201
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Kiekebusch D, Thanbichler M. Spatiotemporal organization of microbial cells by protein concentration gradients. Trends Microbiol 2014; 22:65-73. [DOI: 10.1016/j.tim.2013.11.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 11/12/2013] [Accepted: 11/14/2013] [Indexed: 11/29/2022]
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202
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Abstract
This review summarizes the models that researchers use to represent the conformations and dynamics of cytoskeletal and DNA filaments. It focuses on models that address individual filaments in continuous space. Conformation models include the freely jointed, Gaussian, angle-biased chain (ABC), and wormlike chain (WLC) models, of which the first three bend at discrete joints and the last bends continuously. Predictions from the WLC model generally agree well with experiment. Dynamics models include the Rouse, Zimm, stiff rod, dynamic WLC, and reptation models, of which the first four apply to isolated filaments and the last to entangled filaments. Experiments show that the dynamic WLC and reptation models are most accurate. They also show that biological filaments typically experience strong hydrodynamic coupling and/or constrained motion. Computer simulation methods that address filament dynamics typically compute filament segment velocities from local forces using the Langevin equation and then integrate these velocities with explicit or implicit methods; the former are more versatile and the latter are more efficient. Much remains to be discovered in biological filament modeling. In particular, filament dynamics in living cells are not well understood, and current computational methods are too slow and not sufficiently versatile. Although primarily a review, this paper also presents new statistical calculations for the ABC and WLC models. Additionally, it corrects several discrepancies in the literature about bending and torsional persistence length definitions, and their relations to flexural and torsional rigidities.
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Affiliation(s)
- Steven S Andrews
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
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203
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Claessen D, Rozen DE, Kuipers OP, Søgaard-Andersen L, van Wezel GP. Bacterial solutions to multicellularity: a tale of biofilms, filaments and fruiting bodies. Nat Rev Microbiol 2014; 12:115-24. [PMID: 24384602 DOI: 10.1038/nrmicro3178] [Citation(s) in RCA: 275] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Although bacteria frequently live as unicellular organisms, many spend at least part of their lives in complex communities, and some have adopted truly multicellular lifestyles and have abandoned unicellular growth. These transitions to multicellularity have occurred independently several times for various ecological reasons, resulting in a broad range of phenotypes. In this Review, we discuss the strategies that are used by bacteria to form and grow in multicellular structures that have hallmark features of multicellularity, including morphological differentiation, programmed cell death and patterning. In addition, we examine the evolutionary and ecological factors that lead to the wide range of coordinated multicellular behaviours that are observed in bacteria.
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Affiliation(s)
- Dennis Claessen
- 1] Molecular Biotechnology, Institute of Biology Leiden, Leiden University, Sylviusweg 72, P.O. Box 9502, 2300 RA Leiden, The Netherlands. [2]
| | - Daniel E Rozen
- 1] Molecular Biotechnology, Institute of Biology Leiden, Leiden University, Sylviusweg 72, P.O. Box 9502, 2300 RA Leiden, The Netherlands. [2]
| | - Oscar P Kuipers
- 1] Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Linnaeusborg, Nijenborgh 7, 9747 AG, Groningen, The Netherlands. [2] Kluyver Center for Genomics of Industrial Fermentation, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043, Marburg, Germany
| | - Gilles P van Wezel
- Molecular Biotechnology, Institute of Biology Leiden, Leiden University, Sylviusweg 72, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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204
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Abstract
Plastid division is fundamental to the biology of plant cells. Division by binary fission entails the coordinated assembly and constriction of four concentric rings, two internal and two external to the organelle. The internal FtsZ ring and external dynamin-like ARC5/DRP5B ring are connected across the two envelopes by the membrane proteins ARC6, PARC6, PDV1, and PDV2. Assembly-stimulated GTPase activity drives constriction of the FtsZ and ARC5/DRP5B rings, which together with the plastid-dividing rings pull and squeeze the envelope membranes until the two daughter plastids are formed, with the final separation requiring additional proteins. The positioning of the division machinery is controlled by the chloroplast Min system, which confines FtsZ-ring formation to the plastid midpoint. The dynamic morphology of plastids, especially nongreen plastids, is also considered here, particularly in relation to the production of stromules and plastid-derived vesicles and their possible roles in cellular communication and plastid functionality.
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205
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Abstract
Cell morphodynamics during bacterial cell division is extensively investigated by a combination of a phase field model for rod-shaped cells and a kinetic description for FtsZ ring maintenance.
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Affiliation(s)
- Zhuan Liu
- College of Materials Science and Engineering
- Hunan University
- Changsha, China
| | - Kunkun Guo
- College of Materials Science and Engineering
- Hunan University
- Changsha, China
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206
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Ucci AP, Martins PMM, Lau IF, Bacci M, Belasque J, Ferreira H. Asymmetric chromosome segregation in Xanthomonas citri ssp. citri. Microbiologyopen 2013; 3:29-41. [PMID: 24339434 PMCID: PMC3937727 DOI: 10.1002/mbo3.145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/24/2013] [Accepted: 11/04/2013] [Indexed: 12/02/2022] Open
Abstract
This study was intended to characterize the chromosome segregation process of Xanthomonas citri ssp. citri (Xac) by investigating the functionality of the ParB factor encoded on its chromosome, and its requirement for cell viability and virulence. Using TAP tagging we show that ParB is expressed in Xac. Disruption of parB increased the cell doubling time and precluded the ability of Xac to colonize the host citrus. Moreover, Xac mutant cells expressing only truncated forms of ParB exhibited the classical phenotype of aberrant chromosome organization, and seemed affected in cell division judged by their reduced growth rate and the propensity to form filaments. The ParB-GFP localization pattern in Xac was suggestive of an asymmetric mode of replicon partitioning, which together with the filamentation phenotype support the idea that Xac may control septum placement using mechanisms probably analogous to Caulobacter crescentus, and perhaps Vibrio cholerae, and Corynebacterium glutamicum. Xac exhibits asymmetric chromosome segregation, and the perturbation of this process leads to an inability to colonize the host plant.
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Affiliation(s)
- Amanda P Ucci
- Depto. de Ciências Biológicas, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista, Rodovia Araraquara/Jaú Km 1, CP 502, Araraquara, São Paulo, 14801-902, Brazil
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207
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Theriot JA. Why are bacteria different from eukaryotes? BMC Biol 2013; 11:119. [PMID: 24330667 PMCID: PMC3874686 DOI: 10.1186/1741-7007-11-119] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 12/09/2013] [Indexed: 01/09/2023] Open
Affiliation(s)
- Julie A Theriot
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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208
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How to get (a)round: mechanisms controlling growth and division of coccoid bacteria. Nat Rev Microbiol 2013; 11:601-14. [PMID: 23949602 DOI: 10.1038/nrmicro3088] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bacteria come in a range of shapes, including round, rod-shaped, curved and spiral cells. This morphological diversity implies that different mechanisms exist to guide proper cell growth, division and chromosome segregation. Although the majority of studies on cell division have focused on rod-shaped cells, the development of new genetic and cell biology tools has provided mechanistic insight into the cell cycles of bacteria with different shapes, allowing us to appreciate the underlying molecular basis for their morphological diversity. In this Review, we discuss recent progress that has advanced our knowledge of the complex mechanisms for chromosome segregation and cell division in bacteria which have, deceptively, the simplest possible shape: the cocci.
