1
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Humphrey ED, Sukhodolets MV. Isolation and Partial Characterization of Novel, Structurally Uniform (Hfq 6) n≥8 Assemblies Carrying Accessory Transcription and Translation Factors. Biochemistry 2024; 63:1647-1662. [PMID: 38869079 DOI: 10.1021/acs.biochem.3c00728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
In growing E. coli cells, the transcription-translation complexes (TTCs) form characteristic foci; however, the exact molecular composition of these superstructures is not known with certainty. Herein, we report that, during our recently developed "fast" procedures for purification of E. coli RNA polymerase (RP), a fraction of the RP's α/RpoA subunits is displaced from the core RP complexes and copurifies with multiprotein superstructures carrying the nucleic acid-binding protein Hfq and the ribosomal protein S6. We show that the main components of these large multiprotein assemblies are fixed protein copy-number (Hfq6)n≥8 complexes; these complexes have a high level of structural uniformity and are distinctly unlike the previously described (Hfq6)n "head-to-tail" polymers. We describe purification of these novel, structurally uniform (Hfq6)n≥8 complexes to near homogeneity and show that they also contain small nonprotein molecules and accessory S6. We demonstrate that Hfq, S6, and RP have similar solubility profiles and present evidence pointing to a role of the Hfq C-termini in superstructure formation. Taken together, our data offer new insights into the composition of the macromolecular assemblies likely acting as scaffolds for transcription complexes and ribosomes during bacterial cells' active growth.
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Affiliation(s)
- Elijah D Humphrey
- Department of Chemistry and Biochemistry, Lamar University, Beaumont, Texas 77710, United States
| | - Maxim V Sukhodolets
- Department of Chemistry and Biochemistry, Lamar University, Beaumont, Texas 77710, United States
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2
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Bignaud A, Koszul R. [Transcription: The backbone of bacterial chromosome architecture]. Med Sci (Paris) 2024; 40:412-413. [PMID: 38819274 DOI: 10.1051/medsci/2024057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024] Open
Affiliation(s)
- Amaury Bignaud
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation spatiale des génomes, Paris, France
| | - Romain Koszul
- Institut Pasteur, CNRS UMR3525, Université Paris Cité, Unité Régulation spatiale des génomes, Paris, France
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3
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Chaboche Q, Campos-Villalobos G, Giunta G, Dijkstra M, Cosentino Lagomarsino M, Scolari VF. A mean-field theory for predicting single polymer collapse induced by neutral crowders. SOFT MATTER 2024; 20:3271-3282. [PMID: 38456237 DOI: 10.1039/d3sm01522j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Macromolecular crowding can induce the collapse of a single long polymer into a globular form due to depletion forces of entropic nature. This phenomenon has been shown to play a significant role in compacting the genome within the bacterium Escherichia coli into a well-defined region of the cell known as the nucleoid. Motivated by the biological significance of this process, numerous theoretical and computational studies have searched for the primary determinants of the behavior of polymer-crowder phases. However, our understanding of this process remains incomplete and there is debate on a quantitatively unified description. In particular, different simulation studies with explicit crowders have proposed different order parameters as potential predictors for the collapse transition. In this work, we present a comprehensive analysis of published simulation data obtained from different sources. Based on the common behavior we find in this data, we develop a unified phenomenological model that we show to be predictive. Finally, to further validate the accuracy of the model, we conduct new simulations on polymers of various sizes, and investigate the role of jamming of the crowders.
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Affiliation(s)
- Quentin Chaboche
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physique des Cellules et Cancer, 75005 Paris, France
- IFOM ETS, The AIRC Institute of Molecular Oncology, 20139, Milan, Italy.
| | - Gerardo Campos-Villalobos
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Giuliana Giunta
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
- BASF SE, Carl-Bosch-Strasse 38, 67056 Ludwigshafen am Rhein, Germany
| | - Marjolein Dijkstra
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Marco Cosentino Lagomarsino
- IFOM ETS, The AIRC Institute of Molecular Oncology, 20139, Milan, Italy.
- Physics Department, University of Milan, and INFN, Milan, Italy
| | - Vittore F Scolari
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physique des Cellules et Cancer, 75005 Paris, France
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.
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4
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Kuzminov A. Bacterial nucleoid is a riddle wrapped in a mystery inside an enigma. J Bacteriol 2024; 206:e0021123. [PMID: 38358278 PMCID: PMC10994824 DOI: 10.1128/jb.00211-23] [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] [Indexed: 02/16/2024] Open
Abstract
Bacterial chromosome, the nucleoid, is traditionally modeled as a rosette of DNA mega-loops, organized around proteinaceous central scaffold by nucleoid-associated proteins (NAPs), and mixed with the cytoplasm by transcription and translation. Electron microscopy of fixed cells confirms dispersal of the cloud-like nucleoid within the ribosome-filled cytoplasm. Here, I discuss evidence that the nucleoid in live cells forms DNA phase separate from riboprotein phase, the "riboid." I argue that the nucleoid-riboid interphase, where DNA interacts with NAPs, transcribing RNA polymerases, nascent transcripts, and ssRNA chaperones, forms the transcription zone. An active part of phase separation, transcription zone enforces segregation of the centrally positioned information phase (the nucleoid) from the surrounding action phase (the riboid), where translation happens, protein accumulates, and metabolism occurs. I speculate that HU NAP mostly tiles up the nucleoid periphery-facilitating DNA mobility but also supporting transcription in the interphase. Besides extruding plectonemically supercoiled DNA mega-loops, condensins could compact them into solenoids of uniform rings, while HU could support rigidity and rotation of these DNA rings. The two-phase cytoplasm arrangement allows the bacterial cell to organize the central dogma activities, where (from the cell center to its periphery) DNA replicates and segregates, DNA is transcribed, nascent mRNA is handed over to ribosomes, mRNA is translated into proteins, and finally, the used mRNA is recycled into nucleotides at the inner membrane. The resulting information-action conveyor, with one activity naturally leading to the next one, explains the efficiency of prokaryotic cell design-even though its main intracellular transportation mode is free diffusion.
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Affiliation(s)
- Andrei Kuzminov
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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5
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Bignaud A, Cockram C, Borde C, Groseille J, Allemand E, Thierry A, Marbouty M, Mozziconacci J, Espéli O, Koszul R. Transcription-induced domains form the elementary constraining building blocks of bacterial chromosomes. Nat Struct Mol Biol 2024; 31:489-497. [PMID: 38177686 PMCID: PMC10948358 DOI: 10.1038/s41594-023-01178-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/10/2023] [Indexed: 01/06/2024]
Abstract
Transcription generates local topological and mechanical constraints on the DNA fiber, leading to the generation of supercoiled chromosome domains in bacteria. However, the global impact of transcription on chromosome organization remains elusive, as the scale of genes and operons in bacteria remains well below the resolution of chromosomal contact maps generated using Hi-C (~5-10 kb). Here we combined sub-kb Hi-C contact maps and chromosome engineering to visualize individual transcriptional units. We show that transcriptional units form discrete three-dimensional transcription-induced domains that impose mechanical and topological constraints on their neighboring sequences at larger scales, modifying their localization and dynamics. These results show that transcriptional domains constitute primary building blocks of bacterial chromosome folding and locally impose structural and dynamic constraints.
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Affiliation(s)
- Amaury Bignaud
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Collège Doctoral, Sorbonne Université, Paris, France
| | - Charlotte Cockram
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Céline Borde
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Justine Groseille
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
- Collège Doctoral, Sorbonne Université, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Eric Allemand
- INSERM-U1163, Unité mécanismes cellulaires et moléculaires des désordres hématologiques et implications thérapeutiques, Institut Imagine, Paris, France
| | - Agnès Thierry
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
| | - Martial Marbouty
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France
| | - Julien Mozziconacci
- Laboratoire Structure et Instabilité des Génomes, UMR 7196, Muséum National d'Histoire Naturelle, Paris, France
| | - Olivier Espéli
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France.
| | - Romain Koszul
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, Paris, France.
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6
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Wasim A, Bera P, Mondal J. Development of a Data-Driven Integrative Model of a Bacterial Chromosome. J Chem Theory Comput 2024; 20:1673-1688. [PMID: 37083406 DOI: 10.1021/acs.jctc.3c00118] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
The chromosome of archetypal bacteria E. coli is known for a complex topology with a 4.6 × 106 base pairs (bp) long sequence of nucleotides packed within a micrometer-sized cellular confinement. The inherent organization underlying this chromosome eludes general consensus due to the lack of a high-resolution picture of its conformation. Here we present our development of an integrative model of E. coli at a 500 bp resolution (https://github.com/JMLab-tifrh/ecoli_finer), which optimally combines a set of multiresolution genome-wide experimentally measured data within a framework of polymer based architecture. In particular the model is informed with an intragenome contact probability map at 5000 bp resolution derived via the Hi-C experiment and RNA-sequencing data at 500 bp resolution. Via dynamical simulations, this data-driven polymer based model generates an appropriate conformational ensemble commensurate with chromosome architectures that E. coli adopts. As a key hallmark of the E. coli chromosome the model spontaneously self-organizes into a set of nonoverlapping macrodomains and suitably locates plectonemic loops near the cell membrane. As novel extensions, it predicts a contact probability map simulated at a higher resolution than precedent experiments and can demonstrate segregation of chromosomes in a partially replicating cell. Finally, the modular nature of the model helps us devise control simulations to quantify the individual role of key features in hierarchical organization of the bacterial chromosome.
