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Breidenstein A, Lamy A, Bader CP, Sun WS, Wanrooij PH, Berntsson RPA. PrgE: an OB-fold protein from plasmid pCF10 with striking differences to prototypical bacterial SSBs. Life Sci Alliance 2024; 7:e202402693. [PMID: 38811160 PMCID: PMC11137577 DOI: 10.26508/lsa.202402693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/08/2024] [Accepted: 05/08/2024] [Indexed: 05/31/2024] Open
Abstract
A major pathway for horizontal gene transfer is the transmission of DNA from donor to recipient cells via plasmid-encoded type IV secretion systems (T4SSs). Many conjugative plasmids encode for a single-stranded DNA-binding protein (SSB) together with their T4SS. Some of these SSBs have been suggested to aid in establishing the plasmid in the recipient cell, but for many, their function remains unclear. Here, we characterize PrgE, a proposed SSB from the Enterococcus faecalis plasmid pCF10. We show that PrgE is not essential for conjugation. Structurally, it has the characteristic OB-fold of SSBs, but it has very unusual DNA-binding properties. Our DNA-bound structure shows that PrgE binds ssDNA like beads on a string supported by its N-terminal tail. In vitro studies highlight the plasticity of PrgE oligomerization and confirm the importance of the N-terminus. Unlike other SSBs, PrgE binds both double- and single-stranded DNA equally well. This shows that PrgE has a quaternary assembly and DNA-binding properties that are very different from the prototypical bacterial SSB, but also different from eukaryotic SSBs.
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Affiliation(s)
- Annika Breidenstein
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- https://ror.org/05kb8h459 Wallenberg Centre for Molecular Medicine and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Anaïs Lamy
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- https://ror.org/05kb8h459 Wallenberg Centre for Molecular Medicine and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Cyrielle Pj Bader
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Wei-Sheng Sun
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- https://ror.org/05kb8h459 Wallenberg Centre for Molecular Medicine and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Paulina H Wanrooij
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Ronnie P-A Berntsson
- https://ror.org/05kb8h459 Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- https://ror.org/05kb8h459 Wallenberg Centre for Molecular Medicine and Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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Couturier A, Virolle C, Goldlust K, Berne-Dedieu A, Reuter A, Nolivos S, Yamaichi Y, Bigot S, Lesterlin C. Real-time visualisation of the intracellular dynamics of conjugative plasmid transfer. Nat Commun 2023; 14:294. [PMID: 36653393 PMCID: PMC9849209 DOI: 10.1038/s41467-023-35978-3] [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: 10/05/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
Conjugation is a contact-dependent mechanism for the transfer of plasmid DNA between bacterial cells, which contributes to the dissemination of antibiotic resistance. Here, we use live-cell microscopy to visualise the intracellular dynamics of conjugative transfer of F-plasmid in E. coli, in real time. We show that the transfer of plasmid in single-stranded form (ssDNA) and its subsequent conversion into double-stranded DNA (dsDNA) are fast and efficient processes that occur with specific timing and subcellular localisation. Notably, the ssDNA-to-dsDNA conversion determines the timing of plasmid-encoded protein production. The leading region that first enters the recipient cell carries single-stranded promoters that allow the early and transient synthesis of leading proteins immediately upon entry of the ssDNA plasmid. The subsequent conversion into dsDNA turns off leading gene expression, and activates the expression of other plasmid genes under the control of conventional double-stranded promoters. This molecular strategy allows for the timely production of factors sequentially involved in establishing, maintaining and disseminating the plasmid.
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Affiliation(s)
- Agathe Couturier
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Chloé Virolle
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Kelly Goldlust
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Annick Berne-Dedieu
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Audrey Reuter
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Sophie Nolivos
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France
| | - Yoshiharu Yamaichi
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Sarah Bigot
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France.
| | - Christian Lesterlin
- Molecular Microbiology and Structural Biochemistry (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, 69007, Lyon, France.
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Darphorn TS, Brul S, Ter Kuile BH. Genetic editing of multi-resistance plasmids in Escherichia coli isolated from meat during transfer. Plasmid 2022; 122:102640. [PMID: 35870604 DOI: 10.1016/j.plasmid.2022.102640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 07/18/2022] [Indexed: 11/17/2022]
Abstract
Resistance plasmids mediate the rapid spread of antimicrobial resistance, which poses a threat to veterinary and human healthcare. This study addresses the question whether resistance plasmids from Escherichia coli isolated from foodstuffs always transfer unchanged to recipient E. coli cells, or that genetic editing can occur. Strains containing between one and five different plasmids were co-incubated with a standard recipient strain. Plasmids isolated from transconjugant strains were sequenced using short and long read technologies and compared to the original plasmids from the donor strains. After one hour of co-incubation only a single plasmid was transferred from donor to recipient strains. If the donor possessed several plasmids, longer co-incubation resulted in multiple plasmids being transferred. Transferred plasmids showed mutations, mostly in mobile genetic elements, in the conjugative transfer gene pilV and in genes involved in plasmid maintenance. In one transconjugant, a resistance cluster encoding tetracycline resistance was acquired by the IncI1 plasmid from the IncX1 plasmid that was also present in the donor strain, but that was not transferred. A single plasmid transferred twelve times back and forth between E. coli strains resulted in a fully conserved plasmid with no mutations, apart from repetitive rearrangements of pilV from and back to its original conformation in the donor strain. The overall outcome suggests that some genetic mutations and rearrangements can occur during plasmid transfer. The possibility of such mutations should be taken into consideration in epidemiological research aimed at attribution of resistance to specific sources.
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Affiliation(s)
- Tania S Darphorn
- Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Stanley Brul
- Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Benno H Ter Kuile
- Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands; Netherlands Food and Consumer Product Safety Authority, Office for Risk Assessment, Utrecht, the Netherlands.
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Protein Transfer through an F Plasmid-Encoded Type IV Secretion System Suppresses the Mating-Induced SOS Response. mBio 2021; 12:e0162921. [PMID: 34253063 PMCID: PMC8406263 DOI: 10.1128/mbio.01629-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Bacterial type IV secretion systems (T4SSs) mediate the conjugative transfer of mobile genetic elements (MGEs) and their cargoes of antibiotic resistance and virulence genes. Here, we report that the pED208-encoded T4SS (TrapED208) translocates not only this F plasmid but several plasmid-encoded proteins, including ParA, ParB1, single-stranded DNA-binding protein SSB, ParB2, PsiB, and PsiA, to recipient cells. Conjugative protein translocation through the TrapED208 T4SS required engagement of the pED208 relaxosome with the TraD substrate receptor or coupling protein. T4SSs translocate MGEs as single-stranded DNA intermediates (T-strands), which triggers the SOS response in recipient cells. Transfer of pED208 deleted of psiB or ssb, which, respectively, encode the SOS inhibitor protein PsiB and single-stranded DNA-binding protein SSB, elicited a significantly stronger SOS response than pED208 or mutant plasmids deleted of psiA, parA, parB1, or parB2. Conversely, translocation of PsiB or SSB, but not PsiA, through the TrapED208 T4SS suppressed the mating-induced SOS response. Our findings expand the repertoire of known substrates of conjugation systems to include proteins with functions associated with plasmid maintenance. Furthermore, for this and other F-encoded Tra systems, docking of the DNA substrate with the TraD receptor appears to serve as a critical activating signal for protein translocation. Finally, the observed effects of PsiB and SSB on suppression of the mating-induced SOS response establishes a novel biological function for conjugative protein translocation and suggests the potential for interbacterial protein translocation to manifest in diverse outcomes influencing bacterial communication, physiology, and evolution.
