1
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Mao W, Renner LD, Cornilleau C, Li de la Sierra-Gallay I, Afensiss S, Benlamara S, Ah-Seng Y, Van Tilbeurgh H, Nessler S, Bertin A, Chastanet A, Carballido-Lopez R. On the role of nucleotides and lipids in the polymerization of the actin homolog MreB from a Gram-positive bacterium. eLife 2023; 12:e84505. [PMID: 37818717 PMCID: PMC10718530 DOI: 10.7554/elife.84505] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 10/08/2023] [Indexed: 10/12/2023] Open
Abstract
In vivo, bacterial actin MreB assembles into dynamic membrane-associated filamentous structures that exhibit circumferential motion around the cell. Current knowledge of MreB biochemical and polymerization properties in vitro remains limited and is mostly based on MreB proteins from Gram-negative species. In this study, we report the first observation of organized protofilaments by electron microscopy and the first 3D-structure of MreB from a Gram-positive bacterium. We show that Geobacillus stearothermophilus MreB forms straight pairs of protofilaments on lipid surfaces in the presence of ATP or GTP, but not in the presence of ADP, GDP or non-hydrolysable ATP analogs. We demonstrate that membrane anchoring is mediated by two spatially close short hydrophobic sequences while electrostatic interactions also contribute to lipid binding, and show that the population of membrane-bound protofilament doublets is in steady-state. In solution, protofilament doublets were not detected in any condition tested. Instead, MreB formed large sheets regardless of the bound nucleotide, albeit at a higher critical concentration. Altogether, our results indicate that both lipids and ATP are facilitators of MreB polymerization, and are consistent with a dual effect of ATP hydrolysis, in promoting both membrane binding and filaments assembly/disassembly.
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Affiliation(s)
- Wei Mao
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Lars D Renner
- Leibniz Institute of Polymer Research, and the Max-Bergmann-Center of BiomaterialsDresdenGermany
| | - Charlène Cornilleau
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Ines Li de la Sierra-Gallay
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRSGif-sur-YvetteFrance
| | - Sana Afensiss
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Sarah Benlamara
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Yoan Ah-Seng
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Herman Van Tilbeurgh
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRSGif-sur-YvetteFrance
| | - Sylvie Nessler
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRSGif-sur-YvetteFrance
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Sorbonne Université, 75005ParisFrance
| | - Arnaud Chastanet
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
| | - Rut Carballido-Lopez
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis InstituteJouy-en-JosasFrance
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2
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Ramos-León F, Ramamurthi K. Cytoskeletal proteins: Lessons learned from bacteria. Phys Biol 2022; 19. [PMID: 35081523 DOI: 10.1088/1478-3975/ac4ef0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 01/26/2022] [Indexed: 11/11/2022]
Abstract
Cytoskeletal proteins are classified as a group that is defined functionally, whose members are capable of polymerizing into higher order structures, either dynamically or statically, to perform structural roles during a variety of cellular processes. In eukaryotes, the most well-studied cytoskeletal proteins are actin, tubulin, and intermediate filaments, and are essential for cell shape and movement, chromosome segregation, and intracellular cargo transport. Prokaryotes often harbor homologs of these proteins, but in bacterial cells, these homologs are usually not employed in roles that can be strictly defined as "cytoskeletal". However, several bacteria encode other proteins capable of polymerizing which, although they do not appear to have a eukaryotic counterpart, nonetheless appear to perform a more traditional "cytoskeletal" function. In this review, we discuss recent reports that cover the structure and functions of prokaryotic proteins that are broadly termed as cytoskeletal, either by sequence homology or by function, to highlight how the enzymatic properties of traditionally studied cytoskeletal proteins may be used for other types of cellular functions; and to demonstrate how truly "cytoskeletal" functions may be performed by uniquely bacterial proteins that do not display homology to eukaryotic proteins.
