1
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Ortiz Charneco G, McDonnell B, Kelleher P, Buivydas A, Dashko S, de Waal PP, van Rijswijck I, van Peij NNME, Mahony J, Van Sinderen D. Plasmid-mediated horizontal gene mobilisation: Insights from two lactococcal conjugative plasmids. Microb Biotechnol 2024; 17:e14421. [PMID: 38752994 PMCID: PMC11097999 DOI: 10.1111/1751-7915.14421] [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: 10/31/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 05/18/2024] Open
Abstract
The distinct conjugation machineries encoded by plasmids pNP40 and pUC11B represent the most prevalent plasmid transfer systems among lactococcal strains. In the current study, we identified genetic determinants that underpin pNP40- and pUC11B-mediated, high-frequency mobilisation of other, non-conjugative plasmids. The mobilisation frequencies of the smaller, non-conjugative plasmids and the minimal sequences required for their mobilisation were determined, owing to the determination of the oriT sequences of both pNP40 and pUC11B, which allowed the identification of similar sequences in some of the non-conjugative plasmids that were shown to promote their mobilisation. Furthermore, the auxiliary gene mobC, two distinct functional homologues of which are present in several plasmids harboured by the pNP40- and pUC11B-carrying host strains, was observed to confer a high-frequency mobilisation phenotype. These findings provide mechanistic insights into how lactococcal conjugative plasmids achieve conjugation and promote mobilisation of non-conjugative plasmids. Ultimately, these insights would be harnessed to optimise conjugation and mobilisation strategies for the rapid and predictable development of robust and technologically improved strains.
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Affiliation(s)
| | - Brian McDonnell
- School of Microbiology & APC Microbiome IrelandUniversity College CorkCorkIreland
| | - Philip Kelleher
- School of Microbiology & APC Microbiome IrelandUniversity College CorkCorkIreland
| | - Andrius Buivydas
- School of Microbiology & APC Microbiome IrelandUniversity College CorkCorkIreland
| | - Sofia Dashko
- dsm‐firmenich, Taste, Texture & Health, Center for Food InnovationDelftThe Netherlands
| | - Paul P. de Waal
- dsm‐firmenich, Taste, Texture & Health, Center for Food InnovationDelftThe Netherlands
| | - Irma van Rijswijck
- dsm‐firmenich, Taste, Texture & Health, Center for Food InnovationDelftThe Netherlands
| | | | - Jennifer Mahony
- School of Microbiology & APC Microbiome IrelandUniversity College CorkCorkIreland
| | - Douwe Van Sinderen
- School of Microbiology & APC Microbiome IrelandUniversity College CorkCorkIreland
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2
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Hinnekens P, Fayad N, Gillis A, Mahillon J. Conjugation across Bacillus cereus and kin: A review. Front Microbiol 2022; 13:1034440. [PMID: 36406448 PMCID: PMC9673590 DOI: 10.3389/fmicb.2022.1034440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
Horizontal gene transfer (HGT) is a major driving force in shaping bacterial communities. Key elements responsible for HGT are conjugation-like events and transmissible plasmids. Conjugative plasmids can promote their own transfer as well as that of co-resident plasmids. Bacillus cereus and relatives harbor a plethora of plasmids, including conjugative plasmids, which are at the heart of the group species differentiation and specification. Since the first report of a conjugation-like event between strains of B. cereus sensu lato (s.l.) 40 years ago, many have studied the potential of plasmid transfer across the group, especially for plasmids encoding major toxins. Over the years, more than 20 plasmids from B. cereus isolates have been reported as conjugative. However, with the increasing number of genomic data available, in silico analyses indicate that more plasmids from B. cereus s.l. genomes present self-transfer potential. B. cereus s.l. bacteria occupy diverse environmental niches, which were mimicked in laboratory conditions to study conjugation-related mechanisms. Laboratory mating conditions remain nonetheless simplistic compared to the complex interactions occurring in natural environments. Given the health, economic and ecological importance of strains of B. cereus s.l., it is of prime importance to consider the impact of conjugation within this bacterial group.
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Affiliation(s)
- Pauline Hinnekens
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
| | - Nancy Fayad
- Multi-Omics Laboratory, School of Pharmacy, Lebanese American University, Byblos, Lebanon
| | - Annika Gillis
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
| | - Jacques Mahillon
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
- *Correspondence: Jacques Mahillon,
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3
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Smits WK, Roseboom AM, Corver J. Plasmids of Clostridioides difficile. Curr Opin Microbiol 2021; 65:87-94. [PMID: 34775173 DOI: 10.1016/j.mib.2021.10.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/20/2021] [Accepted: 10/23/2021] [Indexed: 12/16/2022]
Abstract
Plasmids are ubiquitous in the bacterial world. In many microorganisms, plasmids have been implicated in important aspects of bacterial physiology and contribute to horizontal gene transfer. In contrast, knowledge on plasmids of the enteropathogen Clostridioides difficile is limited, and there appears to be no phenotypic consequence to carriage of many of the identified plasmids. Emerging evidence suggests, however, that plasmids are common in C. difficile and may encode functions relevant to pathogenesis, such as antimicrobial resistance and toxin production. Here, we review our current knowledge about the abundance, functions and clinical relevance of plasmids in C. difficile.