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209
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MinC, MinD, and MinE drive counter-oscillation of early-cell-division proteins prior to Escherichia coli septum formation. mBio 2013; 4:e00856-13. [PMID: 24327341 PMCID: PMC3870257 DOI: 10.1128/mbio.00856-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Bacterial cell division initiates with the formation of a ring-like structure at the cell center composed of the tubulin homolog FtsZ (the Z-ring), which acts as a scaffold for the assembly of the cell division complex, the divisome. Previous studies have suggested that the divisome is initially composed of FtsZ polymers stabilized by membrane anchors FtsA and ZipA, which then recruit the remaining division proteins. The MinCDE proteins prevent the formation of the Z-ring at poles by oscillating from pole to pole, thereby ensuring that the concentration of the Z-ring inhibitor, MinC, is lowest at the cell center. We show that prior to septum formation, the early-division proteins ZipA, ZapA, and ZapB, along with FtsZ, assemble into complexes that counter-oscillate with respect to MinC, and with the same period. We propose that FtsZ molecules distal from high concentrations of MinC form relatively slowly diffusing filaments that are bound by ZapAB and targeted to the inner membrane by ZipA or FtsA. These complexes may facilitate the early stages of divisome assembly at midcell. As MinC oscillates toward these complexes, FtsZ oligomerization and bundling are inhibited, leading to shorter or monomeric FtsZ complexes, which become less visible by epifluorescence microscopy because of their rapid diffusion. Reconstitution of FtsZ-Min waves on lipid bilayers shows that FtsZ bundles partition away from high concentrations of MinC and that ZapA appears to protect FtsZ from MinC by inhibiting FtsZ turnover. A big issue in biology for the past 100 years has been that of how a cell finds its middle. In Escherichia coli, over 20 proteins assemble at the cell center at the time of division. We show that the MinCDE proteins, which prevent the formation of septa at the cell pole by inhibiting FtsZ, drive the counter-oscillation of early-cell-division proteins ZapA, ZapB, and ZipA, along with FtsZ. We propose that FtsZ forms filaments at the pole where the MinC concentration is the lowest and acts as a scaffold for binding of ZapA, ZapB, and ZipA: such complexes are disassembled by MinC and reform within the MinC oscillation period before accumulating at the cell center at the time of division. The ability of FtsZ to be targeted to the cell center in the form of oligomers bound by ZipA and ZapAB may facilitate the early stages of divisome assembly.
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210
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Bonny M, Fischer-Friedrich E, Loose M, Schwille P, Kruse K. Membrane binding of MinE allows for a comprehensive description of Min-protein pattern formation. PLoS Comput Biol 2013; 9:e1003347. [PMID: 24339757 PMCID: PMC3854456 DOI: 10.1371/journal.pcbi.1003347] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/03/2013] [Indexed: 11/23/2022] Open
Abstract
The rod-shaped bacterium Escherichia coli selects the cell center as site of division with the help of the proteins MinC, MinD, and MinE. This protein system collectively oscillates between the two cell poles by alternately binding to the membrane in one of the two cell halves. This dynamic behavior, which emerges from the interaction of the ATPase MinD and its activator MinE on the cell membrane, has become a paradigm for protein self-organization. Recently, it has been found that not only the binding of MinD to the membrane, but also interactions of MinE with the membrane contribute to Min-protein self-organization. Here, we show that by accounting for this finding in a computational model, we can comprehensively describe all observed Min-protein patterns in vivo and in vitro. Furthermore, by varying the system's geometry, our computations predict patterns that have not yet been reported. We confirm these predictions experimentally. Cellular protein structures have long been suggested to form by protein self-organization. A particularly clear example is provided by the proteins MinC, MinD, and MinE selecting the center as site of cell division in the rod-shaped bacterium Escherichia coli. Based on binding of MinD to the cytoplasmic membrane and an antagonistic action of MinE, which induces the release of MinD into the cytoplasm, these proteins oscillate from pole to pole, where they inhibit cell division. Supporting the idea of self-organization being the cause of the Min oscillations, purified Min proteins were found to spontaneously form traveling waves on supported lipid bilayers. A comprehensive understanding of the Min patterns formed under various conditions remains elusive. We have performed a computational analysis of Min-protein dynamics taking into account the recently discovered persistent action of MinE. We show that this property allows to reproduce all observed Min-protein patterns in a unified framework. Furthermore, our analysis predicts new structures, which we observed experimentally. Our study highlights that mechanisms underlying the spontaneous formation of protein patterns under purified in vitro conditions can also generate patterns inside complex intracellular environments.
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Affiliation(s)
- Mike Bonny
- Theoretische Physik, Universität des Saarlandes, Saarbrücken, Germany
| | - Elisabeth Fischer-Friedrich
- Max-Planck-Institut für Zellbiologie und Genetik, Dresden, Germany
- Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany
| | - Martin Loose
- Department of Systems Biology, Harvard Medical School, Boston, Massachussetts, United States of America
| | | | - Karsten Kruse
- Theoretische Physik, Universität des Saarlandes, Saarbrücken, Germany
- * E-mail:
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211
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An JY, Kim TG, Park KR, Lee JG, Youn HS, Lee Y, Kang JY, Kang GB, Eom SH. Crystal structure of the N-terminal domain of MinC dimerized via domain swapping. JOURNAL OF SYNCHROTRON RADIATION 2013; 20:984-8. [PMID: 24121353 PMCID: PMC3795569 DOI: 10.1107/s0909049513022760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 08/13/2013] [Indexed: 06/02/2023]
Abstract
Proper cell division at the mid-site of gram-negative bacteria reflects critical regulation by the min system (MinC, MinD and MinE) of the cytokinetic Z ring, which is a polymer composed of FtsZ subunits. MinC and MinD act together to inhibit aberrantly positioned Z-ring formation. MinC consists of two domains: an N-terminal domain (MinCNTD), which interacts with FtsZ and inhibits FtsZ polymerization, and a C-terminal domain (MinCCTD), which interacts with MinD and inhibits the bundling of FtsZ filaments. These two domains reportedly function together, and both are essential for normal cell division. The full-length dimeric structure of MinC from Thermotoga maritima has been reported, and shows that MinC dimerization occurs via MinCCTD; MinCNTD is not involved in dimerization. Here the crystal structure of Escherichia coli MinCNTD (EcoMinCNTD) is reported. EcoMinCNTD forms a dimer via domain swapping between the first β strands in each subunit. It is therefore suggested that the dimerization of full-length EcoMinC occurs via both MinCCTD and MinCNTD, and that the dimerized EcoMinCNTD likely plays an important role in inhibiting aberrant Z-ring localization.
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Affiliation(s)
- Jun Yop An
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Tae Gyun Kim
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Kyoung Ryoung Park
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Jung-Gyu Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Hyung-Seop Youn
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Youngjin Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Jung Youn Kang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Gil Bu Kang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Soo Hyun Eom
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
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212
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Martos A, Petrasek Z, Schwille P. Propagation of MinCDE waves on free-standing membranes. Environ Microbiol 2013; 15:3319-26. [PMID: 24118679 DOI: 10.1111/1462-2920.12295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 09/24/2013] [Indexed: 11/30/2022]
Abstract
As a spatial modulator of cytokinesis in Escherichia coli, the Min system cooperates with the nucleoid occlusion mechanism to target the divisome assembly towards mid-cell. Based on a reaction-diffusion mechanism powered by ATP (adenosine triphosphate) hydrolysis, the Min proteins propagate in waves on the cell membrane, resulting in oscillations between the cell poles, thus preventing the formation of the division ring everywhere but in the cell centre. The dynamic behaviour of Min proteins has been successfully reconstructed in vitro on supported lipid bilayers (SLBs), reproducing many of the features observed in the cell. However, there has been a marked discrepancy between the speed of propagation of Min protein waves in vitro, compared with the cellular system. A very plausible explanation is the different mobility of proteins on model membranes, compared with the inner membrane of bacteria. To quantitatively demonstrate how membrane diffusion influences Min wave propagation, we compared Min waves on SLBs with free-standing giant unilamellar vesicles (GUV) membranes which display higher fluidity. Intriguingly, the propagation velocity and wavelength on GUVs are three times higher than those reported on supported bilayers, but the wave period is conserved. This suggests that the shorter spatial period of the patterns in vivo might indeed be primarily explained by lower diffusion coefficients of proteins on the bacterial inner membrane.
