1
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Nieto C, Vargas-García CA, Pedraza JM, Singh A. Mechanisms of cell size regulation in slow-growing Escherichia coli cells: discriminating models beyond the adder. NPJ Syst Biol Appl 2024; 10:61. [PMID: 38811603 PMCID: PMC11137094 DOI: 10.1038/s41540-024-00383-z] [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: 09/11/2023] [Accepted: 05/09/2024] [Indexed: 05/31/2024] Open
Abstract
Under ideal conditions, Escherichia coli cells divide after adding a fixed cell size, a strategy known as the adder. This concept applies to various microbes and is often explained as the division that occurs after a certain number of stages, associated with the accumulation of precursor proteins at a rate proportional to cell size. However, under poor media conditions, E. coli cells exhibit a different size regulation. They are smaller and follow a sizer-like division strategy where the added size is inversely proportional to the size at birth. We explore three potential causes for this deviation: degradation of the precursor protein and two models where the propensity for accumulation depends on the cell size: a nonlinear accumulation rate, and accumulation starting at a threshold size termed the commitment size. These models fit the mean trends but predict different distributions given the birth size. To quantify the precision of the models to explain the data, we used the Akaike information criterion and compared them to open datasets of slow-growing E. coli cells in different media. We found that none of the models alone can consistently explain the data. However, the degradation model better explains the division strategy when cells are larger, whereas size-related models (power-law and commitment size) account for smaller cells. Our methodology proposes a data-based method in which different mechanisms can be tested systematically.
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Affiliation(s)
- César Nieto
- Department of Physics, Universidad de los Andes, Bogotá, Colombia
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE, 19716, USA
| | | | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE, 19716, USA.
- Department of Electrical and Computer Engineering, Biomedical Engineering, Mathematical Sciences, Center of Bioinformatic and Computational Biology, University of Delaware, Newark, DE, 19716, USA.
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2
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Vashistha H, Jammal-Touma J, Singh K, Rabin Y, Salman H. Bacterial cell-size changes resulting from altering the relative expression of Min proteins. Nat Commun 2023; 14:5710. [PMID: 37714867 PMCID: PMC10504268 DOI: 10.1038/s41467-023-41487-0] [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: 10/14/2022] [Accepted: 09/06/2023] [Indexed: 09/17/2023] Open
Abstract
The timing of cell division, and thus cell size in bacteria, is determined in part by the accumulation dynamics of the protein FtsZ, which forms the septal ring. FtsZ localization depends on membrane-associated Min proteins, which inhibit FtsZ binding to the cell pole membrane. Changes in the relative concentrations of Min proteins can disrupt FtsZ binding to the membrane, which in turn can delay cell division until a certain cell size is reached, in which the dynamics of Min proteins frees the cell membrane long enough to allow FtsZ ring formation. Here, we study the effect of Min proteins relative expression on the dynamics of FtsZ ring formation and cell size in individual Escherichia coli bacteria. Upon inducing overexpression of minE, cell size increases gradually to a new steady-state value. Concurrently, the time required to initiate FtsZ ring formation grows as the size approaches the new steady-state, at which point the ring formation initiates as early as before induction. These results highlight the contribution of Min proteins to cell size control, which may be partially responsible for the size fluctuations observed in bacterial populations, and may clarify how the size difference acquired during asymmetric cell division is offset.
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Affiliation(s)
- Harsh Vashistha
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Joanna Jammal-Touma
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kulveer Singh
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, Israel
| | - Yitzhak Rabin
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, Israel
| | - Hanna Salman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA.
