1
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Köhler R, Murray SM. Plasmid partitioning driven by collective migration of ParA between nucleoid lobes. Proc Natl Acad Sci U S A 2024; 121:e2319205121. [PMID: 38652748 PMCID: PMC11067062 DOI: 10.1073/pnas.2319205121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/27/2024] [Indexed: 04/25/2024] Open
Abstract
The ParABS system is crucial for the faithful segregation and inheritance of many bacterial chromosomes and low-copy-number plasmids. However, despite extensive research, the spatiotemporal dynamics of the ATPase ParA and its connection to the dynamics and positioning of the ParB-coated cargo have remained unclear. In this study, we utilize high-throughput imaging, quantitative data analysis, and computational modeling to explore the in vivo dynamics of ParA and its interaction with ParB-coated plasmids and the nucleoid. As previously observed, we find that F-plasmid ParA undergoes collective migrations ("flips") between cell halves multiple times per cell cycle. We reveal that a constricting nucleoid is required for these migrations and that they are triggered by a plasmid crossing into the cell half with greater ParA. Using simulations, we show that these dynamics can be explained by the combination of nucleoid constriction and cooperative ParA binding to the DNA, in line with the behavior of other ParA proteins. We further show that these ParA flips act to equally partition plasmids between the two lobes of the constricted nucleoid and are therefore important for plasmid stability, especially in fast growth conditions for which the nucleoid constricts early in the cell cycle. Overall, our work identifies a second mode of action of the ParABS system and deepens our understanding of how this important segregation system functions.
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Affiliation(s)
- Robin Köhler
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and Centre for Synthetic Microbiology (SYNMIKRO), Marburg35043, Germany
| | - Seán M. Murray
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and Centre for Synthetic Microbiology (SYNMIKRO), Marburg35043, Germany
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2
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Murányi G, Szabó M, Acsai K, Kiss J. Two birds with one stone: SGI1 can stabilize itself and expel the IncC helper by hijacking the plasmid parABS system. Nucleic Acids Res 2024; 52:2498-2518. [PMID: 38300764 PMCID: PMC10954446 DOI: 10.1093/nar/gkae050] [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: 07/21/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 02/03/2024] Open
Abstract
The SGI1 family integrative mobilizable elements, which are efficient agents in distribution of multidrug resistance in Gammaproteobacteria, have a complex, parasitic relationship with their IncC conjugative helper plasmids. Besides exploiting the transfer apparatus, SGI1 also hijacks IncC plasmid control mechanisms to time its own excision, replication and expression of self-encoded T4SS components, which provides advantages for SGI1 over its helpers in conjugal transfer and stable maintenance. Furthermore, SGI1 destabilizes its helpers in an unknown, replication-dependent way when they are concomitantly present in the same host. Here we report how SGI1 exploits the helper plasmid partitioning system to displace the plasmid and simultaneously increase its own stability. We show that SGI1 carries two copies of sequences mimicking the parS sites of IncC plasmids. These parS-like elements bind the ParB protein encoded by the plasmid and increase SGI1 stability by utilizing the parABS system of the plasmid for its own partitioning, through which SGI1 also destabilizes the helper plasmid. Furthermore, SGI1 expresses a small protein, Sci, which significantly strengthens this plasmid-destabilizing effect, as well as SGI1 maintenance. The plasmid-induced replication of SGI1 results in an increased copy-number of parS-like sequences and Sci expression leading to strong incompatibility with the helper plasmid.
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Affiliation(s)
- Gábor Murányi
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
| | - Mónika Szabó
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Gödöllő, H2100 Hungary
| | - Károly Acsai
- Ceva Animal Health, Ceva-Phylaxia, Budapest, H1107 Hungary
| | - János Kiss
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Gödöllő, H2100 Hungary
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3
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Rozwandowicz M, Kant A, Wagenaar J, Mevius D, Hordijk J, Brouwer M. Understanding the genetic basis of the incompatibility of IncK1 and IncK2 plasmids. OPEN RESEARCH EUROPE 2023; 3:53. [PMID: 38106640 PMCID: PMC10724649 DOI: 10.12688/openreseurope.15121.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 10/23/2023] [Indexed: 12/19/2023]
Abstract
Antimicrobial resistance is a persistent challenge in human and veterinary medicine, which is often encoded on plasmids which are transmissible between bacterial cells. Incompatibility is the inability of two plasmids to be stably maintained in one cell which is caused by the presence of identical or closely related shared determinants between two plasmids originating from partition or replication mechanisms. For I-complex plasmids in Enterobacteriacae, replication- based incompatibility is caused by the small antisense RNA stem-loop structure called RNAI. The I-complex plasmid group IncK consists of two compatible subgroups, IncK1 and IncK2, for which the RNAI differs only by five nucleotides. In this study we focussed on the interaction of the IncK1 and IncK2 RNAI structures by constructing minireplicons containing the replication region of IncK1 or IncK2 plasmids coupled with a kanamycin resistance marker. Using minireplicons excludes involvement of incompatibility mechanisms other than RNAI. Additionally, we performed single nucleotide mutagenesis targeting the five nucleotides that differ between the IncK1 and IncK2 RNAI sequences of these minireplicons. The obtained results show that a single nucleotide change in the RNAI structure is responsible for the compatible phenotype of IncK1 with IncK2 plasmids. Only nucleotides in the RNAI top loop and interior loop have an effect on minireplicon incompatibility with wild type plasmids, while mutations in the stem of the RNAI structure had no significant effect on incompatibility. Understanding the molecular basis of incompatibility is relevant for future in silico predictions of plasmid incompatibility.
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Affiliation(s)
- Marta Rozwandowicz
- National Institute for Public Health and the Environment, Bilthoven, 3721 MA, The Netherlands
| | - Arie Kant
- Wageningen Bioveterinary Research, Lelystd, 8221 RA, The Netherlands
| | - Jaap Wagenaar
- Utrecht University, Utrecht, 3584 CS, The Netherlands
| | - Dik Mevius
- Wageningen Bioveterinary Research, Lelystd, 8221 RA, The Netherlands
| | - Joost Hordijk
- National Institute for Public Health and the Environment, Bilthoven, 3721 MA, The Netherlands
| | - Michael Brouwer
- Wageningen Bioveterinary Research, Lelystd, 8221 RA, The Netherlands
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4
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Köhler R, Sadhir I, Murray SM. ★Track: Inferred counting and tracking of replicating DNA loci. Biophys J 2023; 122:1577-1585. [PMID: 36966362 PMCID: PMC10183378 DOI: 10.1016/j.bpj.2023.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/10/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023] Open
Abstract
Fluorescent microscopy is the primary method to study DNA organization within cells. However, the variability and low signal/noise commonly associated with live-cell time-lapse imaging challenges quantitative measurements. In particular, obtaining quantitative or mechanistic insight often depends on the accurate tracking of fluorescent particles. Here, we present ★Track, an inference method that determines the most likely temporal tracking of replicating intracellular particles such DNA loci while accounting for missing, merged, and spurious detections. It allows the accurate prediction of particle copy numbers as well as the timing of replication events. We demonstrate ★Track's abilities and gain new insight into plasmid copy number control and the volume dependence of bacterial chromosome replication initiation. By enabling the accurate tracking of DNA loci, ★Track can help to uncover the mechanistic principles of chromosome organization and dynamics across a range of systems.
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Affiliation(s)
- Robin Köhler
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Ismath Sadhir
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Seán M Murray
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany.