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Virolle C, Goldlust K, Djermoun S, Bigot S, Lesterlin C. Plasmid Transfer by Conjugation in Gram-Negative Bacteria: From the Cellular to the Community Level. Genes (Basel) 2020; 11:genes11111239. [PMID: 33105635 PMCID: PMC7690428 DOI: 10.3390/genes11111239] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/15/2020] [Accepted: 10/20/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial conjugation, also referred to as bacterial sex, is a major horizontal gene transfer mechanism through which DNA is transferred from a donor to a recipient bacterium by direct contact. Conjugation is universally conserved among bacteria and occurs in a wide range of environments (soil, plant surfaces, water, sewage, biofilms, and host-associated bacterial communities). Within these habitats, conjugation drives the rapid evolution and adaptation of bacterial strains by mediating the propagation of various metabolic properties, including symbiotic lifestyle, virulence, biofilm formation, resistance to heavy metals, and, most importantly, resistance to antibiotics. These properties make conjugation a fundamentally important process, and it is thus the focus of extensive study. Here, we review the key steps of plasmid transfer by conjugation in Gram-negative bacteria, by following the life cycle of the F factor during its transfer from the donor to the recipient cell. We also discuss our current knowledge of the extent and impact of conjugation within an environmentally and clinically relevant bacterial habitat, bacterial biofilms.
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Baishya S, Kangsa Banik S, Das Talukdar A, Anbarasu A, Bhattacharjee A, Dutta Choudhury M. Full title: Identification of potential drug targets against carbapenem resistant Enterobacteriaceae (CRE) strains using in silico gene network analysis. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2018.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Moran RA, Hall RM. pBuzz: A cryptic rolling-circle plasmid from a commensal Escherichia coli has two inversely oriented oriTs and is mobilised by a B/O plasmid. Plasmid 2018; 101:10-19. [PMID: 30468749 DOI: 10.1016/j.plasmid.2018.11.001] [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] [Received: 08/31/2018] [Revised: 11/01/2018] [Accepted: 11/12/2018] [Indexed: 11/25/2022]
Abstract
Ampicillin, streptomycin and sulphamethoxazole resistant commensal E. coli 838-3B contains five plasmids that range in size from >90 kb to <2 kb. The resistance genes blaTEM (ampicillin), strA (streptomycin) and sul2 (sulphamethoxazole) transferred along with a B/O plasmid named p838B-R. However, three plasmids smaller than 7 kb were also found in transconjugants, suggesting that they could be mobilised by the B/O plasmid. The complete sequences of p838B-R and pBuzz, a small plasmid mobilised by p838B-R with 70% efficiency, were determined. p838B-R is 94,803 bp and contains an 8400 bp resistance island that includes the three antibiotic resistance genes. The p838B-R backbone contains a complete conjugative transfer region, including an oriT site upstream of nikAB that resembles the experimentally-defined oriT of R64. The 1982 bp pBuzz contains a rep gene and sites associated with replication that resemble those of pC194/pUB110 family rolling-circle plasmids. It also contains two, inversely oriented copies of an 84 bp sequence that differs from the oriT region in p838B-R at just 6 positions. These oriT-like sites likely explain the ability of pBuzz to co-transfer with the B/O plasmid using the NikB relaxase and NikA accessory protein encoded by p838B-R, i.e. pBuzz utilises relaxase-in trans mobilisation. Several rolling-circle plasmids related to pBuzz were found in the GenBank non-redundant nucleotide database. They contain diverse potential oriTs, including sequences similar to known oriTs found in conjugative plasmids of I-complex (I1, B/O, K, Z and I2), L or M types.
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Affiliation(s)
- Robert A Moran
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia.
| | - Ruth M Hall
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
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8
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Genome sequence of lung pathogenic Escherichia coli O78, a chimeric strain isolated from pneumonia forest musk deer. Genes Genomics 2017. [DOI: 10.1007/s13258-017-0545-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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9
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Wegrzyn KE, Gross M, Uciechowska U, Konieczny I. Replisome Assembly at Bacterial Chromosomes and Iteron Plasmids. Front Mol Biosci 2016; 3:39. [PMID: 27563644 PMCID: PMC4980987 DOI: 10.3389/fmolb.2016.00039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/25/2016] [Indexed: 11/13/2022] Open
Abstract
The proper initiation and occurrence of DNA synthesis depends on the formation and rearrangements of nucleoprotein complexes within the origin of DNA replication. In this review article, we present the current knowledge on the molecular mechanism of replication complex assembly at the origin of bacterial chromosome and plasmid replicon containing direct repeats (iterons) within the origin sequence. We describe recent findings on chromosomal and plasmid replication initiators, DnaA and Rep proteins, respectively, and their sequence-specific interactions with double- and single-stranded DNA. Also, we discuss the current understanding of the activities of DnaA and Rep proteins required for replisome assembly that is fundamental to the duplication and stability of genetic information in bacterial cells.
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Affiliation(s)
- Katarzyna E Wegrzyn
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Marta Gross
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Urszula Uciechowska
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Igor Konieczny
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
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Zong Z, Ginn AN, Dobiasova H, Iredell JR, Partridge SR. Different IncI1 plasmids from Escherichia coli carry ISEcp1-blaCTX-M-15 associated with different Tn2-derived elements. Plasmid 2015; 80:118-26. [PMID: 25929173 DOI: 10.1016/j.plasmid.2015.04.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 04/20/2015] [Accepted: 04/22/2015] [Indexed: 02/05/2023]
Abstract
The bla(CTX-M-15) gene, encoding the globally dominant CTX-M-15 extended-spectrum β-lactamase, has generally been found in a 2.971-kb ISEcp1-bla(CTX-M-15)-orf477Δ transposition unit, with ISEcp1 providing a promoter. In available IncF plasmid sequences from Escherichia coli, this transposition unit interrupts a truncated copy of transposon Tn2 that lies within larger multiresistance regions. In E. coli, bla(CTX-M-15) is also commonly associated with IncI1 plasmids and here three such plasmids from E. coli clinical isolates from western Sydney 2006-2007 have been sequenced. The plasmid backbones are organised similarly to those of other IncI1 plasmids, but have insertions and/or deletions and sequence differences. Each plasmid also has a different insertion carrying bla(CTX-M-15). pJIE113 (IncI1 sequence type ST31) is almost identical to plasmids isolated from the 2011 E. coli O104:H4 outbreak in Europe, where the typical bla(CTX-M-15) transposition unit interrupts a complete Tn2 inserted directly in the plasmid backbone. In the novel plasmid pJIE139 (ST88), ISEcp1-blaC(TX-M-15)-orf477Δ lies within a Tn2/3 hybrid transposon. Homologous recombination could explain movement of ISEcp1-bla(CTX-M-15)-orf477Δ between copies of Tn2 on IncF and IncI1 plasmids and generation of the Tn2/3 hybrid. pJIE174 (ST37) is almost identical to pESBL-12 from the Netherlands and in these plasmids bla(CTX-M-15) is flanked by two copies of IS26 that truncate the transposition unit within a larger region bounded by the ends of Tn2. bla(CTX-M-15) and the associated ISEcp1-derived promoter may be able to move from this structure by the actions of IS26, independently of both ISEcp1 and Tn2.
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Affiliation(s)
- Zhiyong Zong
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia; Department of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China
| | - Andrew N Ginn
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia
| | - Hana Dobiasova
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia; Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic; CEITEC VFU, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Jonathan R Iredell
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia
| | - Sally R Partridge
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia.