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Affiliation(s)
- Ariadna Martos
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152, Martinsried, Germany
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213
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Camley BA, Zhao Y, Li B, Levine H, Rappel WJ. Periodic migration in a physical model of cells on micropatterns. PHYSICAL REVIEW LETTERS 2013; 111:158102. [PMID: 24160631 PMCID: PMC3855234 DOI: 10.1103/physrevlett.111.158102] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Indexed: 05/14/2023]
Abstract
We extend a model for the morphology and dynamics of a crawling eukaryotic cell to describe cells on micropatterned substrates. This model couples cell morphology, adhesion, and cytoskeletal flow in response to active stresses induced by actin and myosin. We propose that protrusive stresses are only generated where the cell adheres, leading to the cell's effective confinement to the pattern. Consistent with experimental results, simulated cells exhibit a broad range of behaviors, including steady motion, turning, bipedal motion, and periodic migration, in which the cell crawls persistently in one direction before reversing periodically. We show that periodic motion emerges naturally from the coupling of cell polarization to cell shape by reducing the model to a simplified one-dimensional form that can be understood analytically.
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Affiliation(s)
- Brian A Camley
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA and Center for Theoretical Biological Physics, University of California, San Diego, La Jolla, California 92093, USA
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214
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215
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Buss J, Coltharp C, Huang T, Pohlmeyer C, Wang SC, Hatem C, Xiao J. In vivo organization of the FtsZ-ring by ZapA and ZapB revealed by quantitative super-resolution microscopy. Mol Microbiol 2013; 89:1099-120. [PMID: 23859153 PMCID: PMC3894617 DOI: 10.1111/mmi.12331] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2013] [Indexed: 12/13/2022]
Abstract
In most bacterial cells, cell division is dependent on the polymerization of the FtsZ protein to form a ring-like structure (Z-ring) at the midcell. Despite its essential role, the molecular architecture of the Z-ring remains elusive. In this work we examine the roles of two FtsZ-associated proteins, ZapA and ZapB, in the assembly dynamics and structure of the Z-ring in Escherichia coli cells. In cells deleted of zapA or zapB, we observed abnormal septa and highly dynamic FtsZ structures. While details of these FtsZ structures are difficult to discern under conventional fluorescence microscopy, single-molecule-based super-resolution imaging method Photoactivated Localization Microscopy (PALM) reveals that these FtsZ structures arise from disordered arrangements of FtsZ clusters. Quantitative analysis finds these clusters are larger and comprise more molecules than a single FtsZ protofilament, and likely represent a distinct polymeric species that is inherent to the assembly pathway of the Z-ring. Furthermore, we find these clusters are not due to the loss of ZapB-MatP interaction in ΔzapA and ΔzapB cells. Our results suggest that the main function of ZapA and ZapB in vivo may not be to promote the association of individual protofilaments but to align FtsZ clusters that consist of multiple FtsZ protofilaments.
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Affiliation(s)
- Jackson Buss
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Carla Coltharp
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Tao Huang
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Chris Pohlmeyer
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Shih-Chin Wang
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Christine Hatem
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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216
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Almendro-Vedia VG, Monroy F, Cao FJ. Mechanics of constriction during cell division: a variational approach. PLoS One 2013; 8:e69750. [PMID: 23990888 PMCID: PMC3749217 DOI: 10.1371/journal.pone.0069750] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 06/12/2013] [Indexed: 11/19/2022] Open
Abstract
During symmetric division cells undergo large constriction deformations at a stable midcell site. Using a variational approach, we investigate the mechanical route for symmetric constriction by computing the bending energy of deformed vesicles with rotational symmetry. Forces required for constriction are explicitly computed at constant area and constant volume, and their values are found to be determined by cell size and bending modulus. For cell-sized vesicles, considering typical bending modulus of [Formula: see text], we calculate constriction forces in the range [Formula: see text]. The instability of symmetrical constriction is shown and quantified with a characteristic coefficient of the order of [Formula: see text], thus evidencing that cells need a robust mechanism to stabilize constriction at midcell.
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Affiliation(s)
- Victor G. Almendro-Vedia
- Departamento de Física Atómica, Molecular y Nuclear and Departamento de Química Física I, Universidad Complutense, Avenida Complutense s/n, Madrid, Spain
| | - Francisco Monroy
- Departamento de Química Física I, Universidad Complutense, Avenida Complutense s/n, Madrid, Spain
| | - Francisco J. Cao
- Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense, Avenida Complutense s/n, Madrid, Spain
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217
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Natale P, Pazos M, Vicente M. TheEscherichia colidivisome: born to divide. Environ Microbiol 2013; 15:3169-82. [DOI: 10.1111/1462-2920.12227] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/18/2013] [Accepted: 07/23/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Paolo Natale
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
| | - Manuel Pazos
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
| | - Miguel Vicente
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
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218
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Chiou PY, Luo CH, Chang KC, Lin NT. Maintenance of the cell morphology by MinC in Helicobacter pylori. PLoS One 2013; 8:e71208. [PMID: 23936493 PMCID: PMC3731275 DOI: 10.1371/journal.pone.0071208] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/03/2013] [Indexed: 11/18/2022] Open
Abstract
In the model organism Escherichia coli, Min proteins are involved in regulating the division of septa formation. The computational genome analysis of Helicobacter pylori, a gram-negative microaerophilic bacterium causing gastritis and peptic ulceration, also identified MinC, MinD, and MinE. However, MinC (HP1053) shares a low identity with those of other bacteria and its function in H. pylori remains unclear. In this study, we used morphological and genetic approaches to examine the molecular role of MinC. The results were shown that an H. pylori mutant lacking MinC forms filamentous cells, while the wild-type strain retains the shape of short rods. In addition, a minC mutant regains the short rods when complemented with an intact minCHp gene. The overexpression of MinCHp in E. coli did not affect the growth and cell morphology. Immunofluorescence microscopy revealed that MinCHp forms helix-form structures in H. pylori, whereas MinCHp localizes at cell poles and pole of new daughter cell in E. coli. In addition, co-immunoprecipitation showed MinC can interact with MinD but not with FtsZ during mid-exponential stage of H. pylori. Altogether, our results show that MinCHp plays a key role in maintaining proper cell morphology and its function differs from those of MinCEc.
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Affiliation(s)
- Pei-Yu Chiou
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Cheng-Hung Luo
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Kai-Chih Chang
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan
- * E-mail: (K-CC); (N-TL)
| | - Nien-Tsung Lin
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
- Department of Microbiology, Tzu Chi University, Hualien, Taiwan
- * E-mail: (K-CC); (N-TL)
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ParA encoded on chromosome II of Deinococcus radiodurans binds to nucleoid and inhibits cell division in Escherichia coli. J Biosci 2013; 38:487-97. [DOI: 10.1007/s12038-013-9352-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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220
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Hernández-Rocamora VM, García-Montañés C, Reija B, Monterroso B, Margolin W, Alfonso C, Zorrilla S, Rivas G. MinC protein shortens FtsZ protofilaments by preferentially interacting with GDP-bound subunits. J Biol Chem 2013; 288:24625-35. [PMID: 23853099 DOI: 10.1074/jbc.m113.483222] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The interaction of MinC with FtsZ and its effects on FtsZ polymerization were studied under close to physiological conditions by a combination of biophysical methods. The Min system is a widely conserved mechanism in bacteria that ensures the correct placement of the division machinery at midcell. MinC is the component of this system that effectively interacts with FtsZ and inhibits the formation of the Z-ring. Here we report that MinC produces a concentration-dependent reduction in the size of GTP-induced FtsZ protofilaments (FtsZ-GTP) as demonstrated by analytical ultracentrifugation, dynamic light scattering, fluorescence correlation spectroscopy, and electron microscopy. Our experiments show that, despite being shorter, FtsZ protofilaments maintain their narrow distribution in size in the presence of MinC. The protein had the same effect regardless of its addition prior to or after FtsZ polymerization. Fluorescence anisotropy measurements indicated that MinC bound to FtsZ-GDP with a moderate affinity (apparent KD ∼10 μM at 100 mm KCl and pH 7.5) very close to the MinC concentration corresponding to the midpoint of the inhibition of FtsZ assembly. Only marginal binding of MinC to FtsZ-GTP protofilaments was observed by analytical ultracentrifugation and fluorescence correlation spectroscopy. Remarkably, MinC effects on FtsZ-GTP protofilaments and binding affinity to FtsZ-GDP were strongly dependent on ionic strength, being severely reduced at 500 mM KCl compared with 100 mM KCl. Our results support a mechanism in which MinC interacts with FtsZ-GDP, resulting in smaller protofilaments of defined size and having the same effect on both preassembled and growing FtsZ protofilaments.