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5
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Köhler R, Kaganovitch E, Murray SM. High-throughput imaging and quantitative analysis uncovers the nature of plasmid positioning by ParABS. eLife 2022; 11:78743. [PMID: 36374535 PMCID: PMC9662831 DOI: 10.7554/elife.78743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 10/23/2022] [Indexed: 11/16/2022] Open
Abstract
The faithful segregation and inheritance of bacterial chromosomes and low-copy number plasmids requires dedicated partitioning systems. The most common of these, ParABS, consists of ParA, a DNA-binding ATPase and ParB, a protein that binds to centromeric-like parS sequences on the DNA cargo. The resulting nucleoprotein complexes are believed to move up a self-generated gradient of nucleoid-associated ParA. However, it remains unclear how this leads to the observed cargo positioning and dynamics. In particular, the evaluation of models of plasmid positioning has been hindered by the lack of quantitative measurements of plasmid dynamics. Here, we use high-throughput imaging, analysis and modelling to determine the dynamical nature of these systems. We find that F plasmid is actively brought to specific subcellular home positions within the cell with dynamics akin to an over-damped spring. We develop a unified stochastic model that quantitatively explains this behaviour and predicts that cells with the lowest plasmid concentration transition to oscillatory dynamics. We confirm this prediction for F plasmid as well as a distantly-related ParABS system. Our results indicate that ParABS regularly positions plasmids across the nucleoid but operates just below the threshold of an oscillatory instability, which according to our model, minimises ATP consumption. Our work also clarifies how various plasmid dynamics are achievable in a single unified stochastic model. Overall, this work uncovers the dynamical nature of plasmid positioning by ParABS and provides insights relevant for chromosome-based systems.
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Affiliation(s)
- Robin Köhler
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Seán M Murray
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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6
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Guo L, Zhao Y, Zhang Q, Feng Y, Bi L, Zhang X, Wang T, Liu C, Ma H, Sun B. Stochastically multimerized ParB orchestrates DNA assembly as unveiled by single-molecule analysis. Nucleic Acids Res 2022; 50:9294-9305. [PMID: 35904809 PMCID: PMC9458438 DOI: 10.1093/nar/gkac651] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/11/2022] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
The tripartite ParABS system mediates chromosome segregation in a wide range of bacteria. Dimeric ParB was proposed to nucleate on parS sites and spread to neighboring DNA. However, how properly distributed ParB dimers further compact chromosomal DNA into a higher-order nucleoprotein complex for partitioning remains poorly understood. Here, using a single-molecule approach, we show that tens of Bacillus subtilis ParB (Spo0J) proteins can stochastically multimerize on and stably bind to nonspecific DNA. The introduction of CTP promotes the formation and diffusion of the multimeric ParB along DNA, offering an opportunity for ParB proteins to further forgather and cluster. Intriguingly, ParB multimers can recognize parS motifs and are more inclined to remain immobile on them. Importantly, the ParB multimer features distinct capabilities of not only bridging two independent DNA molecules but also mediating their transportation, both of which are enhanced by the presence of either CTP or parS in the DNA. These findings shed new light on ParB dynamics in self-multimerization and DNA organization and help to better comprehend the assembly of the ParB-DNA partition complex.
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Affiliation(s)
- Lijuan Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yilin Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qian Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ying Feng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,School of Biotechnology, East China University of Science and Technology, Shanghai 200237, China
| | - Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Teng Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
| | - Hanhui Ma
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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7
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Sugawara T, Kaneko K. Chemophoresis engine: A general mechanism of ATPase-driven cargo transport. PLoS Comput Biol 2022; 18:e1010324. [PMID: 35877681 PMCID: PMC9363008 DOI: 10.1371/journal.pcbi.1010324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 08/09/2022] [Accepted: 06/23/2022] [Indexed: 11/18/2022] Open
Abstract
Cell polarity regulates the orientation of the cytoskeleton members that directs intracellular transport for cargo-like organelles, using chemical gradients sustained by ATP or GTP hydrolysis. However, how cargo transports are directly mediated by chemical gradients remains unknown. We previously proposed a physical mechanism that enables directed movement of cargos, referred to as chemophoresis. According to the mechanism, a cargo with reaction sites is subjected to a chemophoresis force in the direction of the increased concentration. Based on this, we introduce an extended model, the chemophoresis engine, as a general mechanism of cargo motion, which transforms chemical free energy into directed motion through the catalytic ATP hydrolysis. We applied the engine to plasmid motion in a ParABS system to demonstrate the self-organization system for directed plasmid movement and pattern dynamics of ParA-ATP concentration, thereby explaining plasmid equi-positioning and pole-to-pole oscillation observed in bacterial cells and in vitro experiments. We mathematically show the existence and stability of the plasmid-surfing pattern, which allows the cargo-directed motion through the symmetry-breaking transition of the ParA-ATP spatiotemporal pattern. We also quantitatively demonstrate that the chemophoresis engine can work even under in vivo conditions. Finally, we discuss the chemophoresis engine as one of the general mechanisms of hydrolysis-driven intracellular transport. The formation of organelle/macromolecule patterns depending on chemical concentration under non-equilibrium conditions, first observed during macroscopic morphogenesis, has recently been observed at the intracellular level as well, and its relevance as intracellular morphogen has been demonstrated in the case of bacterial cell division. These studies have discussed how cargos maintain positional information provided by chemical concentration gradients/localization. However, how cargo transports are directly mediated by chemical gradients remains unknown. Based on the previously proposed mechanism of chemotaxis-like behavior of cargos (referred to as chemophoresis), we introduce a chemophoresis engine as a physicochemical mechanism of cargo motion, which transforms chemical free energy to directed motion. The engine is based on the chemophoresis force to make cargoes move in the direction of the increasing ATPase(-ATP) concentration and an enhanced catalytic ATPase hydrolysis at the positions of the cargoes. Applying the engine to ATPase-driven movement of plasmid-DNAs in bacterial cells, we constructed a mathematical model to demonstrate the self-organization for directed plasmid motion and pattern dynamics of ATPase concentration, as is consistent with in vitro and in vivo experiments. We propose that this chemophoresis engine works as a general mechanism of hydrolysis-driven intracellular transport.
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Affiliation(s)
- Takeshi Sugawara
- Universal Biology Institute, The University of Tokyo, Tokyo, Japan
- * E-mail:
| | - Kunihiko Kaneko
- Center for Complex Systems Biology, Universal Biology Institute, The University of Tokyo, Meguro-ku, Tokyo, Japan
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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8
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The Specificity of ParR Binding Determines the Incompatibility of Conjugative Plasmids in Clostridium perfringens. mBio 2022; 13:e0135622. [PMID: 35726914 PMCID: PMC9426499 DOI: 10.1128/mbio.01356-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Plasmids that encode the same replication machinery are generally unable to coexist in the same bacterial cell. However, Clostridium perfringens strains often carry multiple conjugative toxin or antibiotic resistance plasmids that are closely related and encode similar Rep proteins. In many bacteria, plasmid partitioning upon cell division involves a ParMRC system; in C. perfringens plasmids, there are approximately 10 different ParMRC families, with significant differences in amino acid sequences between each ParM family (15% to 54% identity). Since plasmids carrying genes belonging to the same ParMRC family are not observed in the same strain, these families appear to represent the basis for plasmid compatibility in C. perfringens. To understand this process, we examined the key recognition steps between ParR DNA-binding proteins and their parC binding sites. The ParR proteins bound to sequences within a parC site from the same ParMRC family but could not interact with a parC site from a different ParMRC family. These data provide evidence that compatibility of the conjugative toxin plasmids of C. perfringens is mediated by their parMRC-like partitioning systems. This process provides a selective advantage by enabling the host bacterium to maintain separate plasmids that encode toxins that are specific for different host targets.
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Igler C, Huisman JS, Siedentop B, Bonhoeffer S, Lehtinen S. Plasmid co-infection: linking biological mechanisms to ecological and evolutionary dynamics. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200478. [PMID: 34839701 PMCID: PMC8628072 DOI: 10.1098/rstb.2020.0478] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/09/2021] [Indexed: 12/27/2022] Open
Abstract
As infectious agents of bacteria and vehicles of horizontal gene transfer, plasmids play a key role in bacterial ecology and evolution. Plasmid dynamics are shaped not only by plasmid-host interactions but also by ecological interactions between plasmid variants. These interactions are complex: plasmids can co-infect the same cell and the consequences for the co-resident plasmid can be either beneficial or detrimental. Many of the biological processes that govern plasmid co-infection-from systems that exclude infection by other plasmids to interactions in the regulation of plasmid copy number-are well characterized at a mechanistic level. Modelling plays a central role in translating such mechanistic insights into predictions about plasmid dynamics and the impact of these dynamics on bacterial evolution. Theoretical work in evolutionary epidemiology has shown that formulating models of co-infection is not trivial, as some modelling choices can introduce unintended ecological assumptions. Here, we review how the biological processes that govern co-infection can be represented in a mathematical model, discuss potential modelling pitfalls, and analyse this model to provide general insights into how co-infection impacts ecological and evolutionary outcomes. In particular, we demonstrate how beneficial and detrimental effects of co-infection give rise to frequency-dependent selection on plasmid variants. This article is part of the theme issue 'The secret lives of microbial mobile genetic elements'.