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Affiliation(s)
- Wiep Klaas Smits
- Experimental Bacteriology Group, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands; Centre for Microbial Cell Biology, Leiden, The Netherlands; Leiden University Center for Infectious Diseases (LU-CID), Leiden, The Netherlands.
| | - Anna Maria Roseboom
- Experimental Bacteriology Group, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jeroen Corver
- Experimental Bacteriology Group, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands; Centre for Microbial Cell Biology, Leiden, The Netherlands; Leiden University Center for Infectious Diseases (LU-CID), Leiden, The Netherlands
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4
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Solano-Collado V, Ruiz-Cruz S, Lorenzo-Díaz F, Pluta R, Espinosa M, Bravo A. Recognition of Streptococcal Promoters by the Pneumococcal SigA Protein. Front Mol Biosci 2021; 8:666504. [PMID: 34250014 PMCID: PMC8264293 DOI: 10.3389/fmolb.2021.666504] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
Promoter recognition by RNA polymerase is a key step in the regulation of gene expression. The bacterial RNA polymerase core enzyme is a complex of five subunits that interacts transitory with one of a set of sigma factors forming the RNA polymerase holoenzyme. The sigma factor confers promoter specificity to the RNA polymerase. In the Gram-positive pathogenic bacterium Streptococcus pneumoniae, most promoters are likely recognized by SigA, a poorly studied housekeeping sigma factor. Here we present a sequence conservation analysis and show that SigA has similar protein architecture to Escherichia coli and Bacillus subtilis homologs, namely the poorly conserved N-terminal 100 residues and well-conserved rest of the protein (domains 2, 3, and 4). Further, we have purified the native (untagged) SigA protein encoded by the pneumococcal R6 strain and reconstituted an RNA polymerase holoenzyme composed of the E. coli core enzyme and the sigma factor SigA (RNAP-SigA). By in vitro transcription, we have found that RNAP-SigA was able to recognize particular promoters, not only from the pneumococcal chromosome but also from the S. agalactiae promiscuous antibiotic-resistance plasmid pMV158. Specifically, SigA was able to direct the RNA polymerase to transcribe genes involved in replication and conjugative mobilization of plasmid pMV158. Our results point to the versatility of SigA in promoter recognition and its contribution to the promiscuity of plasmid pMV158.
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Affiliation(s)
| | - Sofía Ruiz-Cruz
- School of Microbiology, University College Cork, Cork, Ireland
| | - Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Tenerife, Spain
| | - Radoslaw Pluta
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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5
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Singh PK, Serrano E, Ramachandran G, Miguel-Arribas A, Gago-Cordoba C, Val-Calvo J, López-Pérez A, Alfonso C, Wu LJ, Luque-Ortega JR, Meijer WJJ. Reversible regulation of conjugation of Bacillus subtilis plasmid pLS20 by the quorum sensing peptide responsive anti-repressor RappLS20. Nucleic Acids Res 2020; 48:10785-10801. [PMID: 33045732 PMCID: PMC7641744 DOI: 10.1093/nar/gkaa797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/02/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022] Open
Abstract
Quorum sensing plays crucial roles in bacterial communication including in the process of conjugation, which has large economical and health-related impacts by spreading antibiotic resistance. The conjugative Bacillus subtilis plasmid pLS20 uses quorum sensing to determine when to activate the conjugation genes. The main conjugation promoter, Pc, is by default repressed by a regulator RcopLS20 involving DNA looping. A plasmid-encoded signalling peptide, Phr*pLS20, inactivates the anti-repressor of RcopLS20, named RappLS20, which belongs to the large group of RRNPP family of regulatory proteins. Here we show that DNA looping occurs through interactions between two RcopLS20 tetramers, each bound to an operator site. We determined the relative promoter strengths for all the promoters involved in synthesizing the regulatory proteins of the conjugation genes, and constructed an in vivo system uncoupling these regulatory genes to show that RappLS20 is sufficient for activating conjugation in vivo. We also show that RappLS20 actively detaches RcopLS20 from DNA by preferentially acting on the RcopLS20 molecules involved in DNA looping, resulting in sequestration but not inactivation of RcopLS20. Finally, results presented here in combination with our previous results show that activation of conjugation inhibits competence and competence development inhibits conjugation, indicating that both processes are mutually exclusive.
