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Vélez M. How Does the Spatial Confinement of FtsZ to a Membrane Surface Affect Its Polymerization Properties and Function? Front Microbiol 2022; 13:757711. [PMID: 35592002 PMCID: PMC9111741 DOI: 10.3389/fmicb.2022.757711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 01/27/2022] [Indexed: 11/15/2022] Open
Abstract
FtsZ is the cytoskeletal protein that organizes the formation of the septal ring and orchestrates bacterial cell division. Its association to the membrane is essential for its function. In this mini-review I will address the question of how this association can interfere with the structure and dynamic properties of the filaments and argue that its dynamics could also remodel the underlying lipid membrane through its activity. Thus, lipid rearrangement might need to be considered when trying to understand FtsZ’s function. This new element could help understand how FtsZ assembly coordinates positioning and recruitment of the proteins forming the septal ring inside the cell with the activity of the machinery involved in peptidoglycan synthesis located in the periplasmic space.
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Affiliation(s)
- Marisela Vélez
- Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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2
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The dynamics of shapes of vesicle membranes with time dependent spontaneous curvature. PLoS One 2020; 15:e0227562. [PMID: 31935248 PMCID: PMC6959615 DOI: 10.1371/journal.pone.0227562] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/21/2019] [Indexed: 11/19/2022] Open
Abstract
We study the time evolution of the shape of a vesicle membrane under time-dependent spontaneous curvature by means of phase-field model. We introduce the variation in time of the spontaneous curvature via a second field which represents the concentration of a substance that anchors with the lipid bilayer thus changing the local curvature and producing constriction. This constriction is mediated by the action on the membrane of an structure resembling the role of a Z ring. Our phase-field model is able to reproduce a number of different shapes that have been experimentally observed. Different shapes are associated with different constraints imposed upon the model regarding conservation of membrane area. In particular, we show that if area is conserved our model reproduces the so-called L-form shape. By contrast, if the area of the membrane is allowed to grow, our model reproduces the formation of a septum in the vicinity of the constriction. Furthermore, we propose a new term in the free energy which allows the membrane to evolve towards eventual pinching.
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3
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Surface Orientation and Binding Strength Modulate Shape of FtsZ on Lipid Surfaces. Int J Mol Sci 2019; 20:ijms20102545. [PMID: 31137602 PMCID: PMC6566678 DOI: 10.3390/ijms20102545] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/15/2019] [Accepted: 05/23/2019] [Indexed: 01/16/2023] Open
Abstract
We have used a simple model system to test the prediction that surface attachment strength of filaments presenting a torsion would affect their shape and properties. FtsZ from E. coli containing one cysteine in position 2 was covalently attached to a lipid bilayer containing maleimide lipids either in their head group (to simulate tight attachment) or at the end of a polyethylene glycol molecule attached to the head group (to simulate loose binding). We found that filaments tightly attached grew straight, growing from both ends, until they formed a two-dimensional lattice. Further monomer additions to their sides generated a dense layer of oriented filaments that fully covered the lipid membrane. After this point the surface became unstable and the bilayer detached from the surface. Filaments with a loose binding were initially curved and later evolved into straight thicker bundles that destabilized the membrane after reaching a certain surface density. Previously described theoretical models of FtsZ filament assembly on surfaces that include lateral interactions, spontaneous curvature, torsion, anchoring to the membrane, relative geometry of the surface and the filament ‘living-polymer’ condition in the presence of guanosine triphosphate (GTP) can offer some clues about the driving forces inducing these filament rearrangements.
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4
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Mateos-Gil P, Tarazona P, Vélez M. Bacterial cell division: modeling FtsZ assembly and force generation from single filament experimental data. FEMS Microbiol Rev 2019; 43:73-87. [PMID: 30376053 DOI: 10.1093/femsre/fuy039] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 10/26/2018] [Indexed: 12/24/2022] Open
Abstract
The bacterial cytoskeletal protein FtsZ binds and hydrolyzes GTP, self-aggregates into dynamic filaments and guides the assembly of the septal ring on the inner side of the membrane at midcell. This ring constricts the cell during division and is present in most bacteria. Despite exhaustive studies undertaken in the last 25 years after its discovery, we do not yet know the mechanism by which this GTP-dependent self-aggregating protein exerts force on the underlying membrane. This paper reviews recent experiments and theoretical models proposed to explain FtsZ filament dynamic assembly and force generation. It highlights how recent observations of single filaments on reconstituted model systems and computational modeling are contributing to develop new multiscale models that stress the importance of previously overlooked elements as monomer internal flexibility, filament twist and flexible anchoring to the cell membrane. These elements contribute to understand the rich behavior of these GTP consuming dynamic filaments on surfaces. The aim of this review is 2-fold: (1) to summarize recent multiscale models and their implications to understand the molecular mechanism of FtsZ assembly and force generation and (2) to update theoreticians with recent experimental results.