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3
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Nieto C, Vargas-García C, Pedraza JM, Singh A. Mechanisms of Cell Size Regulation in Slow-Growing Escherichia coli Cells: Discriminating Models Beyond the Adder. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557238. [PMID: 37745550 PMCID: PMC10515837 DOI: 10.1101/2023.09.11.557238] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Under ideal conditions, Escherichia coli cells divide after adding a fixed cell size, a strategy known as the adder. This concept applies to various microbes and is often explained as the division that occurs after a certain number of stages, associated with the accumulation of precursor proteins at a rate proportional to cell size. However, under poor media conditions, E. coli cells exhibit a different size regulation. They are smaller and follow a sizer-like division strategy where the added size is inversely proportional to the size at birth. We explore three potential causes for this deviation: precursor protein degradation, nonlinear accumulation rate, and a threshold size termed the commitment size. These models fit mean trends but predict different distributions given the birth size. To validate these models, we used the Akaike information criterion and compared them to open datasets of slow-growing E. coli cells in different media. the degradation model could explain the division strategy for media where cells are larger, while the commitment size model could account for smaller cells. The power-law model, finally, better fits the data at intermediate regimes.
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Affiliation(s)
- César Nieto
- Department of Physics, Universidad de los Andes, Bogotá, Colombia
- Department of Electrical and Computing Engineering, University of Delaware. Newark, DE 19716, USA
| | - César Vargas-García
- AGROSAVIA Corporación Colombiana de Investigación Agropecuaria. Mosquera. Colombia
| | | | - Abhyudai Singh
- Department of Electrical and Computing Engineering, University of Delaware. Newark, DE 19716, USA
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4
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Kohiyama M, Herrick J, Norris V. Open Questions about the Roles of DnaA, Related Proteins, and Hyperstructure Dynamics in the Cell Cycle. Life (Basel) 2023; 13:1890. [PMID: 37763294 PMCID: PMC10532879 DOI: 10.3390/life13091890] [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: 07/18/2023] [Revised: 08/29/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
The DnaA protein has long been considered to play the key role in the initiation of chromosome replication in modern bacteria. Many questions about this role, however, remain unanswered. Here, we raise these questions within a framework based on the dynamics of hyperstructures, alias large assemblies of molecules and macromolecules that perform a function. In these dynamics, hyperstructures can (1) emit and receive signals or (2) fuse and separate from one another. We ask whether the DnaA-based initiation hyperstructure acts as a logic gate receiving information from the membrane, the chromosome, and metabolism to trigger replication; we try to phrase some of these questions in terms of DNA supercoiling, strand opening, glycolytic enzymes, SeqA, ribonucleotide reductase, the macromolecular synthesis operon, post-translational modifications, and metabolic pools. Finally, we ask whether, underpinning the regulation of the cell cycle, there is a physico-chemical clock inherited from the first protocells, and whether this clock emits a single signal that triggers both chromosome replication and cell division.
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Affiliation(s)
- Masamichi Kohiyama
- Institut Jacques Monod, Université Paris Cité, CNRS, 75013 Paris, France;
| | - John Herrick
- Independent Researcher, 3 rue des Jeûneurs, 75002 Paris, France;
| | - Vic Norris
- CBSA UR 4312, University of Rouen Normandy, University of Caen Normandy, Normandy University, 76000 Rouen, France
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5
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Kar P, Tiruvadi-Krishnan S, Männik J, Männik J, Amir A. Using conditional independence tests to elucidate causal links in cell cycle regulation in Escherichia coli. Proc Natl Acad Sci U S A 2023; 120:e2214796120. [PMID: 36897981 PMCID: PMC10089181 DOI: 10.1073/pnas.2214796120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 01/09/2023] [Indexed: 03/12/2023] Open
Abstract
How cells regulate their cell cycles is a central question for cell biology. Models of cell size homeostasis have been proposed for bacteria, archaea, yeast, plant, and mammalian cells. New experiments bring forth high volumes of data suitable for testing existing models of cell size regulation and proposing new mechanisms. In this paper, we use conditional independence tests in conjunction with data of cell size at key cell cycle events (birth, initiation of DNA replication, and constriction) in the model bacterium Escherichia coli to select between the competing cell cycle models. We find that in all growth conditions that we study, the division event is controlled by the onset of constriction at midcell. In slow growth, we corroborate a model where replication-related processes control the onset of constriction at midcell. In faster growth, we find that the onset of constriction is affected by additional cues beyond DNA replication. Finally, we also find evidence for the presence of additional cues triggering initiations of DNA replication apart from the conventional notion where the mother cells solely determine the initiation event in the daughter cells via an adder per origin model. The use of conditional independence tests is a different approach in the context of understanding cell cycle regulation and it can be used in future studies to further explore the causal links between cell events.