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Affiliation(s)
- Praveen K Singh
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Ester Serrano
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Gayetri Ramachandran
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Andrés Miguel-Arribas
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - César Gago-Cordoba
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Jorge Val-Calvo
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Arancha López-Pérez
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas Margarita Salas (CSIC), C. Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Juan R Luque-Ortega
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas (CSIC), C. Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Wilfried J J Meijer
- Centro de Biología Molecular “Severo Ochoa’’ (CSIC-UAM), C. Nicolás Cabrera 1, Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
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6
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Kohler V, Keller W, Grohmann E. Regulation of Gram-Positive Conjugation. Front Microbiol 2019; 10:1134. [PMID: 31191478 PMCID: PMC6540685 DOI: 10.3389/fmicb.2019.01134] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/03/2019] [Indexed: 12/20/2022] Open
Abstract
Type IV Secretion Systems (T4SSs) are membrane-spanning multiprotein complexes dedicated to protein secretion or conjugative DNA transport (conjugation systems) in bacteria. The prototype and best-characterized T4SS is that of the Gram-negative soil bacterium Agrobacterium tumefaciens. For Gram-positive bacteria, only conjugative T4SSs have been characterized in some biochemical, structural, and mechanistic details. These conjugation systems are predominantly encoded by self-transmissible plasmids but are also increasingly detected on integrative and conjugative elements (ICEs) and transposons. Here, we report regulatory details of conjugation systems from Enterococcus model plasmids pIP501 and pCF10, Bacillus plasmid pLS1, Clostridium plasmid pCW3, and staphylococcal plasmid pSK41. In addition, regulation of conjugative processes of ICEs (ICEBs1, ICESt1, ICESt3) by master regulators belonging to diverse repressor families will be discussed. A special focus of this review lies on the comparison of regulatory mechanisms executed by proteins belonging to the RRNPP family. These regulators share a common fold and govern several essential bacterial processes, including conjugative transfer.
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Affiliation(s)
- Verena Kohler
- Institute of Molecular Biosciences, BioTechMed Graz, University of Graz, Graz, Austria
| | - Walter Keller
- Institute of Molecular Biosciences, BioTechMed Graz, University of Graz, Graz, Austria
| | - Elisabeth Grohmann
- Life Sciences and Technology, Beuth University of Applied Sciences Berlin, Berlin, Germany
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7
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Pluta R, Espinosa M. Antisense and yet sensitive: Copy number control of rolling circle-replicating plasmids by small RNAs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1500. [PMID: 30074293 DOI: 10.1002/wrna.1500] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/27/2018] [Accepted: 07/01/2018] [Indexed: 12/27/2022]
Abstract
Bacterial plasmids constitute a wealth of shared DNA amounting to about 20% of the total prokaryotic pangenome. Plasmids replicate autonomously and control their replication by maintaining a fairly constant number of copies within a given host. Plasmids should acquire a good fitness to their hosts so that they do not constitute a genetic load. Here we review some basic concepts in plasmid biology, pertaining to the control of replication and distribution of plasmid copies among daughter cells. A particular class of plasmids is constituted by those that replicate by the rolling circle mode (rolling circle-replicating [RCR]-plasmids). They are small double-stranded DNA molecules, with a rather high number of copies in the original host. RCR-plasmids control their replication by means of a small short-lived antisense RNA, alone or in combination with a plasmid-encoded transcriptional repressor protein. Two plasmid prototypes have been studied in depth, namely the staphylococcal plasmid pT181 and the streptococcal plasmid pMV158, each corresponding to the two types of replication control circuits, respectively. We further discuss possible applications of the plasmid-encoded antisense RNAs and address some future directions that, in our opinion, should be pursued in the study of these small molecules. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Radoslaw Pluta
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, Madrid, Spain
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8
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Lorenzo-Díaz F, Fernández-López C, Guillén-Guío B, Bravo A, Espinosa M. Relaxase MobM Induces a Molecular Switch at Its Cognate Origin of Transfer. Front Mol Biosci 2018; 5:17. [PMID: 29600250 PMCID: PMC5863519 DOI: 10.3389/fmolb.2018.00017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/09/2018] [Indexed: 11/13/2022] Open
Abstract
The MOBV1 family of relaxases is broadly distributed in plasmids and other mobile genetic elements isolated from staphylococci, enterococci, and streptococci. The prototype of this family is protein MobM encoded by the streptococcal promiscuous plasmid pMV158. MobM cleaves the phosphodiester bond of a specific dinucleotide within the origin of transfer (oriT) to initiate conjugative transfer. Differently from other relaxases, MobM and probably other members of the family, cleaves its target single-stranded DNA through a histidine residue rather than the commonly used tyrosine. The oriT of the MOBV1 family differs from other well-known conjugative systems since it has sequences with three inverted repeats, which were predicted to generate three mutually-exclusive hairpins on supercoiled DNA. In this work, such hypothesis was evaluated through footprinting experiments on supercoiled plasmid DNA. We have found a change in hairpin extrusion mediated by protein MobM. This conformational change involves a shift from the main hairpin generated on “naked” DNA to a different hairpin in which the nick site is positioned in a single-stranded configuration. Our results indicate that the oriTpMV158 acts as a molecular switch in which, depending on the inverted repeat recognized by MobM, pMV158 mobilization could be turned “on” or “off.”