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Affiliation(s)
- Pablo Mateos-Gil
- Institute of Molecular Biology and Biotechnology, FO.R.T.H, Vassilika Vouton, 70013 Heraklion, Greece
| | - Pedro Tarazona
- Condensed Matter Physics Center (IFIMAC) and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Marisela Vélez
- Instituto de Catálisis y Petroleoquímica CSIC, c/ Marie Curie 2, Cantoblanco, 28049 Madrid, Spain
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5
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Márquez IF, Mateos-Gil P, Shin JY, Lagos R, Monasterio O, Vélez M. Mutations on FtsZ lateral helix H3 that disrupt cell viability hamper reorganization of polymers on lipid surfaces. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017. [PMID: 28642045 DOI: 10.1016/j.bbamem.2017.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
FtsZ filaments localize at the middle of the bacterial cell and participate in the formation of a contractile ring responsible for cell division. Previous studies demonstrated that the highly conserved negative charge of glutamate 83 and the positive charge of arginine 85 located in the lateral helix H3 bend of Escherichia coli FtsZ are required for in vivo cell division. In order to understand how these lateral mutations impair the formation of a contractile ring,we extend previous in vitro characterization of these mutants in solution to study their behavior on lipid modified surfaces. We study their interaction with ZipAand look at their reorganization on the surface. We found that the dynamic bundling capacity of the mutant proteins is deficient, and this impairment increases the more the composition and spatial arrangement of the reconstituted system resembles the situation inside the cell: mutant proteins completely fail to reorganize to form higher order aggregates when bound to an E.coli lipid surface through oriented ZipA.We conclude that these surface lateral point mutations affect the dynamic reorganization of FtsZ filaments into bundles on the cell membrane, suggesting that this event is relevant for generating force and completing bacterial division.
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Affiliation(s)
- Ileana F Márquez
- Instituto de Catálisis y Petroleoquímica, c/Marie Curie 2, Cantoblanco, Madrid 28049, Spain
| | - Pablo Mateos-Gil
- Instituto de Catálisis y Petroleoquímica, c/Marie Curie 2, Cantoblanco, Madrid 28049, Spain
| | - Jae Yen Shin
- Departamento de Biología, Facultad de Ciencias, Casilla 653, Santiago 1, Chile
| | - Rosalba Lagos
- Departamento de Biología, Facultad de Ciencias, Casilla 653, Santiago 1, Chile
| | - Octavio Monasterio
- Departamento de Biología, Facultad de Ciencias, Casilla 653, Santiago 1, Chile
| | - Marisela Vélez
- Instituto de Catálisis y Petroleoquímica, c/Marie Curie 2, Cantoblanco, Madrid 28049, Spain.
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6
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Yao Q, Jewett AI, Chang YW, Oikonomou CM, Beeby M, Iancu CV, Briegel A, Ghosal D, Jensen GJ. Short FtsZ filaments can drive asymmetric cell envelope constriction at the onset of bacterial cytokinesis. EMBO J 2017; 36:1577-1589. [PMID: 28438890 DOI: 10.15252/embj.201696235] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 03/17/2017] [Accepted: 03/23/2017] [Indexed: 11/09/2022] Open
Abstract
FtsZ, the bacterial homologue of eukaryotic tubulin, plays a central role in cell division in nearly all bacteria and many archaea. It forms filaments under the cytoplasmic membrane at the division site where, together with other proteins it recruits, it drives peptidoglycan synthesis and constricts the cell. Despite extensive study, the arrangement of FtsZ filaments and their role in division continue to be debated. Here, we apply electron cryotomography to image the native structure of intact dividing cells and show that constriction in a variety of Gram-negative bacterial cells, including Proteus mirabilis and Caulobacter crescentus, initiates asymmetrically, accompanied by asymmetric peptidoglycan incorporation and short FtsZ-like filament formation. These results show that a complete ring of FtsZ is not required for constriction and lead us to propose a model for FtsZ-driven division in which short dynamic FtsZ filaments can drive initial peptidoglycan synthesis and envelope constriction at the onset of cytokinesis, later increasing in length and number to encircle the division plane and complete constriction.
