chromosomes and low-copy number plasmids of bacterial pathogens. One such system is carried by the low copy number plasmid pSM19035 of the pathogenic bacterium Streptococcus pyogenes. This plasmid encodes an omega-epsilon-zeta cassette that ensures its stable maintenance by post-segregational killing of plasmid-free cells. In this study, the activity of the ω-ε-ζ cassette was examined in various Gram-positive bacteria with a low G/C content in their DNA. The broad host range of pSM19035 was confirmed and the copy number of a truncated derivative in transformed strains was determined by real-time qPCR.
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Affiliation(s)
- Iwona Brzozowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawińskiego 5A, 02-106 Warsaw, Poland
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25
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Mutschler H, Meinhart A. ε/ζ systems: their role in resistance, virulence, and their potential for antibiotic development. J Mol Med (Berl) 2011; 89:1183-94. [PMID: 21822621 PMCID: PMC3218275 DOI: 10.1007/s00109-011-0797-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/19/2011] [Accepted: 07/22/2011] [Indexed: 12/17/2022]
Abstract
Cell death in bacteria can be triggered by activation of self-inflicted molecular mechanisms. Pathogenic bacteria often make use of suicide mechanisms in which the death of individual cells benefits survival of the population. Important elements for programmed cell death in bacteria are proteinaceous toxin-antitoxin systems. While the toxin generally resides dormant in the bacterial cytosol in complex with its antitoxin, conditions such as impaired de novo synthesis of the antitoxin or nutritional stress lead to antitoxin degradation and toxin activation. A widespread toxin-antitoxin family consists of the ε/ζ systems, which are distributed over plasmids and chromosomes of various pathogenic bacteria. In its inactive state, the bacteriotoxic ζ toxin protein is inhibited by its cognate antitoxin ε. Upon degradation of ε, the ζ toxin is released allowing this enzyme to poison bacterial cell wall synthesis, which eventually triggers autolysis. ε/ζ systems ensure stable plasmid inheritance by inducing death in plasmid-deprived offspring cells. In contrast, chromosomally encoded ε/ζ systems were reported to contribute to virulence of pathogenic bacteria, possibly by inducing autolysis in individual cells under stressful conditions. The capability of toxin-antitoxin systems to kill bacteria has made them potential targets for new therapeutic compounds. Toxin activation could be hijacked to induce suicide of bacteria. Likewise, the unique mechanism of ζ toxins could serve as template for new drugs. Contrarily, inhibition of virulence-associated ζ toxins might attenuate infections. Here we provide an overview of ε/ζ toxin-antitoxin family and its potential role in the development of new therapeutic approaches in microbial defense.
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Affiliation(s)
- Hannes Mutschler
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
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26
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Laverde Gomez JA, Hendrickx APA, Willems RJ, Top J, Sava I, Huebner J, Witte W, Werner G. Intra- and interspecies genomic transfer of the Enterococcus faecalis pathogenicity island. PLoS One 2011; 6:e16720. [PMID: 21559082 PMCID: PMC3084688 DOI: 10.1371/journal.pone.0016720] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 12/23/2010] [Indexed: 12/11/2022] Open
Abstract
Enterococci are the third leading cause of hospital associated infections and have gained increased importance due to their fast adaptation to the clinical environment by acquisition of antibiotic resistance and pathogenicity traits. Enterococcus faecalis harbours a pathogenicity island (PAI) of 153 kb containing several virulence factors including the enterococcal surface protein (esp). Until now only internal fragments of the PAI or larger chromosomal regions containing it have been transferred. Here we demonstrate precise excision, circularization and horizontal transfer of the entire PAI element from the chromosome of E. faecalis strain UW3114. This PAI (ca. 200 kb) contained some deletions and insertions as compared to the PAI of the reference strain MMH594, transferred precisely and integrated site-specifically into the chromosome of E. faecalis (intergenic region) and Enterococcus faecium (tRNAlys). The internal PAI structure was maintained after transfer. We assessed phenotypic changes accompanying acquisition of the PAI and expression of some of its determinants. The esp gene is expressed on the surface of donor and both transconjugants. Biofilm formation and cytolytic activity were enhanced in E. faecalis transconjugants after acquisition of the PAI. No differences in pathogenicity of E. faecalis were detected using a mouse bacteraemia and a mouse peritonitis models (tail vein and intraperitoneal injection). A 66 kb conjugative pheromone-responsive plasmid encoding erm(B) (pLG2) that was transferred in parallel with the PAI was sequenced. pLG2 is a pheromone responsive plasmid that probably promotes the PAI horizontal transfer, encodes antibiotic resistance features and contains complete replication and conjugation modules of enterococcal origin in a mosaic-like composition. The E. faecalis PAI can undergo precise intra- and interspecies transfer probably with the help of conjugative elements like conjugative resistance plasmids, supporting the role of horizontal gene transfer and antibiotic selective pressure in the successful establishment of certain enterococci as nosocomial pathogens.