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Affiliation(s)
- Claudia Igler
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
| | - Jana S. Huisman
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Berit Siedentop
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
| | - Sebastian Bonhoeffer
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
| | - Sonja Lehtinen
- Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
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10
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Hu L, Rech J, Bouet JY, Liu J. Spatial control over near-critical-point operation ensures fidelity of ParABS-mediated DNA partition. Biophys J 2021; 120:3911-3924. [PMID: 34418367 PMCID: PMC8511131 DOI: 10.1016/j.bpj.2021.08.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/26/2021] [Accepted: 08/13/2021] [Indexed: 01/20/2023] Open
Abstract
In bacteria, most low-copy-number plasmid and chromosomally encoded partition systems belong to the tripartite ParABS partition machinery. Despite the importance in genetic inheritance, the mechanisms of ParABS-mediated genome partition are not well understood. Combining theory and experiment, we provided evidence that the ParABS system-DNA partitioning in vivo via the ParA-gradient-based Brownian ratcheting-operates near a transition point in parameter space (i.e., a critical point), across which the system displays qualitatively different motile behaviors. This near-critical-point operation adapts the segregation distance of replicated plasmids to the half length of the elongating nucleoid, ensuring both cell halves to inherit one copy of the plasmids. Further, we demonstrated that the plasmid localizes the cytoplasmic ParA to buffer the partition fidelity against the large cell-to-cell fluctuations in ParA level. The spatial control over the near-critical-point operation not only ensures both sensitive adaptation and robust execution of partitioning but also sheds light on the fundamental question in cell biology: how do cells faithfully measure cellular-scale distance by only using molecular-scale interactions?
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Affiliation(s)
- Longhua Hu
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jérôme Rech
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Centre National de la Recherche Scientifique, Université de Toulouse, UPS, Toulouse, France
| | - Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Centre National de la Recherche Scientifique, Université de Toulouse, UPS, Toulouse, France.
| | - Jian Liu
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
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11
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Physical Modeling of a Sliding Clamp Mechanism for the Spreading of ParB at Short Genomic Distance from Bacterial Centromere Sites. iScience 2020; 23:101861. [PMID: 33319179 PMCID: PMC7725951 DOI: 10.1016/j.isci.2020.101861] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/16/2020] [Accepted: 11/19/2020] [Indexed: 12/20/2022] Open
Abstract
Bacterial ParB partitioning proteins involved in chromosomes and low-copy-number plasmid segregation are cytosine triphosphate (CTP)-dependent molecular switches. CTP-binding converts ParB dimers to DNA clamps, allowing unidimensional diffusion along the DNA. This sliding property has been proposed to explain the ParB spreading over large distances from parS centromere sites where ParB is specifically loaded. We modeled such a "clamping and sliding" mechanism as a typical reaction-diffusion system, compared it to the F plasmid ParB DNA binding pattern, and found that it can account neither for the long range of ParB binding to DNA nor for the rapid assembly kinetics observed in vivo after parS duplication. Also, it predicts a strong effect on the F plasmid ParB binding pattern from the presence of a roadblock that is not observed in ChIP-sequencing (ChIP-seq). We conclude that although "clamping and sliding" can occur at short distances from parS, another mechanism must apply for ParB recruitment at larger genomic distances.
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12
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Guilhas B, Walter JC, Rech J, David G, Walliser NO, Palmeri J, Mathieu-Demaziere C, Parmeggiani A, Bouet JY, Le Gall A, Nollmann M. ATP-Driven Separation of Liquid Phase Condensates in Bacteria. Mol Cell 2020; 79:293-303.e4. [PMID: 32679076 DOI: 10.1016/j.molcel.2020.06.034] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 04/08/2020] [Accepted: 06/22/2020] [Indexed: 12/18/2022]
Abstract
Liquid-liquid phase-separated (LLPS) states are key to compartmentalizing components in the absence of membranes; however, it is unclear whether LLPS condensates are actively and specifically organized in the subcellular space and by which mechanisms. Here, we address this question by focusing on the ParABS DNA segregation system, composed of a centromeric-like sequence (parS), a DNA-binding protein (ParB), and a motor (ParA). We show that parS and ParB associate to form nanometer-sized, round condensates. ParB molecules diffuse rapidly within the nucleoid volume but display confined motions when trapped inside ParB condensates. Single ParB molecules are able to rapidly diffuse between different condensates, and nucleation is strongly favored by parS. Notably, the ParA motor is required to prevent the fusion of ParB condensates. These results describe a novel active mechanism that splits, segregates, and localizes non-canonical LLPS condensates in the subcellular space.
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Affiliation(s)
- Baptiste Guilhas
- Centre de Biochimie Structurale, CNRS UMR 5048, INSERM U1054, Université de Montpellier, 60 rue de Navacelles, 34090 Montpellier, France
| | - Jean-Charles Walter
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Jerome Rech
- LMGM, CBI, CNRS, Université de Toulouse, UPS, Toulouse, France
| | - Gabriel David
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Nils Ole Walliser
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - John Palmeri
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | | | - Andrea Parmeggiani
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France; LPHI, CNRS, Université de Montpellier, Montpellier, France
| | - Jean-Yves Bouet
- LMGM, CBI, CNRS, Université de Toulouse, UPS, Toulouse, France
| | - Antoine Le Gall
- Centre de Biochimie Structurale, CNRS UMR 5048, INSERM U1054, Université de Montpellier, 60 rue de Navacelles, 34090 Montpellier, France.
| | - Marcelo Nollmann
- Centre de Biochimie Structurale, CNRS UMR 5048, INSERM U1054, Université de Montpellier, 60 rue de Navacelles, 34090 Montpellier, France.
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13
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Addressing the role of centromere sites in activation of ParB proteins for partition complex assembly. PLoS One 2020; 15:e0226472. [PMID: 32379828 PMCID: PMC7205306 DOI: 10.1371/journal.pone.0226472] [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: 11/29/2019] [Accepted: 04/15/2020] [Indexed: 11/19/2022] Open
Abstract
The ParB-parS partition complexes that bacterial replicons use to ensure their faithful inheritance also find employment in visualization of DNA loci, as less intrusive alternatives to fluorescent repressor-operator systems. The ability of ParB molecules to interact via their N-terminal domains and to bind to non-specific DNA enables expansion of the initial complex to a size both functional in partition and, via fusion to fluorescent peptides, visible by light microscopy. We have investigated whether it is possible to dispense with the need to insert parS in the genomic locus of interest, by determining whether ParB fused to proteins that bind specifically to natural DNA sequences can still assemble visible complexes. In yeast cells, coproduction of fusions of ParB to a fluorescent peptide and to a TALE protein targeting an endogenous sequence did not yield visible foci; nor did any of several variants of these components. In E.coli, coproduction of fusions of SopB (F plasmid ParB) to fluorescent peptide, and to dCas9 together with specific guide RNAs, likewise yielded no foci. The result of coproducing analogous fusions of SopB proteins with distinct binding specificities was also negative. Our observations imply that in order to assemble higher order partition complexes, ParB proteins need specific activation through binding to their cognate parS sites.
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Abstract
Plasmids are ubiquitous in the microbial world and have been identified in almost all species of bacteria that have been examined. Their localization inside the bacterial cell has been examined for about two decades; typically, they are not randomly distributed, and their positioning depends on copy number and their mode of segregation. Low-copy-number plasmids promote their own stable inheritance in their bacterial hosts by encoding active partition systems, which ensure that copies are positioned in both halves of a dividing cell. High-copy plasmids rely on passive diffusion of some copies, but many remain clustered together in the nucleoid-free regions of the cell. Here we review plasmid localization and partition (Par) systems, with particular emphasis on plasmids from Enterobacteriaceae and on recent results describing the in vivo localization properties and molecular mechanisms of each system. Partition systems also cause plasmid incompatibility such that distinct plasmids (with different replicons) with the same Par system cannot be stably maintained in the same cells. We discuss how partition-mediated incompatibility is a consequence of the partition mechanism.