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Affiliation(s)
- Qing Yao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Andrew I Jewett
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Yi-Wei Chang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Morgan Beeby
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Cristina V Iancu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Ariane Briegel
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Debnath Ghosal
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA .,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
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7
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Abstract
In bacteria and archaea, the most widespread cell division system is based on the tubulin homologue FtsZ protein, whose filaments form the cytokinetic Z-ring. FtsZ filaments are tethered to the membrane by anchors such as FtsA and SepF and are regulated by accessory proteins. One such set of proteins is responsible for Z-ring's spatiotemporal regulation, essential for the production of two equal-sized daughter cells. Here, we describe how our still partial understanding of the FtsZ-based cell division process has been progressed by visualising near-atomic structures of Z-rings and complexes that control Z-ring positioning in cells, most notably the MinCDE and Noc systems that act by negatively regulating FtsZ filaments. We summarise available data and how they inform mechanistic models for the cell division process.
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8
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González de Prado Salas P, Tarazona P. Collective effects of torsion in FtsZ filaments. Phys Rev E 2016; 93:042407. [PMID: 27176329 DOI: 10.1103/physreve.93.042407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 11/07/2022]
Abstract
Recent evidence points to the presence of torsion in FtsZ bonds. In addition, experiments with FtsZ mutants on surfaces resulted in new aggregates that cannot be explained by older models for FtsZ dynamics. We use an interaction model for FtsZ derived from molecular dynamics simulations and expand a fine-grained lattice model used to describe FtsZ aggregates on a surface. This new model includes different anchoring angles for the monomers and allows bond twist, two ingredients that oppose each other resulting in a more dynamic and interesting system. We study the role and importance of these conflicting elements and how the aggregates are characterized by the different interaction parameters.
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Affiliation(s)
| | - Pedro Tarazona
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Institute (IFIMAC) and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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9
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Picallo CB, Barrio RA, Varea C, Alarcón T, Hernandez-Machado A. Phase-field modelling of the dynamics of Z-ring formation in liposomes: Onset of constriction and coarsening. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:61. [PMID: 26105960 DOI: 10.1140/epje/i2015-15061-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/25/2015] [Accepted: 05/27/2015] [Indexed: 06/04/2023]
Abstract
We propose a model for the dynamics of the formation of rings of FtsZ on tubular liposomes which produce constriction on the corresponding membrane. Our phase-field model is based on a simple bending energy that captures the dynamics of the interplay between the protein and the membrane. The short-time regime is analyzed by a linear dispersion relation, with which we are able to predict the number of rings per unit length on a tubular liposome. We study numerically the long-time dynamics of the system in the non-linear regime where we observe coarsening of Z-rings on tubular liposomes. In particular, our numerical results show that, during the coarsening process, the number of Z-rings decreases as the radius of tubular liposome increases. This is consistent with the experimental observation that the separation between rings is proportional to the radius of the liposome. Our model predicts that the mechanism for the increased rate of coarsening in liposomes of larger radius is a consequence of the increased interface energy.
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Affiliation(s)
- C B Picallo
- Departament ECM, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028, Barcelona, Spain
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622, Villeurbanne cedex, France
| | - R A Barrio
- Instituto de Física, U.N.A.M., Apartado Postal 20-364, 01000, Mexico D.F., Mexico
| | - C Varea
- Instituto de Física, U.N.A.M., Apartado Postal 20-364, 01000, Mexico D.F., Mexico
| | - T Alarcón
- Campus de Bellaterra, Centre de Recerca Matemàtica, Barcelona, Spain
- Departament de Matemàtiques, Universitat Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain
| | - A Hernandez-Machado
- Departament ECM, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028, Barcelona, Spain.
- Campus de Bellaterra, Centre de Recerca Matemàtica, Barcelona, Spain.