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Affiliation(s)
- Víctor M Hernández-Rocamora
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
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221
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SIMIBI twins in protein targeting and localization. Nat Struct Mol Biol 2013; 20:776-80. [DOI: 10.1038/nsmb.2605] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/07/2013] [Indexed: 12/31/2022]
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222
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SlmA forms a higher-order structure on DNA that inhibits cytokinetic Z-ring formation over the nucleoid. Proc Natl Acad Sci U S A 2013; 110:10586-91. [PMID: 23754405 DOI: 10.1073/pnas.1221036110] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The spatial and temporal control of Filamenting temperature sensitive mutant Z (FtsZ) Z-ring formation is crucial for proper cell division in bacteria. In Escherichia coli, the synthetic lethal with a defective Min system (SlmA) protein helps mediate nucleoid occlusion, which prevents chromosome fragmentation by binding FtsZ and inhibiting Z-ring formation over the nucleoid. However, to perform its function, SlmA must be bound to the nucleoid. To deduce the basis for this chromosomal requirement, we performed biochemical, cellular, and structural studies. Strikingly, structures show that SlmA dramatically distorts DNA, allowing it to bind as an orientated dimer-of-dimers. Biochemical data indicate that SlmA dimer-of-dimers can spread along the DNA. Combined structural and biochemical data suggest that this DNA-activated SlmA oligomerization would prevent FtsZ protofilament propagation and bundling. Bioinformatic analyses localize SlmA DNA sites near membrane-tethered chromosomal regions, and cellular studies show that SlmA inhibits FtsZ reservoirs from forming membrane-tethered Z rings. Thus, our combined data indicate that SlmA DNA helps block Z-ring formation over chromosomal DNA by forming higher-order protein-nucleic acid complexes that disable FtsZ filaments from coalescing into proper structures needed for Z-ring creation.
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223
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Vecchiarelli AG, Havey JC, Ing LL, Wong EOY, Waples WG, Funnell BE. Dissection of the ATPase active site of P1 ParA reveals multiple active forms essential for plasmid partition. J Biol Chem 2013; 288:17823-31. [PMID: 23632076 DOI: 10.1074/jbc.m113.469981] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The segregation, or partition, of bacterial plasmids is driven by the action of plasmid-encoded partition ATPases, which work to position plasmids inside the cell. The most common type of partition ATPase, generally called ParA, is represented by the P1 plasmid ParA protein. ParA interacts with P1 ParB (the site-specific DNA binding protein that recognizes the parS partition site), and interacts with the bacterial chromosome via an ATP-dependent nonspecific DNA binding activity. ParA also regulates expression of the par genes by acting as a transcriptional repressor. ParA requires ATP for multiple steps and in different ways during the partition process. Here, we analyze the properties of mutations in P1 ParA that are altered in a key lysine in the Walker A motif of the ATP binding site. Four different residues at this position (Lys, Glu, Gln, Arg) result in four different phenotypes in vivo. We focus particularly on the arginine substitution (K122R) because it results in a worse-than-null and dominant-negative phenotype called ParPD. We show that ParAK122R binds and hydrolyzes ATP, although the latter activity is reduced compared with wild-type. ParAK122R interacts with ParB, but the consequences of the interaction are damaged. The ability of ParB to stimulate the ATPase activity of ParA in vitro and its repressor activity in vivo is defective. The K122R mutation specifically damages the disassembly of ParA-ParB-DNA partition complexes, which we believe explains the ParPD phenotype in vivo.
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Affiliation(s)
- Anthony G Vecchiarelli
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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224
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Kazmierczak BI, Hendrixson DR. Spatial and numerical regulation of flagellar biosynthesis in polarly flagellated bacteria. Mol Microbiol 2013; 88:655-63. [PMID: 23600726 DOI: 10.1111/mmi.12221] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2013] [Indexed: 12/20/2022]
Abstract
Control of surface organelle number and placement is a crucial aspect of the cell biology of many Gram-positive and Gram-negative bacteria, yet mechanistic insights into how bacteria spatially and numerically organize organelles are lacking. Many surface structures and internal complexes are spatially restricted in the bacterial cell (e.g. type IV pili, holdfasts, chemoreceptors), but perhaps none show so many distinct patterns in terms of number and localization as the flagellum. In this review, we discuss two proteins, FlhF and FlhG (also annotated FleN/YlxH), which control aspects of flagellar assembly, placement and number in polar flagellates, and may influence flagellation in some bacteria that produce peritrichous flagella. Experimental data obtained in a number of bacterial species suggest that these proteins may have acquired distinct attributes influencing flagellar assembly that reflect the diversity of flagellation patterns seen in different polar flagellates. Recent findings also suggest FlhF and FlhG are involved in other processes, such as influencing the rotation of flagella and proper cell division. Continued examination of these proteins in polar flagellates is expected to reveal how different bacteria have adapted FlhF or FlhG with specific activities to tailor flagellar biosynthesis and motility to fit the needs of each species.
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Affiliation(s)
- Barbara I Kazmierczak
- Departments of Medicine & Microbial Pathogenesis, Yale University School of Medicine, 333 Cedar St, New Haven, CT 06520-8022, USA.
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225
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Blasios V, Bisson-Filho AW, Castellen P, Nogueira MLC, Bettini J, Portugal RV, Zeri ACM, Gueiros-Filho FJ. Genetic and biochemical characterization of the MinC-FtsZ interaction in Bacillus subtilis. PLoS One 2013; 8:e60690. [PMID: 23577149 PMCID: PMC3618327 DOI: 10.1371/journal.pone.0060690] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 03/01/2013] [Indexed: 11/22/2022] Open
Abstract
Cell division in bacteria is regulated by proteins that interact with FtsZ and modulate its ability to polymerize into the Z ring structure. The best studied of these regulators is MinC, an inhibitor of FtsZ polymerization that plays a crucial role in the spatial control of Z ring formation. Recent work established that E. coli MinC interacts with two regions of FtsZ, the bottom face of the H10 helix and the extreme C-terminal peptide (CTP). Here we determined the binding site for MinC on Bacillus subtilis FtsZ. Selection of a library of FtsZ mutants for survival in the presence of Min overexpression resulted in the isolation of 13 Min-resistant mutants. Most of the substitutions that gave rise to Min resistance clustered around the H9 and H10 helices in the C-terminal domain of FtsZ. In addition, a mutation in the CTP of B. subtilis FtsZ also produced MinC resistance. Biochemical characterization of some of the mutant proteins showed that they exhibited normal polymerization properties but reduced interaction with MinC, as expected for binding site mutations. Thus, our study shows that the overall architecture of the MinC-FtsZ interaction is conserved in E. coli and B. subtilis. Nevertheless, there was a clear difference in the mutations that conferred Min resistance, with those in B. subtilis FtsZ pointing to the side of the molecule rather than to its polymerization interface. This observation suggests that the mechanism of Z ring inhibition by MinC differs in both species.