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Affiliation(s)
- Abdul Wasim
- Tata Institute of Fundamental Research Hyderabad, Hyderabad, Telangana 500046, India
| | - Palash Bera
- Tata Institute of Fundamental Research Hyderabad, Hyderabad, Telangana 500046, India
| | - Jagannath Mondal
- Tata Institute of Fundamental Research Hyderabad, Hyderabad, Telangana 500046, India
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7
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Shang W, Lichtenberg E, Mlesnita AM, Wilde A, Koch HG. The contribution of mRNA targeting to spatial protein localization in bacteria. FEBS J 2024. [PMID: 38226707 DOI: 10.1111/febs.17054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/27/2023] [Accepted: 01/08/2024] [Indexed: 01/17/2024]
Abstract
About 30% of all bacterial proteins execute their function outside of the cytosol and must be inserted into or translocated across the cytoplasmic membrane. This requires efficient targeting systems that recognize N-terminal signal sequences in client proteins and deliver them to protein transport complexes in the membrane. While the importance of these protein transport machineries for the spatial organization of the bacterial cell is well documented in multiple studies, the contribution of mRNA targeting and localized translation to protein transport is only beginning to emerge. mRNAs can exhibit diverse subcellular localizations in the bacterial cell and can accumulate at sites where new protein is required. This is frequently observed for mRNAs encoding membrane proteins, but the physiological importance of membrane enrichment of mRNAs and the consequences it has for the insertion of the encoded protein have not been explored in detail. Here, we briefly highlight some basic concepts of signal sequence-based protein targeting and describe in more detail strategies that enable the monitoring of mRNA localization in bacterial cells and potential mechanisms that route mRNAs to particular positions within the cell. Finally, we summarize some recent developments that demonstrate that mRNA targeting and localized translation can sustain membrane protein insertion under stress conditions when the protein-targeting machinery is compromised. Thus, mRNA targeting likely acts as a back-up strategy and complements the canonical signal sequence-based protein targeting.
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Affiliation(s)
- Wenkang Shang
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs University Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs University Freiburg, Germany
| | | | - Andreea Mihaela Mlesnita
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs University Freiburg, Germany
| | - Annegret Wilde
- Faculty of Biology, Albert-Ludwigs University Freiburg, Germany
| | - Hans-Georg Koch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs University Freiburg, Germany
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8
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Cornet F, Blanchais C, Dusfour-Castan R, Meunier A, Quebre V, Sekkouri Alaoui H, Boudsoq F, Campos M, Crozat E, Guynet C, Pasta F, Rousseau P, Ton Hoang B, Bouet JY. DNA Segregation in Enterobacteria. EcoSal Plus 2023; 11:eesp00382020. [PMID: 37220081 PMCID: PMC10729935 DOI: 10.1128/ecosalplus.esp-0038-2020] [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: 11/24/2022] [Accepted: 04/13/2023] [Indexed: 01/28/2024]
Abstract
DNA segregation ensures that cell offspring receive at least one copy of each DNA molecule, or replicon, after their replication. This important cellular process includes different phases leading to the physical separation of the replicons and their movement toward the future daughter cells. Here, we review these phases and processes in enterobacteria with emphasis on the molecular mechanisms at play and their controls.
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Affiliation(s)
- François Cornet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Corentin Blanchais
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Romane Dusfour-Castan
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Alix Meunier
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Valentin Quebre
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Hicham Sekkouri Alaoui
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - François Boudsoq
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Manuel Campos
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Estelle Crozat
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Catherine Guynet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Franck Pasta
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Philippe Rousseau
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Bao Ton Hoang
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, Toulouse, France
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9
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Puentes-Rodriguez SG, Norcross J, Mera PE. To let go or not to let go: how ParA can impact the release of the chromosomal anchoring in Caulobacter crescentus. Nucleic Acids Res 2023; 51:12275-12287. [PMID: 37933842 PMCID: PMC10711552 DOI: 10.1093/nar/gkad982] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/06/2023] [Accepted: 10/17/2023] [Indexed: 11/08/2023] Open
Abstract
Chromosomal maintenance is vital for the survival of bacteria. In Caulobacter crescentus, chromosome replication initiates at ori and segregation is delayed until the nearby centromere-like region parS is replicated. Our understanding of how this sequence of events is regulated remains limited. The segregation of parS has been shown to involve multiple steps including polar release from anchoring protein PopZ, slow movement and fast ParA-dependent movement to the opposite cell pole. In this study, we demonstrate that ParA's competing attractions from PopZ and from DNA are critical for segregation of parS. Interfering with this balance of attractions-by expressing a variant ParA-R195E unable to bind DNA and thus favoring interactions exclusively between ParA-PopZ-results in cell death. Our data revealed that ParA-R195E's sole interactions with PopZ obstruct PopZ's ability to release the polar anchoring of parS, resulting in cells with multiple parS loci fixed at one cell pole. We show that the inability to separate and segregate multiple parS loci from the pole is specifically dependent on the interaction between ParA and PopZ. Collectively, our results reveal that the initial steps in chromosome segregation are highly regulated.
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Affiliation(s)
| | - John D Norcross
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Paola E Mera
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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10
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Junier I, Ghobadpour E, Espeli O, Everaers R. DNA supercoiling in bacteria: state of play and challenges from a viewpoint of physics based modeling. Front Microbiol 2023; 14:1192831. [PMID: 37965550 PMCID: PMC10642903 DOI: 10.3389/fmicb.2023.1192831] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 09/25/2023] [Indexed: 11/16/2023] Open
Abstract
DNA supercoiling is central to many fundamental processes of living organisms. Its average level along the chromosome and over time reflects the dynamic equilibrium of opposite activities of topoisomerases, which are required to relax mechanical stresses that are inevitably produced during DNA replication and gene transcription. Supercoiling affects all scales of the spatio-temporal organization of bacterial DNA, from the base pair to the large scale chromosome conformation. Highlighted in vitro and in vivo in the 1960s and 1970s, respectively, the first physical models were proposed concomitantly in order to predict the deformation properties of the double helix. About fifteen years later, polymer physics models demonstrated on larger scales the plectonemic nature and the tree-like organization of supercoiled DNA. Since then, many works have tried to establish a better understanding of the multiple structuring and physiological properties of bacterial DNA in thermodynamic equilibrium and far from equilibrium. The purpose of this essay is to address upcoming challenges by thoroughly exploring the relevance, predictive capacity, and limitations of current physical models, with a specific focus on structural properties beyond the scale of the double helix. We discuss more particularly the problem of DNA conformations, the interplay between DNA supercoiling with gene transcription and DNA replication, its role on nucleoid formation and, finally, the problem of scaling up models. Our primary objective is to foster increased collaboration between physicists and biologists. To achieve this, we have reduced the respective jargon to a minimum and we provide some explanatory background material for the two communities.
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Affiliation(s)
- Ivan Junier
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, Grenoble, France
| | - Elham Ghobadpour
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, Grenoble, France
- École Normale Supérieure (ENS) de Lyon, CNRS, Laboratoire de Physique and Centre Blaise Pascal de l'ENS de Lyon, Lyon, France
| | - Olivier Espeli
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Ralf Everaers
- École Normale Supérieure (ENS) de Lyon, CNRS, Laboratoire de Physique and Centre Blaise Pascal de l'ENS de Lyon, Lyon, France
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11
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Puentes-Rodriguez SG, Norcross J, Mera PE. To let go or not to let go: how ParA can impact the release of the chromosomal anchoring in Caulobacter crescentus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536610. [PMID: 37090538 PMCID: PMC10120649 DOI: 10.1101/2023.04.12.536610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Chromosomal maintenance is vital for the survival of bacteria. In Caulobacter crescentus, chromosome replication initiates at ori and segregation is delayed until the nearby centromere-like region parS is replicated. Our understanding of how this sequence of events is regulated remains limited. The segregation of parS has been shown to involve multiple steps including polar release from anchoring protein PopZ, slow movement, and fast ParA-dependent movement to opposite cell pole. In this study, we demonstrate that ParA's competing attractions from PopZ and from DNA are critical for segregation of parS. Interfering with this balance of attractions - by expressing a variant ParA-R195E unable to bind DNA and thus favoring interactions exclusively between ParA-PopZ - results in cell death. Our data revealed that ParA-R195E's sole interactions with PopZ obstruct PopZ's ability to release the polar anchoring of parS resulting in cells with multiple parS loci fixed at one cell pole. We show that the inability to separate and segregate multiple parS loci from the pole is specifically dependent on the interaction between ParA and PopZ. Interfering with interactions between PopZ and the partitioning protein ParB, which is the interaction that anchors parS at the cell pole, does not rescue the ability of cells to separate the fixed parS loci when expressing parA-R195E. Thus, ParA and PopZ appear to have a distinct conversation from ParB yet can impact the release of ParB-parS from the anchoring at the cell pole. Collectively, our results reveal that the initial steps in chromosome segregation are highly regulated.
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Affiliation(s)
| | - J.D. Norcross
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Paola E. Mera
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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12
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Arbel-Goren R, McKeithen-Mead SA, Voglmaier D, Afremov I, Teza G, Grossman AD, Stavans J. Target search by an imported conjugative DNA element for a unique integration site along a bacterial chromosome during horizontal gene transfer. Nucleic Acids Res 2023; 51:3116-3129. [PMID: 36762480 PMCID: PMC10123120 DOI: 10.1093/nar/gkad068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/18/2023] [Accepted: 01/25/2023] [Indexed: 02/11/2023] Open
Abstract
Integrative and conjugative elements (ICEs) are mobile genetic elements that can transfer by conjugation to recipient cells. Some ICEs integrate into a unique site in the genome of their hosts. We studied quantitatively the process by which an ICE searches for its unique integration site in the Bacillus subtilis chromosome. We followed the motion of both ICEBs1 and the chromosomal integration site in real time within individual cells. ICEBs1 exhibited a wide spectrum of dynamical behaviors, ranging from rapid sub-diffusive displacements crisscrossing the cell, to kinetically trapped states. The chromosomal integration site moved sub-diffusively and exhibited pronounced dynamical asymmetry between longitudinal and transversal motions, highlighting the role of chromosomal structure and the heterogeneity of the bacterial interior in the search. The successful search for and subsequent recombination into the integration site is a key step in the acquisition of integrating mobile genetic elements. Our findings provide new insights into intracellular transport processes involving large DNA molecules.