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Affiliation(s)
- Prathitha Kar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA02134
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA02138
| | | | - Jaana Männik
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN37996
| | - Jaan Männik
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN37996
| | - Ariel Amir
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA02134
- Department of Complex Systems, Weizmann Institute of Science, Rehovot7610001, Israel
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6
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Cayron J, Dedieu-Berne A, Lesterlin C. Bacterial filaments recover by successive and accelerated asymmetric divisions that allow rapid post-stress cell proliferation. Mol Microbiol 2023; 119:237-251. [PMID: 36527185 DOI: 10.1111/mmi.15016] [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: 07/19/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Filamentation is a reversible morphological change triggered in response to various stresses that bacteria might encounter in the environment, during host infection or antibiotic treatments. Here we re-visit the dynamics of filament formation and recovery using a consistent framework based on live-cells microscopy. We compare the fate of filamentous Escherichia coli induced by cephalexin that inhibits cell division or by UV-induced DNA-damage that additionally perturbs chromosome segregation. We show that both filament types recover by successive and accelerated rounds of divisions that preferentially occur at the filaments' tip, thus resulting in the rapid production of multiple daughter cells with tightly regulated size. The DNA content, viability and further division of the daughter cells essentially depends on the coordination between chromosome segregation and division within the mother filament. Septum positioning at the filaments' tip depends on the Min system, while the nucleoid occlusion protein SlmA regulates the timing of division to prevent septum closure on unsegregated chromosomes. Our results not only recapitulate earlier conclusions but provide a higher level of detail regarding filaments division and the fate of the daughter cells. Together with previous reports, this work uncovers how filamentation recovery allows for a rapid cell proliferation after stress treatment.
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Affiliation(s)
- Julien Cayron
- Microbiologie Moléculaire et Biochimie Structurale (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, Lyon, France
| | - Annick Dedieu-Berne
- Microbiologie Moléculaire et Biochimie Structurale (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, Lyon, France
| | - Christian Lesterlin
- Microbiologie Moléculaire et Biochimie Structurale (MMSB), Université Lyon 1, CNRS, Inserm, UMR5086, Lyon, France
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7
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Yu Z, Goodall ECA, Henderson IR, Guo J. Plasmids Can Shift Bacterial Morphological Response against Antibiotic Stress. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2203260. [PMID: 36424175 PMCID: PMC9839882 DOI: 10.1002/advs.202203260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Bacterial cell filamentation is a morphological change wherein cell division is blocked, which can improve bacterial survival under unfavorable conditions (e.g., antibiotic stress that causes DNA damage). As an extrachromosomal DNA molecule, plasmids can confer additionally advantageous traits including antibiotic resistance on the host. However, little is known about whether plasmids could shift bacterial morphological responses to antibiotic stress. Here, it is reported that plasmid-free cells, rather than plasmid-bearing cells, exhibit filamentation and asymmetrical cell division under exposure to sub-inhibitory concentrations of antibiotics (ciprofloxacin and cephalexin). The underlying mechanism is revealed by investigating DNA damage, cell division inhibitor sulA, the SOS response, toxin-antitoxin module (parDE) located on plasmids, and efflux pumps. Significantly higher expression of sulA is observed in plasmid-free cells, compared to plasmid-bearing cells. Plasmid carriage enables the hosts to suffer less DNA damage, exhibit stronger efflux pump activities, and thus have a higher antibiotic tolerance. These benefits are attributed to the parDE module that mediates stress responses from plasmid-bearing cells and mainly contributes to cell morphological changes. Collectively, the findings demonstrate that plasmids can confer additional innate defenses on the host to antibiotics, thus advancing the understanding of how plasmids affect bacterial evolution in hostile environments.