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Jain S, Zweig M, Peeters E, Siewering K, Hackett KT, Dillard JP, van der Does C. Characterization of the single stranded DNA binding protein SsbB encoded in the Gonoccocal Genetic Island. PLoS One 2012; 7:e35285. [PMID: 22536367 PMCID: PMC3334931 DOI: 10.1371/journal.pone.0035285] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 03/14/2012] [Indexed: 11/18/2022] Open
Abstract
Background Most strains of Neisseria gonorrhoeae carry a Gonococcal Genetic Island which encodes a type IV secretion system involved in the secretion of ssDNA. We characterize the GGI-encoded ssDNA binding protein, SsbB. Close homologs of SsbB are located within a conserved genetic cluster found in genetic islands of different proteobacteria. This cluster encodes DNA-processing enzymes such as the ParA and ParB partitioning proteins, the TopB topoisomerase, and four conserved hypothetical proteins. The SsbB homologs found in these clusters form a family separated from other ssDNA binding proteins. Methodology/Principal Findings In contrast to most other SSBs, SsbB did not complement the Escherichia coli ssb deletion mutant. Purified SsbB forms a stable tetramer. Electrophoretic mobility shift assays and fluorescence titration assays, as well as atomic force microscopy demonstrate that SsbB binds ssDNA specifically with high affinity. SsbB binds single-stranded DNA with minimal binding frames for one or two SsbB tetramers of 15 and 70 nucleotides. The binding mode was independent of increasing Mg2+ or NaCl concentrations. No role of SsbB in ssDNA secretion or DNA uptake could be identified, but SsbB strongly stimulated Topoisomerase I activity. Conclusions/Significance We propose that these novel SsbBs play an unknown role in the maintenance of genetic islands.
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Affiliation(s)
- Samta Jain
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Maria Zweig
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Eveline Peeters
- Research Group of Microbiology, Department of Sciences and Bio-engineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Katja Siewering
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Kathleen T. Hackett
- Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Joseph P. Dillard
- Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Chris van der Does
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
- * E-mail:
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Johnson TJ, Shepard SM, Rivet B, Danzeisen JL, Carattoli A. Comparative genomics and phylogeny of the IncI1 plasmids: A common plasmid type among porcine enterotoxigenic Escherichia coli. Plasmid 2011; 66:144-51. [DOI: 10.1016/j.plasmid.2011.07.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/17/2011] [Accepted: 07/19/2011] [Indexed: 11/25/2022]
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Garcillán-Barcia MP, Alvarado A, de la Cruz F. Identification of bacterial plasmids based on mobility and plasmid population biology. FEMS Microbiol Rev 2011; 35:936-56. [PMID: 21711366 DOI: 10.1111/j.1574-6976.2011.00291.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Plasmids contain a backbone of core genes that remains relatively stable for long evolutionary periods, making sense to speak about plasmid species. The identification and characterization of the core genes of a plasmid species has a special relevance in the study of its epidemiology and modes of transmission. Besides, this knowledge will help to unveil the main routes that genes, for example antibiotic resistance (AbR) genes, use to travel from environmental reservoirs to human pathogens. Global dissemination of multiple antibiotic resistances and virulence traits by plasmids is an increasing threat for the treatment of many bacterial infectious diseases. To follow the dissemination of virulence and AbR genes, we need to identify the causative plasmids and follow their path from reservoirs to pathogens. In this review, we discuss how the existing diversity in plasmid genetic structures gives rise to a large diversity in propagation strategies. We would like to propose that, using an identification methodology based on plasmid mobility types, we can follow the propagation routes of most plasmids in Gammaproteobacteria, as well as their cargo genes, in complex ecosystems. Once the dissemination routes are known, designing antidissemination drugs and testing their efficacy will become feasible. We discuss in this review how the existing diversity in plasmid genetic structures gives rise to a large diversity in propagation strategies. We would like to propose that, by using an identification methodology based on plasmid mobility types, we can follow the propagation routes of most plasmids in ?-proteobacteria, as well as their cargo genes, in complex ecosystems.
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Affiliation(s)
- Maria Pilar Garcillán-Barcia
- Departamento de Biología Molecular e Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-IDICAN, C. Herrera Oria s/n, Santander, Spain
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Baharoglu Z, Bikard D, Mazel D. Conjugative DNA transfer induces the bacterial SOS response and promotes antibiotic resistance development through integron activation. PLoS Genet 2010; 6:e1001165. [PMID: 20975940 PMCID: PMC2958807 DOI: 10.1371/journal.pgen.1001165] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 09/17/2010] [Indexed: 11/21/2022] Open
Abstract
Conjugation is one mechanism for intra- and inter-species horizontal gene transfer among bacteria. Conjugative elements have been instrumental in many bacterial species to face the threat of antibiotics, by allowing them to evolve and adapt to these hostile conditions. Conjugative plasmids are transferred to plasmidless recipient cells as single-stranded DNA. We used lacZ and gfp fusions to address whether conjugation induces the SOS response and the integron integrase. The SOS response controls a series of genes responsible for DNA damage repair, which can lead to recombination and mutagenesis. In this manuscript, we show that conjugative transfer of ssDNA induces the bacterial SOS stress response, unless an anti-SOS factor is present to alleviate this response. We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements. Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell. Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria. Bacteria exchange DNA in their natural environments. The process called conjugation consists of DNA transfer by cell contact from one bacterium to another. Conjugative circular plasmids have been identified as shuttles and reservoirs for adaptive genes. It is now established that such lateral gene transfer plays an essential role, especially for the antibiotic resistance development and dissemination among bacteria. Moreover, integrons, platforms of mobile gene cassettes, have been instrumental in this phenomenon, through their successful association with conjugative resistance plasmids. We demonstrate in this study that the conjugative transfer of plasmids triggers a bacterial stress response—the SOS response—in recipient cells and can impact the cassette content of integrons. The SOS response is already known to induce various genome modifications. Human and animal pathogens cohabit with environmental bacteria, in niches which will favor DNA exchange. SOS induction during conjugation is thus most probably able to impact a wide range of genomes. Bacterial SOS response could then be a suitable target for co-treatment of infections in order to prevent exchange of antibiotic resistance/adaptation genes.
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Affiliation(s)
- Zeynep Baharoglu
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France
- CNRS, URA2171, Paris, France
| | - David Bikard
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France
- CNRS, URA2171, Paris, France
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Paris, France
- CNRS, URA2171, Paris, France
- * E-mail:
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15
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Reisner A, Höller BM, Molin S, Zechner EL. Synergistic effects in mixed Escherichia coli biofilms: conjugative plasmid transfer drives biofilm expansion. J Bacteriol 2006; 188:3582-8. [PMID: 16672612 PMCID: PMC1482856 DOI: 10.1128/jb.188.10.3582-3588.2006] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial biofilms, often composed of multiple species and genetically distinct strains, develop under complex influences of cell-cell interactions. Although detailed knowledge about the mechanisms underlying formation of single-species laboratory biofilms has emerged, little is known about the pathways governing development of more complex heterogeneous communities. In this study, we established a laboratory model where biofilm-stimulating effects due to interactions between genetically diverse strains of Escherichia coli were monitored. Synergistic induction of biofilm formation resulting from the cocultivation of 403 undomesticated E. coli strains with a characterized E. coli K-12 strain was detected at a significant frequency. The survey suggests that different mechanisms underlie the observed stimulation, yet synergistic development of biofilm within the subset of E. coli isolates (n = 56) exhibiting the strongest effects was most often linked to conjugative transmission of natural plasmids carried by the E. coli isolates (70%). Thus, the capacity of an isolate to promote the biofilm through cocultivation was (i) transferable to the K-12 strain, (ii) was linked with the acquisition of conjugation genes present initially in the isolate, and (iii) was inhibited through the presence in the cocultured K-12 strain of a related conjugative plasmid, presumably due to surface exclusion functions. Synergistic effects of cocultivation of pairs of natural isolates were also observed, demonstrating that biofilm promotion in this system is not dependent on the laboratory strain and that the described model system could provide relevant insights on mechanisms of biofilm development in natural E. coli populations.