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Affiliation(s)
- Rinat Arbel-Goren
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Dominik Voglmaier
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Idana Afremov
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gianluca Teza
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alan D Grossman
- Department of Biology Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Joel Stavans
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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13
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Waszkiewicz R, Ranasinghe M, Fogg JM, Catanese DJ, Ekiel-Jeżewska ML, Lisicki M, Demeler B, Zechiedrich L, Szymczak P. DNA supercoiling-induced shapes alter minicircle hydrodynamic properties. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522747. [PMID: 36711572 PMCID: PMC9881935 DOI: 10.1101/2023.01.04.522747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA in cells is organized in negatively supercoiled loops. The resulting torsional and bending strain allows DNA to adopt a surprisingly wide variety of 3-D shapes. This interplay between negative supercoiling, looping, and shape influences how DNA is stored, replicated, transcribed, repaired, and likely every other aspect of DNA activity. To understand the consequences of negative supercoiling and curvature on the hydrodynamic properties of DNA, we submitted 336 bp and 672 bp DNA minicircles to analytical ultracentrifugation (AUC). We found that the diffusion coefficient, sedimentation coefficient, and the DNA hydrodynamic radius strongly depended on circularity, loop length, and degree of negative supercoiling. Because AUC cannot ascertain shape beyond degree of non-globularity, we applied linear elasticity theory to predict DNA shapes, and combined these with hydrodynamic calculations to interpret the AUC data, with reasonable agreement between theory and experiment. These complementary approaches, together with earlier electron cryotomography data, provide a framework for understanding and predicting the effects of supercoiling on the shape and hydrodynamic properties of DNA.
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Affiliation(s)
- Radost Waszkiewicz
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Maduni Ranasinghe
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Alberta, T1K3M4, Canada
| | - Jonathan M. Fogg
- Department of Molecular Virology and Microbiology, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Department of Pharmacology and Chemical Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Daniel J. Catanese
- Department of Biosciences, Rice University, 6100 Main St., Houston, TX 77005-1827, USA
| | - Maria L. Ekiel-Jeżewska
- Institute of Fundamental Technological Research, Polish Academy of Sciences, A. Pawińskiego 5B, 02-106 Warsaw, Poland,Co-contributing authors: MLE-J: , ML: , BD: , LZ: , PS:
| | - Maciej Lisicki
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland,Co-contributing authors: MLE-J: , ML: , BD: , LZ: , PS:
| | - Borries Demeler
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Alberta, T1K3M4, Canada,University of Montana, Dept. of Chemistry and Biochemistry, Missoula, MT 59812, USA,Co-contributing authors: MLE-J: , ML: , BD: , LZ: , PS:
| | - Lynn Zechiedrich
- Department of Molecular Virology and Microbiology, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Department of Pharmacology and Chemical Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA,Co-contributing authors: MLE-J: , ML: , BD: , LZ: , PS:
| | - Piotr Szymczak
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland,Co-contributing authors: MLE-J: , ML: , BD: , LZ: , PS:
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14
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Mitra D, Pande S, Chatterji A. Polymer architecture orchestrates the segregation and spatial organization of replicating E. coli chromosomes in slow growth. SOFT MATTER 2022; 18:5615-5631. [PMID: 35861071 DOI: 10.1039/d2sm00734g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The mechanism of chromosome segregation and organization in the bacterial cell cycle of E. coli is one of the least understood aspects in its life cycle. The E. coli chromosome is often modelled as a bead spring ring polymer. We introduce cross-links in the DNA-ring polymer, resulting in the formation of loops within each replicating bacterial chromosome. We use simulations to show that the chosen polymer-topology ensures its self-organization along the cell long-axis, such that various chromosomal loci get spatially localized as seen in vivo. The localization of loci arises due to entropic repulsion between polymer loops within each daughter DNA confined in a cylinder. The cellular addresses of the loci in our model are in fair agreement with those seen in experiments as given in J. A. Cass et al., Biophys. J., 2016, 110, 2597-2609. We also show that the adoption of such modified polymer architectures by the daughter DNAs leads to an enhanced propensity of their spatial segregation. Secondly, we match other experimentally reported results, including observation of the cohesion time and the ter-transition. Additionally, the contact map generated from our simulations reproduces the macro-domain like organization as seen in the experimentally obtained Hi-C map. Lastly, we have also proposed a plausible reconciliation of the 'Train Track' and the 'Replication Factory' models which provide conflicting descriptions of the spatial organization of the replication forks. Thus, we reconcile observations from complementary experimental techniques probing bacterial chromosome organization.
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15
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Subcellular Dynamics of a Conserved Bacterial Polar Scaffold Protein. Genes (Basel) 2022; 13:genes13020278. [PMID: 35205323 PMCID: PMC8872289 DOI: 10.3390/genes13020278] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 02/05/2023] Open
Abstract
In order to survive, bacterial cells rely on precise spatiotemporal organization and coordination of essential processes such as cell growth, chromosome segregation, and cell division. Given the general lack of organelles, most bacteria are forced to depend on alternative localization mechanisms, such as, for example, geometrical cues. DivIVA proteins are widely distributed in mainly Gram-positive bacteria and were shown to bind the membrane, typically in regions of strong negative curvature, such as the cell poles and division septa. Here, they have been shown to be involved in a multitude of processes: from apical cell growth and chromosome segregation in actinobacteria to sporulation and inhibition of division re-initiation in firmicutes. Structural analyses revealed that DivIVA proteins can form oligomeric assemblies that constitute a scaffold for recruitment of other proteins. However, it remained unclear whether interaction with partner proteins influences DivIVA dynamics. Using structured illumination microscopy (SIM), single-particle tracking (SPT) microscopy, and fluorescent recovery after photobleaching (FRAP) experiments, we show that DivIVA from Corynebacterium glutamicum is mobilized by its binding partner ParB. In contrast, we show that the interaction between Bacillus subtilis DivIVA and its partner protein MinJ reduces DivIVA mobility. Furthermore, we show that the loss of the rod-shape leads to an increase in DivIVA dynamics in both organisms. Taken together, our study reveals the modulation of the polar scaffold protein by protein interactors and cell morphology. We reason that this leads to a very simple, yet robust way for actinobacteria to maintain polar growth and their rod-shape. In B. subtilis, however, the DivIVA protein is tailored towards a more dynamic function that allows quick relocalization from poles to septa upon division.
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16
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Troung SF, Sukhodolets MV. The bacterial protein Hfq: Stable modifications and growth phase-dependent changes in SPAM profiles. J Chromatogr B Analyt Technol Biomed Life Sci 2021; 1183:122958. [PMID: 34628185 DOI: 10.1016/j.jchromb.2021.122958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/25/2022]
Abstract
In bacteria transcription is coupled to translation, and while it is broadly accepted that transcription-translation complexes (TTCs) are formed in growing bacterial cells, the exact spatial organization of these macromolecular assemblies is not known with certainty. Recent studies indicated the formation of orderly cytosolic superstructures in growing E. coli cells. The bacterial nucleic acid (NA)-binding protein Hfq has been shown to function at the interface of RNA synthesis-degradation machinery; multiple, independent studies link Hfq to orderly cytosolic assemblies. In this work, using fast cell lysis/2D-PAGE and in vitro reconstitution analyses we studied the Hfq modifications and small protein-associated molecules (SPAM). We demonstrate that native Hfq carries stable modifications and simulate 2D patterns of native Hfq-SPAM complexes in reconstitution experiments with purified Hfq and synthetic NA probes. We also demonstrate that genetically engineered Hfq lacking the conserved arginine residues positioned near the rim of the disc formed by the subunits' N-terminal domains binds DNA with a reduced affinity in comparison with wild-type Hfq. These results are consistent with the proposed Hfq-mediated DNA remodeling and point to the involvement of this patch of conserved arginines in interactions with DNA.
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Affiliation(s)
- Stanley F Troung
- Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX 77710, United States
| | - Maxim V Sukhodolets
- Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX 77710, United States.
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17
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Fogg JM, Judge AK, Stricker E, Chan HL, Zechiedrich L. Supercoiling and looping promote DNA base accessibility and coordination among distant sites. Nat Commun 2021; 12:5683. [PMID: 34584096 PMCID: PMC8478907 DOI: 10.1038/s41467-021-25936-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 08/30/2021] [Indexed: 11/29/2022] Open
Abstract
DNA in cells is supercoiled and constrained into loops and this supercoiling and looping influence every aspect of DNA activity. We show here that negative supercoiling transmits mechanical stress along the DNA backbone to disrupt base pairing at specific distant sites. Cooperativity among distant sites localizes certain sequences to superhelical apices. Base pair disruption allows sharp bending at superhelical apices, which facilitates DNA writhing to relieve torsional strain. The coupling of these processes may help prevent extensive denaturation associated with genomic instability. Our results provide a model for how DNA can form short loops, which are required for many essential processes, and how cells may use DNA loops to position nicks to facilitate repair. Furthermore, our results reveal a complex interplay between site-specific disruptions to base pairing and the 3-D conformation of DNA, which influences how genomes are stored, replicated, transcribed, repaired, and many other aspects of DNA activity.