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Affiliation(s)
- Félix Ramos-León
- National Institutes of Health, 37 Convent Dr., Bldg 37, Room 5132, Bethesda, Maryland, 20892, UNITED STATES
| | - Kumaran Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, 37 Convent Dr, Bldg 37, Room 5132, Bethesda, Maryland, 20892, UNITED STATES
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3
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Garner EC. Toward a Mechanistic Understanding of Bacterial Rod Shape Formation and Regulation. Annu Rev Cell Dev Biol 2021; 37:1-21. [PMID: 34186006 DOI: 10.1146/annurev-cellbio-010521-010834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One of the most common bacterial shapes is a rod, yet we have a limited understanding of how this simple shape is constructed. While only six proteins are required for rod shape, we are just beginning to understand how they self-organize to build the micron-sized enveloping structures that define bacterial shape out of nanometer-sized glycan strains. Here, we detail and summarize the insights gained over the last 20 years into this complex problem that have been achieved with a wide variety of different approaches. We also explain and compare both current and past models of rod shape formation and maintenance and then highlight recent insights into how the Rod complex might be regulated. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA;
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4
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Landajuela A, Braun M, Rodrigues CDA, Martínez-Calvo A, Doan T, Horenkamp F, Andronicos A, Shteyn V, Williams ND, Lin C, Wingreen NS, Rudner DZ, Karatekin E. FisB relies on homo-oligomerization and lipid binding to catalyze membrane fission in bacteria. PLoS Biol 2021; 19:e3001314. [PMID: 34185788 PMCID: PMC8274934 DOI: 10.1371/journal.pbio.3001314] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 07/12/2021] [Accepted: 06/07/2021] [Indexed: 11/18/2022] Open
Abstract
Little is known about mechanisms of membrane fission in bacteria despite their requirement for cytokinesis. The only known dedicated membrane fission machinery in bacteria, fission protein B (FisB), is expressed during sporulation in Bacillus subtilis and is required to release the developing spore into the mother cell cytoplasm. Here, we characterized the requirements for FisB-mediated membrane fission. FisB forms mobile clusters of approximately 12 molecules that give way to an immobile cluster at the engulfment pole containing approximately 40 proteins at the time of membrane fission. Analysis of FisB mutants revealed that binding to acidic lipids and homo-oligomerization are both critical for targeting FisB to the engulfment pole and membrane fission. Experiments using artificial membranes and filamentous cells suggest that FisB does not have an intrinsic ability to sense or induce membrane curvature but can bridge membranes. Finally, modeling suggests that homo-oligomerization and trans-interactions with membranes are sufficient to explain FisB accumulation at the membrane neck that connects the engulfment membrane to the rest of the mother cell membrane during late stages of engulfment. Together, our results show that FisB is a robust and unusual membrane fission protein that relies on homo-oligomerization, lipid binding, and the unique membrane topology generated during engulfment for localization and membrane scission, but surprisingly, not on lipid microdomains, negative-curvature lipids, or curvature sensing.
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Affiliation(s)
- Ane Landajuela
- Cellular and Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
| | - Martha Braun
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
- Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | | | | | - Thierry Doan
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Aix-Marseille Université, Marseilles, France
| | - Florian Horenkamp
- Cell Biology, Yale University, New Haven, Connecticut, United States of America
| | - Anna Andronicos
- Cellular and Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
| | - Vladimir Shteyn
- Cellular and Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
| | - Nathan D Williams
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
- Cell Biology, Yale University, New Haven, Connecticut, United States of America
| | - Chenxiang Lin
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
- Cell Biology, Yale University, New Haven, Connecticut, United States of America
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Erdem Karatekin
- Cellular and Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Nanobiology Institute, Yale University, West Haven, Connecticut, United States of America
- Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Université de Paris, SPPIN-Saints-Pères Paris Institute for the Neurosciences, Centre National de la Recherche Scientifique (CNRS), Paris, France
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5
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Liang B, Quan B, Li J, Loton C, Bredeche MF, Lindner AB, Xu L. Artificial modulation of cell width significantly affects the division time of Escherichia coli. Sci Rep 2020; 10:17847. [PMID: 33082450 PMCID: PMC7576201 DOI: 10.1038/s41598-020-74778-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/07/2020] [Indexed: 12/14/2022] Open
Abstract
Bacterial cells have characteristic spatial and temporal scales. For instance, Escherichia coli, the typical rod-shaped bacteria, always maintains a relatively constant cell width and cell division time. However, whether the external physical perturbation of cell width has an impact on cell division time remains largely unexplored. In this work, we developed two microchannel chips, namely straight channels and ‘necked’ channels, to precisely regulate the width of E. coli cells and to investigate the correlation between cell width and division time of the cells. Our results show that, in the straight channels, the wide cells divide much slower than narrow cells. In the ‘necked’ channels, the cell division is remarkably promoted compared to that in straight channels with the same width. Besides, fluorescence time-lapse microscopy imaging of FtsZ dynamics shows that the cell pre-constriction time is more sensitive to cell width perturbation than cell constriction time. Finally, we revealed a significant anticorrelation between the death rate and the division rate of cell populations with different widths. Our work provides new insights into the correlation between the geometrical property and division time of E. coli cells and sheds new light on the future study of spatial–temporal correlation in cell physiology.