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Affiliation(s)
- Zhigang Yu
- Australian Centre for Water and Environmental BiotechnologyThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Emily C. A. Goodall
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Ian R. Henderson
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
| | - Jianhua Guo
- Australian Centre for Water and Environmental BiotechnologyThe University of QueenslandSt. LuciaBrisbaneQueensland4072Australia
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8
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Spinnato MC, Lo Sciuto A, Mercolino J, Lucidi M, Leoni L, Rampioni G, Visca P, Imperi F. Effect of a Defective Clamp Loader Complex of DNA Polymerase III on Growth and SOS Response in Pseudomonas aeruginosa. Microorganisms 2022; 10:423. [PMID: 35208877 PMCID: PMC8879598 DOI: 10.3390/microorganisms10020423] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 11/17/2022] Open
Abstract
DNA polymerase III (Pol III) is the replicative enzyme in bacteria. It consists of three subcomplexes, the catalytic core, the β clamp, and the clamp loader. While this complex has been thoroughly characterized in the model organism Escherichia coli, much less is known about its functioning and/or its specific properties in other bacteria. Biochemical studies highlighted specific features in the clamp loader subunit ψ of Pseudomonas aeruginosa as compared to its E. coli counterpart, and transposon mutagenesis projects identified the ψ-encoding gene holD among the strictly essential core genes of P. aeruginosa. By generating a P. aeruginosa holD conditional mutant, here we demonstrate that, as previously observed for E. coli holD mutants, HolD-depleted P. aeruginosa cells show strongly decreased growth, induction of the SOS response, and emergence of suppressor mutants at high frequency. However, differently from what was observed in E. coli, the growth of P. aeruginosa cells lacking HolD cannot be rescued by the deletion of genes for specialized DNA polymerases. We also observed that the residual growth of HolD-depleted cells is strictly dependent on homologous recombination functions, suggesting that recombination-mediated rescue of stalled replication forks is crucial to support replication by a ψ-deficient Pol III enzyme in P. aeruginosa.
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Affiliation(s)
- Maria Concetta Spinnato
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
| | - Alessandra Lo Sciuto
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
| | - Jessica Mercolino
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
| | - Massimiliano Lucidi
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
| | - Livia Leoni
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
| | - Giordano Rampioni
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, 00146 Rome, Italy; (M.C.S.); (A.L.S.); (J.M.); (M.L.); (L.L.); (G.R.); (P.V.)
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
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9
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Panikov NS. Genome-Scale Reconstruction of Microbial Dynamic Phenotype: Successes and Challenges. Microorganisms 2021; 9:2352. [PMID: 34835477 PMCID: PMC8621822 DOI: 10.3390/microorganisms9112352] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/18/2021] [Accepted: 10/27/2021] [Indexed: 12/04/2022] Open
Abstract
This review is a part of the SI 'Genome-Scale Modeling of Microorganisms in the Real World'. The goal of GEM is the accurate prediction of the phenotype from its respective genotype under specified environmental conditions. This review focuses on the dynamic phenotype; prediction of the real-life behaviors of microorganisms, such as cell proliferation, dormancy, and mortality; balanced and unbalanced growth; steady-state and transient processes; primary and secondary metabolism; stress responses; etc. Constraint-based metabolic reconstructions were successfully started two decades ago as FBA, followed by more advanced models, but this review starts from the earlier nongenomic predecessors to show that some GEMs inherited the outdated biokinetic frameworks compromising their performances. The most essential deficiencies are: (i) an inadequate account of environmental conditions, such as various degrees of nutrients limitation and other factors shaping phenotypes; (ii) a failure to simulate the adaptive changes of MMCC (MacroMolecular Cell Composition) in response to the fluctuating environment; (iii) the misinterpretation of the SGR (Specific Growth Rate) as either a fixed constant parameter of the model or independent factor affecting the conditional expression of macromolecules; (iv) neglecting stress resistance as an important objective function; and (v) inefficient experimental verification of GEM against simple growth (constant MMCC and SGR) data. Finally, we propose several ways to improve GEMs, such as replacing the outdated Monod equation with the SCM (Synthetic Chemostat Model) that establishes the quantitative relationships between primary and secondary metabolism, growth rate and stress resistance, process kinetics, and cell composition.