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Affiliation(s)
- Jonathan M Fogg
- Department of Molecular Virology and Microbiology, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA
- Department of Pharmacology and Chemical Biology, Houston, TX, USA
| | - Allison K Judge
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA
| | - Erik Stricker
- Department of Molecular Virology and Microbiology, Houston, TX, USA
| | - Hilda L Chan
- Graduate Program in Immunology and Microbiology, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
| | - Lynn Zechiedrich
- Department of Molecular Virology and Microbiology, Houston, TX, USA.
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA.
- Department of Pharmacology and Chemical Biology, Houston, TX, USA.
- Graduate Program in Immunology and Microbiology, Houston, TX, USA.
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18
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Gogou C, Japaridze A, Dekker C. Mechanisms for Chromosome Segregation in Bacteria. Front Microbiol 2021; 12:685687. [PMID: 34220773 PMCID: PMC8242196 DOI: 10.3389/fmicb.2021.685687] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/19/2021] [Indexed: 11/13/2022] Open
Abstract
The process of DNA segregation, the redistribution of newly replicated genomic material to daughter cells, is a crucial step in the life cycle of all living systems. Here, we review DNA segregation in bacteria which evolved a variety of mechanisms for partitioning newly replicated DNA. Bacterial species such as Caulobacter crescentus and Bacillus subtilis contain pushing and pulling mechanisms that exert forces and directionality to mediate the moving of newly synthesized chromosomes to the bacterial poles. Other bacteria such as Escherichia coli lack such active segregation systems, yet exhibit a spontaneous de-mixing of chromosomes due to entropic forces as DNA is being replicated under the confinement of the cell wall. Furthermore, we present a synopsis of the main players that contribute to prokaryotic genome segregation. We finish with emphasizing the importance of bottom-up approaches for the investigation of the various factors that contribute to genome segregation.
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Affiliation(s)
- Christos Gogou
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Aleksandre Japaridze
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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19
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Wasim A, Gupta A, Mondal J. A Hi-C data-integrated model elucidates E. coli chromosome's multiscale organization at various replication stages. Nucleic Acids Res 2021; 49:3077-3091. [PMID: 33660781 PMCID: PMC8034658 DOI: 10.1093/nar/gkab094] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 01/31/2021] [Accepted: 02/17/2021] [Indexed: 11/13/2022] Open
Abstract
The chromosome of Escherichia coli is riddled with multi-faceted complexity. The emergence of chromosome conformation capture techniques are providing newer ways to explore chromosome organization. Here we combine a beads-on-a-spring polymer-based framework with recently reported Hi-C data for E. coli chromosome, in rich growth condition, to develop a comprehensive model of its chromosome at 5 kb resolution. The investigation focuses on a range of diverse chromosome architectures of E. coli at various replication states corresponding to a collection of cells, individually present in different stages of cell cycle. The Hi-C data-integrated model captures the self-organization of E. coli chromosome into multiple macrodomains within a ring-like architecture. The model demonstrates that the position of oriC is dependent on architecture and replication state of chromosomes. The distance profiles extracted from the model reconcile fluorescence microscopy and DNA-recombination assay experiments. Investigations into writhe of the chromosome model reveal that it adopts helix-like conformation with no net chirality, earlier hypothesized in experiments. A genome-wide radius of gyration map captures multiple chromosomal interaction domains and identifies the precise locations of rrn operons in the chromosome. We show that a model devoid of Hi-C encoded information would fail to recapitulate most genomic features unique to E. coli.
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Affiliation(s)
- Abdul Wasim
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500046, India
| | - Ankit Gupta
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500046, India
| | - Jagannath Mondal
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500046, India
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20
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Lioy VS, Junier I, Lagage V, Vallet I, Boccard F. Distinct Activities of Bacterial Condensins for Chromosome Management in Pseudomonas aeruginosa. Cell Rep 2021; 33:108344. [PMID: 33147461 DOI: 10.1016/j.celrep.2020.108344] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/11/2020] [Accepted: 10/12/2020] [Indexed: 12/17/2022] Open
Abstract
Three types of structurally related structural maintenance of chromosomes (SMC) complexes, referred to as condensins, have been identified in bacteria. Smc-ScpAB is present in most bacteria, whereas MukBEF is found in enterobacteria and MksBEF is scattered over the phylogenic tree. The contributions of these condensins to chromosome management were characterized in Pseudomonas aeruginosa, which carries both Smc-ScpAB and MksBEF. In this bacterium, SMC-ScpAB controls chromosome disposition by juxtaposing chromosome arms. In contrast, MksBEF is critical for chromosome segregation in the absence of the main segregation system, and it affects the higher-order architecture of the chromosome by promoting DNA contacts in the megabase range. Strikingly, our results reveal a prevalence of Smc-ScpAB over MksBEF involving a coordination of their activities with chromosome replication. They also show that E. coli MukBEF can substitute for MksBEF in P. aeruginosa while prevailing over Smc-ScpAB. Our results reveal a hierarchy between activities of bacterial condensins on the same chromosome.
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Affiliation(s)
- Virginia S Lioy
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Ivan Junier
- CNRS, Université Grenoble Alpes, TIMC-IMAG, 38000 Grenoble, France
| | - Valentine Lagage
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Isabelle Vallet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Frédéric Boccard
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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21
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Szafran MJ, Jakimowicz D, Elliot MA. Compaction and control-the role of chromosome-organizing proteins in Streptomyces. FEMS Microbiol Rev 2021; 44:725-739. [PMID: 32658291 DOI: 10.1093/femsre/fuaa028] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/09/2020] [Indexed: 12/17/2022] Open
Abstract
Chromosomes are dynamic entities, whose organization and structure depend on the concerted activity of DNA-binding proteins and DNA-processing enzymes. In bacteria, chromosome replication, segregation, compaction and transcription are all occurring simultaneously, and to ensure that these processes are appropriately coordinated, all bacteria employ a mix of well-conserved and species-specific proteins. Unusually, Streptomyces bacteria have large, linear chromosomes and life cycle stages that include multigenomic filamentous hyphae and unigenomic spores. Moreover, their prolific secondary metabolism yields a wealth of bioactive natural products. These different life cycle stages are associated with profound changes in nucleoid structure and chromosome compaction, and require distinct repertoires of architectural-and regulatory-proteins. To date, chromosome organization is best understood during Streptomyces sporulation, when chromosome segregation and condensation are most evident, and these processes are coordinated with synchronous rounds of cell division. Advances are, however, now being made in understanding how chromosome organization is achieved in multigenomic hyphal compartments, in defining the functional and regulatory interplay between different architectural elements, and in appreciating the transcriptional control exerted by these 'structural' proteins.
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Affiliation(s)
- Marcin J Szafran
- Laboratory of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland
| | - Dagmara Jakimowicz
- Laboratory of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland
| | - Marie A Elliot
- Department of Biology, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, L8S 4K1, Canada
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22
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CcrZ is a pneumococcal spatiotemporal cell cycle regulator that interacts with FtsZ and controls DNA replication by modulating the activity of DnaA. Nat Microbiol 2021; 6:1175-1187. [PMID: 34373624 PMCID: PMC8387234 DOI: 10.1038/s41564-021-00949-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/07/2021] [Indexed: 02/07/2023]
Abstract
Most bacteria replicate and segregate their DNA concomitantly while growing, before cell division takes place. How bacteria synchronize these different cell cycle events to ensure faithful chromosome inheritance by daughter cells is poorly understood. Here, we identify Cell Cycle Regulator protein interacting with FtsZ (CcrZ) as a conserved and essential protein in pneumococci and related Firmicutes such as Bacillus subtilis and Staphylococcus aureus. CcrZ couples cell division with DNA replication by controlling the activity of the master initiator of DNA replication, DnaA. The absence of CcrZ causes mis-timed and reduced initiation of DNA replication, which subsequently results in aberrant cell division. We show that CcrZ from Streptococcus pneumoniae interacts directly with the cytoskeleton protein FtsZ, which places CcrZ in the middle of the newborn cell where the DnaA-bound origin is positioned. This work uncovers a mechanism for control of the bacterial cell cycle in which CcrZ controls DnaA activity to ensure that the chromosome is replicated at the right time during the cell cycle.
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23
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Raghunathan S, Chimthanawala A, Krishna S, Vecchiarelli AG, Badrinarayanan A. Asymmetric chromosome segregation and cell division in DNA damage-induced bacterial filaments. Mol Biol Cell 2020; 31:2920-2931. [PMID: 33112716 PMCID: PMC7927188 DOI: 10.1091/mbc.e20-08-0547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Faithful propagation of life requires coordination of DNA replication and segregation with cell growth and division. In bacteria, this results in cell size homeostasis and periodicity in replication and division. The situation is perturbed under stress such as DNA damage, which induces filamentation as cell cycle progression is blocked to allow for repair. Mechanisms that release this morphological state for reentry into wild-type growth are unclear. Here we show that damage-induced Escherichia coli filaments divide asymmetrically, producing short daughter cells that tend to be devoid of damage and have wild-type size and growth dynamics. The Min-system primarily determines division site location in the filament, with additional regulation of division completion by chromosome segregation. Collectively, we propose that coordination between chromosome (and specifically terminus) segregation and cell division may result in asymmetric division in damage-induced filaments and facilitate recovery from a stressed state.