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.,Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | | | - Beatriz Guillén-Guío
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.,Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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9
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Lorenzo-Diaz F, Fernández-Lopez C, Douarre PE, Baez-Ortega A, Flores C, Glaser P, Espinosa M. Streptococcal group B integrative and mobilizable element IMESag-rpsI encodes a functional relaxase involved in its transfer. Open Biol 2017; 6:rsob.160084. [PMID: 27707895 PMCID: PMC5090054 DOI: 10.1098/rsob.160084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 09/12/2016] [Indexed: 12/13/2022] Open
Abstract
Streptococcus agalactiae or Group B Streptococcus (GBS) are opportunistic bacteria that can cause lethal sepsis in children and immuno-compromised patients. Their genome is a reservoir of mobile genetic elements that can be horizontally transferred. Among them, integrative and conjugative elements (ICEs) and the smaller integrative and mobilizable elements (IMEs) primarily reside in the bacterial chromosome, yet have the ability to be transferred between cells by conjugation. ICEs and IMEs are therefore a source of genetic variability that participates in the spread of antibiotic resistance. Although IMEs seem to be the most prevalent class of elements transferable by conjugation, they are poorly known. Here, we have studied a GBS-IME, termed IMESag-rpsI, which is widely distributed in GBS despite not carrying any apparent virulence trait. Analyses of 240 whole genomes showed that IMESag-rpsI is present in approximately 47% of the genomes, has a roughly constant size (approx. 9 kb) and is always integrated at a single location, the 3′-end of the gene encoding the ribosomal protein S9 (rpsI). Based on their genetic variation, several IMESag-rpsI types were defined (A–J) and classified in clonal complexes (CCs). CC1 was the most populated by IMESag-rpsI (more than 95%), mostly of type-A (71%). One CC1 strain (S. agalactiae HRC) was deep-sequenced to understand the rationale underlying type-A IMESag-rpsI enrichment in GBS. Thirteen open reading frames were identified, one of them encoding a protein (MobSag) belonging to the broadly distributed family of relaxases MOBV1. Protein MobSag was purified and, by a newly developed method, shown to cleave DNA at a specific dinucleotide. The S. agalactiae HRC-IMESag-rpsI is able to excise from the chromosome, as shown by the presence of circular intermediates, and it harbours a fully functional mobilization module. Further, the mobSag gene encoded by this mobile element is able to promote plasmid transfer among pneumococcal strains, suggesting that MobSag facilitates the spread of IMESag-rpsI and that this spread would explain the presence of the same IMESag-rpsI type in GBS strains belonging to different CCs.
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Affiliation(s)
- Fabian Lorenzo-Diaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez s/n, 38071 Santa Cruz de Tenerife, Spain Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | | | - Pierre-Emmanuel Douarre
- Institut Pasteur, Unité Ecologie et Evolution de la Résistance aux Antibiotiques, Paris CNRS UMR3525, France
| | - Adrian Baez-Ortega
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, UK
| | - Carlos Flores
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Philippe Glaser
- Institut Pasteur, Unité Ecologie et Evolution de la Résistance aux Antibiotiques, Paris CNRS UMR3525, France
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10
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Lorenzo-Díaz F, Fernández-López C, Lurz R, Bravo A, Espinosa M. Crosstalk between vertical and horizontal gene transfer: plasmid replication control by a conjugative relaxase. Nucleic Acids Res 2017; 45:7774-7785. [PMID: 28525572 PMCID: PMC5737340 DOI: 10.1093/nar/gkx450] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/25/2017] [Accepted: 05/09/2017] [Indexed: 01/09/2023] Open
Abstract
Horizontal gene transfer is a key process in the evolution of bacteria and also represents a source of genetic variation in eukaryotes. Among elements participating in gene transfer, thousands of small (<10 kb) mobile bacterial plasmids that replicate by the rolling circle mechanism represent a driving force in the spread of antibiotic resistances. In general, these plasmids are built as genetic modules that encode a replicase, an antibiotic-resistance determinant, and a relaxase that participates in their conjugative mobilization. Further, they control their relatively high copy number (∼30 copies per genome equivalent) by antisense RNAs alone or combined with a repressor protein. We report here that the MobM conjugative relaxase encoded by the promiscuous plasmid pMV158 participates in regulation of the plasmid copy number by transcriptional repression of the antisense RNA, thus increasing the number of plasmid molecules ready to be horizontally transferred (mobilization) and/or vertically inherited (replication). This type of crosstalk between genetic modules involved in vertical and horizontal gene flow has not been reported before.