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10
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Eun YJ, Kapoor M, Hussain S, Garner EC. Bacterial Filament Systems: Toward Understanding Their Emergent Behavior and Cellular Functions. J Biol Chem 2015; 290:17181-9. [PMID: 25957405 DOI: 10.1074/jbc.r115.637876] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacteria use homologs of eukaryotic cytoskeletal filaments to conduct many different tasks, controlling cell shape, division, and DNA segregation. These filaments, combined with factors that regulate their polymerization, create emergent self-organizing machines. Here, we summarize the current understanding of the assembly of these polymers and their spatial regulation by accessory factors, framing them in the context of being dynamical systems. We highlight how comparing the in vivo dynamics of the filaments with those measured in vitro has provided insight into the regulation, emergent behavior, and cellular functions of these polymeric systems.
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Affiliation(s)
- Ye-Jin Eun
- From the Molecular and Cellular Biology Department and Faculty of Arts and Sciences (FAS) Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Mrinal Kapoor
- From the Molecular and Cellular Biology Department and Faculty of Arts and Sciences (FAS) Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Saman Hussain
- From the Molecular and Cellular Biology Department and Faculty of Arts and Sciences (FAS) Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Ethan C Garner
- From the Molecular and Cellular Biology Department and Faculty of Arts and Sciences (FAS) Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138
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11
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González de Prado Salas P, Hörger I, Martín-García F, Mendieta J, Alonso Á, Encinar M, Gómez-Puertas P, Vélez M, Tarazona P. Torsion and curvature of FtsZ filaments. SOFT MATTER 2014; 10:1977-1986. [PMID: 24652404 DOI: 10.1039/c3sm52516c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
FtsZ filaments participate in bacterial cell division, but it is still not clear how their dynamic polymerization and shape exert force on the underlying membrane. We present a theoretical description of individual filaments that incorporates information from molecular dynamic simulations. The structure of the crystallized Methanococcus jannaschii FtsZ dimer was used to model a FtsZ pentamer that showed a curvature and a twist. The estimated bending and torsion angles between monomers and their fluctuations were included in the theoretical description. The MD data also permitted positioning the curvature with respect to the protein coordinates and allowed us to explore the effect of the relative orientation of the preferred curvature with respect to the surface plane. We find that maximum tension is attained when filaments are firmly attached and oriented with their curvature perpendicular to the surface and that the twist serves as a valve to release or to tighten the tension exerted by the curved filaments on the membrane. The theoretical model also shows that the presence of torsion can explain the shape distribution of short filaments observed by Atomic Force Microscopy in previously published experiments. New experiments with FtsZ covalently attached to lipid membranes show that the filament on-plane curvature depends on lipid head charge, confirming the predicted monomer orientation effects. This new model underlines the fact that the combination of the three elements, filament curvature, twist and the strength and orientation of its surface attachment, can modulate the force exerted on the membrane during cell division.
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12
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Dow CE, Rodger A, Roper DI, van den Berg HA. A model of membrane contraction predicting initiation and completion of bacterial cell division. Integr Biol (Camb) 2013; 5:778-95. [DOI: 10.1039/c3ib20273a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Negative-stain electron microscopy of inside-out FtsZ rings reconstituted on artificial membrane tubules show ribbons of protofilaments. Biophys J 2012; 103:59-68. [PMID: 22828332 DOI: 10.1016/j.bpj.2012.05.035] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 05/22/2012] [Accepted: 05/23/2012] [Indexed: 12/20/2022] Open
Abstract
FtsZ, the primary cytoskeletal element of the Z ring, which constricts to divide bacteria, assembles into short, one-stranded filaments in vitro. These must be further assembled to make the Z ring in bacteria. Conventional electron microscopy (EM) has failed to image the Z ring or resolve its substructure. Here we describe a procedure that enabled us to image reconstructed, inside-out FtsZ rings by negative-stain EM, revealing the arrangement of filaments. We took advantage of a unique lipid that spontaneously forms 500 nm diameter tubules in solution. We optimized conditions for Z-ring assembly with fluorescence light microscopy and then prepared specimens for negative-stain EM. Reconstituted FtsZ rings, encircling the tubules, were clearly resolved. The rings appeared as ribbons of filaments packed side by side with virtually no space between neighboring filaments. The rings were separated by variable expanses of empty tubule as seen by light microscopy or EM. The width varied considerably from one ring to another, but each ring maintained a constant width around its circumference. The inside-out FtsZ rings moved back and forth along the tubules and exchanged subunits with solution, similarly to Z rings reconstituted outside or inside tubular liposomes. FtsZ from Escherichia coli and Mycobacterium tuberculosis assembled rings of similar structure, suggesting a universal structure across bacterial species. Previous models for the Z ring in bacteria have favored a structure of widely scattered filaments that are not in contact. The ribbon structure that we discovered here for reconstituted inside-out FtsZ rings provides what to our knowledge is new evidence that the Z ring in bacteria may involve lateral association of protofilaments.