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Affiliation(s)
- Baihui Liang
- Center for Nano and Micro Mechanics, School of Aerospace Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Baogang Quan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Junjie Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.,Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, People's Republic of China
| | - Chantal Loton
- Systems Engineering and Evolution Dynamics Lab, INSERM U1001, Paris Descartes University, 75014, Paris, France.,Faculty of Medicine, Paris Descartes University, 75014, Paris, France
| | - Marie-Florence Bredeche
- Systems Engineering and Evolution Dynamics Lab, INSERM U1001, Paris Descartes University, 75014, Paris, France.,Faculty of Medicine, Paris Descartes University, 75014, Paris, France
| | - Ariel B Lindner
- Systems Engineering and Evolution Dynamics Lab, INSERM U1001, Paris Descartes University, 75014, Paris, France.,Faculty of Medicine, Paris Descartes University, 75014, Paris, France.,Centre for Research and Interdisciplinarity (CRI), Paris Descartes University, 75014, Paris, France
| | - Luping Xu
- Center for Nano and Micro Mechanics, School of Aerospace Engineering, Tsinghua University, Beijing, 100084, People's Republic of China.
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6
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Jurásek M, Flärdh K, Vácha R. Effect of membrane composition on DivIVA-membrane interaction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183144. [PMID: 31821790 DOI: 10.1016/j.bbamem.2019.183144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/27/2019] [Accepted: 11/29/2019] [Indexed: 12/31/2022]
Abstract
DivIVA is a crucial membrane-binding protein that helps to localize other proteins to negatively curved membranes at cellular poles and division septa in Gram-positive bacteria. The N-terminal domain of DivIVA is responsible for membrane binding. However, to which lipids the domain binds or how it recognizes the membrane negative curvature remains elusive. Using computer simulations, we demonstrate that the N-terminal domain of Streptomyces coelicolor DivIVA adsorbs to membranes with affinity and orientation dependent on the lipid composition. The domain interacts non-specifically with lipid phosphates via its arginine-rich tip and the strongest interaction is with cardiolipin. Moreover, we observed a specific attraction between a negatively charged side patch of the domain and ethanolamine lipids, which addition caused the change of the domain orientation from perpendicular to parallel alignment to the membrane plane. Similar but less electrostatically dependent behavior was observed for the N-terminal domain of Bacillus subtilis. The domain propensity for lipids which prefer negatively curved membranes could be a mechanism for the cellular localization of DivIVA protein.
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Affiliation(s)
- Miroslav Jurásek
- Faculty of Science, Masaryk University,Kamenice 753/5, Brno 625 00, Czech Republic
| | - Klas Flärdh
- Department of Biology, Lund University, Sölvegatan 35, Lund 223 62, Sweden
| | - Robert Vácha
- Faculty of Science, Masaryk University,Kamenice 753/5, Brno 625 00, Czech Republic; CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic.
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7
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Abstract
Reproduction in the bacterial kingdom predominantly occurs through binary fission-a process in which one parental cell is divided into two similarly sized daughter cells. How cell division, in conjunction with cell elongation and chromosome segregation, is orchestrated by a multitude of proteins has been an active area of research spanning the past few decades. Together, the monumental endeavors of multiple laboratories have identified several cell division and cell shape regulators as well as their underlying regulatory mechanisms in rod-shaped Escherichia coli and Bacillus subtilis, which serve as model organisms for Gram-negative and Gram-positive bacteria, respectively. Yet our understanding of bacterial cell division and morphology regulation is far from complete, especially in noncanonical and non-rod-shaped organisms. In this review, we focus on two proteins that are highly conserved in Gram-positive organisms, DivIVA and its homolog GpsB, and attempt to summarize the recent advances in this area of research and discuss their various roles in cell division, cell growth, and chromosome segregation in addition to their interactome and posttranslational regulation.
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8
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Wong F, Garner EC, Amir A. Mechanics and dynamics of translocating MreB filaments on curved membranes. eLife 2019; 8:40472. [PMID: 30775967 PMCID: PMC6504236 DOI: 10.7554/elife.40472] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 02/15/2019] [Indexed: 12/14/2022] Open
Abstract
MreB is an actin homolog that is essential for coordinating the cell wall synthesis required for the rod shape of many bacteria. Previously we have shown that filaments of MreB bind to the curved membranes of bacteria and translocate in directions determined by principal membrane curvatures to create and reinforce the rod shape (Hussain et al., 2018). Here, in order to understand how MreB filament dynamics affects their cellular distribution, we model how MreB filaments bind and translocate on membranes with different geometries. We find that it is both energetically favorable and robust for filaments to bind and orient along directions of largest membrane curvature. Furthermore, significant localization to different membrane regions results from processive MreB motion in various geometries. These results demonstrate that the in vivo localization of MreB observed in many different experiments, including those examining negative Gaussian curvature, can arise from translocation dynamics alone.