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Physical Views on ParABS-Mediated DNA Segregation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1267:45-58. [PMID: 32894476 DOI: 10.1007/978-3-030-46886-6_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
In this chapter, we will focus on ParABS: an apparently simple, three-component system, required for the segregation of bacterial chromosomes and plasmids. We will specifically describe how biophysical measurements combined with physical modeling advanced our understanding of the mechanism of ParABS-mediated complex assembly, segregation and positioning.
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Debaugny RE, Sanchez A, Rech J, Labourdette D, Dorignac J, Geniet F, Palmeri J, Parmeggiani A, Boudsocq F, Anton Leberre V, Walter JC, Bouet JY. A conserved mechanism drives partition complex assembly on bacterial chromosomes and plasmids. Mol Syst Biol 2018; 14:e8516. [PMID: 30446599 PMCID: PMC6238139 DOI: 10.15252/msb.20188516] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/22/2018] [Indexed: 11/29/2022] Open
Abstract
Chromosome and plasmid segregation in bacteria are mostly driven by ParABS systems. These DNA partitioning machineries rely on large nucleoprotein complexes assembled on centromere sites (parS). However, the mechanism of how a few parS-bound ParB proteins nucleate the formation of highly concentrated ParB clusters remains unclear despite several proposed physico-mathematical models. We discriminated between these different models by varying some key parameters in vivo using the F plasmid partition system. We found that "Nucleation & caging" is the only coherent model recapitulating in vivo data. We also showed that the stochastic self-assembly of partition complexes (i) is a robust mechanism, (ii) does not directly involve ParA ATPase, (iii) results in a dynamic structure of discrete size independent of ParB concentration, and (iv) is not perturbed by active transcription but is by protein complexes. We refined the "Nucleation & caging" model and successfully applied it to the chromosomally encoded Par system of Vibrio cholerae, indicating that this stochastic self-assembly mechanism is widely conserved from plasmids to chromosomes.
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Affiliation(s)
- Roxanne E Debaugny
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, Toulouse, France
| | - Aurore Sanchez
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, Toulouse, France
| | - Jérôme Rech
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, Toulouse, France
| | | | - Jérôme Dorignac
- Laboratoire Charles Coulomb, CNRS-Université Montpellier, Montpellier, France
| | - Frédéric Geniet
- Laboratoire Charles Coulomb, CNRS-Université Montpellier, Montpellier, France
| | - John Palmeri
- Laboratoire Charles Coulomb, CNRS-Université Montpellier, Montpellier, France
| | - Andrea Parmeggiani
- Laboratoire Charles Coulomb, CNRS-Université Montpellier, Montpellier, France
- Dynamique des Interactions Membranaires Normales et Pathologiques, CNRS-Université Montpellier, Montpellier, France
| | - François Boudsocq
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, Toulouse, France
| | | | - Jean-Charles Walter
- Laboratoire Charles Coulomb, CNRS-Université Montpellier, Montpellier, France
| | - Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, Toulouse, France
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Walter JC, Dorignac J, Lorman V, Rech J, Bouet JY, Nollmann M, Palmeri J, Parmeggiani A, Geniet F. Surfing on Protein Waves: Proteophoresis as a Mechanism for Bacterial Genome Partitioning. PHYSICAL REVIEW LETTERS 2017; 119:028101. [PMID: 28753349 DOI: 10.1103/physrevlett.119.028101] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Indexed: 05/11/2023]
Abstract
Efficient bacterial chromosome segregation typically requires the coordinated action of a three-component machinery, fueled by adenosine triphosphate, called the partition complex. We present a phenomenological model accounting for the dynamic activity of this system that is also relevant for the physics of catalytic particles in active environments. The model is obtained by coupling simple linear reaction-diffusion equations with a proteophoresis, or "volumetric" chemophoresis, force field that arises from protein-protein interactions and provides a physically viable mechanism for complex translocation. This minimal description captures most known experimental observations: dynamic oscillations of complex components, complex separation, and subsequent symmetrical positioning. The predictions of our model are in phenomenological agreement with and provide substantial insight into recent experiments. From a nonlinear physics view point, this system explores the active separation of matter at micrometric scales with a dynamical instability between static positioning and traveling wave regimes triggered by the dynamical spontaneous breaking of rotational symmetry.
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Affiliation(s)
- J-C Walter
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
| | - J Dorignac
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
| | - V Lorman
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
| | - J Rech
- LMGM, CBI, CNRS, Université Toulouse, UPS, F-31000 Toulouse, France
| | - J-Y Bouet
- LMGM, CBI, CNRS, Université Toulouse, UPS, F-31000 Toulouse, France
| | - M Nollmann
- CBS, CNRS, INSERM, Université Montpellier, F-34090 Montpellier, France
| | - J Palmeri
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
| | - A Parmeggiani
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
- DIMNP, CNRS, Université Montpellier, F-34095 Montpellier, France
| | - F Geniet
- Laboratoire Charles Coulomb (L2C), Université Montpellier, CNRS, F-34095 Montpellier, France
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Hu L, Vecchiarelli AG, Mizuuchi K, Neuman KC, Liu J. Brownian ratchet mechanisms of ParA-mediated partitioning. Plasmid 2017; 92:12-16. [PMID: 28529035 PMCID: PMC5568458 DOI: 10.1016/j.plasmid.2017.05.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 11/16/2022]
Affiliation(s)
- Longhua Hu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, United States
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology (MCDB), University of Michigan, Ann Arbor, MI, United States
| | - Kiyoshi Mizuuchi
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, United States
| | - Keir C Neuman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, United States
| | - Jian Liu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, United States.
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Watts TD, Johanesen PA, Lyras D, Rood JI, Adams V. Evidence that compatibility of closely related replicons in Clostridium perfringens depends on linkage to parMRC-like partitioning systems of different subfamilies. Plasmid 2017; 91:68-75. [PMID: 28390955 DOI: 10.1016/j.plasmid.2017.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/29/2017] [Accepted: 03/30/2017] [Indexed: 11/17/2022]
Abstract
Clostridium perfringens produces an extensive repertoire of toxins and extracellular enzymes, many of which are intimately involved in the progression of disease and are encoded by genes on conjugative plasmids. In addition, many C. perfringens strains can carry up to five of these conjugative toxin or antimicrobial resistance plasmids, each of which has a similar 35kb backbone. This conserved backbone includes the tcp conjugation locus and the central control region (CCR), which encodes genes involved in plasmid regulation, replication and partitioning, including a parMRC partitioning locus. Most conjugative plasmids in C. perfringens have a conserved replication protein, raising questions as to how multiple, closely related plasmids are maintained within a single strain. Bioinformatics analysis has highlighted the presence of at least 10 different parMRC partitioning system families (parMRCA-J) in these plasmids, with differences in amino acid sequence identity between each ParM family ranging from 15% to 54%. No two plasmids that encode genes belonging to the same partitioning family have been observed in a single strain, suggesting that these families represent the basis for plasmid incompatibility. In an attempt to validate the proposed parMRC incompatibility groups, genetically marked C. perfringens plasmids encoding identical parMRCC or parMRCD homologues or different combinations of parMRCA, parMRCC and parMRCD family homologues were introduced into a single strain via conjugation. The stability of each plasmid was determined using an incompatibility assay in which the plasmid profile of each strain was monitored over the course of two days in the absence of direct selection. The results showed that plasmids with identical parMRCC or parMRCD homologues were incompatible and could not coexist in the absence of external selection. By contrast, plasmids that encoded different parMRC homologues were compatible and could coexist in the same cell in the absence of selection, with the exception of strains housing parMRCC and parMRCD combinations, which showed a minor incompatibility phenotype. In conclusion, we have provided the first direct evidence of plasmid incompatibility in Clostridium spp. and have shown experimentally that the compatibility of conjugative C. perfringens plasmids correlates with the presence of parMRC-like partitioning systems of different phylogenetic subfamilies.