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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Binding Sites
- Conjugation, Genetic
- DNA Copy Number Variations
- DNA Replication
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Superhelical/chemistry
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- Drug Resistance, Bacterial/genetics
- Endodeoxyribonucleases/genetics
- Endodeoxyribonucleases/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Evolution, Molecular
- Gene Flow
- Gene Transfer, Horizontal
- Microscopy, Electron
- Models, Biological
- Plasmids/genetics
- Promoter Regions, Genetic
- Replicon
- Streptococcus pneumoniae/genetics
- Streptococcus pneumoniae/metabolism
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna. Av. Astrofísico Francisco Sánchez s/n, 38071 Santa Cruz de Tenerife, Spain
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
| | - Cris Fernández-López
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Rudi Lurz
- Max-Plank Institut für molekulare Genetik, Ihnestrasse 63-73, D-14195 Berlin, Germany
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040 Madrid, Spain
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11
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Ramsay JP, Firth N. Diverse mobilization strategies facilitate transfer of non-conjugative mobile genetic elements. Curr Opin Microbiol 2017; 38:1-9. [PMID: 28391142 DOI: 10.1016/j.mib.2017.03.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
Abstract
Conjugation is a dominant mechanism of horizontal gene transfer and substantially contributes to the plasticity and evolvability of prokaryotic genomes. The impact of conjugation on genetic flux extends well beyond self-transmissible conjugative elements, because non-conjugative 'mobilizable elements' utilize other elements' conjugative apparatus for transfer. Bacterial genome comparisons highlight plasmids as vehicles for dissemination of pathogenesis and antimicrobial-resistance determinants, but for most non-conjugative plasmids, a mobilization mechanism is not apparent. Recently we discovered many Staphylococcus aureus plasmids lacking mobilization genes carry oriT sequences that mimic those on conjugative plasmids, suggesting that significantly more elements may be mobilizable than previously recognized. Here we summarize our findings, review the diverse mobilization strategies employed by mobile genetic elements and discuss implications for future gene-transfer research.
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Affiliation(s)
- Joshua P Ramsay
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia.
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
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12
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Lu Y, Zeng J, Wu B, E S, Wang L, Cai R, Zhang N, Li Y, Huang X, Huang B, Chen C. Quorum Sensing N-acyl Homoserine Lactones-SdiA Suppresses Escherichia coli- Pseudomonas aeruginosa Conjugation through Inhibiting traI Expression. Front Cell Infect Microbiol 2017; 7:7. [PMID: 28164039 PMCID: PMC5247672 DOI: 10.3389/fcimb.2017.00007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/05/2017] [Indexed: 01/03/2023] Open
Abstract
Conjugation is a key mechanism for horizontal gene transfer and plays an important role in bacterial evolution, especially with respect to antibiotic resistance. However, little is known about the role of donor and recipient cells in regulation of conjugation. Here, using an Escherichia coli (SM10λπ)-Pseudomonas aeruginosa (PAO1) conjugation model, we demonstrated that deficiency of lasI/rhlI, genes associated with generation of the quorum sensing signals N-acyl homoserine lactones (AHLs) in PAO1, or deletion of the AHLs receptor SdiA in the donor SM10λπ both facilitated conjugation. When using another AHLs-non-producing E. coli strain EC600 as recipient cells, deficiency of sdiA in donor SM10λπ hardly affect the conjugation. More importantly, in the presence of exogenous AHLs, the conjugation efficiency between SM10λπ and EC600 was dramatically decreased, while deficiency of sdiA in SM10λπ attenuated AHLs-inhibited conjugation. These data suggest the conjugation suppression function of AHLs-SdiA chemical signaling. Further bioinformatics analysis, β-galactosidase reporter system and electrophoretic mobility shift assays characterized the binding site of SdiA on the promoter region of traI gene. Furthermore, deletion of lasI/rhlI or sdiA promoted traI mRNA expression in SM10λπ and PAO1 co-culture system, which was abrogated by AHLs. Collectively, our results provide new insight into an important contribution of quorum sensing system AHLs-SdiA to the networks that regulate conjugation.