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Affiliation(s)
- Andreas Reisner
- Institut für Molekulare Biowissenschaften, Karl-Franzens-Universität Graz, Austria.
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16
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Nasim MT, Eperon IC, Wilkins BM, Brammar WJ. The activity of a single-stranded promoter of plasmid ColIb-P9 depends on its secondary structure. Mol Microbiol 2004; 53:405-17. [PMID: 15228523 DOI: 10.1111/j.1365-2958.2004.04114.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The leading region of the conjugal bacterial plasmid ColIb-P9 contains three dispersed repeats of a 328 bp sequence homologous to Frpo, a sequence from plasmid F that acts as a promoter in single-stranded DNA. One of these sequences, ssi3, inactive in the double-stranded form, promoted in vitro transcription exclusively from the single strand that is transferred during conjugation. Promoter activity was dependent on the presence of RNA polymerase holoenzyme containing sigma 70. Transcription initiated from the position predicted from folding the single-stranded DNA to form a pseudo double-stranded hairpin structure containing recognizable -35 and -10 promoter elements. Footprinting of RNA polymerase holoenzyme on single-stranded ssi3 DNA was consistent with this suggestion. Mutagenesis of the putative -35 region inactivated the promoter, but random mutations in the -10 region had little effect. The putative -10 region is a poor match to the consensus sequence and contains mismatched bases. Elimination of these mismatches invariably destroyed single-strand promoter activity. These observations reveal the crucial contribution of the unpaired bases in the -10 region in potentiating the formation of the productive open complex with RNA polymerase.
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Affiliation(s)
- M T Nasim
- Department of Biochemistry, University of Leicester, Leicester LE1 7RH, UK
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17
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Bendtsen JD, Nilsson AS, Lehnherr H. Phylogenetic and functional analysis of the bacteriophage P1 single-stranded DNA-binding protein. J Virol 2002; 76:9695-701. [PMID: 12208948 PMCID: PMC136491 DOI: 10.1128/jvi.76.19.9695-9701.2002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriophage P1 encodes a single-stranded DNA-binding protein (SSB-P1), which shows 66% amino acid sequence identity to the SSB protein of the host bacterium Escherichia coli. A phylogenetic analysis indicated that the P1 ssb gene coexists with its E. coli counterpart as an independent unit and does not represent a recent acquisition of the phage. The P1 and E. coli SSB proteins are fully functionally interchangeable. SSB-P1 is nonessential for phage growth in an exponentially growing E. coli host, and it is sufficient to promote bacterial growth in the absence of the E. coli SSB protein. Expression studies showed that the P1 ssb gene is transcribed only, in an rpoS-independent fashion, during stationary-phase growth in E. coli. Mixed infection experiments demonstrated that a wild-type phage has a selective advantage over an ssb-null mutant when exposed to a bacterial host in the stationary phase. These results reconciled the observed evolutionary conservation with the seemingly redundant presence of ssb genes in many bacteriophages and conjugative plasmids.
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Affiliation(s)
- Jannick Dyrløv Bendtsen
- Department of Genetics and Biochemistry, Institute of Microbiology, Ernst-Moritz-Arndt-Universität Greifswald, D-17487 Greifswald, Germany
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18
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Kolb FA, Westhof E, Ehresmann B, Ehresmann C, Wagner EG, Romby P. Four-way junctions in antisense RNA-mRNA complexes involved in plasmid replication control: a common theme? J Mol Biol 2001; 309:605-14. [PMID: 11397083 DOI: 10.1006/jmbi.2001.4677] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In several groups of bacterial plasmids, antisense RNAs regulate copy number through inhibition of replication initiator protein synthesis. In plasmid R1, we have recently shown that the inhibitory complex between the antisense RNA (CopA) and its target mRNA (CopT) is characterized by the formation of two intermolecular helices, resulting in a four-way junction structure and a side-by-side helical alignment. Based on lead-induced cleavage and ribonuclease (RNase) V(1) probing combined with molecular modeling, a strikingly similar topology is supported for the complex formed between the antisense RNA (Inc) and mRNA (RepZ) of plasmid Col1b-P9. In particular, the position of the four-way junction and the location of divalent ion-binding site(s) indicate that the structural features of these two complexes are essentially the same in spite of sequence differences. Comparisons of several target and antisense RNAs in other plasmids further indicate that similar binding pathways are used to form the inhibitory antisense-target RNA complexes. Thus, in all these systems, the structural features of both antisense and target RNAs determine the topologically possible and kinetically favored pathway that is essential for efficient in vivo control.
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MESH Headings
- Base Sequence
- Binding Sites
- Cations, Divalent/metabolism
- Cations, Divalent/pharmacology
- DNA Replication
- DNA, Bacterial/biosynthesis
- DNA, Bacterial/genetics
- Endoribonucleases/metabolism
- Hydrolysis/drug effects
- Lead/metabolism
- Lead/pharmacology
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Plasmids/biosynthesis
- Plasmids/genetics
- RNA, Antisense/chemistry
- RNA, Antisense/genetics
- RNA, Antisense/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Templates, Genetic
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Affiliation(s)
- F A Kolb
- UPR 9002 du CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 Rue R. Descartes, Strasbourg Cedex, F-67084, France
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19
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20
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Lehnherr H, Bendtsen JD, Preuss F, Ilyina TV. Identification and characterization of the single-stranded DNA-binding protein of bacteriophage P1. J Bacteriol 1999; 181:6463-8. [PMID: 10515938 PMCID: PMC103783 DOI: 10.1128/jb.181.20.6463-6468.1999] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of bacteriophage P1 harbors a gene coding for a 162-amino-acid protein which shows 66% amino acid sequence identity to the Escherichia coli single-stranded DNA-binding protein (SSB). The expression of the P1 gene is tightly regulated by P1 immunity proteins. It is completely repressed during lysogenic growth and only weakly expressed during lytic growth, as assayed by an ssb-P1/lacZ fusion construct. When cloned on an intermediate-copy-number plasmid, the P1 gene is able to suppress the temperature-sensitive defect of an E. coli ssb mutant, indicating that the two proteins are functionally interchangeable. Many bacteriophages and conjugative plasmids do not rely on the SSB protein provided by their host organism but code for their own SSB proteins. However, the close relationship between SSB-P1 and the SSB protein of the P1 host, E. coli, raises questions about the functional significance of the phage protein.
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Affiliation(s)
- H Lehnherr
- Institute of Molecular Biology, University of Southern Denmark, Main Campus Odense University, DK-5230 Odense M, Denmark.
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21
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Bates S, Roscoe RA, Althorpe NJ, Brammar WJ, Wilkins BM. Expression of leading region genes on IncI1 plasmid ColIb-P9: genetic evidence for single-stranded DNA transcription. MICROBIOLOGY (READING, ENGLAND) 1999; 145 ( Pt 10):2655-62. [PMID: 10537187 DOI: 10.1099/00221287-145-10-2655] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The leading region of a plasmid is the first sector to enter the recipient cell in bacterial conjugation. This sector of IncI1 plasmid ColIb-P9 includes genes that are transcribed in a transient pulse early in the conjugatively infected cell to promote establishment of the immigrant plasmid. Evidence is presented that the burst of gene expression is regulated by a process which is independent of a repressor but dependent on the orientation of the genes on the unique plasmid strand transferred in conjugation. The nucleotide sequence of 11.7 kb of the leading region was determined and found to contain 10 ORFs; all are orientated such that the template strand for transcription corresponds to the transferred strand. The leading region contains three dispersed repeats of a sequence homologous to a novel promoter in ssDNA described by H. Masai & K. Arai (1997, Cell 89, 897-907). It is proposed that the repeats are promoters that form in the transferring strand of ColIb to support transient transcription of genes transferred early in conjugation.