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Affiliation(s)
- Suchitha Raghunathan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research and.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore 560064, India
| | - Afroze Chimthanawala
- National Centre for Biological Sciences, Tata Institute of Fundamental Research and.,SASTRA University, Thanjavur, Tamil Nadu 613401, India
| | - Sandeep Krishna
- National Centre for Biological Sciences, Tata Institute of Fundamental Research and.,Simons Centre for the Study of Living Machines, Bangalore 560065, India
| | - Anthony G Vecchiarelli
- Molecular, Cellular, and Developmental Biology Department, Biological Sciences Building, University of Michigan, Ann Arbor, Michigan 48109
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24
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Post-replicative pairing of sister ter regions in Escherichia coli involves multiple activities of MatP. Nat Commun 2020; 11:3796. [PMID: 32732900 PMCID: PMC7394560 DOI: 10.1038/s41467-020-17606-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 07/03/2020] [Indexed: 02/07/2023] Open
Abstract
The ter region of the bacterial chromosome, where replication terminates, is the last to be segregated before cell division in Escherichia coli. Delayed segregation is controlled by the MatP protein, which binds to specific sites (matS) within ter, and interacts with other proteins such as ZapB. Here, we investigate the role of MatP by combining short-time mobility analyses of the ter locus with biochemical approaches. We find that ter mobility is similar to that of a non ter locus, except when sister ter loci are paired after replication. This effect depends on MatP, the persistence of catenanes, and ZapB. We characterise MatP/DNA complexes and conclude that MatP binds DNA as a tetramer, but bridging matS sites in a DNA-rich environment remains infrequent. We propose that tetramerisation of MatP links matS sites with ZapB and/or with non-specific DNA to promote optimal pairing of sister ter regions until cell division. Protein, MatP, binds to and delays segregation of the ter region of the bacterial chromosome before cell division. Here, the authors show that MatP displays multiple activities to promote optimal pairing of sister ter regions until cell division.
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25
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Remesh SG, Verma SC, Chen JH, Ekman AA, Larabell CA, Adhya S, Hammel M. Nucleoid remodeling during environmental adaptation is regulated by HU-dependent DNA bundling. Nat Commun 2020; 11:2905. [PMID: 32518228 PMCID: PMC7283360 DOI: 10.1038/s41467-020-16724-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/19/2020] [Indexed: 01/26/2023] Open
Abstract
Bacterial nucleoid remodeling dependent on conserved histone-like protein, HU is one of the determining factors in global gene regulation. By imaging of near-native, unlabeled E. coli cells by soft X-ray tomography, we show that HU remodels nucleoids by promoting the formation of a dense condensed core surrounded by less condensed isolated domains. Nucleoid remodeling during cell growth and environmental adaptation correlate with pH and ionic strength controlled molecular switch that regulated HUαα dependent intermolecular DNA bundling. Through crystallographic and solution-based studies we show that these effects mechanistically rely on HUαα promiscuity in forming multiple electrostatically driven multimerization interfaces. Changes in DNA bundling consequently affects gene expression globally, likely by constrained DNA supercoiling. Taken together our findings unveil a critical function of HU–DNA interaction in nucleoid remodeling that may serve as a general microbial mechanism for transcriptional regulation to synchronize genetic responses during the cell cycle and adapt to changing environments. HU is among the most conserved and abundant nucleoid-associated proteins in eubacteria. Here the authors investigate the role of histone-like proteins (HU) in the 3D organization of the bacteria DNA and show via soft X-ray tomography the process of nucleoid remodeling.
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Affiliation(s)
- Soumya G Remesh
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.,Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Subhash C Verma
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA
| | - Jian-Hua Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Anatomy, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Axel A Ekman
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Anatomy, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Carolyn A Larabell
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Anatomy, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Sankar Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA
| | - Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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26
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Bateman A. Division of labour in a matrix, rather than phagocytosis or endosymbiosis, as a route for the origin of eukaryotic cells. Biol Direct 2020; 15:8. [PMID: 32345370 PMCID: PMC7187495 DOI: 10.1186/s13062-020-00260-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 02/25/2020] [Indexed: 12/13/2022] Open
Abstract
Abstract Two apparently irreconcilable models dominate research into the origin of eukaryotes. In one model, amitochondrial proto-eukaryotes emerged autogenously from the last universal common ancestor of all cells. Proto-eukaryotes subsequently acquired mitochondrial progenitors by the phagocytic capture of bacteria. In the second model, two prokaryotes, probably an archaeon and a bacterial cell, engaged in prokaryotic endosymbiosis, with the species resident within the host becoming the mitochondrial progenitor. Both models have limitations. A search was therefore undertaken for alternative routes towards the origin of eukaryotic cells. The question was addressed by considering classes of potential pathways from prokaryotic to eukaryotic cells based on considerations of cellular topology. Among the solutions identified, one, called here the “third-space model”, has not been widely explored. A version is presented in which an extracellular space (the third-space), serves as a proxy cytoplasm for mixed populations of archaea and bacteria to “merge” as a transitionary complex without obligatory endosymbiosis or phagocytosis and to form a precursor cell. Incipient nuclei and mitochondria diverge by division of labour. The third-space model can accommodate the reorganization of prokaryote-like genomes to a more eukaryote-like genome structure. Nuclei with multiple chromosomes and mitosis emerge as a natural feature of the model. The model is compatible with the loss of archaeal lipid biochemistry while retaining archaeal genes and provides a route for the development of membranous organelles such as the Golgi apparatus and endoplasmic reticulum. Advantages, limitations and variations of the “third-space” models are discussed. Reviewers This article was reviewed by Damien Devos, Buzz Baum and Michael Gray.
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Affiliation(s)
- Andrew Bateman
- Division of Experimental Medicine, Department of Medicine, McGill University, Glen Site Pavilion E, 1001 Boulevard Decarie, Montreal, Quebec, H4A 3J1, Canada. .,Centre for Translational Biology, Research Institute of McGill University Health Centre, Glen Site Pavilion E, 1001 Boulevard Decarie, Montreal, Quebec, H4A 3J1, Canada.
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Pióro M, Jakimowicz D. Chromosome Segregation Proteins as Coordinators of Cell Cycle in Response to Environmental Conditions. Front Microbiol 2020; 11:588. [PMID: 32351468 PMCID: PMC7174722 DOI: 10.3389/fmicb.2020.00588] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022] Open
Abstract
Chromosome segregation is a crucial stage of the cell cycle. In general, proteins involved in this process are DNA-binding proteins, and in most bacteria, ParA and ParB are the main players; however, some bacteria manage this process by employing other proteins, such as condensins. The dynamic interaction between ParA and ParB drives movement and exerts positioning of the chromosomal origin of replication (oriC) within the cell. In addition, both ParA and ParB were shown to interact with the other proteins, including those involved in cell division or cell elongation. The significance of these interactions for the progression of the cell cycle is currently under investigation. Remarkably, DNA binding by ParA and ParB as well as their interactions with protein partners conceivably may be modulated by intra- and extracellular conditions. This notion provokes the question of whether chromosome segregation can be regarded as a regulatory stage of the cell cycle. To address this question, we discuss how environmental conditions affect chromosome segregation and how segregation proteins influence other cell cycle processes.
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Affiliation(s)
- Monika Pióro
- Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Dagmara Jakimowicz
- Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
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28
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Chromosome organization by a conserved condensin-ParB system in the actinobacterium Corynebacterium glutamicum. Nat Commun 2020; 11:1485. [PMID: 32198399 PMCID: PMC7083940 DOI: 10.1038/s41467-020-15238-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 02/21/2020] [Indexed: 01/23/2023] Open
Abstract
Higher-order chromosome folding and segregation are tightly regulated in all domains of life. In bacteria, details on nucleoid organization regulatory mechanisms and function remain poorly characterized, especially in non-model species. Here, we investigate the role of DNA-partitioning protein ParB and SMC condensin complexes in the actinobacterium Corynebacterium glutamicum. Chromosome conformation capture reveals SMC-mediated long-range interactions around ten centromere-like parS sites clustered at the replication origin (oriC). At least one oriC-proximal parS site is necessary for reliable chromosome segregation. We use chromatin immunoprecipitation and photoactivated single-molecule localization microscopy to show the formation of distinct, parS-dependent ParB-nucleoprotein subclusters. We further show that SMC/ScpAB complexes, loaded via ParB at parS sites, mediate chromosomal inter-arm contacts (as previously shown in Bacillus subtilis). However, the MukBEF-like SMC complex MksBEFG does not contribute to chromosomal DNA-folding; instead, this complex is involved in plasmid maintenance and interacts with the polar oriC-tethering factor DivIVA. Our results complement current models of ParB-SMC/ScpAB crosstalk and show that some condensin complexes evolved functions that are apparently uncoupled from chromosome folding. The regulation of higher-order chromosome folding and segregation in bacteria is poorly understood. Here, Böhm et al. provide insights into the roles of DNA partitioning protein ParB and SMC condensin complexes in Corynebacterium glutamicum.
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29
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Dissecting the in vivo dynamics of transcription locking due to positive supercoiling buildup. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194515. [PMID: 32113983 DOI: 10.1016/j.bbagrm.2020.194515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 02/07/2020] [Accepted: 02/20/2020] [Indexed: 01/04/2023]
Abstract
Positive supercoiling buildup (PSB) is a pervasive phenomenon in the transcriptional programs of Escherichia coli. After finding a range of Gyrase concentrations where the inverse of the transcription rate of a chromosome-integrated gene changes linearly with the inverse of Gyrase concentration, we apply a LineWeaver-Burk plot to dissect the expected in vivo transcription rate in absence of PSB. We validate the estimation by time-lapse microscopy of single-RNA production kinetics of the same gene when single-copy plasmid-borne, shown to be impervious to Gyrase inhibition. Next, we estimate the fraction of time in locked states and number of transcription events prior to locking, which we validate by measurements under Gyrase inhibition. Replacing the gene of interest by one with slower transcription rate decreases the fraction of time in locked states due to PSB. Finally, we combine data from both constructs to infer a range of possible transcription initiation locking kinetics in a chromosomal location, obtainable by tuning the transcription rate. We validate with measurements of transcription activity at different induction levels. This strategy for dissecting transcription initiation locking kinetics due to PSB can contribute to resolve the transcriptional programs of E. coli and in the engineering of synthetic genetic circuits.