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Affiliation(s)
- Felix Wong
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Center for Systems Biology, Harvard University, Cambridge, United States
| | - Ariel Amir
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
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9
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Shi H, Bratton BP, Gitai Z, Huang KC. How to Build a Bacterial Cell: MreB as the Foreman of E. coli Construction. Cell 2019. [PMID: 29522748 DOI: 10.1016/j.cell.2018.02.050] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cell shape matters across the kingdoms of life, and cells have the remarkable capacity to define and maintain specific shapes and sizes. But how are the shapes of micron-sized cells determined from the coordinated activities of nanometer-sized proteins? Here, we review general principles that have surfaced through the study of rod-shaped bacterial growth. Imaging approaches have revealed that polymers of the actin homolog MreB play a central role. MreB both senses and changes cell shape, thereby generating a self-organizing feedback system for shape maintenance. At the molecular level, structural and computational studies indicate that MreB filaments exhibit tunable mechanical properties that explain their preference for certain geometries and orientations along the cylindrical cell body. We illustrate the regulatory landscape of rod-shape formation and the connectivity between cell shape, cell growth, and other aspects of cell physiology. These discoveries provide a framework for future investigations into the architecture and construction of microbes.
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Affiliation(s)
- Handuo Shi
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Benjamin P Bratton
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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10
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Abstract
This article describes the design and fabrication of microchambers that are used for the study of bacterial cells. The design allows for the confinement and precise manipulation of bacterial cell shape. The application of fluorescent dyes and fluorescent proteins enables the precise analysis of the localization of biomolecules within confined bacterial cell. This article also outlines three methods to engineer cell shape from a filamentous cell type and from spheroplasts without a cell wall using soft lithography-based technologies. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Lars David Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials Dresden, Dresden, Germany
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11
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den Blaauwen T. Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis? Front Microbiol 2018; 9:822. [PMID: 29867786 PMCID: PMC5952006 DOI: 10.3389/fmicb.2018.00822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 04/11/2018] [Indexed: 01/21/2023] Open
Abstract
The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.
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Affiliation(s)
- Tanneke den Blaauwen
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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12
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van Teeffelen S, Renner LD. Recent advances in understanding how rod-like bacteria stably maintain their cell shapes. F1000Res 2018; 7:241. [PMID: 29560261 PMCID: PMC5832919 DOI: 10.12688/f1000research.12663.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/22/2018] [Indexed: 01/14/2023] Open
Abstract
Cell shape and cell volume are important for many bacterial functions. In recent years, we have seen a range of experimental and theoretical work that led to a better understanding of the determinants of cell shape and size. The roles of different molecular machineries for cell-wall expansion have been detailed and partially redefined, mechanical forces have been shown to influence cell shape, and new connections between metabolism and cell shape have been proposed. Yet the fundamental determinants of the different cellular dimensions remain to be identified. Here, we highlight some of the recent developments and focus on the determinants of rod-like cell shape and size in the well-studied model organisms
Escherichia coli and
Bacillus subtilis.
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Affiliation(s)
- Sven van Teeffelen
- Department of Microbiology, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Lars D Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, 01069 Dresden, Germany
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13
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Hussain S, Wivagg CN, Szwedziak P, Wong F, Schaefer K, Izoré T, Renner LD, Holmes MJ, Sun Y, Bisson-Filho AW, Walker S, Amir A, Löwe J, Garner EC. MreB filaments align along greatest principal membrane curvature to orient cell wall synthesis. eLife 2018; 7:32471. [PMID: 29469806 PMCID: PMC5854468 DOI: 10.7554/elife.32471] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/21/2018] [Indexed: 12/26/2022] Open
Abstract