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Affiliation(s)
- S Bates
- Department of Genetics, University of Leicester, UK
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22
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Althorpe NJ, Chilley PM, Thomas AT, Brammar WJ, Wilkins BM. Transient transcriptional activation of the Incl1 plasmid anti-restriction gene (ardA) and SOS inhibition gene (psiB) early in conjugating recipient bacteria. Mol Microbiol 1999; 31:133-42. [PMID: 9987116 DOI: 10.1046/j.1365-2958.1999.01153.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ardA gene of the enterobacterial plasmid CollbP-9 acts to alleviate restriction of DNA by type I systems, while psiB inhibits induction of the bacterial SOS response. Both genes are transferred early in a round of bacterial conjugation as part of the plasmid leading region. We report here that ardA and psiB are transcribed transiently after their conjugative transport into the recipient cell. Transcript levels, monitored by competitive reverse transcription-polymerase chain reaction (RT-PCR) amplification of RNA templates, started to increase about 5 min after the initiation of conjugation in a cell population and probably before the first round of plasmid transfer was completed. Genetic evidence is given that the expression of ardA and psiB is activated when the genes enter the recipient cell on the transferring plasmid strand. It is proposed that these and other leading region genes function to promote the establishment of the immigrant plasmid in the new host and are expressed by transcription from promoters active only in single-stranded DNA.
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Affiliation(s)
- N J Althorpe
- Department of Genetics, University of Leicester, UK
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23
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Campbell EA, Choi SY, Masure HR. A competence regulon in Streptococcus pneumoniae revealed by genomic analysis. Mol Microbiol 1998; 27:929-39. [PMID: 9535083 DOI: 10.1046/j.1365-2958.1998.00737.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Transformation in bacteria is the uptake and incorporation of exogenous DNA into a cell's genome. Several species transform naturally during a regulated state defined as competence. Genetic elements in Streptococcus pneumoniae induced during transformation were identified by combining a genetic screen with genomic analysis. Six loci were discovered that composed a competence-induced regulon. These loci shared a consensus promoter sequence and encoded proteins, some of which were similar to proteins involved in DNA processing during transformation in other bacteria. Each locus was induced during competence and essential for genetic transformation.
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Affiliation(s)
- E A Campbell
- Laboratory of Molecular Infectious Diseases, Rockefeller University, New York, NY 10021, USA
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24
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Delver EP, Belogurov AA. Organization of the leading region of IncN plasmid pKM101 (R46): a regulation controlled by CUP sequence elements. J Mol Biol 1997; 271:13-30. [PMID: 9300052 DOI: 10.1006/jmbi.1997.1124] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Analysis of the nucleotide sequence of the 13.8 kb leading region of the IncN plasmid pKM101 (a deletion derivative of R46) revealed eight copies of highly conserved repetitive elements, CUP (Conserved UPstream), and at least nine novel open reading frames (ORFs). Appropriate protein products were identified for eight ORFs and the analysis of their deduced amino acid sequences revealed similarities with some well-known proteins (KorA of RK2/RP4, RecX and PsiB) that may play a role in the adaptation of promiscuous plasmids to the new host. Comparison of CUP elements revealed that the CUP core is 417 nucleotides long and consists of two portions that markedly differ in GC content. The larger portion (307 nucleotides) of the core is about 74% GC and contains at least one NotI site, while the other (110 nucleotides) is only about 40% GC. The remarkable features of CUP elements is that five of them are oriented in the same direction and fused in a similar mode to the open reading frames (ORFs) that are able to encode unrelated proteins. The spacings between the right boundary of the CUP core and the potential ATG start codons of these ORFs are slightly different in length (16 to 18 bp), highly divergent in sequence but in all cases contain the conserved hexamer 5'-AGGAGT-3' at the position that is typical for the ribosome binding site of Escherichia coli. The A+T-rich portion of the CUP sequences contains the strong negatively regulated promoter and appears to function as a genetic switch that coordinately controls the expression of CUP-fused genes during the conjugal transfer. These findings suggest that seven plasmid genes fused to the CUP elements including repA and two ard genes encoding positively acting replication protein and antirestriction proteins, respectively, may be members of one regulatory network based on the CUP elements and two plasmid-encoded regulatory proteins ArdK and ArdR. At least, the ArdK protein may act as a typical repressor by binding to the promoter region of the CUP sequence. Most of the structural and functional features of organization of the CUP-controlled regulatory network are associated with the idea that the CUP elements may be involved in the natural genetic engineering process of organizing various functionally related genes in one regulon.
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Affiliation(s)
- E P Delver
- Department of Genetic Engineering, Cardiology Research Center, Moscow, Russia
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25
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Haase J, Kalkum M, Lanka E. TrbK, a small cytoplasmic membrane lipoprotein, functions in entry exclusion of the IncP alpha plasmid RP4. J Bacteriol 1996; 178:6720-9. [PMID: 8955288 PMCID: PMC178567 DOI: 10.1128/jb.178.23.6720-6729.1996] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
TrbK is the only plasmid-encoded gene product involved in entry exclusion of the broad-host-range plasmid RP4. The corresponding gene, trbK, coding for a protein of 69 amino acid residues maps in the Tra2 region within the mating pair formation genes. TrbK carries a lipid moiety at the N-terminal cysteine of the mature 47-residue polypeptide. The mutant protein TrbKC23G cannot be modified or proteolytically processed but still acts in entry exclusion with reduced efficiency. An 8-amino-acid truncation at the C terminus of TrbK results in a complete loss of the entry exclusion activity but still allows the protein to be processed. TrbK localizes predominately to the cytoplasmic membrane. Its function depends on presence in the recipient cell but not in the donor cell. TrbK excludes plasmids of homologous systems of the P complex; it is inert towards the IncI system. The likely target for TrbK action is the mating pair formation system, because DNA or any of the components of the relaxosome were excluded as possible targets.
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Affiliation(s)
- J Haase
- Max-Planck-Institut für Molekulare Genetik, Dahlem, Berlin, Germany
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26
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De Vries J, Genschel J, Urbanke C, Thole H, Wackernagel W. The single-stranded-DNA-binding proteins (SSB) of Proteus mirabilis and Serratia marcescens. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:613-22. [PMID: 7925378 DOI: 10.1111/j.1432-1033.1994.00613.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The single-stranded-DNA-binding (SSB) proteins from Proteus mirabilis and Serratia marcescens were purified from overproducing Escherichia coli strains, which were devoid of their own ssb gene. The strains harboured an endA insertion mutation and a xonA mutation resulting in the absence of endonuclease I and exonuclease I activities from the preparations. The amino acid sequences of the SSB of all three species are nearly identical in the N-terminal parts of the proteins that contain the DNA-binding domain, but differ in the C-terminal parts. Both proteins have an apparent binding-site size of 65 and 35 nucleotides at high and low salt concentrations, respectively. The association-rate constant for binding to poly(dT) is 3.2 x 10(8) M-1 s-1 for P. mirabilis SSB (PmiSSB) and 3.4 x 10(8) M-1 s-1 for S. marcescens SSB (SmaSSB). These binding parameters are very similar to those of E. coli SSB (EcoSSB). The structural similarity of the proteins is also documented by the finding that they can exchange subunits among each other to form mixed tetramers. The transcriptional regulation of the ssb and uvrA genes from P. mirabilis and S. marcescens in SOS-induced E. coli cells was studied using lacZ fusions. While the uvrA genes were inducible, there was no induction of the ssb genes transcribed divergently from the uvrA genes. Apparently, regions with nucleotide sequence similarity to the E. coli SOS-box preceding the ssb genes of P. mirabilis and S. marcescens had no gross effect on the transcription. Studies on growth of the cells and recovery from ultraviolet damage indicate that the heterologous SSB proteins support DNA replication and recombinational DNA repair of E. coli with the same efficiency as the E. coli SSB protein. Interactions with other E. coli proteins involved in these processes either do not occur, or are not impeded.