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14
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López-Montero I, López-Navajas P, Mingorance J, Vélez M, Vicente M, Monroy F. Membrane reconstitution of FtsZ-ZipA complex inside giant spherical vesicles made of E. coli lipids: large membrane dilation and analysis of membrane plasticity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:687-98. [PMID: 23149342 DOI: 10.1016/j.bbamem.2012.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 10/26/2012] [Accepted: 11/05/2012] [Indexed: 01/28/2023]
Abstract
During the division process of Escherichia coli, the globular protein FtsZ is early recruited at the constriction site. The Z-ring, based on FtsZ filaments associated to the inner cell membrane, has been postulated to exert constriction forces. Membrane anchoring is mediated by ZipA, an essential transmembrane protein able to specifically bind FtsZ. In this work, an artificial complex of FtsZ-ZipA has been reconstituted at the inner side of spherical giant unilamellar vesicles made of E. coli lipids. Under these conditions, FtsZ polymerization, triggered when a caged GTP analogue is UV-irradiated, was followed by up to 40% vesicle inflation. The homogeneous membrane dilation was accompanied by the visualization of discrete FtsZ assemblies at the membrane. Complementary rheological data revealed enhanced elasticity under lateral dilation. This explains why vesicles can undergo large dilations in the regime of mechanical stability. A mechanical role for FtsZ polymers as promoters of membrane softening and plasticization is hypothesized.
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Affiliation(s)
- I López-Montero
- Departamento de Química Física I, Universidad Complutense, 28040 Madrid, Spain.
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15
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Surface Topology Engineering of Membranes for the Mechanical Investigation of the Tubulin Homologue FtsZ. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201204332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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16
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Arumugam S, Chwastek G, Fischer-Friedrich E, Ehrig C, Mönch I, Schwille P. Surface topology engineering of membranes for the mechanical investigation of the tubulin homologue FtsZ. Angew Chem Int Ed Engl 2012; 51:11858-62. [PMID: 22936525 DOI: 10.1002/anie.201204332] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/05/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Senthil Arumugam
- Max Planck Institute for Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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17
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Abstract
Bacterial cells utilize three-dimensional (3D) protein assemblies to perform important cellular functions such as growth, division, chemoreception, and motility. These assemblies are composed of mechanoproteins that can mechanically deform and exert force. Sometimes, small-nucleotide hydrolysis is coupled to mechanical deformations. In this review, we describe the general principle for an understanding of the coupling of mechanics with chemistry in mechanochemical systems. We apply this principle to understand bacterial cell shape and morphogenesis and how mechanical forces can influence peptidoglycan cell wall growth. We review a model that can potentially reconcile the growth dynamics of the cell wall with the role of cytoskeletal proteins such as MreB and crescentin. We also review the application of mechanochemical principles to understand the assembly and constriction of the FtsZ ring. A number of potential mechanisms are proposed, and important questions are discussed.
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18
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López-Montero I, Mateos-Gil P, Sferrazza M, Navajas PL, Rivas G, Vélez M, Monroy F. Active membrane viscoelasticity by the bacterial FtsZ-division protein. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:4744-4753. [PMID: 22329688 DOI: 10.1021/la204742b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
At the early stages of the division process in Escherichia coli, the protein FtsZ forms a septal ring at the midcell. This Z-ring causes membrane constriction during bacterial division. The Z-ring associates to the lipid membrane through several membrane proteins, ZipA among them. Here, a simplified FtsZ-ZipA model was reconstituted onto Langmuir monolayers based in E. coli polar lipid extract. Brewster angle and atomic force microscopy have revealed membrane FtsZ-polymerization upon GTP hydrolysis. The compression viscoelasticity of these monolayers has been also investigated. The presence of protein induced softening and fluidization with respect to the bare lipid membrane. An active mechanism, based on the internal forces stressed by FtsZ filaments and transduced to the lipid membrane by ZipA, was suggested to underlie the observed behavior.