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27
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Soberón NE, Lioy VS, Pratto F, Volante A, Alonso JC. Molecular anatomy of the Streptococcus pyogenes pSM19035 partition and segrosome complexes. Nucleic Acids Res 2010; 39:2624-37. [PMID: 21138966 PMCID: PMC3074150 DOI: 10.1093/nar/gkq1245] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Vancomycin or erythromycin resistance and the stability determinants, δω and ωεζ, of Enterococci and Streptococci plasmids are genetically linked. To unravel the mechanisms that promoted the stable persistence of resistance determinants, the early stages of Streptococcus pyogenes pSM19035 partitioning were biochemically dissected. First, the homodimeric centromere-binding protein, ω2, bound parS DNA to form a short-lived partition complex 1 (PC1). The interaction of PC1 with homodimeric δ [δ2 even in the apo form (Apo-δ2)], significantly stimulated the formation of a long-lived ω2·parS complex (PC2) without spreading into neighbouring DNA sequences. In the ATP·Mg2+ bound form, δ2 bound DNA, without sequence specificity, to form a transient dynamic complex (DC). Second, parS bound ω2 interacted with and promoted δ2 redistribution to co-localize with the PC2, leading to transient segrosome complex (SC, parS·ω2·δ2) formation. Third, δ2, in the SC, interacted with a second SC and promoted formation of a bridging complex (BC). Finally, increasing ω2 concentrations stimulated the ATPase activity of δ2 and the BC was disassembled. We propose that PC, DC, SC and BC formation were dynamic processes and that the molar ω2:δ2 ratio and parS DNA control their temporal and spatial assembly during partition of pSM19035 before cell division.
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Affiliation(s)
- Nora E Soberón
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
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28
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Complete nucleotide sequence and determination of the replication region of the sporulation inhibiting plasmid p576 from Bacillus pumilus NRS576. Res Microbiol 2010; 161:772-82. [PMID: 20863889 DOI: 10.1016/j.resmic.2010.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 07/27/2010] [Indexed: 01/08/2023]
Abstract
Large plasmids, presumably replicating via the theta mechanism, have been identified in numerous gram-positive bacteria. However, their characterization is rather poor and predominantly limited to those harbored by some (opportunistic) pathogenic bacteria. Here we determined the DNA sequence of the 43.3 kb plasmid p576 from Bacillus pumilus strain NRS576, the first B. pumilus theta-replicating plasmid sequenced. Plasmid p576 has a modular structure, but surprisingly, it does not seem to encode a Rep protein found on most theta-replicating plasmids. However, a ∼1 kb region was identified showing homology with the Rep-independent replication region of Bacillus subtilis plasmid pLS20, and we demonstrated that this region is sufficient for autonomous replication. The plasmid contains various large direct repeat sequences. A likely function could be attributed to at least 15 putative p576 genes. Some of these are predicted to be involved in stable maintenance of the plasmid; others are likely to encode proteins involved in conjugation. p576 also carries a rap-phr cassette whose possible function is discussed.
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