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Affiliation(s)
- J De Vries
- Genetik, Fachbereich Biologie, Universität Oldenburg, Germany
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27
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Jarosik GP, Hansen EJ. Cloning and sequencing of the Haemophilus influenzae ssb gene encoding single-strand DNA-binding protein. Gene 1994; 146:101-3. [PMID: 8063092 DOI: 10.1016/0378-1119(94)90841-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ssb gene of Haemophilus influenzae was cloned and sequenced. The deduced protein possessed 61 and 60% identity with the Serratia marcescens and Escherichia coli SSB proteins, respectively. H. influenzae ssb was also shown to complement an E. coli ssb-1 mutation.
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Affiliation(s)
- G P Jarosik
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas 75235-9048
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28
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Frost LS, Ippen-Ihler K, Skurray RA. Analysis of the sequence and gene products of the transfer region of the F sex factor. Microbiol Rev 1994; 58:162-210. [PMID: 7915817 PMCID: PMC372961 DOI: 10.1128/mr.58.2.162-210.1994] [Citation(s) in RCA: 274] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bacterial conjugation results in the transfer of DNA of either plasmid or chromosomal origin between microorganisms. Transfer begins at a defined point in the DNA sequence, usually called the origin of transfer (oriT). The capacity of conjugative DNA transfer is a property of self-transmissible plasmids and conjugative transposons, which will mobilize other plasmids and DNA sequences that include a compatible oriT locus. This review will concentrate on the genes required for bacterial conjugation that are encoded within the transfer region (or regions) of conjugative plasmids. One of the best-defined conjugation systems is that of the F plasmid, which has been the paradigm for conjugation systems since it was discovered nearly 50 years ago. The F transfer region (over 33 kb) contains about 40 genes, arranged contiguously. These are involved in the synthesis of pili, extracellular filaments which establish contact between donor and recipient cells; mating-pair stabilization; prevention of mating between similar donor cells in a process termed surface exclusions; DNA nicking and transfer during conjugation; and the regulation of expression of these functions. This review is a compendium of the products and other features found in the F transfer region as well as a discussion of their role in conjugation. While the genetics of F transfer have been described extensively, the mechanism of conjugation has proved elusive, in large part because of the low levels of expression of the pilus and the numerous envelope components essential for F plasmid transfer. The advent of molecular genetic techniques has, however, resulted in considerable recent progress. This summary of the known properties of the F transfer region is provided in the hope that it will form a useful basis for future comparison with other conjugation systems.
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Affiliation(s)
- L S Frost
- Department of Microbiology, University of Alberta, Edmonton, Canada
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29
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Firth N, Ridgway KP, Byrne ME, Fink PD, Johnson L, Paulsen IT, Skurray RA. Analysis of a transfer region from the staphylococcal conjugative plasmid pSK41. Gene X 1993; 136:13-25. [PMID: 8293996 DOI: 10.1016/0378-1119(93)90442-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The nucleotide sequence of a 14.4-kb region (tra) associated with DNA transfer of the staphylococcal conjugative plasmid, pSK41, has been determined. Analysis of the sequence revealed the presence of 15 genes potentially involved in the conjugative process. Polypeptide products likely to correspond to ten of these genes have been identified, of which one was found to be a lipoprotein. Comparison of the deduced tra products to the protein databases revealed several interesting similarities, one of which suggests an evolutionary link between this Gram+ bacterial conjugation system and DNA transfer systems of Gram- bacteria, such as Escherichia coli and Agrobacterium tumefaciens. The nt sequence also provided an insight into the transcriptional organisation and regulation of the region.
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Affiliation(s)
- N Firth
- School of Biological Sciences, University of Sydney, NSW, Australia
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30
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de Vries J, Wackernagel W. Cloning and sequencing of the Serratia marcescens gene encoding a single-stranded DNA-binding protein (SSB) and its promoter region. Gene X 1993; 127:39-45. [PMID: 8486286 DOI: 10.1016/0378-1119(93)90614-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The gene (ssb) coding for a single-stranded DNA-binding protein (SSB) was identified on a 1.2-kb EcoRI-SalI fragment cloned from chromosomal DNA of Serratia marcescens. The cloned fragment conferred increased resistance against UV and mitomycin C (MC) to ssb- mutants of Escherichia coli. The nucleotide (nt) sequence revealed that SSB consists of 175 amino acids (aa) and has an M(r) of 18,677. It shows 89% aa sequence homology with the SSB of E. coli. The nt sequence preceding the gene contains three promoters. Two of them overlap with a presumptive SOS box, and the distal one overlaps with a second SOS box that coincides with the promoter of the adjacent uvrA (gene encoding the UvrA protein). The uvrA is transcribed in a direction opposite to that of ssb. The sequence coding for the N terminus of the UvrA of S. marcescens indicates that the first 74 aa are identical to those of the E. coli protein. The results suggest that the two bacterial SSBs are members of a group which differs from the known SSBs of prokaryotic transmissible plasmids, because their aa sequence homology with these proteins is only about 60%.
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Affiliation(s)
- J de Vries
- Fachbereich Biologie, Universität Oldenburg, Germany
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31
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Belogurov AA, Delver EP, Rodzevich OV. IncN plasmid pKM101 and IncI1 plasmid ColIb-P9 encode homologous antirestriction proteins in their leading regions. J Bacteriol 1992; 174:5079-85. [PMID: 1321121 PMCID: PMC206324 DOI: 10.1128/jb.174.15.5079-5085.1992] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The IncN plasmid pKM101 (a derivative of R46), like the IncI1 plasmid ColIb-P9, carries a gene (ardA, for alleviation of restriction of DNA) encoding an antirestriction function. ardA was located about 4 kb from the origin of transfer, in the region transferred early during bacterial conjugation. The nucleotide sequence of ardA was determined, and an appropriate polypeptide with the predicted molecular weight of about 19,500 was identified in maxicells of Escherichia coli. Comparison of the deduced amino acid sequences of the antirestriction proteins of the unrelated plasmids pKM101 and ColIb (ArdA and Ard, respectively) revealed that these proteins have about 60% identity. Like ColIb Ard, pKM101 ArdA specifically inhibits both the restriction and modification activities of five type I systems of E. coli tested and does not influence type III (EcoP1) restriction or the 5-methylcytosine-specific restriction systems McrA and McrB. However, in contrast to ColIb Ard, pKM101 ArdA is effective against the type II enzyme EcoRI. The Ard proteins are believed to overcome the host restriction barrier during bacterial conjugation. We have also identified two other genes of pKM101, ardR and ardK, which seem to control ardA activity and ardA-mediated lethality, respectively. Our findings suggest that ardR may serve as a genetic switch that determines whether the ardA-encoded antirestriction function is induced during mating.
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Affiliation(s)
- A A Belogurov
- Department of Genetic Engineering, National Cardiology Research Center, Moscow, Russia
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32
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Jovanovic OS, Ayres EK, Figurski DH. The replication initiator operon of promiscuous plasmid RK2 encodes a gene that complements an Escherichia coli mutant defective in single-stranded DNA-binding protein. J Bacteriol 1992; 174:4842-6. [PMID: 1624472 PMCID: PMC206285 DOI: 10.1128/jb.174.14.4842-4846.1992] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The amino acid sequence of the 13-kDa polypeptide (P116) encoded by the first gene of the trfA operon of IncP plasmid RK2 shows significant similarity to several known single-stranded DNA-binding proteins. We found that unregulated expression of this gene from its natural promoter (trfAp) or induced expression from a strong heterologous promoter (trcp) was sufficient to complement the temperature-sensitive growth phenotype of an Escherichia coli ssb-1 mutant. The RK2 ssb gene is the first example of a plasmid single-stranded DNA-binding protein-encoding gene that is coregulated with replication functions, indicating a possible role in plasmid replication.