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Affiliation(s)
- Valdir Blasios
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | | | - Patricia Castellen
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
- Brazilian Biosciences National Laboratory (LNBio), Centro Nacional de Pesquisas em Energia e Materiais (CNPEM), Campinas, Brasil
| | - Maria Luiza C. Nogueira
- Brazilian Biosciences National Laboratory (LNBio), Centro Nacional de Pesquisas em Energia e Materiais (CNPEM), Campinas, Brasil
| | - Jefferson Bettini
- Nanotechnology National Laboratory (LNNano), Centro Nacional de Pesquisas em Energia e Materiais (CNPEM), Campinas, Brasil
| | - Rodrigo V. Portugal
- Nanotechnology National Laboratory (LNNano), Centro Nacional de Pesquisas em Energia e Materiais (CNPEM), Campinas, Brasil
| | - Ana Carolina M. Zeri
- Brazilian Biosciences National Laboratory (LNBio), Centro Nacional de Pesquisas em Energia e Materiais (CNPEM), Campinas, Brasil
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226
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Singh B, Nitharwal RG, Ramesh M, Pettersson BMF, Kirsebom LA, Dasgupta S. Asymmetric growth and division inMycobacteriumspp.: compensatory mechanisms for non-medial septa. Mol Microbiol 2013; 88:64-76. [DOI: 10.1111/mmi.12169] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Bhupender Singh
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
| | - Ram Gopal Nitharwal
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
| | - Malavika Ramesh
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
| | - B. M. Fredrik Pettersson
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
| | - Leif A. Kirsebom
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
| | - Santanu Dasgupta
- Department of Cell and Molecular Biology; Uppsala University Biomedical Center; Box 596; 751 24; Uppsala; Sweden
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227
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Zhang Z, Morgan JJ, Lindahl PA. Mathematical model for positioning the FtsZ contractile ring in Escherichia coli. J Math Biol 2013; 68:911-30. [DOI: 10.1007/s00285-013-0652-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 01/28/2013] [Indexed: 11/30/2022]
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228
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Identification of the SlmA active site responsible for blocking bacterial cytokinetic ring assembly over the chromosome. PLoS Genet 2013; 9:e1003304. [PMID: 23459366 PMCID: PMC3573117 DOI: 10.1371/journal.pgen.1003304] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 12/19/2012] [Indexed: 11/19/2022] Open
Abstract
Bacterial cells use chromosome-associated division inhibitors to help coordinate the processes of DNA replication and segregation with cytokinesis. SlmA from Escherichia coli, a member of the tetracycline repressor (TetR)-like protein family, is one example of this class of regulator. It blocks the assembly of the bacterial cytokinetic ring by interfering with the polymerization of the tubulin-like FtsZ protein in a manner that is dramatically stimulated upon specific DNA binding. Here we used a combination of molecular genetics and biochemistry to identify the active site of SlmA responsible for disrupting FtsZ polymerization. Interestingly, this site maps to a region of SlmA that in the published DNA-free structure is partially occluded by the DNA-binding domains. In this conformation, the SlmA structure resembles the drug/inducer-bound conformers of other TetR-like proteins, which in the absence of inducer require an inward rotation of their DNA-binding domains to bind successive major grooves on operator DNA. Our results are therefore consistent with a model in which DNA-binding activates SlmA by promoting a rotational movement of the DNA-binding domains that fully exposes the FtsZ-binding sites. SlmA may thus represent a special subclass of TetR-like proteins that have adapted conformational changes normally associated with inducer sensing in order to modulate an interaction with a partner protein. In this case, the adaptation ensures that SlmA only blocks cytokinesis in regions of the cell occupied by the origin-proximal portion of the chromosome where SlmA-binding sites are enriched.
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229
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Unusual biophysics of intrinsically disordered proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:932-51. [PMID: 23269364 DOI: 10.1016/j.bbapap.2012.12.008] [Citation(s) in RCA: 412] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 11/21/2012] [Accepted: 12/12/2012] [Indexed: 02/08/2023]
Abstract
Research of a past decade and a half leaves no doubt that complete understanding of protein functionality requires close consideration of the fact that many functional proteins do not have well-folded structures. These intrinsically disordered proteins (IDPs) and proteins with intrinsically disordered protein regions (IDPRs) are highly abundant in nature and play a number of crucial roles in a living cell. Their functions, which are typically associated with a wide range of intermolecular interactions where IDPs possess remarkable binding promiscuity, complement functional repertoire of ordered proteins. All this requires a close attention to the peculiarities of biophysics of these proteins. In this review, some key biophysical features of IDPs are covered. In addition to the peculiar sequence characteristics of IDPs these biophysical features include sequential, structural, and spatiotemporal heterogeneity of IDPs; their rough and relatively flat energy landscapes; their ability to undergo both induced folding and induced unfolding; the ability to interact specifically with structurally unrelated partners; the ability to gain different structures at binding to different partners; and the ability to keep essential amount of disorder even in the bound form. IDPs are also characterized by the "turned-out" response to the changes in their environment, where they gain some structure under conditions resulting in denaturation or even unfolding of ordered proteins. It is proposed that the heterogeneous spatiotemporal structure of IDPs/IDPRs can be described as a set of foldons, inducible foldons, semi-foldons, non-foldons, and unfoldons. They may lose their function when folded, and activation of some IDPs is associated with the awaking of the dormant disorder. It is possible that IDPs represent the "edge of chaos" systems which operate in a region between order and complete randomness or chaos, where the complexity is maximal. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly.
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230
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Monahan LG, Harry EJ. Identifying how bacterial cells find their middle: a new perspective. Mol Microbiol 2012. [PMID: 23190137 DOI: 10.1111/mmi.12114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacterial cell division begins with the polymerization of the FtsZ protein to form a Z ring at the division site. This ring subsequently recruits the division machinery to allow cytokinesis. How the Z ring is positioned correctly remains a challenging question in biology and our knowledge in this area has been restricted to a few model species. Spatial regulation of division in these bacteria has been considered to be negatively controlled, with Z rings assembling in the area of least inhibition: the cell centre. An article in this issue of Molecular Microbiology reports the discovery of a new protein in Myxococcus xanthus, called PomZ (Positioning at midcell of FtsZ), that is required for the efficient recruitment of the Z ring to the division site. PomZ is a member of the Mrp/Min family of P loop ATPases that includes a diverse range of proteins involved in spatial regulation in bacteria. PomZ is the first positive regulator of Z ring positioning to be identified in vegetatively growing bacterial cells. Positive spatial regulation of division has previously been observed during sporulation in Streptomyces coelicolor and has been suggested to occur in Bacillus subtilis. Perhaps this will emerge as a common theme in the future.
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Affiliation(s)
- L G Monahan
- The ithree institute, University of Technology, Sydney, NSW 2007, Australia
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231
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Yamaichi Y, Bruckner R, Ringgaard S, Möll A, Cameron DE, Briegel A, Jensen GJ, Davis BM, Waldor MK. A multidomain hub anchors the chromosome segregation and chemotactic machinery to the bacterial pole. Genes Dev 2012; 26:2348-60. [PMID: 23070816 DOI: 10.1101/gad.199869.112] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The cell poles constitute key subcellular domains that are often critical for motility, chemotaxis, and chromosome segregation in rod-shaped bacteria. However, in nearly all rods, the processes that underlie the formation, recognition, and perpetuation of the polar domains are largely unknown. Here, in Vibrio cholerae, we identified HubP (hub of the pole), a polar transmembrane protein conserved in all vibrios, that anchors three ParA-like ATPases to the cell poles and, through them, controls polar localization of the chromosome origin, the chemotactic machinery, and the flagellum. In the absence of HubP, oriCI is not targeted to the cell poles, chemotaxis is impaired, and a small but increased fraction of cells produces multiple, rather than single, flagella. Distinct cytoplasmic domains within HubP are required for polar targeting of the three ATPases, while a periplasmic portion of HubP is required for its localization. HubP partially relocalizes from the poles to the mid-cell prior to cell division, thereby enabling perpetuation of the polar domain in future daughter cells. Thus, a single polar hub is instrumental for establishing polar identity and organization.