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30
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White MA, Darmon E, Lopez-Vernaza MA, Leach DRF. DNA double strand break repair in Escherichia coli perturbs cell division and chromosome dynamics. PLoS Genet 2020; 16:e1008473. [PMID: 31895943 PMCID: PMC6959608 DOI: 10.1371/journal.pgen.1008473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/14/2020] [Accepted: 12/16/2019] [Indexed: 11/18/2022] Open
Abstract
To prevent the transmission of damaged genomic material between generations, cells require a system for accommodating DNA repair within their cell cycles. We have previously shown that Escherichia coli cells subject to a single, repairable site-specific DNA double-strand break (DSB) per DNA replication cycle reach a new average cell length, with a negligible effect on population growth rate. We show here that this new cell size distribution is caused by a DSB repair-dependent delay in completion of cell division. This delay occurs despite unperturbed cell size regulated initiation of both chromosomal DNA replication and cell division. Furthermore, despite DSB repair altering the profile of DNA replication across the genome, the time required to complete chromosomal duplication is invariant. The delay in completion of cell division is accompanied by a DSB repair-dependent delay in individualization of sister nucleoids. We suggest that DSB repair events create inter-sister connections that persist until those chromosomes are separated by a closing septum.
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Affiliation(s)
- Martin A. White
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, The King’s Buildings, Edinburgh, United Kingdom
- Department of Molecular and Cellular Biology, Harvard University, Cambridge MA, United States of America
| | - Elise Darmon
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, The King’s Buildings, Edinburgh, United Kingdom
| | - Manuel A. Lopez-Vernaza
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, The King’s Buildings, Edinburgh, United Kingdom
| | - David R. F. Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, The King’s Buildings, Edinburgh, United Kingdom
- * E-mail:
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31
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Abstract
How genomes are organized within cells and how the 3D architecture of a genome influences cellular functions are significant questions in biology. A bacterial genomic DNA resides inside cells in a highly condensed and functionally organized form called nucleoid (nucleus-like structure without a nuclear membrane). The Escherichia coli chromosome or nucleoid is composed of the genomic DNA, RNA, and protein. The nucleoid forms by condensation and functional arrangement of a single chromosomal DNA with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. Although a high-resolution structure of a bacterial nucleoid is yet to come, five decades of research has established the following salient features of the E. coli nucleoid elaborated below: 1) The chromosomal DNA is on the average a negatively supercoiled molecule that is folded as plectonemic loops, which are confined into many independent topological domains due to supercoiling diffusion barriers; 2) The loops spatially organize into megabase size regions called macrodomains, which are defined by more frequent physical interactions among DNA sites within the same macrodomain than between different macrodomains; 3) The condensed and spatially organized DNA takes the form of a helical ellipsoid radially confined in the cell; and 4) The DNA in the chromosome appears to have a condition-dependent 3-D structure that is linked to gene expression so that the nucleoid architecture and gene transcription are tightly interdependent, influencing each other reciprocally. Current advents of high-resolution microscopy, single-molecule analysis and molecular structure determination of the components are expected to reveal the total structure and function of the bacterial nucleoid.
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Affiliation(s)
- Subhash C. Verma
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
| | - Zhong Qian
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sankar L. Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
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32
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Affiliation(s)
- Mark C Field
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom;
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic
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33
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Lebedev N, Stroud RM, Yates MD, Tender LM. Spatially Resolved Chemical Analysis of Geobacter sulfurreducens Cell Surface. ACS NANO 2019; 13:4834-4842. [PMID: 30943001 DOI: 10.1021/acsnano.9b02032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Geobacter sulfurreducens is of interest for the highest efficiency of power generation and extremely long extracellular electron transfer (EET) between the bacterium and electrodes. Despite more than 15 years of intensive molecular biological research, there is still no clear answer which molecules are responsible for these processes. In the present work, we look at the problem from another (atomic) perspective and identify the location and shape of the compounds that are known to be conductive, particularly those containing Fe atoms. By using highly sophisticated energy dispersive X-ray spectroscopy combined with high-angle annular dark-field transmission electron microscopy enabling detection, identification, and localization of chemical compounds on the surface at nearly atomic spatial resolution, we analyze Fe spatial distribution within the G. sulfurreducens community. We discover the presence of small Fe-containing particles on the surface of the bacterium cells. The size of the particles (diameter 5.6 nm) is highly reproducible and comparable with the size of a single protein. The particles cover about 2% of the cell surface, which is similar to that expected for molecular conductors responsible for electron transfer through the bacterium cell wall. We find that G. sulfurreducens filaments ("bacterial molecular wires") also contain Fe atoms in their bundles. We observe that the bacterium enable changing the distance between the Fe-containing bundles in the filaments from separated to attached (the latter is needed for the efficient electron transfer between the Fe-containing particles), depending on the bacterium metabolic activity and attachment to extracellular substrates. These results are consistent with the recently published research about the role of Fe atoms in protein molecular conductance ( Phys. Chem. Chem. Phys. , 2018 , 20 , 14072 - 14081 ) and show what type of Fe-containing particles are involved in the bacterial extracellular communication. They can be used for the design and construction of artificial biomolecular wires and bioinorganic interfaces.
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Affiliation(s)
- Nikolai Lebedev
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Rhonda M Stroud
- Materials Science and Technology Division , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Matthew D Yates
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Leonard Martin Tender
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
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34
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Hürtgen D, Härtel T, Murray SM, Sourjik V, Schwille P. Functional Modules of Minimal Cell Division for Synthetic Biology. ACTA ACUST UNITED AC 2019; 3:e1800315. [PMID: 32648714 DOI: 10.1002/adbi.201800315] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 03/11/2019] [Indexed: 12/22/2022]
Abstract
Cellular reproduction is one of the fundamental hallmarks of life. Therefore, the development of a minimal division machinery capable of proper genome condensation and organization, mid-cell positioning and segregation in space and time, and the final septation process constitute a fundamental challenge for synthetic biology. It is therefore important to be able to engineer such modules for the production of artificial minimal cells. A bottom-up assembly of molecular machines from bulk biochemicals complemented by in vivo experiments as well as computational modelling helps to approach such key cellular processes. Here, minimal functional modules involved in genome segregation and the division machinery and their spatial organization and positioning are reviewed, setting into perspective the design of a minimal cell. Furthermore, the milestones of recent in vitro reconstitution experiments in the context of cell division are discussed and their role in shedding light on fundamental cellular mechanisms that constitute spatiotemporal order is described. Lastly, current challenges in the field of bottom-up synthetic biology as well as possible future developments toward the development of minimal biomimetic systems are discussed.
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Affiliation(s)
- Daniel Hürtgen
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (Synmikro), Karl-von-Frisch Straße 16, 35043, Marburg, Germany
| | - Tobias Härtel
- Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Seán M Murray
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (Synmikro), Karl-von-Frisch Straße 16, 35043, Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (Synmikro), Karl-von-Frisch Straße 16, 35043, Marburg, Germany
| | - Petra Schwille
- Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
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35
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Hsu TM, Chang YR. High-Copy-Number Plasmid Segregation-Single-Molecule Dynamics in Single Cells. Biophys J 2019; 116:772-780. [PMID: 30773297 DOI: 10.1016/j.bpj.2019.01.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/18/2019] [Accepted: 01/22/2019] [Indexed: 12/21/2022] Open
Abstract
Bacterial high-copy-number (hcn) plasmids provide an excellent model to study the underlying physical mechanisms of DNA segment segregation in an intracellular context. Using two-color fluorescent repressor-operator systems and a synthetic repressible replication origin, we tracked the motion and segregation of single hcn plasmid molecules in individual cells. The plasmid diffusion dynamics revealed between-plasmid temporal associations (clustering) as well as entropic and elastic recoiling forces in the confined intracellular spaces outside of nucleoids. These two effects could be effectively used in models to predict the heterogeneity of segregation. Additionally, the motile behaviors of hcn plasmids provide quantitative estimates of entropic exclusion strength and dynamic associations between DNA segments. Overall, this study utilizes a, to our knowledge, novel approach to predict the polymer dynamics of DNA segments in spatially confined, crowded cellular compartments as well as during bacterial chromosome segregation.
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Affiliation(s)
- Tai-Ming Hsu
- Department of Physics, National Taiwan Normal University, Taipei, Taiwan
| | - Yi-Ren Chang
- Department of Physics, National Taiwan Normal University, Taipei, Taiwan.
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36
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Abstract
In bacteria, chromosomes are highly organized within the limited volume of the cell to form a nucleoid. Recent application of microscopy and chromosome conformation capture techniques have together provided a comprehensive understanding of the nature of this organization and the role of factors such as the structural maintenance of chromosomes (SMC) proteins in the establishment and maintenance of the same. In this chapter, we outline a microfluidics-based approach for live cell imaging of Escherichia coli chromosome dynamics in wild-type cells. This assay can be used to track the activity of the SMC complex, MukBEF, on DNA and assess the impact of perturbations such as DNA damage on chromosome organization and segregation.