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Affiliation(s)
- Iván López-Montero
- Departamento de Química Física I, Universidad Complutense de Madrid, Madrid, Spain
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19
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Cytrynbaum EN, Li YD, Allard JF, Mehrabian H. Estimating the bending modulus of a FtsZ bacterial-division protein filament. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:011902. [PMID: 22400586 DOI: 10.1103/physreve.85.011902] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 12/08/2011] [Indexed: 05/31/2023]
Abstract
FtsZ, a cytoskeletal protein homologous to tubulin, is the principle constituent of the division ring in bacterial cells. It is known to have force-generating capacity in vitro and has been conjectured to be the source of the constriction force in vivo. Several models have been proposed to explain the generation of force by the Z ring. Here we re-examine data from in vitro experiments in which Z rings formed and constricted inside tubular liposomes, and we carry out image analysis on previously published data with which to better estimate important model parameters that have proven difficult to measure by direct means. We introduce a membrane-energy-based model for the dynamics of multiple Z rings moving and colliding inside a tubular liposome and a fluid model for the drag of a Z ring as it moves through the tube. Using this model, we estimate an effective membrane bending modulus of 500-700 pN nm. If we assume that FtsZ force generation is driven by hydrolysis into a highly curved conformation, we estimate the FtsZ filament bending modulus to be 310-390 pN nm(2). If we assume instead that force is generated by the non-hydrolysis-dependent intermediate curvature conformation, we find that B(f)>1400 pN nm(2). The former value sits at the lower end of the range of previously estimated values and, if correct, may raise challenges for models that rely on filament bending to generate force.
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Affiliation(s)
- Eric N Cytrynbaum
- Department of Mathematics, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada.
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20
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FtsZ in bacterial cytokinesis: cytoskeleton and force generator all in one. Microbiol Mol Biol Rev 2011; 74:504-28. [PMID: 21119015 DOI: 10.1128/mmbr.00021-10] [Citation(s) in RCA: 460] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
FtsZ, a bacterial homolog of tubulin, is well established as forming the cytoskeletal framework for the cytokinetic ring. Recent work has shown that purified FtsZ, in the absence of any other division proteins, can assemble Z rings when incorporated inside tubular liposomes. Moreover, these artificial Z rings can generate a constriction force, demonstrating that FtsZ is its own force generator. Here we review light microscope observations of how Z rings assemble in bacteria. Assembly begins with long-pitch helices that condense into the Z ring. Once formed, the Z ring can transition to short-pitch helices that are suggestive of its structure. FtsZ assembles in vitro into short protofilaments that are ∼30 subunits long. We present models for how these protofilaments might be further assembled into the Z ring. We discuss recent experiments on assembly dynamics of FtsZ in vitro, with particular attention to how two regulatory proteins, SulA and MinC, inhibit assembly. Recent efforts to develop antibacterial drugs that target FtsZ are reviewed. Finally, we discuss evidence of how FtsZ generates a constriction force: by protofilament bending into a curved conformation.
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Hörger I, Campelo F, Hernández-Machado A, Tarazona P. Constricting force of filamentary protein rings evaluated from experimental results. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:031922. [PMID: 20365785 DOI: 10.1103/physreve.81.031922] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 01/14/2010] [Indexed: 05/29/2023]
Abstract
We present a model of Z -ring constriction in bacteria based on different experimental in vitro results. The forces produced by the Z ring due to lateral attraction of its constituent parts, estimated in previous studies that were based on FtsZ filaments observed by atomic force microscopy, are in good agreement with an estimation of the force required for recently found deformations in liposomes caused by FtsZ. These forces are calculated within the usual Helfrich energy formalism. In this context, we also explain the apparent attraction of multiple Z rings in the liposomes initially separated by small distances, as well as the stable distribution of rings separated by distances greater than approximately twice the diameter of the cylindrical liposomes. We adapted the model to the in vivo conditions imposed by the bacterial cell wall, concluding that the proposed mechanism gives a qualitative explanation for the force generation during bacterial division.