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Affiliation(s)
- Thomas D Watts
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Priscilla A Johanesen
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Dena Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Julian I Rood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Vicki Adams
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Victoria 3800, Australia.
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Uphoff S, Lord ND, Okumus B, Potvin-Trottier L, Sherratt DJ, Paulsson J. Stochastic activation of a DNA damage response causes cell-to-cell mutation rate variation. Science 2016; 351:1094-7. [PMID: 26941321 PMCID: PMC4827329 DOI: 10.1126/science.aac9786] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cells rely on the precise action of proteins that detect and repair DNA damage. However, gene expression noise causes fluctuations in protein abundances that may compromise repair. For the Ada protein in Escherichia coli, which induces its own expression upon repairing DNA alkylation damage, we found that undamaged cells on average produce one Ada molecule per generation. Because production is stochastic, many cells have no Ada molecules and cannot induce the damage response until the first expression event occurs, which sometimes delays the response for generations. This creates a subpopulation of cells with increased mutation rates. Nongenetic variation in protein abundances thus leads to genetic heterogeneity in the population. Our results further suggest that cells balance reliable repair against toxic side effects of abundant DNA repair proteins.
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Affiliation(s)
- Stephan Uphoff
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK. Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
| | - Nathan D Lord
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Burak Okumus
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Laurent Potvin-Trottier
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA. Biophysics Ph.D. Program, Harvard Medical School, USA
| | - David J Sherratt
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Johan Paulsson
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
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21
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Sanchez A, Cattoni D, Walter JC, Rech J, Parmeggiani A, Nollmann M, Bouet JY. Stochastic Self-Assembly of ParB Proteins Builds the Bacterial DNA Segregation Apparatus. Cell Syst 2015; 1:163-73. [DOI: 10.1016/j.cels.2015.07.013] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/15/2015] [Accepted: 07/30/2015] [Indexed: 11/25/2022]
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22
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Diaz R, Rech J, Bouet JY. Imaging centromere-based incompatibilities: Insights into the mechanism of incompatibility mediated by low-copy number plasmids. Plasmid 2015; 80:54-62. [DOI: 10.1016/j.plasmid.2015.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/24/2015] [Accepted: 03/30/2015] [Indexed: 11/15/2022]
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23
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Bouet JY, Stouf M, Lebailly E, Cornet F. Mechanisms for chromosome segregation. Curr Opin Microbiol 2014; 22:60-5. [DOI: 10.1016/j.mib.2014.09.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/15/2014] [Indexed: 11/25/2022]
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A propagating ATPase gradient drives transport of surface-confined cellular cargo. Proc Natl Acad Sci U S A 2014; 111:4880-5. [PMID: 24567408 DOI: 10.1073/pnas.1401025111] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The faithful segregation of duplicated genetic material into daughter cells is critical to all organisms. In many bacteria, the segregation of chromosomes involves transport of "centromere-like" loci over the main body of the chromosome, the nucleoid, mediated by a two-protein partition system: a nonspecific DNA-binding ATPase, ParA, and an ATPase stimulator, ParB, which binds to the centromere-like loci. These systems have previously been proposed to function through a filament-based mechanism, analogous to actin- or microtubule-based movement. Here, we reconstituted the F-plasmid partition system using a DNA-carpeted flow cell as an artificial nucleoid surface and magnetic beads coated with plasmid partition complexes as surface-confined cargo. This minimal system recapitulated directed cargo motion driven by a surface ATPase gradient that propagated with the cargo. The dynamics are consistent with a diffusion-ratchet model, whereby the cargo dynamically establishes, and interacts with, a concentration gradient of the ATPase. A chemophoresis force ensues as the cargo perpetually chases the ATPase gradient, allowing the cargo to essentially "surf" the nucleoid on a continuously traveling wave of the ATPase. Demonstration of this non-filament-based motility mechanism in a biological context establishes a distinct class of motor system used for the transport and positioning of large cellular cargo.
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Ah-Seng Y, Rech J, Lane D, Bouet JY. Defining the role of ATP hydrolysis in mitotic segregation of bacterial plasmids. PLoS Genet 2013; 9:e1003956. [PMID: 24367270 PMCID: PMC3868542 DOI: 10.1371/journal.pgen.1003956] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 09/30/2013] [Indexed: 11/21/2022] Open
Abstract
Hydrolysis of ATP by partition ATPases, although considered a key step in the segregation mechanism that assures stable inheritance of plasmids, is intrinsically very weak. The cognate centromere-binding protein (CBP), together with DNA, stimulates the ATPase to hydrolyse ATP and to undertake the relocation that incites plasmid movement, apparently confirming the need for hydrolysis in partition. However, ATP-binding alone changes ATPase conformation and properties, making it difficult to rigorously distinguish the substrate and cofactor roles of ATP in vivo. We had shown that mutation of arginines R36 and R42 in the F plasmid CBP, SopB, reduces stimulation of SopA-catalyzed ATP hydrolysis without changing SopA-SopB affinity, suggesting the role of hydrolysis could be analyzed using SopA with normal conformational responses to ATP. Here, we report that strongly reducing SopB-mediated stimulation of ATP hydrolysis results in only slight destabilization of mini-F, although the instability, as well as an increase in mini-F clustering, is proportional to the ATPase deficit. Unexpectedly, the reduced stimulation also increased the frequency of SopA relocation over the nucleoid. The increase was due to drastic shortening of the period spent by SopA at nucleoid ends; average speed of migration per se was unchanged. Reduced ATP hydrolysis was also associated with pronounced deviations in positioning of mini-F, though time-averaged positions changed only modestly. Thus, by specifically targeting SopB-stimulated ATP hydrolysis our study reveals that even at levels of ATPase which reduce the efficiency of splitting clusters and the constancy of plasmid positioning, SopB still activates SopA mobility and plasmid positioning, and sustains near wild type levels of plasmid stability. Genes enabling bacteria to survive and thrive in challenging environments are very often found on small, non-essential DNA molecules called plasmids. Many plasmids are naturally present in the cell in very few copies and so risk being lost from one of the daughter cells upon division. These plasmids elaborate a partition system, functionally similar to mitosis, which assures their faithful inheritance. Chromosomes also generally possess such systems. We know that partition systems involve two proteins, that one (B) stimulates the other (A) to hydrolyse ATP, and that upon binding to A protein ATP confers properties needed for partition. ATP's double action, as hydrolysis substrate and cofactor, complicates definition of its role in the mechanism. The novelty of our approach lies in use of B protein mutants that do not stimulate hydrolysis. Our results reveal that the major function of ATP hydrolysis is not to displace plasmid molecules to their positions in each cell half, as generally thought, but to split initial sibling plasmid pairs and prevent their reforming. This study is the first to dissect ATPase activity in vivo using normal A-protein ATPase, and so opens a new avenue to exploration of the mechanisms that ensure plasmid and chromosome inheritance.
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Affiliation(s)
- Yoan Ah-Seng
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique et l'Université Paul Sabatier, Toulouse, France
| | - Jérôme Rech
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique et l'Université Paul Sabatier, Toulouse, France
| | - David Lane
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique et l'Université Paul Sabatier, Toulouse, France
- * E-mail:
| | - Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique et l'Université Paul Sabatier, Toulouse, France
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Cell-free study of F plasmid partition provides evidence for cargo transport by a diffusion-ratchet mechanism. Proc Natl Acad Sci U S A 2013; 110:E1390-7. [PMID: 23479605 DOI: 10.1073/pnas.1302745110] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Increasingly diverse types of cargo are being found to be segregated and positioned by ParA-type ATPases. Several minimalistic systems described in bacteria are self-organizing and are known to affect the transport of plasmids, protein machineries, and chromosomal loci. One well-studied model is the F plasmid partition system, SopABC. In vivo, SopA ATPase forms dynamic patterns on the nucleoid in the presence of the ATPase stimulator, SopB, which binds to the sopC site on the plasmid, demarcating it as the cargo. To understand the relationship between nucleoid patterning and plasmid transport, we established a cell-free system to study plasmid partition reactions in a DNA-carpeted flowcell. We observed depletion zones of the partition ATPase on the DNA carpet surrounding partition complexes. The findings favor a diffusion-ratchet model for plasmid motion whereby partition complexes create an ATPase concentration gradient and then climb up this gradient toward higher concentrations of the ATPase. Here, we report on the dynamic properties of the Sop system on a DNA-carpet substrate, which further support the proposed diffusion-ratchet mechanism.