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Affiliation(s)
- O S Jovanovic
- Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032
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33
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Read TD, Thomas AT, Wilkins BM. Evasion of type I and type II DNA restriction systems by IncI1 plasmid CoIIb-P9 during transfer by bacterial conjugation. Mol Microbiol 1992; 6:1933-41. [PMID: 1508042 DOI: 10.1111/j.1365-2958.1992.tb01366.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transmission of unmodified plasmid CoIIb-P9 by bacterial conjugation is markedly resistant to restriction compared with transfer by transformation. One process allowing evasion of type I and II restriction systems involves conjugative transfer of multiple copies of the plasmid. A more specialized evasion mechanism requires the Ard (alleviation of restriction of DNA) system encoded by CoIIb. The ard gene is transferred early in conjugation and specifically alleviates DNA restriction by all known families of type I enzyme, including EcoK. CoIIb has no effect on EcoK modification but this activity is impaired by multicopy recombinant plasmids supporting overexpression of ard. Genetic evidence shows that Ard protects CoIIb from EcoK restriction following conjugative transfer and that this protection requires expression of the gene on the immigrant plasmid. It is proposed that carriage of ard facilitates transfer of CoIIb between its natural enterobacterial hosts and that the route of DNA entry is important to the restriction-evasion mechanism.
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Affiliation(s)
- T D Read
- Department of Genetics, University of Leicester, UK
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34
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Bagdasarian M, Bailone A, Angulo JF, Scholz P, Bagdasarian M, Devoret R. PsiB, and anti-SOS protein, is transiently expressed by the F sex factor during its transmission to an Escherichia coli K-12 recipient. Mol Microbiol 1992; 6:885-93. [PMID: 1318487 DOI: 10.1111/j.1365-2958.1992.tb01539.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
PsiB, an anti-SOS protein, shown previously to prevent activation of RecA protein, was purified from the crude extract of PsiB overproducing cells. PsiB is probably a tetrameric protein, whose subunit has a sequence-deduced molecular mass of 15741 daltons. Using an immuno-assay with anti-PsiB antibodies, we have monitored PsiB cell concentrations produced by F and R6-5 plasmids: the latter type produces a detectable level of PsiB protein while the former does not. The discrepancy can be assigned to a Tn10 out-going promoter located upstream of psiB. When we inserted a Tn10 promoter upstream of F psiB, the F PsiB protein concentration reached the level of R6-5 PsiB. We describe here the physiological role that PsiB protein may have in the cell and how it causes an anti-SOS function. We observed that PsiB protein was transiently expressed by a wild-type F sex factor during its transmission to an Escherichia coli K-12 recipient. In an F+ x F- cross, PsiB concentration increased at least 10-fold in F- recipient bacteria after 90 minutes and declined thereafter; the psiB gene may be repressed when F plasmid replicates vegetatively. PsiB protein may be induced zygotically so as to protect F single-stranded DNA transferred upon conjugation. PsiB protein, when overproduced, may interfere with RecA protein at chromosomal single-stranded DNA sites generated by discontinuous DNA replication, thus causing an SOS inhibitory phenotype.
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35
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Barth PT, Bolton L, Thomson JC. Cloning and partial sequencing of an operon encoding two Pseudomonas putida haloalkanoate dehalogenases of opposite stereospecificity. J Bacteriol 1992; 174:2612-9. [PMID: 1556080 PMCID: PMC205901 DOI: 10.1128/jb.174.8.2612-2619.1992] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have cloned fragments of DNA (up to 13 kb), from Pseudomonas putida AJ1, that code for two stereospecific haloalkanoate dehalogenases. These enzymes are highly specific for D and L substrates. The two genes, designated hadD and hadL, have been isolated and independently expressed in Escherichia coli and P. putida hosts by using broad-host-range vectors. They are closely adjacent and inducible in what appears to be an operon with an upstream open reading frame of unknown function. Nucleotide sequence determination of hadD predicts a mature, cytoplasmic protein of 300 amino acid residues (molecular weight of 33,601). This has no significant homology with the L-specific haloalkanoate dehalogenases from Pseudomonas sp. strain CBS3 (B. Schneider, R. Muller, R. Frank, and F. Lingens, J. Bacteriol. 173:1530-1535, 1991) nor with any other known DNA or protein sequences.
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Affiliation(s)
- P T Barth
- Biotechnology Department, ICI Pharmaceuticals, Macclesfield, Cheshire, United Kingdom
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36
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Jones AL, Barth PT, Wilkins BM. Zygotic induction of plasmid ssb and psiB genes following conjugative transfer of Incl1 plasmid Collb-P9. Mol Microbiol 1992; 6:605-13. [PMID: 1552860 DOI: 10.1111/j.1365-2958.1992.tb01507.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Incl1 conjugative plasmid Collb-P9 carries a psiB gene that prevents induction of the SOS response in host bacteria. This locus is located 2.5 kb downstream of the ssb (single-stranded DNA-binding protein) gene in the leading region. This portion of Collb is strikingly similar to part of the leading region of the otherwise distinct F plasmid. Expression of psiB and ssb is increased when the host cell is exposed to an SOS-inducing treatment or the Collb transfer system is derepressed. Moreover, expression of both genes on a derepressed plasmid is strongly enhanced in conjugatively infected recipient cells. Carriage of the psiB gene by Collb is shown to prevent a low level of SOS induction following conjugation. Plasmid ssb and psiB genes may function to promote installation of the replicon in the new cell.
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Affiliation(s)
- A L Jones
- Department of Genetics, University of Leicester, UK
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37
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Delver EP, Kotova VU, Zavilgelsky GB, Belogurov AA. Nucleotide sequence of the gene (ard) encoding the antirestriction protein of plasmid colIb-P9. J Bacteriol 1991; 173:5887-92. [PMID: 1653225 PMCID: PMC208323 DOI: 10.1128/jb.173.18.5887-5892.1991] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The IncI1 plasmid ColIb-P9 was found to encode an antirestriction function. The relevant gene, ard (alleviation of restriction of DNA), maps about 5 kb from the origin of transfer, in the region transferred early during bacterial conjugation. Ard inhibits both restriction and modification by each of the four type I systems of Escherichia coli tested, but it had no effect on restriction by either EcoRI, a type II system, or EcoP1, a type III system. The nucleotide sequence of the ColIb ard gene was determined; the predicted molecular weight of the Ard polypeptide is 19,193. The proposed polypeptide chain contains an excess of 25 negatively charged amino acids, suggesting that its overall character is very acidic. Deletion analysis of the gene revealed that the Ard protein contained a distinct functional domain located in the COOH-terminal half of the polypeptide. We suggest that the biological role of the ColIb Ard protein is associated with overcoming host-controlled restriction during bacterial conjugation.