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Affiliation(s)
- Nicolai S Panikov
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, MA 02115, USA
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10
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Colin A, Micali G, Faure L, Cosentino Lagomarsino M, van Teeffelen S. Two different cell-cycle processes determine the timing of cell division in Escherichia coli. eLife 2021; 10:67495. [PMID: 34612203 PMCID: PMC8555983 DOI: 10.7554/elife.67495] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 10/05/2021] [Indexed: 11/13/2022] Open
Abstract
Cells must control the cell cycle to ensure that key processes are brought to completion. In Escherichia coli, it is controversial whether cell division is tied to chromosome replication or to a replication-independent inter-division process. A recent model suggests instead that both processes may limit cell division with comparable odds in single cells. Here, we tested this possibility experimentally by monitoring single-cell division and replication over multiple generations at slow growth. We then perturbed cell width, causing an increase of the time between replication termination and division. As a consequence, replication became decreasingly limiting for cell division, while correlations between birth and division and between subsequent replication-initiation events were maintained. Our experiments support the hypothesis that both chromosome replication and a replication-independent inter-division process can limit cell division: the two processes have balanced contributions in non-perturbed cells, while our width perturbations increase the odds of the replication-independent process being limiting.
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Affiliation(s)
- Alexandra Colin
- Microbial Morphogenesis and Growth Laboratory, Institut Pasteur, Paris, France
| | - Gabriele Micali
- Department of Environmental Microbiology, Dübendorf, Switzerland.,Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Louis Faure
- Microbial Morphogenesis and Growth Laboratory, Institut Pasteur, Paris, France
| | - Marco Cosentino Lagomarsino
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy.,Physics Department, University of Milan, and INFN, Milan, Italy
| | - Sven van Teeffelen
- Microbial Morphogenesis and Growth Laboratory, Institut Pasteur, Paris, France.,Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Canada
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11
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Threshold accumulation of a constitutive protein explains E. coli cell-division behavior in nutrient upshifts. Proc Natl Acad Sci U S A 2021; 118:2016391118. [PMID: 33931503 DOI: 10.1073/pnas.2016391118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Despite a boost of recent progress in dynamic single-cell measurements and analyses in Escherichia coli, we still lack a mechanistic understanding of the determinants of the decision to divide. Specifically, the debate is open regarding the processes linking growth and chromosome replication to division and on the molecular origin of the observed "adder correlations," whereby cells divide, adding roughly a constant volume independent of their initial volume. In order to gain insight into these questions, we interrogate dynamic size-growth behavior of single cells across nutrient upshifts with a high-precision microfluidic device. We find that the division rate changes quickly after nutrients change, much before growth rate goes to a steady state, and in a way that adder correlations are robustly conserved. Comparison of these data to simple mathematical models falsifies proposed mechanisms, where replication-segregation or septum completions are the limiting step for cell division. Instead, we show that the accumulation of a putative constitutively expressed "P-sector divisor" protein explains the behavior during the shift.
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12
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Meunier A, Cornet F, Campos M. Bacterial cell proliferation: from molecules to cells. FEMS Microbiol Rev 2021; 45:fuaa046. [PMID: 32990752 PMCID: PMC7794046 DOI: 10.1093/femsre/fuaa046] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Bacterial cell proliferation is highly efficient, both because bacteria grow fast and multiply with a low failure rate. This efficiency is underpinned by the robustness of the cell cycle and its synchronization with cell growth and cytokinesis. Recent advances in bacterial cell biology brought about by single-cell physiology in microfluidic chambers suggest a series of simple phenomenological models at the cellular scale, coupling cell size and growth with the cell cycle. We contrast the apparent simplicity of these mechanisms based on the addition of a constant size between cell cycle events (e.g. two consecutive initiation of DNA replication or cell division) with the complexity of the underlying regulatory networks. Beyond the paradigm of cell cycle checkpoints, the coordination between the DNA and division cycles and cell growth is largely mediated by a wealth of other mechanisms. We propose our perspective on these mechanisms, through the prism of the known crosstalk between DNA replication and segregation, cell division and cell growth or size. We argue that the precise knowledge of these molecular mechanisms is critical to integrate the diverse layers of controls at different time and space scales into synthetic and verifiable models.