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Miyakoshi M, Shintani M, Inoue K, Terabayashi T, Sai F, Ohkuma M, Nojiri H, Nagata Y, Tsuda M. ParI, an orphan ParA family protein from Pseudomonas putida KT2440-specific genomic island, interferes with the partition system of IncP-7 plasmids. Environ Microbiol 2012; 14:2946-59. [PMID: 22925377 DOI: 10.1111/j.1462-2920.2012.02861.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 07/26/2012] [Accepted: 07/28/2012] [Indexed: 01/09/2023]
Abstract
Pseudomonas putida KT2440 is an ideal soil bacterium for expanding the range of degradable compounds via the recruitment of various catabolic plasmids. In the course of our investigation of the host range of IncP-7 catabolic plasmids pCAR1, pDK1 and pWW53, we found that the IncP-7 miniplasmids composed of replication and partition loci were exceptionally unstable in KT2440, which is the authentic host of the archetypal IncP-9 plasmid pWW0. This study identified ParI, a homologue of ParA family of plasmid partitioning proteins encoded on the KT2440-specific cryptic genomic island, as a negative host factor for the maintenance of IncP-7 plasmids. The miniplasmids were destabilized by ectopic expression of ParI, and the loss rate correlated with the copy number of ParB binding sites in the centromeric parS region. Mutations in the conserved ATPase domains of ParI abolished destabilization of miniplasmids. Furthermore, ParI destabilized miniplasmid derivatives carrying the partition-deficient parA mutations but failed to impact the stability of miniplasmid derivatives with parB mutations in the putative arginine finger. Altogether, these results indicate that ParI interferes with the IncP-7 plasmid partition system. This study extends canonical partition-mediated incompatibility of plasmids beyond heterogeneous mobile genetic elements, namely incompatibility between plasmid and genomic island.
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Affiliation(s)
- Masatoshi Miyakoshi
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan.
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Kadoya R, Chattoraj DK. Insensitivity of chromosome I and the cell cycle to blockage of replication and segregation of Vibrio cholerae chromosome II. mBio 2012; 3:e00067-12. [PMID: 22570276 PMCID: PMC3350373 DOI: 10.1128/mbio.00067-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/02/2012] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Vibrio cholerae has two chromosomes (chrI and chrII) whose replication and segregation are under different genetic controls. The region covering the replication origin of chrI resembles that of the Escherichia coli chromosome, and both origins are under control of the highly conserved initiator, DnaA. The origin region of chrII resembles that of plasmids that have iterated initiator-binding sites (iterons) and is under control of the chrII-specific initiator, RctB. Both chrI and chrII encode chromosome-specific orthologs of plasmid partitioning proteins, ParA and ParB. Here, we have interfered with chrII replication, segregation, or both, using extra copies of sites that titrate RctB or ParB. Under these conditions, replication and segregation of chrI remain unaffected for at least 1 cell cycle. In this respect, chrI behaves similarly to the E. coli chromosome when plasmid maintenance is disturbed in the same cell. Apparently, no checkpoint exists to block cell division before the crippled chromosome is lost by a failure to replicate or to segregate. Whether blocking chrI replication can affect chrII replication remains to be tested. IMPORTANCE Chromosome replication, chromosome segregation, and cell division are the three main events of the cell cycle. They occur in an orderly fashion once per cell cycle. How the sequence of events is controlled is only beginning to be answered in bacteria. The finding of bacteria that possess more than one chromosome raises the important question: how are different chromosomes coordinated in their replication and segregation? It appears that in the evolution of the two-chromosome genome of V. cholerae, either the secondary chromosome adapted to the main chromosome to ensure its maintenance or it is maintained independently, as are bacterial plasmids. An understanding of chromosome coordination is expected to bear on the evolutionary process of chromosome acquisition and on the efficacy of possible strategies for selective elimination of a pathogen by targeting a specific chromosome.
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Affiliation(s)
- Ryosuke Kadoya
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland, USA
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Siddique A, Figurski DH. Different phenotypes of Walker-like A box mutants of ParA homolog IncC of broad-host-range IncP plasmids. Plasmid 2012; 68:93-104. [PMID: 22579980 DOI: 10.1016/j.plasmid.2012.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 03/27/2012] [Accepted: 04/02/2012] [Indexed: 11/30/2022]
Abstract
The promiscuous IncPα plasmids RK2 and R995 encode a broad-host-range partition system, whose essential components include the incC and korB genes and a DNA site (O(B)) to which the korB product binds. IncC2, the smaller of the two incC products, is sufficient for stabilization of R995ΔincC. It is a member of the type Ia ParA family of partition ATPases. To better understand the role of ATP in partition, we constructed three alanine-substitution mutants of IncC2. Each mutation changed a different residue of the Walker-like ATP-binding and hydrolysis motif, including a lysine (K10) conserved solely among members of the ParA and MinD families. All three IncC2 mutants were defective in plasmid partition, but they differed from one another in other respects. The IncC2 T16A mutant, predicted to be defective in Mg²⁺ coordination, was severely impaired in all activities tested. IncC2 K10A, predicted to be defective in ATP hydrolysis, mediated enhanced incompatibility with R995 derivatives. IncC2 K15A, predicted to be defective in ATP binding, exhibited two distinct incompatibility properties depending on the genotype of the target plasmid. When in trans to plasmids carrying a complementable incC deletion, IncC2 K15A caused dramatic plasmid loss, even at low levels of expression. In trans to wild-type R995 or to R995ΔincC carrying a functional P1 partition system, IncC2 K15A-mediated incompatibility was significantly less than that caused by wild-type IncC2. All three Walker-like A box mutants were also defective for the host toxicity that normally results from co-overexpression of incC and korB. The phenotypes of the mutants support a model in which nucleotide hydrolysis is required for separation of paired plasmid complexes and possible interaction with a host factor.
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Affiliation(s)
- Azeem Siddique
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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30
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Pillet F, Sanchez A, Lane D, Anton Leberre V, Bouet JY. Centromere binding specificity in assembly of the F plasmid partition complex. Nucleic Acids Res 2011; 39:7477-86. [PMID: 21653553 PMCID: PMC3177203 DOI: 10.1093/nar/gkr457] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The segregation of plasmid F of Escherichia coli is highly reliable. The Sop partition locus, responsible for this stable maintenance, is composed of two genes, sopA and sopB and a centromere, sopC, consisting of 12 direct repeats of 43 bp. Each repeat carries a 16-bp inverted repeat motif to which SopB binds to form a nucleoprotein assembly called the partition complex. A database search for sequences closely related to sopC revealed unexpected features that appeared highly conserved. We have investigated the requirements for specific SopB-sopC interactions using a surface plasmon resonance imaging technique. We show that (i) only 10 repeats interact specifically with SopB, (ii) no base outside the 16-bp sopC sites is involved in binding specificity, whereas five bases present in each arm are required for interactions, and (iii) the A-C central bases contribute to binding efficiency by conforming to a need for a purine-pyrimidine dinucleotide. We have refined the SopB-sopC binding pattern by electro-mobility shift assay and found that all 16 bp are necessary for optimal SopB binding. These data and the model we propose, define the basis of the high binding specificity of F partition complex assembly, without which, dispersal of SopB over DNA would result in defective segregation.