MreB is essential for rod shape in many bacteria. Membrane-associated MreB filaments move around the rod circumference, helping to insert cell wall in the radial direction to reinforce rod shape. To understand how oriented MreB motion arises, we altered the shape of Bacillus subtilis. MreB motion is isotropic in round cells, and orientation is restored when rod shape is externally imposed. Stationary filaments orient within protoplasts, and purified MreB tubulates liposomes in vitro, orienting within tubes. Together, this demonstrates MreB orients along the greatest principal membrane curvature, a conclusion supported with biophysical modeling. We observed that spherical cells regenerate into rods in a local, self-reinforcing manner: rapidly propagating rods emerge from small bulges, exhibiting oriented MreB motion. We propose that the coupling of MreB filament alignment to shape-reinforcing peptidoglycan synthesis creates a locally-acting, self-organizing mechanism allowing the rapid establishment and stable maintenance of emergent rod shape. Many bacteria are surrounded by both a cell membrane and a cell wall – a rigid outer covering made of sugars and short protein chains. The cell wall often determines which of a variety of shapes – such as rods or spheres – the bacteria grow into. One protein required to form the rod shape is called MreB. This protein forms filaments that bind to the bacteria’s cell membrane and associate with the enzymes that build the cell wall. Together, these filament-enzyme complexes rotate around the cell to build and reinforce the cell wall in a hoop-like manner. But how do the MreB filaments know how to move around the circumference of the rod, instead of moving in any other direction? Using a technique called total internal reflection microscopy to study how MreB filaments move across bacteria cells, Hussain, Wivagg et al. show that the filaments sense the shape of a bacterium by orienting along the direction of greatest curvature. As a result, the filaments in rod-shaped cells orient and move around the rod, while in spherical bacteria they move in all directions. However, spherical bacteria can regenerate into rods from small surface ‘bulges’. The MreB filaments in the bulges move in an oriented way, helping them to generate the rod shape. Hussain, Wivagg et al. also found that forcing cells that lack a cell wall into a rod shape caused the MreB filaments bound to the cell membrane to orient and circle around the rod. This shows that the organization of the filaments is sufficient to shape the cell wall. In the future, determining what factors control the activity of the MreB filaments and the enzymes they associate with might reveal new targets for antibiotics that disrupt the cell wall and so kill the bacteria. This will require higher resolution microscopes to be used to examine the cell wall in more detail. The activity of all the proteins involved in building cell walls will also need to be extensively characterized.
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Affiliation(s)
- Saman Hussain
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Carl N Wivagg
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Piotr Szwedziak
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Felix Wong
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, United States
| | - Kaitlin Schaefer
- Department of Microbiology and Immunology, Harvard University, Cambridge, United States
| | - Thierry Izoré
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Lars D Renner
- Leibniz Institute of Polymer Research, Dresden, Germany
| | - Matthew J Holmes
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Yingjie Sun
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | | | - Suzanne Walker
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Ariel Amir
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, United States
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
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14
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Eun YJ, Ho PY, Kim M, LaRussa S, Robert L, Renner LD, Schmid A, Garner E, Amir A. Archaeal cells share common size control with bacteria despite noisier growth and division. Nat Microbiol 2017; 3:148-154. [PMID: 29255255 DOI: 10.1038/s41564-017-0082-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 11/21/2017] [Indexed: 01/23/2023]
Abstract
In nature, microorganisms exhibit different volumes spanning six orders of magnitude 1 . Despite their capability to create different sizes, a clonal population in a given environment maintains a uniform size across individual cells. Recent studies in eukaryotic and bacterial organisms showed that this homogeneity in cell size can be accomplished by growing a constant size between two cell cycle events (that is, the adder model 2-6 ). Demonstration of the adder model led to the hypothesis that this phenomenon is a consequence of convergent evolution. Given that archaeal cells share characteristics with both bacteria and eukaryotes, we investigated whether and how archaeal cells exhibit control over cell size. To this end, we developed a soft-lithography method of growing the archaeal cells to enable quantitative time-lapse imaging and single-cell analysis, which would be useful for other microorganisms. Using this method, we demonstrated that Halobacterium salinarum, a hypersaline-adapted archaeal organism, grows exponentially at the single-cell level and maintains a narrow-size distribution by adding a constant length between cell division events. Interestingly, the archaeal cells exhibited greater variability in cell division placement and exponential growth rate across individual cells in a population relative to those observed in Escherichia coli 6-9 . Here, we present a theoretical framework that explains how these larger fluctuations in archaeal cell cycle events contribute to cell size variability and control.
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Affiliation(s)
- Ye-Jin Eun
- Department of Molecular and Cellular Biology, Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | - Po-Yi Ho
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Minjeong Kim
- Department of Molecular and Cellular Biology, Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | | | - Lydia Robert
- INRA, UMR 1319 Micalis, Jouy-en-Josas, France.,AgroParisTech, UMR Micalis, Jouy-en-Josas, France.,Laboratoire Jean Perrin, UPMC-CNRS, UMR 8237, UPMC, Paris, France
| | - Lars D Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, Dresden, Germany
| | - Amy Schmid
- Biology Department, Center for Genomics and Computational Biology, Duke University, Durham, NC, USA.
| | - Ethan Garner
- Department of Molecular and Cellular Biology, Center for Systems Biology, Harvard University, Cambridge, MA, USA.