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Affiliation(s)
- E P Delver
- Department of Biotechnology, USSR Cardiology Research Center, Moscow
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38
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Hill PJ, Swift S, Stewart GS. PCR based gene engineering of the Vibrio harveyi lux operon and the Escherichia coli trp operon provides for biochemically functional native and fused gene products. MOLECULAR & GENERAL GENETICS : MGG 1991; 226:41-8. [PMID: 2034229 DOI: 10.1007/bf00273585] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The polymerase chain reaction (PCR) was applied to clone the luxA and luxB genes from Vibrio harveyi, and the trp poL (promoter operator leader) region and the trpB and trpA genes from Escherichia coli. PCR-derived luxA/B and trpB/A genes were shown to express bacterial luciferase and tryptophan synthase respectively, when introduced into E. coli on a plasmid cloning vehicle. The trp poL was used successfully to control the expression of lac alpha, luxAB, trpB and trpA. PCR was also used to construct a functional luxAB translational fusion protein. Primers for this were designed to facilitate precise gene fusion and to provide a silent mutation within an EcoRI site in the luxB gene. Production of functional genes was verified in vitro and in vivo using polyacrylamide gel electrophoresis (PAGE) analysis of transcription-translation products and crude cell extracts, and by monitoring enzyme activity.
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Affiliation(s)
- P J Hill
- Department of Applied Biochemistry and Food Science, University of Nottingham School of Agriculture, Sutton Bonington, Leicestershire, UK
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39
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Porter RD, Black S. The single-stranded-DNA-binding protein encoded by the Escherichia coli F factor can complement a deletion of the chromosomal ssb gene. J Bacteriol 1991; 173:2720-3. [PMID: 2013585 PMCID: PMC207845 DOI: 10.1128/jb.173.8.2720-2723.1991] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Genes encoding single-stranded-DNA-binding proteins (SSBs) are carried by a variety of large self-transmissible plasmids, and it previously has been shown that these plasmid-borne genes can complement conditional lethal alleles of the ssb gene on the Escherichia coli chromosome for cellular viability. We have tested one of the plasmid-borne ssb genes, the ssf gene from the E. coli F factor, for its ability to complement total deletion of the chromosomal ssb gene for viability. We have found that ssf can complement the ssb deletion, but only when it is present on a high-copy-number plasmid. Cells that are totally dependent on the F-factor-encoded SSB for viability manifest growth properties indicative of problems in DNA replication.
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Affiliation(s)
- R D Porter
- Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802
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40
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Ruvolo PP, Keating KM, Williams KR, Chase JW. Single-stranded DNA binding proteins (SSBs) from prokaryotic transmissible plasmids. Proteins 1991; 9:120-34. [PMID: 2008432 DOI: 10.1002/prot.340090206] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The DNA and protein sequences of single-stranded DNA binding proteins (SSBs) encoded by the plP71a, plP231a, and R64 conjugative plasmids have been determined and compared to Escherichia coli SSB and the SSB encoded by F-plasmid. Although the amino acid sequences of all of these proteins are highly conserved within the NH2-terminal two-thirds of the protein, they diverge in the COOH-terminal third region. A number of amino acid residues which have previously been implicated as being either directly or indirectly involved in DNA binding are conserved in all of these SSBs. These residues include Trp-40, Trp-54, Trp-88, His-55, and Phe-60. On the basis of these sequence comparisons and DNA binding studies, a role for Tyr-70 in DNA binding is suggested for the first time. Although the COOH-terminal third of these proteins diverges more than their NH2-terminal regions, the COOH-terminal five amino acid residues of all five of these proteins are identical. In addition, all of these proteins share the characteristic property of having a protease resistant, NH2-terminal core and an acidic COOH-terminal region. Despite the high degree of sequence homology among the plasmid SSB proteins, the F-plasmid SSB appears unique in that it was the only SSB tested that neither bound well to poly(dA) nor was able to stimulate DNA polymerase III holoenzyme elongation rates. Poly [d(A-T)] melting studies suggest that at least three of the plasmid encoded SSBs are better helix-destabilizing proteins than is the E. coli SSB protein.
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Affiliation(s)
- P P Ruvolo
- Department of Molecular Biology and Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
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41
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Rees CE, Wilkins BM. Protein transfer into the recipient cell during bacterial conjugation: studies with F and RP4. Mol Microbiol 1990; 4:1199-205. [PMID: 2172695 DOI: 10.1111/j.1365-2958.1990.tb00695.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Transfer of donor cell proteins to the recipient bacterium was examined in F- and RP4-mediated conjugation. Transfer of a 120 kD polypeptide, identified as the larger product of the plasmid DNA primase gene, was readily detected during RP4-promoted conjugation. The protein was transmitted to the cytoplasm of the recipient, presumably complexed to the transferred ssDNA. F DNA was transferred without detectable association with any cytoplasmic tra protein or with the ssDNA-binding protein encoded by the plasmid. However, a 92 kD protein, possibly F TraD product, was transmitted to the membrane fraction of the recipient cell.
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Affiliation(s)
- C E Rees
- Department of Genetics, University of Leicester, UK
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42
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Horváth A, Maslov DA, Kolesnikov AA. The nucleotide sequence of the 12S ribosomal RNA gene from kinetoplast DNA of the protozoan Crithidia oncopelti. Nucleic Acids Res 1990; 18:2811. [PMID: 2160071 PMCID: PMC330771 DOI: 10.1093/nar/18.9.2811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- A Horváth
- Department of Molecular Biology, Faculty of Biology, M.V. Lomonosov State University, Moscow, USSR
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43
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Thomas CM, Sherlock S. Broad host range plasmid RK2 encodes a polypeptide related to single-stranded DNA binding protein (SSB) of Escherichia coli. Nucleic Acids Res 1990; 18:2812. [PMID: 2187181 PMCID: PMC330772 DOI: 10.1093/nar/18.9.2812] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- C M Thomas
- School of Biological Sciences, University of Birmingham, UK
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44
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Abstract
Plasmid RP4 is stably maintained in strains of Escherichia coli and other Gram-negative bacteria. Inactivation of the plasmid primase gene (pri) or removal of the PstIC fragment gave RP4 derivatives that are slightly unstably maintained in E. coli. Removal of the Tn 1 multimer resolution system (res and tnpR) did not lead to any detectable plasmid loss. Removal of all three of these regions, however, gave rise to pNJ5000 which is lost at high frequency. We have dissected the mechanisms causing this phenomenon. In contrast to RP4, pNJ5000 accumulates significantly as plasmid multimers in a Rec+ host; in a recA host, multimers are not seen and the plasmid is stably maintained. Multimers therefore appear to form by recA-mediated homologous recombination and cause plasmid instability, perhaps by interfering with partition. We demonstrate a mechanism provided by the PstIC fragment which acts on multimers analogously to the Tn1/3 resolution system on plasmid cointegrates, being effective only when cloned in cis. The loss of pri, on the other hand, can be complemented in trans. Our results are consistent with the view that primase prevents multimers forming (rather than resolving them once formed), perhaps by binding specifically to single-stranded regions of the plasmid and preventing homologous pairing.
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Affiliation(s)
- N J Grinter
- Department of Biochemistry and Soil Science, University College of North Wales, Bangor, Gwynedd, United Kingdom
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45
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Rees CE, Wilkins BM. Transfer of tra proteins into the recipient cell during bacterial conjugation mediated by plasmid ColIb-P9. J Bacteriol 1989; 171:3152-7. [PMID: 2656642 PMCID: PMC210029 DOI: 10.1128/jb.171.6.3152-3157.1989] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Selective transfer of the two products of the ColIb primase gene, sog, from donor to recipient cell during conjugation was demonstrated by two independent methods. The transfer of these tra proteins was unidirectional and dependent on DNA transfer. The Sog polypeptides were localized to the cytoplasm of the donor cell, but they appeared to interact with other tra gene products located in the inner membrane. After cell mating, the transferred polypeptides were found to be in the cytoplasm of the recipient cell, and it is estimated that as many as 500 Sog polypeptides were transferred per round of conjugation. It is proposed that these proteins are transferred as a result of an interaction with the single-stranded DNA and that the transferred strand may be coated with Sog polypeptides.
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Affiliation(s)
- C E Rees
- Department of Genetics, University of Leicester, England
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