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Affiliation(s)
- Flavien Pillet
- Université de Toulouse, INSA, UPS, INP, LISBP, Toulouse, France
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31
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Dam B. A type Ib plasmid segregation machinery of the Advenella kashmirensis plasmid pBTK445. Plasmid 2010; 65:185-91. [PMID: 21192970 DOI: 10.1016/j.plasmid.2010.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/17/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
Abstract
pBTK445 is a newly described large (∼60Kb), low-copy number, conjugative plasmid indigenous to the sulfur-chemolithoautotroph Advenella kashmirensis. Based on its minimal replication region, a shuttle vector, pBTKS was constructed which can be used for diverse Alcaligenaceae members. The construct was found to be stably maintained both in the native host as well as in Escherichia coli in the absence of selective pressure which indicated that pBTKS harbors the stabilizing system of pBTK445, that are commonly coded by low-copy-number plasmids. Deletion analyzes of pBTKS confirmed the essentiality of parA (encoding a Walker-type ATPase of 214 amino acids) and the downstream located small parB (encoding an 85 amino acid protein having no sequence homolog in the database) in the faithful partitioning of pBTK445. A 1075bp PCR product, containing parA, parB and an upstream sequence having nine 11bp direct repeats (parS site) was found to comprise the partition functions of pBTK445, stabilizing both low-copy or high-copy number homologous and heterologous replicons in diverse hosts. The incompatibility determinant and the par promoter, P(par) were both found to be present within a 191bp iterated sequence present upstream of parA. ParB was found to regulate the expression of the Par proteins from P(par). The presence of a typical Walker-type ATPase motif in ParA, a short phylogenetically unrelated ParB, that acts as a repressor of P(par), and location of the iterated parS site upstream of parA, confirm that the active partition system of pBTK445 belongs to the type Ib.
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Affiliation(s)
- Bomba Dam
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl Von Frisch Strasse 10, D-35043 Marburg, Germany.
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32
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Ah-Seng Y, Lopez F, Pasta F, Lane D, Bouet JY. Dual role of DNA in regulating ATP hydrolysis by the SopA partition protein. J Biol Chem 2009; 284:30067-75. [PMID: 19740757 DOI: 10.1074/jbc.m109.044800] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In bacteria, mitotic stability of plasmids and many chromosomes depends on replicon-specific systems, which comprise a centromere, a centromere-binding protein and an ATPase. Dynamic self-assembly of the ATPase appears to enable active partition of replicon copies into cell-halves, but for Walker-box partition ATPases the molecular mechanism is unknown. ATPase activity appears to be essential for this process. DNA and centromere-binding proteins are known to stimulate the ATPase activity but molecular details of the stimulation mechanism have not been reported. We have investigated the interactions which stimulate ATP hydrolysis by the SopA partition ATPase of plasmid F. By using SopA and SopB proteins deficient in DNA binding, we have found that the intrinsic ability of SopA to hydrolyze ATP requires direct DNA binding by SopA but not by SopB. Our results show that two independent interactions of SopA act in synergy to stimulate its ATPase. SopA must interact with (i) DNA, through its ATP-dependent nonspecific DNA binding domain and (ii) SopB, which we show here to provide an arginine-finger motif. In addition, the latter interaction stimulates ATPase maximally when SopB is part of the partition complex. Hence, our data demonstrate that DNA acts on SopA in two ways, directly as nonspecific DNA and through SopB as centromeric DNA, to fully activate SopA ATP hydrolysis.
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Affiliation(s)
- Yoan Ah-Seng
- Laboratoire de Microbiologie et Génétique Moléculaires, CNRS, F-31000 Toulouse, France
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33
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Bouet JY, Lane D. Molecular basis of the supercoil deficit induced by the mini-F plasmid partition complex. J Biol Chem 2008; 284:165-173. [PMID: 19001378 DOI: 10.1074/jbc.m802752200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Formation of a partition complex on plasmid F by binding of SopB protein to the sopC centromere is the first step in the partition process that ensures stability of F in dividing cells. Establishment of the complex enables nonspecific binding of SopB to neighboring DNA, which extends the partition complex and provokes reduction of negative supercoiling of the plasmid. This reduction is believed to reflect winding of DNA into positive supercoils about SopB to create a nucleoprotein structure of probable importance to partition. We have searched for evidence that SopB alters plasmid topology. Permutation analysis indicated only modest bending of linear DNA fragments, and in vivo DNase I footprinting revealed no enhanced cleavages indicating curvature. In vitro, SopB binding left no topological trace in relaxed-circular DNA treated with topoisomerase I or in nicked circles closed by ligase. In vivo, novobiocin-mediated inhibition of DNA gyrase relaxed a plasmid carrying the partition complex but left no residue of positive supercoils. Hence, SopB does not reduce plasmid supercoiling directly. We did observe that SopB partly prevented removal of negative supercoils from plasmid DNA by topoisomerase I and partly prevented ligation of nicked circles, indicating that it acts as a physical obstacle. The supercoil deficit is thus better explained as SopB recoating of just-replicated DNA, which shelters it from gyrase and from topological changes in SopB-free DNA. This topological simplicity distinguishes the Sop partition complex from other complexes described.
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Affiliation(s)
- Jean-Yves Bouet
- Laboratoire de Microbiologie et Gánátique Moláculaires, CNRS, F-31000 Toulouse, France and LMGM, Universitáde Toulouse, UPS, F-31000 Toulouse, France; Laboratoire de Microbiologie et Gánátique Moláculaires, CNRS, F-31000 Toulouse, France and LMGM, Universitáde Toulouse, UPS, F-31000 Toulouse, France.
| | - David Lane
- Laboratoire de Microbiologie et Gánátique Moláculaires, CNRS, F-31000 Toulouse, France and LMGM, Universitáde Toulouse, UPS, F-31000 Toulouse, France
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34
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Castaing JP, Bouet JY, Lane D. F plasmid partition depends on interaction of SopA with non-specific DNA. Mol Microbiol 2008; 70:1000-11. [PMID: 18826408 DOI: 10.1111/j.1365-2958.2008.06465.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Bacterial ATPases belonging to the ParA family assure partition of their replicons by forming dynamic assemblies which move replicon copies into the new cell-halves. The mechanism underlying partition is not understood for the Walker-box ATPase class, which includes most plasmid and all chromosomal ParAs. The ATPases studied both polymerize and interact with non-specific DNA in an ATP-dependent manner. Previous work showed that in vitro, polymerization of one such ATPase, SopA of plasmid F, is inhibited by DNA, suggesting that interaction of SopA with the host nucleoid could regulate partition. In an attempt to identify amino acids in SopA that are needed for interaction with non-specific DNA, we have found that mutation of codon 340 (lysine to alanine) reduces ATP-dependent DNA binding > 100-fold and correspondingly diminishes SopA activities that depend on it: inhibition of polymer formation and persistence, stimulation of basal-level ATP hydrolysis and localization over the nucleoid. The K340A mutant retained all other SopA properties tested except plasmid stabilization; substitution of the mutant SopA for wild-type nearly abolished mini-F partition. The behaviour of this mutant indicates a causal link between interaction with the cell's non-specific DNA and promotion of the dynamic behaviour that ensures F plasmid partition.
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Affiliation(s)
- Jean-Philippe Castaing
- Laboratoire de Microbiologie et Génétique Moléculaires, Université Paul Sabatier, F31000 Toulouse, France
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35
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Abstract
The mitotic apparatus that a plasmid uses to ensure its stable inheritance responds to the appearance of an additional copy of the plasmid's centromere by segregating it from the pre-existing copies: if the new copy arises by replication of the plasmid the result is partition, if it arrives on a different plasmid the result is incompatibility. Incompatibility thus serves as a probe of the partition mechanism. Coupling of distinct plasmids via their shared centromeres to form mixed pairs has been the favoured explanation for centromere-based incompatibility, because it supports a long-standing assumption that pairing of plasmid replicas is a prerequisite for their partition into daughter cells. Recent results from molecular genetic and fluorescence microscopy studies challenge this mixed pairing model. Partition incompatibility is seen to result from various processes, including titration, randomized positioning and a form of mixed pairing that is based on co-activation of the same partition event rather than direct contact between partition complexes. The perspectives thus opened onto the partition mechanism confirm the continuing utility of incompatibility as an approach to understanding bacterial mitosis. The results considered are compatible with the view that direct pairing of plasmids is not essential to plasmid partition.