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Affiliation(s)
- Yang Lu
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou, China; Postdoctoral Mobile Station, Guangzhou University of Chinese MedicineGuangzhou, China
| | - Jianming Zeng
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
| | - Binning Wu
- The Second Clinical College, Guangzhou University of Chinese Medicine Guangzhou, China
| | - Shunmei E
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
| | - Lina Wang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
| | - Renxin Cai
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
| | - Ni Zhang
- Clinical Microbiology Laboratory, Guangdong Academy of Medical Science and Guangdong General Hospital Guangzhou, China
| | - Youqiang Li
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
| | - Xianzhang Huang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou, China; Postdoctoral Mobile Station, Guangzhou University of Chinese MedicineGuangzhou, China
| | - Bin Huang
- Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University Guangzhou, China
| | - Cha Chen
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine Guangzhou, China
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13
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Wright LD, Grossman AD. Autonomous Replication of the Conjugative Transposon Tn916. J Bacteriol 2016; 198:3355-3366. [PMID: 27698087 PMCID: PMC5116939 DOI: 10.1128/jb.00639-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 09/29/2016] [Indexed: 01/14/2023] Open
Abstract
Integrative and conjugative elements (ICEs), also known as conjugative transposons, are self-transferable elements that are widely distributed among bacterial phyla and are important drivers of horizontal gene transfer. Many ICEs carry genes that confer antibiotic resistances to their host cells and are involved in the dissemination of these resistance genes. ICEs reside in host chromosomes but under certain conditions can excise to form a plasmid that is typically the substrate for transfer. A few ICEs are known to undergo autonomous replication following activation. However, it is not clear if autonomous replication is a general property of many ICEs. We found that Tn916, the first conjugative transposon identified, replicates autonomously via a rolling-circle mechanism. Replication of Tn916 was dependent on the relaxase encoded by orf20 of Tn916 The origin of transfer of Tn916, oriT(916), also functioned as an origin of replication. Using immunoprecipitation and mass spectrometry, we found that the relaxase (Orf20) and the two putative helicase processivity factors (Orf22 and Orf23) encoded by Tn916 likely interact in a complex and that the Tn916 relaxase contains a previously unidentified conserved helix-turn-helix domain in its N-terminal region that is required for relaxase function and replication. Lastly, we identified a functional single-strand origin of replication (sso) in Tn916 that we predict primes second-strand synthesis during rolling-circle replication. Together these results add to the emerging data that show that several ICEs replicate via a conserved, rolling-circle mechanism. IMPORTANCE Integrative and conjugative elements (ICEs) drive horizontal gene transfer and the spread of antibiotic resistances in bacteria. ICEs reside integrated in a host genome but can excise to create a plasmid that is the substrate for transfer to other cells. Here we show that Tn916, an ICE with broad host range, undergoes autonomous rolling-circle replication when in the plasmid form. We found that the origin of transfer functions as a double-stranded origin of replication and identified a single-stranded origin of replication. It was long thought that ICEs do not undergo autonomous replication. Our work adds to the evidence that ICEs replicate autonomously as part of their normal life cycle and indicates that diverse ICEs use the same replicative mechanism.
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Affiliation(s)
- Laurel D Wright
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Alan D Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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14
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Ramsay JP, Kwong SM, Murphy RJT, Yui Eto K, Price KJ, Nguyen QT, O'Brien FG, Grubb WB, Coombs GW, Firth N. An updated view of plasmid conjugation and mobilization in Staphylococcus. Mob Genet Elements 2016; 6:e1208317. [PMID: 27583185 PMCID: PMC4993578 DOI: 10.1080/2159256x.2016.1208317] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 11/13/2022] Open
Abstract
The horizontal gene transfer facilitated by mobile genetic elements impacts almost all areas of bacterial evolution, including the accretion and dissemination of antimicrobial-resistance genes in the human and animal pathogen Staphylococcus aureus. Genome surveys of staphylococcal plasmids have revealed an unexpected paucity of conjugation and mobilization loci, perhaps suggesting that conjugation plays only a minor role in the evolution of this genus. In this letter we present the DNA sequences of historically documented staphylococcal conjugative plasmids and highlight that at least 3 distinct and widely distributed families of conjugative plasmids currently contribute to the dissemination of antimicrobial resistance in Staphylococcus. We also review the recently documented "relaxase-in trans" mechanism of conjugative mobilization facilitated by conjugative plasmids pWBG749 and pSK41, and discuss how this may facilitate the horizontal transmission of around 90% of plasmids that were previously considered non-mobilizable. Finally, we enumerate unique sequenced S. aureus plasmids with a potential mechanism of mobilization and predict that at least 80% of all non-conjugative S. aureus plasmids are mobilizable by at least one mechanism. We suggest that a greater research focus on the molecular biology of conjugation is essential if we are to recognize gene-transfer mechanisms from our increasingly in silico analyses.