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Affiliation(s)
- Alix Meunier
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
| | - François Cornet
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
| | - Manuel Campos
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
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13
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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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14
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Molecular Characterization of the Burkholderia cenocepacia dcw Operon and FtsZ Interactors as New Targets for Novel Antimicrobial Design. Antibiotics (Basel) 2020; 9:antibiotics9120841. [PMID: 33255486 PMCID: PMC7761207 DOI: 10.3390/antibiotics9120841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/18/2020] [Accepted: 11/23/2020] [Indexed: 12/20/2022] Open
Abstract
The worldwide spread of antimicrobial resistance highlights the need of new druggable cellular targets. The increasing knowledge of bacterial cell division suggested the potentiality of this pathway as a pool of alternative drug targets, mainly based on the essentiality of these proteins, as well as on the divergence from their eukaryotic counterparts. People suffering from cystic fibrosis are particularly challenged by the lack of antibiotic alternatives. Among the opportunistic pathogens that colonize the lungs of these patients, Burkholderia cenocepacia is a well-known multi-drug resistant bacterium, particularly difficult to treat. Here we describe the organization of its division cell wall (dcw) cluster: we found that 15 genes of the dcw operon can be transcribed as a polycistronic mRNA from mraZ to ftsZ and that its transcription is under the control of a strong promoter regulated by MraZ. B. cenocepacia J2315 FtsZ was also shown to interact with the other components of the divisome machinery, with a few differences respect to other bacteria, such as the direct interaction with FtsQ. Using an in vitro sedimentation assay, we validated the role of SulA as FtsZ inhibitor, and the roles of FtsA and ZipA as tethers of FtsZ polymers. Together our results pave the way for future antimicrobial design based on the divisome as pool of antibiotic cellular targets.
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15
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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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16
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Joseph AM, Badrinarayanan A. Visualizing mutagenic repair: novel insights into bacterial translesion synthesis. FEMS Microbiol Rev 2020; 44:572-582. [PMID: 32556198 PMCID: PMC7476773 DOI: 10.1093/femsre/fuaa023] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 06/17/2020] [Indexed: 12/15/2022] Open
Abstract
DNA repair is essential for cell survival. In all domains of life, error-prone and error-free repair pathways ensure maintenance of genome integrity under stress. Mutagenic, low-fidelity repair mechanisms help avoid potential lethality associated with unrepaired damage, thus making them important for genome maintenance and, in some cases, the preferred mode of repair. However, cells carefully regulate pathway choice to restrict activity of these pathways to only certain conditions. One such repair mechanism is translesion synthesis (TLS), where a low-fidelity DNA polymerase is employed to synthesize across a lesion. In bacteria, TLS is a potent source of stress-induced mutagenesis, with potential implications in cellular adaptation as well as antibiotic resistance. Extensive genetic and biochemical studies, predominantly in Escherichia coli, have established a central role for TLS in bypassing bulky DNA lesions associated with ongoing replication, either at or behind the replication fork. More recently, imaging-based approaches have been applied to understand the molecular mechanisms of TLS and how its function is regulated. Together, these studies have highlighted replication-independent roles for TLS as well. In this review, we discuss the current status of research on bacterial TLS, with emphasis on recent insights gained mostly through microscopy at the single-cell and single-molecule level.