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Affiliation(s)
- Yoshiharu Yamaichi
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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232
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Martos A, Jiménez M, Rivas G, Schwille P. Towards a bottom-up reconstitution of bacterial cell division. Trends Cell Biol 2012; 22:634-43. [DOI: 10.1016/j.tcb.2012.09.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 09/05/2012] [Accepted: 09/07/2012] [Indexed: 10/27/2022]
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233
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Jogler C, Waldmann J, Huang X, Jogler M, Glöckner FO, Mascher T, Kolter R. Identification of proteins likely to be involved in morphogenesis, cell division, and signal transduction in Planctomycetes by comparative genomics. J Bacteriol 2012; 194:6419-30. [PMID: 23002222 PMCID: PMC3497475 DOI: 10.1128/jb.01325-12] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 09/14/2012] [Indexed: 12/20/2022] Open
Abstract
Members of the Planctomycetes clade share many unusual features for bacteria. Their cytoplasm contains membrane-bound compartments, they lack peptidoglycan and FtsZ, they divide by polar budding, and they are capable of endocytosis. Planctomycete genomes have remained enigmatic, generally being quite large (up to 9 Mb), and on average, 55% of their predicted proteins are of unknown function. Importantly, proteins related to the unusual traits of Planctomycetes remain largely unknown. Thus, we embarked on bioinformatic analyses of these genomes in an effort to predict proteins that are likely to be involved in compartmentalization, cell division, and signal transduction. We used three complementary strategies. First, we defined the Planctomycetes core genome and subtracted genes of well-studied model organisms. Second, we analyzed the gene content and synteny of morphogenesis and cell division genes and combined both methods using a "guilt-by-association" approach. Third, we identified signal transduction systems as well as sigma factors. These analyses provide a manageable list of candidate genes for future genetic studies and provide evidence for complex signaling in the Planctomycetes akin to that observed for bacteria with complex life-styles, such as Myxococcus xanthus.
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234
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235
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Genome, functional gene annotation, and nuclear transformation of the heterokont oleaginous alga Nannochloropsis oceanica CCMP1779. PLoS Genet 2012; 8:e1003064. [PMID: 23166516 PMCID: PMC3499364 DOI: 10.1371/journal.pgen.1003064] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 08/29/2012] [Indexed: 11/18/2022] Open
Abstract
Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high-value lipid products. First success in applying reverse genetics by targeted gene replacement makes Nannochloropsis oceanica an attractive model to investigate the cell and molecular biology and biochemistry of this fascinating organism group. Here we present the assembly of the 28.7 Mb genome of N. oceanica CCMP1779. RNA sequencing data from nitrogen-replete and nitrogen-depleted growth conditions support a total of 11,973 genes, of which in addition to automatic annotation some were manually inspected to predict the biochemical repertoire for this organism. Among others, more than 100 genes putatively related to lipid metabolism, 114 predicted transcription factors, and 109 transcriptional regulators were annotated. Comparison of the N. oceanica CCMP1779 gene repertoire with the recently published N. gaditana genome identified 2,649 genes likely specific to N. oceanica CCMP1779. Many of these N. oceanica-specific genes have putative orthologs in other species or are supported by transcriptional evidence. However, because similarity-based annotations are limited, functions of most of these species-specific genes remain unknown. Aside from the genome sequence and its analysis, protocols for the transformation of N. oceanica CCMP1779 are provided. The availability of genomic and transcriptomic data for Nannochloropsis oceanica CCMP1779, along with efficient transformation protocols, provides a blueprint for future detailed gene functional analysis and genetic engineering of Nannochloropsis species by a growing academic community focused on this genus.
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236
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TerBush AD, Osteryoung KW. Distinct functions of chloroplast FtsZ1 and FtsZ2 in Z-ring structure and remodeling. J Cell Biol 2012; 199:623-37. [PMID: 23128242 PMCID: PMC3494859 DOI: 10.1083/jcb.201205114] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 10/12/2012] [Indexed: 12/19/2022] Open
Abstract
FtsZ, a cytoskeletal GTPase, forms a contractile ring for cell division in bacteria and chloroplast division in plants. Whereas bacterial Z rings are composed of a single FtsZ, those in chloroplasts contain two distinct FtsZ proteins, FtsZ1 and FtsZ2, whose functional relationship is poorly understood. We expressed fluorescently tagged FtsZ1 and FtsZ2 in fission yeast to investigate their intrinsic assembly and dynamic properties. FtsZ1 and FtsZ2 formed filaments with differing morphologies when expressed separately. FRAP showed that FtsZ2 filaments were less dynamic than FtsZ1 filaments and that GTPase activity was essential for FtsZ2 filament turnover but may not be solely responsible for FtsZ1 turnover. When coexpressed, the proteins colocalized, consistent with coassembly, but exhibited an FtsZ2-like morphology. However, FtsZ1 increased FtsZ2 exchange into coassembled filaments. Our findings suggest that FtsZ2 is the primary determinant of chloroplast Z-ring structure, whereas FtsZ1 facilitates Z-ring remodeling. We also demonstrate that ARC3, a regulator of chloroplast Z-ring positioning, functions as an FtsZ1 assembly inhibitor.
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Affiliation(s)
- Allan D. TerBush
- Biochemistry and Molecular Biology Graduate Program and Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Katherine W. Osteryoung
- Biochemistry and Molecular Biology Graduate Program and Department of Plant Biology, Michigan State University, East Lansing, MI 48824
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237
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Briers Y, Walde P, Schuppler M, Loessner MJ. How did bacterial ancestors reproduce? Lessons from L-form cells and giant lipid vesicles. Bioessays 2012; 34:1078-84. [DOI: 10.1002/bies.201200080] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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238
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Balasubramanian MK, Srinivasan R, Huang Y, Ng KH. Comparing contractile apparatus-driven cytokinesis mechanisms across kingdoms. Cytoskeleton (Hoboken) 2012; 69:942-56. [PMID: 23027576 DOI: 10.1002/cm.21082] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/18/2012] [Indexed: 12/13/2022]
Abstract
Cytokinesis is the final stage of the cell cycle during which a cell physically divides into two daughters through the assembly of new membranes (and cell wall in some cases) between the forming daughters. New membrane assembly can either proceed centripetally behind a contractile apparatus, as in the case of prokaryotes, archaea, fungi, and animals or expand centrifugally, as in the case of higher plants. In this article, we compare the mechanisms of cytokinesis in diverse organisms dividing through the use of a contractile apparatus. While an actomyosin ring participates in cytokinesis in almost all centripetally dividing eukaryotes, the majority of bacteria and archaea (except Crenarchaea) divide using a ring composed of the tubulin-related protein FtsZ. Curiously, despite molecular conservation of the division machinery components, division site placement and its cell cycle regulation occur by a variety of unrelated mechanisms even among organisms from the same kingdom. While molecular motors and cytoskeletal polymer dynamics contribute to force generation during eukaryotic cytokinesis, cytoskeletal polymer dynamics alone appears to be sufficient for force generation during prokaryotic cytokinesis. Intriguingly, there are life forms on this planet that appear to lack molecules currently known to participate in cytokinesis and how these cells perform cytokinesis remains a mystery waiting to be unravelled.
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Affiliation(s)
- Mohan K Balasubramanian
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604.
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239
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Assembly of Bacillus subtilis FtsA: effects of pH, ionic strength and nucleotides on FtsA assembly. Int J Biol Macromol 2012; 52:170-6. [PMID: 23036588 DOI: 10.1016/j.ijbiomac.2012.09.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/18/2012] [Accepted: 09/25/2012] [Indexed: 11/23/2022]
Abstract
In this work, the assembly of purified Bacillus subtilis FtsA was analyzed by several complimentary techniques. FtsA assembled to form filaments and bundles and the polymers disassembled upon dilution. FtsA assembled more efficiently at pH 6.0 as compared to that at pH 7.0 or 8.0 and high salt inhibited the assembly of FtsA. FtsA was found to hydrolyze ATP in vitro; however, neither ATP nor ADP influenced the assembly kinetics of FtsA. Though FtsA is a homologue of actin, cytochalasin D did not inhibit the assembly of FtsA. Interestingly, a hydrophobic molecule, 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid, inhibited the assembly of FtsA.