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Affiliation(s)
- Joshua P. Ramsay
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Stephen M. Kwong
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Riley J. T. Murphy
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Karina Yui Eto
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
- School of Chemistry and Biochemistry, The University of Western Australia, Perth, WA, Australia
| | - Karina J. Price
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Quang T. Nguyen
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Frances G. O'Brien
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Warren B. Grubb
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
| | - Geoffrey W. Coombs
- ACCESS Typing and Research, School of Veterinary Sciences and Life Sciences, Murdoch University and School of Biomedical Sciences, Curtin University, Perth, WA, Australia
- PathWest Laboratory Medicine–WA, Fiona Stanley Hospital, Perth, WA, Australia
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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15
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Abstract
Plasmids are DNA entities that undergo controlled replication independent of the chromosomal DNA, a crucial step that guarantees the prevalence of the plasmid in its host. DNA replication has to cope with the incapacity of the DNA polymerases to start de novo DNA synthesis, and different replication mechanisms offer diverse solutions to this problem. Rolling-circle replication (RCR) is a mechanism adopted by certain plasmids, among other genetic elements, that represents one of the simplest initiation strategies, that is, the nicking by a replication initiator protein on one parental strand to generate the primer for leading-strand initiation and a single priming site for lagging-strand synthesis. All RCR plasmid genomes consist of a number of basic elements: leading strand initiation and control, lagging strand origin, phenotypic determinants, and mobilization, generally in that order of frequency. RCR has been mainly characterized in Gram-positive bacterial plasmids, although it has also been described in Gram-negative bacterial or archaeal plasmids. Here we aim to provide an overview of the RCR plasmids' lifestyle, with emphasis on their characteristic traits, promiscuity, stability, utility as vectors, etc. While RCR is one of the best-characterized plasmid replication mechanisms, there are still many questions left unanswered, which will be pointed out along the way in this review.
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16
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Wright LD, Johnson CM, Grossman AD. Identification of a Single Strand Origin of Replication in the Integrative and Conjugative Element ICEBs1 of Bacillus subtilis. PLoS Genet 2015; 11:e1005556. [PMID: 26440206 PMCID: PMC4595007 DOI: 10.1371/journal.pgen.1005556] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/07/2015] [Indexed: 11/24/2022] Open
Abstract
We identified a functional single strand origin of replication (sso) in the integrative and conjugative element ICEBs1 of Bacillus subtilis. Integrative and conjugative elements (ICEs, also known as conjugative transposons) are DNA elements typically found integrated into a bacterial chromosome where they are transmitted to daughter cells by chromosomal replication and cell division. Under certain conditions, ICEs become activated and excise from the host chromosome and can transfer to neighboring cells via the element-encoded conjugation machinery. Activated ICEBs1 undergoes autonomous rolling circle replication that is needed for the maintenance of the excised element in growing and dividing cells. Rolling circle replication, used by many plasmids and phages, generates single-stranded DNA (ssDNA). In many cases, the presence of an sso enhances the conversion of the ssDNA to double-stranded DNA (dsDNA) by enabling priming of synthesis of the second DNA strand. We initially identified sso1 in ICEBs1 based on sequence similarity to the sso of an RCR plasmid. Several functional assays confirmed Sso activity. Genetic analyses indicated that ICEBs1 uses sso1 and at least one other region for second strand DNA synthesis. We found that Sso activity was important for two key aspects of the ICEBs1 lifecycle: 1) maintenance of the plasmid form of ICEBs1 in cells after excision from the chromosome, and 2) stable acquisition of ICEBs1 following transfer to a new host. We identified sequences similar to known plasmid sso's in several other ICEs. Together, our results indicate that many other ICEs contain at least one single strand origin of replication, that these ICEs likely undergo autonomous replication, and that replication contributes to the stability and spread of these elements. Mobile genetic elements facilitate movement of genes, including those conferring antibiotic resistance and other traits, between bacteria. Integrative and conjugative elements (ICEs) are a large family of mobile genetic elements that are typically found integrated in the chromosome of their host bacterium. Under certain conditions (e.g., DNA damage, high cell density, stationary phase) an ICE excises from the host chromosome to form a circle. A linear single strand of ICE DNA can be transferred to an appropriate recipient through the ICE-encoded conjugation machinery. In addition, following excision from the chromosome, at least some (perhaps most) ICEs undergo autonomous rolling circle replication, a mechanism used by many plasmids and phages. Rolling circle replication generates single-stranded DNA (ssDNA). We found that ICEBs1, from Bacillus subtilis, contains at least two regions that enable conversion of ssDNA to double-stranded DNA. At least one of these regions functions as an sso (single strand origin of replication). ICEBs1 Sso activity was important for the ability of transferred ICEBs1 to be acquired by recipients and for the ability of ICEBs1 to replicate autonomously after excising from its host’s chromosome. We identified putative sso's in several other ICEs, indicating that Sso activity is likely important for the replication, stability and spread of these elements.