| | - Ariel Amir
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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15
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Kim EY, Tyndall ER, Huang KC, Tian F, Ramamurthi KS. Dash-and-Recruit Mechanism Drives Membrane Curvature Recognition by the Small Bacterial Protein SpoVM. Cell Syst 2017; 5:518-526.e3. [PMID: 29102609 DOI: 10.1016/j.cels.2017.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/24/2017] [Accepted: 10/05/2017] [Indexed: 10/18/2022]
Abstract
In Bacillus subtilis, sporulation requires that the 26-amino acid protein SpoVM embeds specifically into the forespore membrane, a structure with convex curvature. How this nanometer-sized protein can detect curves on a micrometer scale is not well understood. Here, we report that SpoVM exploits a "dash-and-recruit" mechanism to preferentially accumulate on the forespore. Using time-resolved imaging and flow cytometry, we observe that SpoVM exhibits a faster adsorption rate onto membranes of higher convex curvature. This preferential adsorption is accurately modeled as a two-step process: first, an initial binding event occurs with a faster on rate, then cooperative recruitment of additional SpoVM molecules follows. We demonstrate that both this biochemical process and effective sporulation in vivo require an unstructured and flexible SpoVM N terminus. We propose that this two-pronged strategy of fast adsorption followed by recruitment of subsequent molecules is a general mechanism that allows small proteins to detect subtle curves with a radius 1,000-fold their size.
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Affiliation(s)
- Edward Y Kim
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Erin R Tyndall
- Department of Biochemistry and Molecular Biology, College of Medicine, Pennsylvania State University, Hershey, PA 17033, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Fang Tian
- Department of Biochemistry and Molecular Biology, College of Medicine, Pennsylvania State University, Hershey, PA 17033, USA.
| | - Kumaran S Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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16
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The Unsolved Problem of How Cells Sense Micron-Scale Curvature. Trends Biochem Sci 2017; 42:961-976. [PMID: 29089160 DOI: 10.1016/j.tibs.2017.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 12/31/2022]
Abstract
Membrane curvature is a fundamental feature of cells and their organelles. Much of what we know about how cells sense curved surfaces comes from studies examining nanometer-sized molecules on nanometer-scale curvatures. We are only just beginning to understand how cells recognize curved topologies at the micron scale. In this review, we provide the reader with an overview of our current understanding of how cells sense and respond to micron-scale membrane curvature.
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17
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El Khoury M, Swain J, Sautrey G, Zimmermann L, Van Der Smissen P, Décout JL, Mingeot-Leclercq MP. Targeting Bacterial Cardiolipin Enriched Microdomains: An Antimicrobial Strategy Used by Amphiphilic Aminoglycoside Antibiotics. Sci Rep 2017; 7:10697. [PMID: 28878347 PMCID: PMC5587548 DOI: 10.1038/s41598-017-10543-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 08/11/2017] [Indexed: 01/31/2023] Open
Abstract
Some bacterial proteins involved in cell division and oxidative phosphorylation are tightly bound to cardiolipin. Cardiolipin is a non-bilayer anionic phospholipid found in bacterial inner membrane. It forms lipid microdomains located at the cell poles and division plane. Mechanisms by which microdomains are affected by membrane-acting antibiotics and the impact of these alterations on membrane properties and protein functions remain unclear. In this study, we demonstrated cardiolipin relocation and clustering as a result of exposure to a cardiolipin-acting amphiphilic aminoglycoside antibiotic, the 3′,6-dinonyl neamine. Changes in the biophysical properties of the bacterial membrane of P. aeruginosa, including decreased fluidity and increased permeability, were observed. Cardiolipin-interacting proteins and functions regulated by cardiolipin were impacted by the amphiphilic aminoglycoside as we demonstrated an inhibition of respiratory chain and changes in bacterial shape. The latter effect was characterized by the loss of bacterial rod shape through a decrease in length and increase in curvature. It resulted from the effect on MreB, a cardiolipin dependent cytoskeleton protein as well as a direct effect of 3′,6-dinonyl neamine on cardiolipin. These results shed light on how targeting cardiolipin microdomains may be of great interest for developing new antibacterial therapies.