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Affiliation(s)
- Asha Mary Joseph
- National Centre for Biological Sciences (Tata Institute of Fundamental Research), Bangalore, Karnataka 560065, India
| | - Anjana Badrinarayanan
- National Centre for Biological Sciences (Tata Institute of Fundamental Research), Bangalore, Karnataka 560065, India
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17
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Japaridze A, Gogou C, Kerssemakers JWJ, Nguyen HM, Dekker C. Direct observation of independently moving replisomes in Escherichia coli. Nat Commun 2020; 11:3109. [PMID: 32561741 PMCID: PMC7305307 DOI: 10.1038/s41467-020-16946-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 05/29/2020] [Indexed: 12/18/2022] Open
Abstract
The replication and transfer of genomic material from a cell to its progeny are vital processes in all living systems. Here we visualize the process of chromosome replication in widened E. coli cells. Monitoring the replication of single chromosomes yields clear examples of replication bubbles that reveal that the two replisomes move independently from the origin to the terminus of replication along each of the two arms of the circular chromosome, providing direct support for the so-called train-track model, and against a factory model for replisomes. The origin of replication duplicates near midcell, initially splitting to random directions and subsequently towards the poles. The probability of successful segregation of chromosomes significantly decreases with increasing cell width, indicating that chromosome confinement by the cell boundary is an important driver of DNA segregation. Our findings resolve long standing questions in bacterial chromosome organization.
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Affiliation(s)
- Aleksandre Japaridze
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Christos Gogou
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Huyen My Nguyen
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
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18
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Liu Y, Chen J, Crisante D, Jaramillo Lopez JM, Mahadevan R. Dynamic Cell Programming with Quorum Sensing-Controlled CRISPRi Circuit. ACS Synth Biol 2020; 9:1284-1291. [PMID: 32485106 DOI: 10.1021/acssynbio.0c00148] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Synthetic biology is enabling rapid advances in the areas of biomanufacturing and live therapeutics. Dynamic circuits that can be used to regulate cellular resources and microbial community behavior represent a defining focus of synthetic biology, and have attracted tremendous interest. However, the existing dynamic circuits are mostly gene editing-dependent or cell lysis-based, which limits their broad and convenient application, and in some cases, such lysis-based circuits can suffer from genetic instability due to evolution. There is limited research in quorum sensing-assisted CRISPRi, which can function in a gene editing-independent manner. Here, we constructed a series of quorum sensing controlled CRISPRi systems (Q-CRISPRi), which can dynamically program bacteria by using customized sgRNA without introducing cell lysis. We successfully applied Q-CRISPRi circuits to dynamically program gene expression, population density, phenotype, physical property, and community composition of microbial consortia. The strategies reported here represent methods for dynamic cell programming and could be effective in programming industrially and medically important microorganisms to offer better control of their metabolism and behavior.
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Affiliation(s)
- Yilan Liu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Jinjin Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - David Crisante
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Jhoselyn Marisol Jaramillo Lopez
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
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19
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General quantitative relations linking cell growth and the cell cycle in Escherichia coli. Nat Microbiol 2020; 5:995-1001. [PMID: 32424336 DOI: 10.1038/s41564-020-0717-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 04/01/2020] [Indexed: 01/15/2023]
Abstract
Growth laws emerging from studies of cell populations provide essential constraints on the global mechanisms that coordinate cell growth1-3. The foundation of bacterial cell cycle studies relies on two interconnected dogmas that were proposed more than 50 years ago-the Schaechter-Maaloe-Kjeldgaard growth law that relates cell mass to growth rate1 and Donachie's hypothesis of a growth-rate-independent initiation mass4. These dogmas spurred many efforts to understand their molecular bases and physiological consequences5-14. Although they are generally accepted in the fast-growth regime, that is, for doubling times below 1 h, extension of these dogmas to the slow-growth regime has not been consistently achieved. Here, through a quantitative physiological study of Escherichia coli cell cycles over an extensive range of growth rates, we report that neither dogma holds in either the slow- or fast-growth regime. In their stead, linear relations between the cell mass and the rate of chromosome replication-segregation were found across the range of growth rates. These relations led us to propose an integral-threshold model in which the cell cycle is controlled by a licensing process, the rate of which is related in a simple way to chromosomal dynamics. These results provide a quantitative basis for predictive understanding of cell growth-cell cycle relationships.