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Affiliation(s)
- I Hörger
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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Murugesan YK, Rey AD. Thermodynamic Model of Structure and Shape in Rigid Polymer-Laden Membranes. MACROMOL THEOR SIMUL 2009. [DOI: 10.1002/mats.200900044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Shlomovitz R, Gov NS. Membrane-mediated interactions drive the condensation and coalescence of FtsZ rings. Phys Biol 2009; 6:046017. [DOI: 10.1088/1478-3975/6/4/046017] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Paez A, Mateos-Gil P, Hörger I, Mingorance J, Rivas G, Vicente M, Vélez M, Tarazona P. Simple modeling of FtsZ polymers on flat and curved surfaces: correlation with experimental in vitro observations. PMC BIOPHYSICS 2009; 2:8. [PMID: 19849848 PMCID: PMC2776577 DOI: 10.1186/1757-5036-2-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 10/22/2009] [Indexed: 11/18/2022]
Abstract
FtsZ is a GTPase that assembles at midcell into a dynamic ring that constricts the membrane to induce cell division in the majority of bacteria, in many archea and several organelles. In vitro, FtsZ polymerizes in a GTP-dependent manner forming a variety of filamentous flexible structures. Based on data derived from the measurement of the in vitro polymerization of Escherichia coli FtsZ cell division protein we have formulated a model in which the fine balance between curvature, flexibility and lateral interactions accounts for structural and dynamic properties of the FtsZ polymers observed with AFM. The experimental results have been used by the model to calibrate the interaction energies and the values obtained indicate that the filaments are very plastic. The extension of the model to explore filament behavior on a cylindrical surface has shown that the FtsZ condensates promoted by lateral interactions can easily form ring structures through minor modulations of either filament curvature or longitudinal bond energies. The condensation of short, monomer exchanging filaments into rings is shown to produce enough force to induce membrane deformations.PACS codes: 87.15.ak, 87.16.ka, 87.17.Ee.
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Affiliation(s)
- Alfonso Paez
- Departamento de Física Teórica de la Materia Condensada, C-V-6a Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Pablo Mateos-Gil
- Instituto Nicolás Cabrera de Ciencia de Materiales, C-XVI-4a, Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Ines Hörger
- Departamento de Física Teórica de la Materia Condensada, C-V-6a Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Jesús Mingorance
- Unidad de Investigación y Servicio de Microbiología, Hospital Universitario La Paz, Paseo de La Castellana, 261, Madrid, E-28046, Spain
| | - Germán Rivas
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain
| | - Miguel Vicente
- Centro Nacional de Biotecnología, CSIC, Campus de Cantoblanco, C/Darwin n 3, Madrid E-28049, Spain
| | - Marisela Vélez
- Instituto de Catálisis y Petroleoquímica, CSIC C/Marie Curie, 2, Cantoblanco, Madrid, E-28049, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia) Facultad de Ciencias, C-IX-3a Cantoblanco, Madrid, E-28049, Spain
| | - Pedro Tarazona
- Departamento de Física Teórica de la Materia Condensada, C-V-6a Universidad Autónoma de Madrid, Madrid E-28049, Spain
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25
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Abstract
The tubulin homolog FtsZ is the major cytoskeletal protein in bacterial cytokinesis. It can generate a constriction force on the bacterial membrane or inside tubular liposomes. Several models have recently been proposed for how this force might be generated. These fall into 2 categories. The first is based on a conformational change from a straight to a curved protofilament. The simplest "hydrolyze and bend" model proposes a 22 degrees bend at every interface containing a GDP. New evidence suggests another curved conformation with a 2.5 degrees bend at every interface and that the relation of curvature to GTP hydrolysis is more complicated than previously thought. However, FtsZ protofilaments do appear to be mechanically rigid enough to bend membranes. A second category of models is based on lateral bonding between protofilaments, postulating that a contraction could be generated when protofilaments slide to increase the number of lateral bonds. Unfortunately these lateral bond models have ignored the contribution of subunit entropy when adding bond energies; if included, the mechanism is seen to be invalid. Finally, I address recent models that try to explain how protofilaments 1-subunit-thick show a cooperative assembly.
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Mendieta J, Rico AI, López-Viñas E, Vicente M, Mingorance J, Gómez-Puertas P. Structural and functional model for ionic (K(+)/Na(+)) and pH dependence of GTPase activity and polymerization of FtsZ, the prokaryotic ortholog of tubulin. J Mol Biol 2009; 390:17-25. [PMID: 19447111 DOI: 10.1016/j.jmb.2009.05.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/28/2009] [Accepted: 05/12/2009] [Indexed: 11/26/2022]
Abstract
Bacterial cell division occurs through the formation of a protein ring (division ring) at the site of division, with FtsZ being its main component in most bacteria. FtsZ is the prokaryotic ortholog of eukaryotic tubulin; it shares GTPase activity properties and the ability to polymerize in vitro. To study the mechanism of action of FtsZ, we used molecular dynamics simulations of the behavior of the FtsZ dimer in the presence of GTP-Mg(2+) and monovalent cations. The presence of a K(+) ion at the GTP binding site allows the positioning of one water molecule that interacts with catalytic residues Asp235 and Asp238, which are also involved in the coordination sphere of K(+). This arrangement might favor dimer stability and GTP hydrolysis. Contrary to this, Na(+) destabilizes the dimer and does not allow the positioning of the catalytic water molecule. Protonation of the GTP gamma-phosphate, simulating low pH, excludes both monovalent cations and the catalytic water molecule from the GTP binding site and stabilizes the dimer. These molecular dynamics predictions were contrasted experimentally by analyzing the GTPase and polymerization activities of purified Methanococcus jannaschii and Escherichia coli FtsZ proteins in vitro.