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240
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Vecchiarelli AG, Mizuuchi K, Funnell BE. Surfing biological surfaces: exploiting the nucleoid for partition and transport in bacteria. Mol Microbiol 2012; 86:513-23. [PMID: 22934804 DOI: 10.1111/mmi.12017] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2012] [Indexed: 12/13/2022]
Abstract
The ParA family of ATPases is responsible for transporting bacterial chromosomes, plasmids and large protein machineries. ParAs pattern the nucleoid in vivo, but how patterning functions or is exploited in transport is of considerable debate. Here we discuss the process of self-organization into patterns on the bacterial nucleoid and explore how it relates to the molecular mechanism of ParA action. We review ParA-mediated DNA partition as a general mechanism of how ATP-driven protein gradients on biological surfaces can result in spatial organization on a mesoscale. We also discuss how the nucleoid acts as a formidable diffusion barrier for large bodies in the cell, and make the case that the ParA family evolved to overcome the barrier by exploiting the nucleoid as a matrix for movement.
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Affiliation(s)
- Anthony G Vecchiarelli
- Laboratory of Molecular Biology, National Institute of Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0540, USA
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241
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Schnatwinkel C, Niswander L. Nubp1 is required for lung branching morphogenesis and distal progenitor cell survival in mice. PLoS One 2012; 7:e44871. [PMID: 23028652 PMCID: PMC3444492 DOI: 10.1371/journal.pone.0044871] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 08/08/2012] [Indexed: 01/08/2023] Open
Abstract
The lung is a complex system in biology and medicine alike. Whereas there is a good understanding of the anatomy and histology of the embryonic and adult lung, less is known about the molecular details and the cellular pathways that ultimately orchestrate lung formation and affect its health. From a forward genetic approach to identify novel genes involved in lung formation, we identified a mutated Nubp1 gene, which leads to syndactyly, eye cataract and lung hypoplasia. In the lung, Nubp1 is expressed in progenitor cells of the distal epithelium. Nubp1(m1Nisw) mutants show increased apoptosis accompanied by a loss of the distal progenitor markers Sftpc, Sox9 and Foxp2. In addition, Nubp1 mutation disrupts localization of the polarity protein Par3 and the mitosis relevant protein Numb. Using knock-down studies in lung epithelial cells, we also demonstrate a function of Nubp1 in regulating centrosome dynamics and microtubule organization. Together, Nubp1 represents an essential protein for lung progenitor survival by coordinating vital cellular processes including cell polarity and centrosomal dynamics.
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Affiliation(s)
- Carsten Schnatwinkel
- Howard Hughes Medical Institute, Department of Pediatrics, University of Colorado School of Medicine and Children’s Hospital Colorado, Aurora, Colorado, United States of America
| | - Lee Niswander
- Howard Hughes Medical Institute, Department of Pediatrics, University of Colorado School of Medicine and Children’s Hospital Colorado, Aurora, Colorado, United States of America
- * E-mail:
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242
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Yun SH, Ji SC, Jeon HJ, Wang X, Kim SW, Bak G, Lee Y, Lim HM. The CnuK9E H-NS complex antagonizes DNA binding of DicA and leads to temperature-dependent filamentous growth in E. coli. PLoS One 2012; 7:e45236. [PMID: 23028867 PMCID: PMC3441716 DOI: 10.1371/journal.pone.0045236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 08/20/2012] [Indexed: 01/07/2023] Open
Abstract
Cnu (an OriC-binding nucleoid protein) associates with H-NS. A variant of Cnu was identified as a key factor for filamentous growth of a wild-type Escherichia coli strain at 37°C. This variant (CnuK9E) bears a substitution of a lysine to glutamic acid, causing a charge reversal in the first helix. The temperature-dependent filamentous growth of E. coli bearing CnuK9E could be reversed by either lowering the temperature to 25°C or lowering the CnuK9E concentration in the cell. Gene expression analysis suggested that downregulation of dicA by CnuK9E causes a burst of dicB transcription, which, in turn, elicits filamentous growth. In vivo assays indicated that DicA transcriptionally activates its own gene, by binding to its operator in a temperature-dependent manner. The antagonizing effect of CnuK9E with H-NS on DNA-binding activity of DicA was stronger at 37°C, presumably due to the lower operator binding of DicA at 37°C. These data suggest that the temperature-dependent negative effect of CnuK9E on DicA binding plays a major role in filamentous growth. The C-terminus of DicA shows significant amino acid sequence similarity to the DNA-binding domains of RovA and SlyA, regulators of pathogenic genes in Yersinia and Salmonella, respectively, which also show better DNA-binding activity at 25°C.
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Affiliation(s)
- Sang Hoon Yun
- Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea
| | - Sang Chun Ji
- Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea
| | - Heung Jin Jeon
- Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea
| | - Xun Wang
- Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea
| | - Si Wouk Kim
- Department of Environmental Engineering, Pioneer Research Center for Controlling of Harmful Algal Blooming, Chosun University, Gwangju, Republic of Korea
| | - Geunu Bak
- Department of Chemistry, KAIST, Daejeon, Republic of Korea
| | - Younghoon Lee
- Department of Chemistry, KAIST, Daejeon, Republic of Korea
| | - Heon M. Lim
- Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea
- * E-mail:
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243
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Chien AC, Zareh SKG, Wang YM, Levin PA. Changes in the oligomerization potential of the division inhibitor UgtP co-ordinate Bacillus subtilis cell size with nutrient availability. Mol Microbiol 2012; 86:594-610. [PMID: 22931116 DOI: 10.1111/mmi.12007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2012] [Indexed: 12/20/2022]
Abstract
How cells co-ordinate size with growth and development is a major, unresolved question in cell biology. In previous work we identified the glucosyltransferase UgtP as a division inhibitor responsible for increasing the size of Bacillus subtilis cells under nutrient-rich conditions. In nutrient-rich medium, UgtP is distributed more or less uniformly throughout the cytoplasm and concentrated at the cell poles and/or the cytokinetic ring. Under these conditions, UgtP interacts directly with FtsZ to inhibit division and increase cell size. Conversely, under nutrient-poor conditions, UgtP is sequestered away from FtsZ in punctate foci, and division proceeds unimpeded resulting in a reduction in average cell size. Here we report that nutrient-dependent changes in UgtP's oligomerization potential serve as a molecular rheostat to precisely co-ordinate B. subtilis cell size with nutrient availability. Our data indicate UgtP interacts with itself and the essential cell division protein FtsZ in a high-affinity manner influenced in part by UDP glucose, an intracellular proxy for nutrient availability. These findings support a model in which UDP-glc-dependent changes in UgtP's oligomerization potential shift the equilibrium between UgtP•UgtP and UgtP•FtsZ, fine-tuning the amount of FtsZ available for assembly into the cytokinetic ring and with it cell size.
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Affiliation(s)
- An-Chun Chien
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
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244
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Joyce G, Williams KJ, Robb M, Noens E, Tizzano B, Shahrezaei V, Robertson BD. Cell division site placement and asymmetric growth in mycobacteria. PLoS One 2012; 7:e44582. [PMID: 22970255 PMCID: PMC3438161 DOI: 10.1371/journal.pone.0044582] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 08/08/2012] [Indexed: 01/12/2023] Open
Abstract
Mycobacteria are members of the actinomycetes that grow by tip extension and lack apparent homologues of the known cell division regulators found in other rod-shaped bacteria. Previous work using static microscopy on dividing mycobacteria led to the hypothesis that these cells can grow and divide asymmetrically, and at a wide range of sizes, in contrast to the cell growth and division patterns observed in the model rod-shaped organisms. In this study, we test this hypothesis using live-cell time-lapse imaging of dividing Mycobacterium smegmatis labelled with fluorescent PBP1a, to probe peptidoglycan synthesis and label the cell septum. We demonstrate that the new septum is placed accurately at mid-cell, and that the asymmetric division observed is a result of differential growth from the cell tips, with a more than 2-fold difference in growth rate between fast and slow growing poles. We also show that the division site is not selected at a characteristic cell length, suggesting this is not an important cue during the mycobacterial cell cycle.