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20
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Walker DM, Freddolino PL, Harshey RM. A Well-Mixed E. coli Genome: Widespread Contacts Revealed by Tracking Mu Transposition. Cell 2020; 180:703-716.e18. [PMID: 32059782 DOI: 10.1016/j.cell.2020.01.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 10/21/2019] [Accepted: 01/22/2020] [Indexed: 02/06/2023]
Abstract
The three-dimensional structures of chromosomes are increasingly being recognized as playing a major role in cellular regulatory states. The efficiency and promiscuity of phage Mu transposition was exploited to directly measure in vivo interactions between genomic loci in E. coli. Two global organizing principles have emerged: first, the chromosome is well-mixed and uncompartmentalized, with transpositions occurring freely between all measured loci; second, several gene families/regions show "clustering": strong three-dimensional co-localization regardless of linear genomic distance. The activities of the SMC/condensin protein MukB and nucleoid-compacting protein subunit HU-α are essential for the well-mixed state; HU-α is also needed for clustering of 6/7 ribosomal RNA-encoding loci. The data are explained by a model in which the chromosomal structure is driven by dynamic competition between DNA replication and chromosomal relaxation, providing a foundation for determining how region-specific properties contribute to both chromosomal structure and gene regulation.
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Affiliation(s)
- David M Walker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Peter L Freddolino
- Department of Biological Chemistry and Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Rasika M Harshey
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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21
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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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22
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Abstract
Bacterial chromosomes harbour a unique origin of bidirectional replication, oriC. They are almost always circular, with replication terminating in a region diametrically opposite to oriC, the terminus. The oriC-terminus organisation is reflected by the orientation of the genes and by the disposition of DNA-binding protein motifs implicated in the coordination of chromosome replication and segregation with cell division. Correspondingly, the E. coli and B. subtilis model bacteria possess a replication fork trap system, Tus/ter and RTP/ter, respectively, which enforces replication termination in the terminus region. Here, we show that tus and rtp are restricted to four clades of bacteria, suggesting that tus was recently domesticated from a plasmid gene. We further demonstrate that there is no replication fork system in Vibrio cholerae, a bacterium closely related to E. coli. Marker frequency analysis showed that replication forks originating from ectopic origins were not blocked in the terminus region of either of the two V. cholerae chromosomes, but progressed normally until they encountered an opposite fork. As expected, termination synchrony of the two chromosomes is disrupted by these ectopic origins. Finally, we show that premature completion of the primary chromosome replication did not modify the choreography of segregation of its terminus region.
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23
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Micali G, Grilli J, Osella M, Cosentino Lagomarsino M. Concurrent processes set E. coli cell division. SCIENCE ADVANCES 2018; 4:eaau3324. [PMID: 30417095 PMCID: PMC6224021 DOI: 10.1126/sciadv.aau3324] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/03/2018] [Indexed: 05/30/2023]
Abstract
A cell can divide only upon completion of chromosome segregation; otherwise, its daughters would lose genetic material. However, we do not know whether the partitioning of chromosomes is the key event for the decision to divide. We show how key trends in single-cell data reject the classic idea of replication-segregation as the rate-limiting process for cell division. Instead, the data agree with a model where two concurrent processes (setting replication initiation and interdivision time) set cell division on competing time scales. During each cell cycle, division is set by the slowest process (an "AND" gate). The concept of transitions between cell cycle stages as decisional processes integrating multiple inputs instead of cascading from orchestrated steps can affect the way we think of the cell cycle in general.
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Affiliation(s)
- Gabriele Micali
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Jacopo Grilli
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
| | - Matteo Osella
- Physics Department, University of Turin, Via Giuria 16, Torino, Italy
- I.N.F.N., Torino, Italy
| | - Marco Cosentino Lagomarsino
- Sorbonne Universités, UPMC University Paris 06, Paris, France
- CNRS, UMR 7238, Paris, France
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
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Micali G, Grilli J, Marchi J, Osella M, Cosentino Lagomarsino M. Dissecting the Control Mechanisms for DNA Replication and Cell Division in E. coli. Cell Rep 2018; 25:761-771.e4. [DOI: 10.1016/j.celrep.2018.09.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/22/2018] [Accepted: 09/19/2018] [Indexed: 12/11/2022] Open
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