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Affiliation(s)
- Jesús Mendieta
- Centro de Biología Molecular "Severo Ochoa", Madrid, Spain
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Force generation by a dynamic Z-ring in Escherichia coli cell division. Proc Natl Acad Sci U S A 2008; 106:145-50. [PMID: 19114664 DOI: 10.1073/pnas.0808657106] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
FtsZ, a bacterial homologue of tubulin, plays a central role in bacterial cell division. It is the first of many proteins recruited to the division site to form the Z-ring, a dynamic structure that recycles on the time scale of seconds and is required for division to proceed. FtsZ has been recently shown to form rings inside tubular liposomes and to constrict the liposome membrane without the presence of other proteins, particularly molecular motors that appear to be absent from the bacterial proteome. Here, we propose a mathematical model for the dynamic turnover of the Z-ring and for its ability to generate a constriction force. Force generation is assumed to derive from GTP hydrolysis, which is known to induce curvature in FtsZ filaments. We find that this transition to a curved state is capable of generating a sufficient force to drive cell-wall invagination in vivo and can also explain the constriction seen in the in vitro liposome experiments. Our observations resolve the question of how FtsZ might accomplish cell division despite the highly dynamic nature of the Z-ring and the lack of molecular motors.
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Navajas PL, Rivas G, Mingorance J, Mateos-Gil P, Hörger I, Velasco E, Tarazona P, Vélez M. In vitro reconstitution of the initial stages of the bacterial cell division machinery. J Biol Phys 2008; 34:237-47. [PMID: 19669505 DOI: 10.1007/s10867-008-9118-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 09/22/2008] [Indexed: 10/21/2022] Open
Abstract
Fission of many prokaryotes as well as some eukaryotic organelles depends on the self-assembly of the FtsZ protein into a membrane-associated ring structure early in the division process. Different components of the machinery are then sequentially recruited. Although the assembly order has been established, the molecular interactions and the understanding of the force-generating mechanism of this dividing machinery have remained elusive. It is desirable to develop simple reconstituted systems that attempt to reproduce, at least partially, some of the stages of the process. High-resolution studies of Escherichia coli FtsZ filaments' structure and dynamics on mica have allowed the identification of relevant interactions between filaments that suggest a mechanism by which the polymers could generate force on the membrane. Reconstituting the membrane-anchoring protein ZipA on E. coli lipid membrane on surfaces is now providing information on how the membrane attachment regulates FtsZ polymer dynamics and indicates the important role played by the lipid composition of the membrane.
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Affiliation(s)
- Pilar López Navajas
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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29
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Srinivasan R, Mishra M, Wu L, Yin Z, Balasubramanian MK. The bacterial cell division protein FtsZ assembles into cytoplasmic rings in fission yeast. Genes Dev 2008; 22:1741-6. [PMID: 18593876 DOI: 10.1101/gad.1660908] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
During cytokinesis, most bacteria assemble a ring-like structure that is composed of the tubulin homolog FtsZ. The mechanisms regulating assembly and organization of FtsZ molecules into rings are not fully understood. Here, we express bacterial FtsZ in the fission yeast Schizosaccharomyces pombe and find that FtsZ filaments assemble into cytoplasmic rings. Investigation of the Escherichia coli FtsZ revealed that ring assembly occurred by a process of closure and/or spooling of linear bundles. We conclude that FtsZ rings can assemble in the absence of all other bacterial cytokinetic proteins and that the process might involve hydrolysis of FtsZ-bound GTP and lateral associations between FtsZ filaments.
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Affiliation(s)
- Ramanujam Srinivasan
- Cell Division Laboratory, Temasek Life Sciences Laboratory, The National University of Singapore, Singapore 117604
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