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Affiliation(s)
- Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique, Campus Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
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36
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Bouet JY, Ah-Seng Y, Benmeradi N, Lane D. Polymerization of SopA partition ATPase: regulation by DNA binding and SopB. Mol Microbiol 2006; 63:468-81. [PMID: 17166176 DOI: 10.1111/j.1365-2958.2006.05537.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In bacteria, mitotic stability of plasmids and many chromosomes depends on replicon-specific systems which comprise a centromere, a centromere-binding protein and an ATPase. Dynamic self-assembly of the ATPase appears to enable active partition of replicon copies into cell-halves, but for most ATPases (the Walker-box type) the mechanism is unknown. Also unknown is how the host cell contributes to partition. We have examined the effects of non-sequence-specific DNA on in vitro self-assembly of the SopA partition ATPase of plasmid F. SopA underwent polymerization provided ATP was present. DNA inhibited this polymerization and caused breakdown of pre-formed polymers. Centromere-binding protein SopB counteracted DNA-mediated inhibition by itself binding to and masking the DNA, as well as by stimulating polymerization directly. The results suggest that in vivo, SopB smothers DNA by spreading from sopC, allowing SopA-ATP polymerization which initiates plasmid displacement. We propose that SopB and nucleoid DNA regulate SopA polymerization and hence partition.
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Affiliation(s)
- Jean-Yves Bouet
- Laboratoire de Microbiologie et de Génétique Moléculaire, UMR5100 CNRS, Toulouse, France.
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37
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Bouet JY, Bouvier M, Lane D. Concerted action of plasmid maintenance functions: partition complexes create a requirement for dimer resolution. Mol Microbiol 2006; 62:1447-59. [PMID: 17059567 DOI: 10.1111/j.1365-2958.2006.05454.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Partition of prokaryotic DNA requires formation of specific protein-centromere complexes, but an excess of the protein can disrupt segregation. The mechanisms underlying this destabilization are unknown. We have found that destabilization by the F plasmid partition protein, SopB, of plasmids carrying the F centromere, sopC, results from the capacity of the SopB-sopC partition complex to stimulate plasmid multimerization. Mutant SopBs unable to destabilize failed to increase multimerization. Stability of wild-type mini-F, whose ResD/rfsF site-specific recombination system enables it to resolve multimers to monomers, was barely affected by excess SopB. Destabilization of plasmids lacking the rfsF site was suppressed by recF, recO and recR, but not by recB, mutant alleles, indicating that multimerization is initiated from single-strand gaps. SopB did not alter the amounts or distribution of replication intermediates, implying that SopB-DNA complexes do not create single-strand gaps by blocking replication forks. Rather, the results are consistent with SopB-DNA complexes channelling gapped molecules into the RecFOR recombination pathway. We suggest that extended SopB-DNA complexes increase the likelihood of recombination between sibling plasmids by keeping them in close contact prior to SopA-mediated segregation. These results cast plasmid site-specific resolution in a new role - compensation for untoward consequences of partition complex formation.
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Affiliation(s)
- Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaire, Centre National de Recherche, Scientifique, Faculté Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
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38
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Adachi S, Hori K, Hiraga S. Subcellular Positioning of F Plasmid Mediated by Dynamic Localization of SopA and SopB. J Mol Biol 2006; 356:850-63. [PMID: 16403518 DOI: 10.1016/j.jmb.2005.11.088] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2005] [Revised: 11/11/2005] [Accepted: 11/30/2005] [Indexed: 11/16/2022]
Abstract
SopA, SopB proteins and the cis-acting sopC DNA region of F plasmid are essential for partitioning of the plasmid, ensuring proper subcellular positioning of the plasmid DNA molecules. We have analyzed by immunofluorescence microscopy the subcellular localization of SopA and SopB. The majority of SopB molecules formed foci, which localized frequently with F plasmid DNA molecules. The foci increased in number in proportion to the cell length. Interestingly, beside the foci formation, SopB formed a spiral structure that was dependent on SopA, which also formed a spiral structure, independent of the presence of SopB, and these two structures partially overlapped. On the basis of these results and previous biochemical studies together with our simulations, we propose a theoretical model named "the reaction-diffusion partitioning model", using reaction-diffusion equations that explain the dynamic subcellular localization of SopA and SopB proteins and the subcellular positioning of F plasmid. We hypothesized that sister copies of plasmid DNA compete with each other for sites at which SopB multimer is at the optimum concentration. The plasmid incompatibility mediated by the Sop system might be explained clearly by this hypothesis.
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Affiliation(s)
- Shun Adachi
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
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39
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Abstract
Bacterial plasmids encode partitioning (par) loci that ensure ordered plasmid segregation prior to cell division. par loci come in two types: those that encode actin-like ATPases and those that encode deviant Walker-type ATPases. ParM, the actin-like ATPase of plasmid R1, forms dynamic filaments that segregate plasmids paired at mid-cell to daughter cells. Like microtubules, ParM filaments exhibit dynamic instability (i.e., catastrophic decay) whose regulation is an important component of the DNA segregation process. The Walker box ParA ATPases are related to MinD and form highly dynamic, oscillating filaments that are required for the subcellular movement and positioning of plasmids. The role of the observed ATPase oscillation is not yet understood. However, we propose a simple model that couples plasmid segregation to ParA oscillation. The model is consistent with the observed movement and localization patterns of plasmid foci and does not require the involvement of plasmid-specific host-encoded factors.
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Affiliation(s)
- Gitte Ebersbach
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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40
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Dabrazhynetskaya A, Sergueev K, Austin S. Species and incompatibility determination within the P1par family of plasmid partition elements. J Bacteriol 2005; 187:5977-83. [PMID: 16109939 PMCID: PMC1196149 DOI: 10.1128/jb.187.17.5977-5983.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The P1par family of active plasmid partition systems consists of at least six members, broadly distributed in a variety of plasmid types and bacterial genera. Each encodes two Par proteins and contains a cis-acting parS site. Individual par systems can show distinct species specificities; the proteins from one type cannot function with the parS site of another. P1par-versus-P7par specificity resides within two hexamer BoxB repeats encoded by parS that contact the ParB protein near the carboxy terminus. Here, we examine the species specificity differences between Yersinia pestis pMT1parS and Escherichia coli P1 and P7parS. pMT1parS site specificity could be altered to that of either P1 or P7 by point mutation changes in the BoxB repeats. Just one base change in a single BoxB repeat sometimes sufficed. The BoxB sequence appears to be able to adopt a number of forms that define exclusive interactions with different ParB species. The looped parS structure may facilitate this repertoire of interaction specificities. Different P1par family members have different partition-mediated incompatibility specificities. This property defines whether two related plasmids can coexist in the same cell and is important in promoting the evolution of new plasmid species. BoxB sequence changes that switch species specificity between P1, P7, and pMT1 species switched partition-mediated plasmid incompatibility in concert. Thus, there is a direct mechanistic link between species specificity and partition-mediated incompatibility, and the BoxB-ParB interaction can be regarded as a special mechanism for facilitating plasmid evolution.
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Affiliation(s)
- Alena Dabrazhynetskaya
- Gene Regulation & Chromosome Biology Laboratory, National Cancer Institute, CCR, NCI-Frederick, Frederick, MD 21702-1201, USA
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41
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Ebersbach G, Sherratt DJ, Gerdes K. Partition-associated incompatibility caused by random assortment of pure plasmid clusters. Mol Microbiol 2005; 56:1430-40. [PMID: 15916596 DOI: 10.1111/j.1365-2958.2005.04643.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Summary Bacterial plasmids and chromosomes encode centromere-like partition loci that actively segregate DNA before cell division. The molecular mechanism behind DNA segregation in bacteria is largely unknown. Here we analyse the mechanism of partition-associated incompatibility for plasmid pB171, a phenotype associated with all known plasmid-encoded centromere loci. An R1 plasmid carrying par2 from plasmid pB171 was destabilized by the presence of an F plasmid carrying parC1, parC2 or the entire par2 locus of pB171. Strikingly, cytological double-labelling experiments revealed no evidence of long-lived pairing of plasmids. Instead, pure R1 and F foci were positioned along the length of the cell, and in a random order. Thus, our results raise the possibility that partition-mediated plasmid incompatibility is not caused by pairing of heterologous plasmids but instead by random positioning of pure plasmid clusters along the long axis of the cell. The strength of the incompatibility was correlated with the capability of the plasmids to compete for the mid-cell position.
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Affiliation(s)
- Gitte Ebersbach
- Department of Biochemistry and Molecular Biology, Campusvej 55, DK-5230 Odense M, University of Southern Denmark, Denmark
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