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Affiliation(s)
- Micheline El Khoury
- Université catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, avenue E. Mounier 73, UCL B1.73.05, 1200, Brussels, Belgium
| | - Jitendriya Swain
- Université catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, avenue E. Mounier 73, UCL B1.73.05, 1200, Brussels, Belgium
| | - Guillaume Sautrey
- Université catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, avenue E. Mounier 73, UCL B1.73.05, 1200, Brussels, Belgium.,Université de Lorraine, UMR CNRS UL 7565, 1 Blvd. Des Aiguillettes, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, Nancy, France
| | - Louis Zimmermann
- Université Grenoble Alpes, Joseph Fourier/CNRS, Institut de Pharmacochimie Moléculaire, rue de la Chimie, F-38041, Grenoble, France
| | - Patrick Van Der Smissen
- Université Catholique de Louvain, de Duve Institute, avenue Hippocrate 75, UCL B1.75.05, 1200, Brussels, Belgium
| | - Jean-Luc Décout
- Université Grenoble Alpes, Joseph Fourier/CNRS, Institut de Pharmacochimie Moléculaire, rue de la Chimie, F-38041, Grenoble, France
| | - Marie-Paule Mingeot-Leclercq
- Université catholique de Louvain, Louvain Drug Research Institute, Pharmacologie Cellulaire et Moléculaire, avenue E. Mounier 73, UCL B1.73.05, 1200, Brussels, Belgium.
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18
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Wong F, Renner LD, Özbaykal G, Paulose J, Weibel DB, van Teeffelen S, Amir A. Mechanical strain sensing implicated in cell shape recovery in Escherichia coli. Nat Microbiol 2017; 2:17115. [PMID: 28737752 PMCID: PMC5540194 DOI: 10.1038/nmicrobiol.2017.115] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 06/16/2017] [Indexed: 12/16/2022]
Abstract
The shapes of most bacteria are imparted by the structures of their peptidoglycan cell walls, which are determined by many dynamic processes that can be described on various length-scales ranging from short-range glycan insertions to cellular-scale elasticity.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 Understanding the mechanisms that maintain stable, rod-like morphologies in certain bacteria has proved to be challenging due to an incomplete understanding of the feedback between growth and the elastic and geometric properties of the cell wall.3, 4, 12, 13, 14 Here we probe the effects of mechanical strain on cell shape by modeling the mechanical strains caused by bending and differential growth of the cell wall. We show that the spatial coupling of growth to regions of high mechanical strain can explain the plastic response of cells to bending4 and quantitatively predict the rate at which bent cells straighten. By growing filamentous E. coli cells in donut-shaped microchambers, we find that the cells recovered their straight, native rod-shaped morphologies when released from captivity at a rate consistent with the theoretical prediction. We then measure the localization of MreB, an actin homolog crucial to cell wall synthesis, inside confinement and during the straightening process and find that it cannot explain the plastic response to bending or the observed straightening rate. Our results implicate mechanical strain-sensing, implemented by components of the elongasome yet to be fully characterized, as an important component of robust shape regulation in E. coli.
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Affiliation(s)
- Felix Wong
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Lars D Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, 01069 Dresden, Germany.,Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Gizem Özbaykal
- Department of Microbiology, Institut Pasteur, 75724 Paris, France
| | - Jayson Paulose
- Departments of Physics and Integrative Biology, University of California, Berkeley, California 94720, USA
| | - Douglas B Weibel
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | - Ariel Amir
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
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19
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Abstract
Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.
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Affiliation(s)
- George K Auer
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Douglas B Weibel
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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20
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Abstract
The bacterial cytoplasmic membrane is composed of roughly equal proportions of lipids and proteins. The main lipid components are phospholipids, which vary in acyl chain length, saturation, and branching and carry head groups that vary in size and charge. Phospholipid variants determine membrane properties such as fluidity and charge that in turn modulate interactions with membrane-associated proteins. We summarize recent advances in understanding bacterial membrane structure and function, focusing particularly on the possible existence and significance of specialized membrane domains. We review the role of membrane curvature as a spatial cue for recruitment and regulation of proteins involved in morphogenic functions, especially elongation and division. Finally, we examine the role of the membrane, especially regulation of synthesis and fluid properties, in the life cycle of cell wall-deficient L-form bacteria.
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Affiliation(s)
- Henrik Strahl
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, NE2 4AX United Kingdom; ,
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, NE2 4AX United Kingdom; ,
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21
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Updegrove TB, Ramamurthi KS. Geometric protein localization cues in bacterial cells. Curr Opin Microbiol 2017; 36:7-13. [PMID: 28110195 DOI: 10.1016/j.mib.2016.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/15/2016] [Accepted: 12/17/2016] [Indexed: 10/20/2022]
Abstract
Bacterial cells are highly organized at a molecular level. Understanding how specific proteins localize to their proper subcellular address has been a major challenge in bacterial cell biology. One mechanism, which appears to be increasingly more common, is the use of 'geometric cues' for protein localization. In this model, certain shape-sensing proteins recognize, and preferentially embed into, either negatively or positively curved (concave or convex, respectively) membranes. Here, we review examples of bacterial proteins that reportedly localize by sensing geometric cues and highlight emerging mechanistic understandings of how proteins may recognize subtle differences in membrane curvature.