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Affiliation(s)
- Graham Joyce
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College, London, United Kingdom
| | - Kerstin J. Williams
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College, London, United Kingdom
| | - Matthew Robb
- Department of Mathematics, Imperial College, London, United Kingdom
| | - Elke Noens
- European Molecular Biology Laboratory, Hamburg, Germany
| | | | - Vahid Shahrezaei
- Department of Mathematics, Imperial College, London, United Kingdom
| | - Brian D. Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College, London, United Kingdom
- * E-mail:
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245
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Abstract
In the living cell, proteins are able to organize space much larger than their dimensions. In return, changes of intracellular space can influence biochemical reactions, allowing cells to sense their size and shape. Despite the possibility to reconstitute protein self-organization with only a few purified components, we still lack knowledge of how geometrical boundaries affect spatiotemporal protein patterns. Following a minimal systems approach, we used purified proteins and photolithographically patterned membranes to study the influence of spatial confinement on the self-organization of the Min system, a spatial regulator of bacterial cytokinesis, in vitro. We found that the emerging protein pattern responds even to the lateral, two-dimensional geometry of the membrane such that, as in the three-dimensional cell, Min protein waves travel along the longest axis of the membrane patch. This shows that for spatial sensing the Min system does not need to be enclosed in a three-dimensional compartment. Using a computational model we quantitatively analyzed our experimental findings and identified persistent binding of MinE to the membrane as requirement for the Min system to sense geometry. Our results give insight into the interplay between geometrical confinement and biochemical patterns emerging from a nonlinear reaction-diffusion system.
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246
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Kraemer JA, Erb ML, Waddling CA, Montabana EA, Zehr EA, Wang H, Nguyen K, Pham DSL, Agard DA, Pogliano J. A phage tubulin assembles dynamic filaments by an atypical mechanism to center viral DNA within the host cell. Cell 2012; 149:1488-99. [PMID: 22726436 DOI: 10.1016/j.cell.2012.04.034] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/27/2012] [Accepted: 04/13/2012] [Indexed: 01/24/2023]
Abstract
Tubulins are essential for the reproduction of many eukaryotic viruses, but historically, bacteriophage were assumed not to require a cytoskeleton. Here, we identify a tubulin-like protein, PhuZ, from bacteriophage 201φ2-1 and show that it forms filaments in vivo and in vitro. The PhuZ structure has a conserved tubulin fold, with an unusual, extended C terminus that we demonstrate to be critical for polymerization in vitro and in vivo. Longitudinal packing in the crystal lattice mimics packing observed by EM of in-vitro-formed filaments, indicating how interactions between the C terminus and the following monomer drive polymerization. PhuZ forms a filamentous array that is required for positioning phage DNA within the bacterial cell. Correct positioning to the cell center and optimal phage reproduction only occur when the PhuZ filament is dynamic. Thus, we show that PhuZ assembles a spindle-like array that functions analogously to the microtubule-based spindles of eukaryotes.
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Affiliation(s)
- James A Kraemer
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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247
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Lutkenhaus J, Pichoff S, Du S. Bacterial cytokinesis: From Z ring to divisome. Cytoskeleton (Hoboken) 2012; 69:778-90. [PMID: 22888013 DOI: 10.1002/cm.21054] [Citation(s) in RCA: 206] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/18/2012] [Accepted: 07/20/2012] [Indexed: 11/07/2022]
Abstract
Ancestral homologues of the major eukaryotic cytoskeletal families, tubulin and actin, play critical roles in cytokinesis of bacterial cells. FtsZ is the ancestral homologue of tubulin and assembles into the Z ring that determines the division plane. FtsA, a member of the actin family, is involved in coordinating cell wall synthesis during cytokinesis. FtsA assists in the formation of the Z ring and also has a critical role in recruiting downstream division proteins to the Z ring to generate the divisome that divides the cell. Spatial regulation of cytokinesis occurs at the stage of Z ring assembly and regulation of cell size occurs at this stage or during Z ring maturation.
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Affiliation(s)
- Joe Lutkenhaus
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas.
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248
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Sengupta S, Derr J, Sain A, Rutenberg AD. Stuttering Min oscillations within E. coli bacteria: a stochastic polymerization model. Phys Biol 2012; 9:056003. [PMID: 22931851 DOI: 10.1088/1478-3975/9/5/056003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have developed a 3D off-lattice stochastic polymerization model to study the subcellular oscillation of Min proteins in the bacteria Escherichia coli, and used it to investigate the experimental phenomenon of Min oscillation stuttering. Stuttering was affected by the rate of immediate rebinding of MinE released from depolymerizing filament tips (processivity), protection of depolymerizing filament tips from MinD binding and fragmentation of MinD filaments due to MinE. Processivity, protection and fragmentation each reduce stuttering, speed oscillations and MinD filament lengths. Neither processivity nor tip protection were, on their own, sufficient to produce fast stutter-free oscillations. While filament fragmentation could, on its own, lead to fast oscillations with infrequent stuttering; high levels of fragmentation degraded oscillations. The infrequent stuttering observed in standard Min oscillations is consistent with short filaments of MinD, while we expect that mutants that exhibit higher stuttering frequencies will exhibit longer MinD filaments. Increased stuttering rate may be a useful diagnostic to find observable MinD polymerization under experimental conditions.
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Affiliation(s)
- Supratim Sengupta
- Centre for Computational Biology and Bioinformatics, School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.
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249
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Spatial ordering of chromosomes enhances the fidelity of chromosome partitioning in cyanobacteria. Proc Natl Acad Sci U S A 2012; 109:13638-43. [PMID: 22869746 DOI: 10.1073/pnas.1211144109] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Many cyanobacteria have been shown to harbor multiple chromosome copies per cell, yet little is known about the organization, replication, and segregation of these chromosomes. Here, we visualize individual chromosomes in the cyanobacterium Synechococcus elongatus via time-lapse fluorescence microscopy. We find that chromosomes are equally spaced along the long axis of the cell and are interspersed with another regularly spaced subcellular compartment, the carboxysome. This remarkable organization of the cytoplasm along with accurate midcell septum placement allows for near-optimal segregation of chromosomes to daughter cells. Disruption of either chromosome ordering or midcell septum placement significantly increases the chromosome partitioning error. We find that chromosome replication is both asynchronous and independent of the position of the chromosome in the cell and that spatial organization is preserved after replication. Our findings on chromosome organization, replication, and segregation in S. elongatus provide a basis for understanding chromosome dynamics in bacteria with multiple chromosomes.
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250
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Rashkov P, Schmitt BA, Søgaard-Andersen L, Lenz P, Dahlke S. A model of oscillatory protein dynamics in bacteria. Bull Math Biol 2012; 74:2183-203. [PMID: 22829180 DOI: 10.1007/s11538-012-9752-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
Abstract
Spatial oscillations of proteins in bacteria have recently attracted much attention. The cellular mechanism underlying these oscillations can be studied at molecular as well as at more macroscopic levels. We construct a minimal mathematical model with two proteins that is able to produce self-sustained regular pole-to-pole oscillations without having to take into account molecular details of the proteins and their interactions. The dynamics of the model is based solely on diffusion across the cell body and protein reactions at the poles, and is independent of stimuli coming from the environment. We solve the associated system of reaction-diffusion equations and perform a parameter scan to demonstrate robustness of the model for two possible sets of the reaction functions.
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Affiliation(s)
- Peter Rashkov
- Department of Mathematics and Informatics, Philipps-Universität Marburg, Hans-Meerwein-Str., 35032, Marburg, Germany
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