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Affiliation(s)
- Laurel D. Wright
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Christopher M. Johnson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Alan D. Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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17
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Cui Y, Hu T, Qu X, Zhang L, Ding Z, Dong A. Plasmids from Food Lactic Acid Bacteria: Diversity, Similarity, and New Developments. Int J Mol Sci 2015; 16:13172-202. [PMID: 26068451 PMCID: PMC4490491 DOI: 10.3390/ijms160613172] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 05/09/2015] [Accepted: 05/22/2015] [Indexed: 12/24/2022] Open
Abstract
Plasmids are widely distributed in different sources of lactic acid bacteria (LAB) as self-replicating extrachromosomal genetic materials, and have received considerable attention due to their close relationship with many important functions as well as some industrially relevant characteristics of the LAB species. They are interesting with regard to the development of food-grade cloning vectors. This review summarizes new developments in the area of lactic acid bacteria plasmids and aims to provide up to date information that can be used in related future research.
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Affiliation(s)
- Yanhua Cui
- School of Food Science and Engineering, Harbin Institute of Technology, Harbin 150090, China.
| | - Tong Hu
- School of Food Science and Engineering, Harbin Institute of Technology, Harbin 150090, China.
| | - Xiaojun Qu
- Institute of Microbiology, Heilongjiang Academy of Sciences, Harbin 150010, China.
| | - Lanwei Zhang
- School of Food Science and Engineering, Harbin Institute of Technology, Harbin 150090, China.
| | - Zhongqing Ding
- School of Food Science and Engineering, Harbin Institute of Technology, Harbin 150090, China.
| | - Aijun Dong
- School of Food Science and Engineering, Harbin Institute of Technology, Harbin 150090, China.
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18
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Lorenzo-Díaz F, Fernández-López C, Garcillán-Barcia MP, Espinosa M. Bringing them together: plasmid pMV158 rolling circle replication and conjugation under an evolutionary perspective. Plasmid 2014; 74:15-31. [PMID: 24942190 PMCID: PMC7103276 DOI: 10.1016/j.plasmid.2014.05.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 11/29/2022]
Abstract
Rolling circle-replicating plasmids constitute a vast family that is particularly abundant in, but not exclusive of, Gram-positive bacteria. These plasmids are constructed as cassettes that harbor genes involved in replication and its control, mobilization, resistance determinants and one or two origins of lagging strand synthesis. Any given plasmid may contain all, some, or just only the replication cassette. We discuss here the family of the promiscuous streptococcal plasmid pMV158, with emphasis on its mobilization functions: the product of the mobM gene, prototype of the MOBV relaxase family, and its cognate origin of transfer, oriT. Amongst the subfamily of MOBV1 plasmids, three groups of oriT sequences, represented by plasmids pMV158, pT181, and p1414 were identified. In the same subfamily, we found four types of single-strand origins, namely ssoA, ssoU, ssoW, and ssoT. We found that plasmids of the rolling-circle Rep_2 family (to which pMV158 belongs) are more frequently found in Lactobacillales than in any other bacterial order, whereas Rep_1 initiators seemed to prefer hosts included in the Bacillales order. In parallel, MOBV1 relaxases associated with Rep_2 initiators tended to cluster separately from those linked to Rep_1 plasmids. The updated inventory of MOBV1 plasmids still contains exclusively mobilizable elements, since no genes associated with conjugative transfer (other than the relaxase) were detected. These plasmids proved to have a great plasticity at using a wide variety of conjugative apparatuses. The promiscuous recognition of non-cognate oriT sequences and the role of replication origins for lagging-strand origin in the host range of these plasmids are also discussed.
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Affiliation(s)
- Fabián Lorenzo-Díaz
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria and Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Centro de Investigaciones Biomédicas de Canarias, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.
| | - Cris Fernández-López
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, E-28040 Madrid, Spain.
| | - M Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria - CSIC-SODERCAN, Santander, Cantabria, Spain.
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, E-28040 Madrid, Spain.
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