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37
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Pióro M, Małecki T, Portas M, Magierowska I, Trojanowski D, Sherratt D, Zakrzewska-Czerwińska J, Ginda K, Jakimowicz D. Competition between DivIVA and the nucleoid for ParA binding promotes segrosome separation and modulates mycobacterial cell elongation. Mol Microbiol 2018; 111:204-220. [PMID: 30318635 PMCID: PMC7379644 DOI: 10.1111/mmi.14149] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2018] [Indexed: 01/03/2023]
Abstract
Although mycobacteria are rod shaped and divide by simple binary fission, their cell cycle exhibits unusual features: unequal cell division producing daughter cells that elongate with different velocities, as well as asymmetric chromosome segregation and positioning throughout the cell cycle. As in other bacteria, mycobacterial chromosomes are segregated by pair of proteins, ParA and ParB. ParA is an ATPase that interacts with nucleoprotein ParB complexes – segrosomes and non‐specifically binds the nucleoid. Uniquely in mycobacteria, ParA interacts with a polar protein DivIVA (Wag31), responsible for asymmetric cell elongation, however the biological role of this interaction remained unknown. We hypothesised that this interaction plays a critical role in coordinating chromosome segregation with cell elongation. Using a set of ParA mutants, we determined that disruption of ParA‐DNA binding enhanced the interaction between ParA and DivIVA, indicating a competition between the nucleoid and DivIVA for ParA binding. Having identified the ParA mutation that disrupts its recruitment to DivIVA, we found that it led to inefficient segrosomes separation and increased the cell elongation rate. Our results suggest that ParA modulates DivIVA activity. Thus, we demonstrate that the ParA‐DivIVA interaction facilitates chromosome segregation and modulates cell elongation.
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Affiliation(s)
- Monika Pióro
- Laboratory of Molecular Biology of Microorganisms, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
| | - Tomasz Małecki
- Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
| | - Magda Portas
- Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
| | - Izabela Magierowska
- Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
| | - Damian Trojanowski
- Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
| | - David Sherratt
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Jolanta Zakrzewska-Czerwińska
- Laboratory of Molecular Biology of Microorganisms, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.,Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
| | - Katarzyna Ginda
- Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland.,Department of Biochemistry, University of Oxford, Oxford, UK
| | - Dagmara Jakimowicz
- Laboratory of Molecular Biology of Microorganisms, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.,Faculty of Biotechnology, Department of Molecular Microbiology, University of Wrocław, Wrocław, Poland
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38
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Miermans CA, Broedersz CP. Bacterial chromosome organization by collective dynamics of SMC condensins. J R Soc Interface 2018; 15:rsif.2018.0495. [PMID: 30333247 DOI: 10.1098/rsif.2018.0495] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/19/2018] [Indexed: 11/12/2022] Open
Abstract
A prominent organizational feature of bacterial chromosomes was revealed by Hi-C experiments, indicating anomalously high contacts between the left and right chromosomal arms. These long-range contacts have been attributed to various nucleoid-associated proteins, including the ATPase Structural Maintenance of Chromosomes (SMC) condensin. Although the molecular structure of these ATPases has been mapped in detail, it still remains unclear by which physical mechanisms they collectively generate long-range chromosomal contacts. Here, we develop a computational model that captures the subtle interplay between molecular-scale activity of slip-links and large-scale chromosome organization. We first consider a scenario in which the ATPase activity of slip-links regulates their DNA-recruitment near the origin of replication, while the slip-link dynamics is assumed to be diffusive. We find that such diffusive slip-links can collectively organize the entire chromosome into a state with aligned arms, but not within physiological constraints. However, slip-links that include motor activity are far more effective at organizing the entire chromosome over all length-scales. The persistence of motor slip-links at physiological densities can generate large, nested loops and drive them into the bulk of the DNA. Finally, our model with motor slip-links can quantitatively account for the rapid arm-arm alignment of chromosomal arms observed in vivo.
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Affiliation(s)
- Christiaan A Miermans
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, 80333 München, Germany
| | - Chase P Broedersz
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, 80333 München, Germany
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39
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Krogh TJ, Møller-Jensen J, Kaleta C. Impact of Chromosomal Architecture on the Function and Evolution of Bacterial Genomes. Front Microbiol 2018; 9:2019. [PMID: 30210483 PMCID: PMC6119826 DOI: 10.3389/fmicb.2018.02019] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/09/2018] [Indexed: 12/14/2022] Open
Abstract
The bacterial nucleoid is highly condensed and forms compartment-like structures within the cell. Much attention has been devoted to investigating the dynamic topology and organization of the nucleoid. In contrast, the specific nucleoid organization, and the relationship between nucleoid structure and function is often neglected with regard to importance for adaption to changing environments and horizontal gene acquisition. In this review, we focus on the structure-function relationship in the bacterial nucleoid. We provide an overview of the fundamental properties that shape the chromosome as a structured yet dynamic macromolecule. These fundamental properties are then considered in the context of the living cell, with focus on how the informational flow affects the nucleoid structure, which in turn impacts on the genetic output. Subsequently, the dynamic living nucleoid will be discussed in the context of evolution. We will address how the acquisition of foreign DNA impacts nucleoid structure, and conversely, how nucleoid structure constrains the successful and sustainable chromosomal integration of novel DNA. Finally, we will discuss current challenges and directions of research in understanding the role of chromosomal architecture in bacterial survival and adaptation.
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Affiliation(s)
- Thøger J Krogh
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jakob Møller-Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Christoph Kaleta
- Institute of Experimental Medicine, Christian-Albrechts-University Kiel, Kiel, Germany
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40
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Lioy VS, Boccard F. Conformational Studies of Bacterial Chromosomes by High-Throughput Sequencing Methods. Methods Enzymol 2018; 612:25-45. [PMID: 30502944 DOI: 10.1016/bs.mie.2018.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The development of next-generation sequencing technologies has allowed the application of different methods dedicated to the study of DNA-protein interactions and chromosome conformation to entire bacterial genome. By combining these approaches, the role of various parameters and factors involved in gene expression and chromosome organization can be disclosed at the molecular level over the full genome. Here we describe two methods that profoundly revolutionized our vision of DNA-protein interactions and spatial organization of chromosomes. Chromosome conformation capture (3C) coupled to deep sequencing (3C-seq) enables studies of the genome-wide chromosome folding and its control by different parameters and structural factors. Chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq) revealed the extent and regulation of DNA-protein interactions in vivo and highlight the role of structural factors in the control of chromosome organization. In this chapter, we describe a detailed protocol of 3C-seq and ChIP-seq experiments that, when combined, allows the spatial study of the chromosome and the factors that promote specific folding. Data processing and analysis for both experiments are also discussed.
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Affiliation(s)
- Virginia S Lioy
- Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France
| | - Frédéric Boccard
- Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
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41
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Boudreau BA, Hron DR, Qin L, van der Valk RA, Kotlajich MV, Dame RT, Landick R. StpA and Hha stimulate pausing by RNA polymerase by promoting DNA-DNA bridging of H-NS filaments. Nucleic Acids Res 2018; 46:5525-5546. [PMID: 29718386 PMCID: PMC6009659 DOI: 10.1093/nar/gky265] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/12/2018] [Accepted: 04/03/2018] [Indexed: 11/22/2022] Open
Abstract
In enterobacteria, AT-rich horizontally acquired genes, including virulence genes, are silenced through the actions of at least three nucleoid-associated proteins (NAPs): H-NS, StpA and Hha. These proteins form gene-silencing nucleoprotein filaments through direct DNA binding by H-NS and StpA homodimers or heterodimers. Both linear and bridged filaments, in which NAPs bind one or two DNA segments, respectively, have been observed. Hha can interact with H-NS or StpA filaments, but itself lacks a DNA-binding domain. Filaments composed of H-NS alone can inhibit transcription initiation and, in the bridged conformation, slow elongating RNA polymerase (RNAP) by promoting backtracking at pause sites. How the other NAPs modulate these effects of H-NS is unknown, despite evidence that they help regulate subsets of silenced genes in vivo (e.g. in pathogenicity islands). Here we report that Hha and StpA greatly enhance H-NS-stimulated pausing by RNAP at 20°C. StpA:H-NS or StpA-only filaments also stimulate pausing at 37°C, a temperature at which Hha:H-NS or H-NS-only filaments have much less effect. In addition, we report that both Hha and StpA greatly stimulate DNA-DNA bridging by H-NS filaments. Together, these observations indicate that Hha and StpA can affect H-NS-mediated gene regulation by stimulating bridging of H-NS/DNA filaments.
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Affiliation(s)
- Beth A Boudreau
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Daniel R Hron
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Liang Qin
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, Netherlands
| | - Ramon A van der Valk
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, Netherlands
| | - Matthew V Kotlajich
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, Netherlands
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI 53706, USA
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42
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Braslavsky I, Stavans J. Application of Algebraic Topology to Homologous Recombination of DNA. iScience 2018; 4:64-67. [PMID: 30240753 PMCID: PMC6146625 DOI: 10.1016/j.isci.2018.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/30/2018] [Accepted: 05/11/2018] [Indexed: 11/23/2022] Open
Abstract
Brouwer's fixed point theorem, a fundamental theorem in algebraic topology proved more than a hundred years ago, states that given any continuous map from a closed, simply connected set into itself, there is a point that is mapped unto itself. Here we point out the connection between a one-dimensional application of Brouwer's fixed point theorem and a mechanism proposed to explain how extension of single-stranded DNA substrates by recombinases of the RecA superfamily facilitates significantly the search for homologous sequences on long chromosomes. RecA family recombinases stretch their DNA substrates by 1.5 Stretching facilitates the search for homologous genomic targets during recombination This facilitating mechanism derives from a foundational theorem of Algebraic Topology
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Affiliation(s)
- Ido Braslavsky
- The Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 7610001, Israel.
| | - Joel Stavans
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel.
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43
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Jun S, Si F, Pugatch R, Scott M. Fundamental principles in bacterial physiology-history, recent progress, and the future with focus on cell size control: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:056601. [PMID: 29313526 PMCID: PMC5897229 DOI: 10.1088/1361-6633/aaa628] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Bacterial physiology is a branch of biology that aims to understand overarching principles of cellular reproduction. Many important issues in bacterial physiology are inherently quantitative, and major contributors to the field have often brought together tools and ways of thinking from multiple disciplines. This article presents a comprehensive overview of major ideas and approaches developed since the early 20th century for anyone who is interested in the fundamental problems in bacterial physiology. This article is divided into two parts. In the first part (sections 1-3), we review the first 'golden era' of bacterial physiology from the 1940s to early 1970s and provide a complete list of major references from that period. In the second part (sections 4-7), we explain how the pioneering work from the first golden era has influenced various rediscoveries of general quantitative principles and significant further development in modern bacterial physiology. Specifically, section 4 presents the history and current progress of the 'adder' principle of cell size homeostasis. Section 5 discusses the implications of coarse-graining the cellular protein composition, and how the coarse-grained proteome 'sectors' re-balance under different growth conditions. Section 6 focuses on physiological invariants, and explains how they are the key to understanding the coordination between growth and the cell cycle underlying cell size control in steady-state growth. Section 7 overviews how the temporal organization of all the internal processes enables balanced growth. In the final section 8, we conclude by discussing the remaining challenges for the future in the field.
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Affiliation(s)
- Suckjoon Jun
- Department of Physics, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, United States of America. Section of Molecular Biology, Division of Biology, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, United States of America
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44
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Misra HS, Maurya GK, Chaudhary R, Misra CS. Interdependence of bacterial cell division and genome segregation and its potential in drug development. Microbiol Res 2018; 208:12-24. [DOI: 10.1016/j.micres.2017.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 12/05/2017] [Accepted: 12/31/2017] [Indexed: 11/28/2022]
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45
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Abstract
Mesoscale molecular modeling is providing a new window into the inner workings of living cells. Modeling of genomes, however, remains a technical challenge, due to their large size and complexity. We describe a lattice method for rapid generation of bacterial nucleoid models that integrates experimental data from a variety of biophysical techniques and provides a starting point for simulation and hypothesis generation. The current method builds models of a circular bacterial genome with supercoiled plectonemes, packed within the small space of the bacterial cell. Lattice models are generated for Mycoplasma genitalium and Escherichia coli nucleoids, and used to simulate interaction data. The method is rapid enough to allow generation of multiple models when analyzing structure/function relationships, and we demonstrate use of the lattice models in creation of an all-atom representation of an entire cell.
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Affiliation(s)
- David S Goodsell
- Department of Integrative Structural and Computational Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California , United States.,Center for Integrative Proteomics Research , Rutgers State University , 174 Frelinghuysen Road , Piscataway , New Jersey , United States
| | - Ludovic Autin
- Department of Integrative Structural and Computational Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California , United States
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California , United States
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46
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Lioy VS, Cournac A, Marbouty M, Duigou S, Mozziconacci J, Espéli O, Boccard F, Koszul R. Multiscale Structuring of the E. coli Chromosome by Nucleoid-Associated and Condensin Proteins. Cell 2018; 172:771-783.e18. [PMID: 29358050 DOI: 10.1016/j.cell.2017.12.027] [Citation(s) in RCA: 207] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 10/02/2017] [Accepted: 12/19/2017] [Indexed: 12/26/2022]
Abstract
As in eukaryotes, bacterial genomes are not randomly folded. Bacterial genetic information is generally carried on a circular chromosome with a single origin of replication from which two replication forks proceed bidirectionally toward the opposite terminus region. Here, we investigate the higher-order architecture of the Escherichia coli genome, showing its partition into two structurally distinct entities by a complex and intertwined network of contacts: the replication terminus (ter) region and the rest of the chromosome. Outside of ter, the condensin MukBEF and the ubiquitous nucleoid-associated protein (NAP) HU promote DNA contacts in the megabase range. Within ter, the MatP protein prevents MukBEF activity, and contacts are restricted to ∼280 kb, creating a domain with distinct structural properties. We also show how other NAPs contribute to nucleoid organization, such as H-NS, which restricts short-range interactions. Combined, these results reveal the contributions of major evolutionarily conserved proteins in a bacterial chromosome organization.
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Affiliation(s)
- Virginia S Lioy
- Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France
| | - Axel Cournac
- Institut Pasteur, Département Génomes et Génétique, Groupe Régulation spatiale des génomes, 75015 Paris, France; CNRS, UMR 3525, 75015 Paris, France
| | - Martial Marbouty
- Institut Pasteur, Département Génomes et Génétique, Groupe Régulation spatiale des génomes, 75015 Paris, France; CNRS, UMR 3525, 75015 Paris, France
| | - Stéphane Duigou
- Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France
| | - Julien Mozziconacci
- Sorbonne Universités, Laboratoire de Physique Théorique de la Matière Condensée, UMR 7600, Université Pierre et Marie Curie, 75005 Paris, France
| | - Olivier Espéli
- Centre Interdisciplinaire de Recherche en Biologie, Collège de France, UMR-CNRS 7241, INSERM U1050, Paris, France
| | - Frédéric Boccard
- Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France.
| | - Romain Koszul
- Institut Pasteur, Département Génomes et Génétique, Groupe Régulation spatiale des génomes, 75015 Paris, France; CNRS, UMR 3525, 75015 Paris, France.
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47
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Hacker WC, Li S, Elcock AH. Features of genomic organization in a nucleotide-resolution molecular model of the Escherichia coli chromosome. Nucleic Acids Res 2017. [PMID: 28645155 PMCID: PMC5570083 DOI: 10.1093/nar/gkx541] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We describe structural models of the Escherichia coli chromosome in which the positions of all 4.6 million nucleotides of each DNA strand are resolved. Models consistent with two basic chromosomal orientations, differing in their positioning of the origin of replication, have been constructed. In both types of model, the chromosome is partitioned into plectoneme-abundant and plectoneme-free regions, with plectoneme lengths and branching patterns matching experimental distributions, and with spatial distributions of highly-transcribed chromosomal regions matching recent experimental measurements of the distribution of RNA polymerases. Physical analysis of the models indicates that the effective persistence length of the DNA and relative contributions of twist and writhe to the chromosome's negative supercoiling are in good correspondence with experimental estimates. The models exhibit characteristics similar to those of ‘fractal globules,’ and even the most genomically-distant parts of the chromosome can be physically connected, through paths combining linear diffusion and inter-segmental transfer, by an average of only ∼10 000 bp. Finally, macrodomain structures and the spatial distributions of co-expressed genes are analyzed: the latter are shown to depend strongly on the overall orientation of the chromosome. We anticipate that the models will prove useful in exploring other static and dynamic features of the bacterial chromosome.
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Affiliation(s)
- William C Hacker
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Shuxiang Li
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Adrian H Elcock
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
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48
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Gherardi M, Calabrese L, Tamm M, Cosentino Lagomarsino M. Model of chromosomal loci dynamics in bacteria as fractional diffusion with intermittent transport. Phys Rev E 2017; 96:042402. [PMID: 29347533 DOI: 10.1103/physreve.96.042402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Indexed: 06/07/2023]
Abstract
The short-time dynamics of bacterial chromosomal loci is a mixture of subdiffusive and active motion, in the form of rapid relocations with near-ballistic dynamics. While previous work has shown that such rapid motions are ubiquitous, we still have little grasp on their physical nature, and no positive model is available that describes them. Here, we propose a minimal theoretical model for loci movements as a fractional Brownian motion subject to a constant but intermittent driving force, and compare simulations and analytical calculations to data from high-resolution dynamic tracking in E. coli. This analysis yields the characteristic time scales for intermittency. Finally, we discuss the possible shortcomings of this model, and show that an increase in the effective local noise felt by the chromosome associates to the active relocations.
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Affiliation(s)
- Marco Gherardi
- Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris, France
- Physics Department, University of Milan, Via Celoria 16, 20133 Milano, Italy
| | - Ludovico Calabrese
- Physics Department, University of Milan, Via Celoria 16, 20133 Milano, Italy
| | - Mikhail Tamm
- Physics Department, University of Moscow, 119991 Moscow, Russia
- Department of Applied Mathematics, Higher School of Economics, 101000 Moscow, Russia
| | - Marco Cosentino Lagomarsino
- Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris, France
- CNRS, UMR 7238, Paris, France
- IFOM, FIRC Institute of Molecular Oncology, 20139 Milan, Italy
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49
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Gherardi M, Cosentino Lagomarsino M. Procedures for Model-Guided Data Analysis of Chromosomal Loci Dynamics at Short Time Scales. Methods Mol Biol 2017; 1624:291-307. [PMID: 28842891 DOI: 10.1007/978-1-4939-7098-8_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
This chapter provides theoretical background and practical procedures for model-guided analysis of mobility of chromosomal loci from movies of many single trajectories. We guide the reader through existing physical models and measurable quantities, illustrating how this knowledge is useful for the interpretation of the measurements.
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Affiliation(s)
- Marco Gherardi
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7238, Computational and Quantitative Biology, 4 Place Jussieu, Paris, France.,FIRC Institute of Molecular Oncology (IFOM), 20139, Milan, Italy
| | - Marco Cosentino Lagomarsino
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7238, Computational and Quantitative Biology, 4 Place Jussieu, Paris, France. .,FIRC Institute of Molecular Oncology (IFOM), 20139, Milan, Italy. .,CNRS, UMR 7238, Paris, France.
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50
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Step by Step, Cell by Cell: Quantification of the Bacterial Cell Cycle. Trends Microbiol 2017; 25:250-256. [DOI: 10.1016/j.tim.2016.12.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/09/2016] [Accepted: 12/12/2016] [Indexed: 11/22/2022]
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