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Affiliation(s)
- Taylor B Updegrove
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Kumaran S Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, United States.
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22
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Abstract
A diverse set of protein polymers, structurally related to actin filaments contributes to the organization of bacterial cells as cytomotive or cytoskeletal filaments. This chapter describes actin homologs encoded by bacterial chromosomes. MamK filaments, unique to magnetotactic bacteria, help establishing magnetic biological compasses by interacting with magnetosomes. Magnetosomes are intracellular membrane invaginations containing biomineralized crystals of iron oxide that are positioned by MamK along the long-axis of the cell. FtsA is widespread across bacteria and it is one of the earliest components of the divisome to arrive at midcell, where it anchors the cell division machinery to the membrane. FtsA binds directly to FtsZ filaments and to the membrane through its C-terminus. FtsA shows altered domain architecture when compared to the canonical actin fold. FtsA's subdomain 1C replaces subdomain 1B of other members of the actin family and is located on the opposite side of the molecule. Nevertheless, when FtsA assembles into protofilaments, the protofilament structure is preserved, as subdomain 1C replaces subdomain IB of the following subunit in a canonical actin filament. MreB has an essential role in shape-maintenance of most rod-shaped bacteria. Unusually, MreB filaments assemble from two protofilaments in a flat and antiparallel arrangement. This non-polar architecture implies that both MreB filament ends are structurally identical. MreB filaments bind directly to membranes where they interact with both cytosolic and membrane proteins, thereby forming a key component of the elongasome. MreB filaments in cells are short and dynamic, moving around the long axis of rod-shaped cells, sensing curvature of the membrane and being implicated in peptidoglycan synthesis.
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Affiliation(s)
- Thierry Izoré
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Fusinita van den Ent
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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23
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Abstract
With the realization that bacteria achieve exquisite levels of spatiotemporal organization has come the challenge of discovering the underlying mechanisms. In this review, we describe three classes of such mechanisms, each of which has physical origins: the use of landmarks, the creation of higher-order structures that enable geometric sensing, and the emergence of length scales from systems of chemical reactions coupled to diffusion. We then examine the diversity of geometric cues that exist even in cells with relatively simple geometries, and end by discussing both new technologies that could drive further discovery and the implications of our current knowledge for the behavior, fitness, and evolution of bacteria. The organizational strategies described here are employed in a wide variety of systems and in species across all kingdoms of life; in many ways they provide a general blueprint for organizing the building blocks of life.
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Affiliation(s)
- Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544;
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24
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Lin TY, Weibel DB. Organization and function of anionic phospholipids in bacteria. Appl Microbiol Biotechnol 2016; 100:4255-67. [PMID: 27026177 DOI: 10.1007/s00253-016-7468-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/04/2016] [Accepted: 03/08/2016] [Indexed: 11/25/2022]
Abstract
In addition to playing a central role as a permeability barrier for controlling the diffusion of molecules and ions in and out of bacterial cells, phospholipid (PL) membranes regulate the spatial and temporal position and function of membrane proteins that play an essential role in a variety of cellular functions. Based on the very large number of membrane-associated proteins encoded in genomes, an understanding of the role of PLs may be central to understanding bacterial cell biology. This area of microbiology has received considerable attention over the past two decades, and the local enrichment of anionic PLs has emerged as a candidate mechanism for biomolecular organization in bacterial cells. In this review, we summarize the current understanding of anionic PLs in bacteria, including their biosynthesis, subcellular localization, and physiological relevance, discuss evidence and mechanisms for enriching anionic PLs in membranes, and conclude with an assessment of future directions for this area of bacterial biochemistry, biophysics, and cell biology.
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Affiliation(s)
- Ti-Yu Lin
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Douglas B Weibel
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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25
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Jahn N, Brantl S, Strahl H. Against the mainstream: the membrane-associated type I toxin BsrG from Bacillus subtilis interferes with cell envelope biosynthesis without increasing membrane permeability. Mol Microbiol 2015; 98:651-66. [PMID: 26234942 DOI: 10.1111/mmi.13146] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 01/09/2023]
Abstract
Toxin-antitoxin loci, which encode a toxic protein alongside with either RNA or a protein able to counteract the toxicity, are widespread among archaea and bacteria. These loci are implicated in persistence, and as addiction modules to ensure stable inheritance of plasmids and phages. In type I toxin-antitoxin systems, a small RNA acts as an antitoxin, which prevents the synthesis of the toxin. Most type I toxins are small hydrophobic membrane proteins generally assumed to induce pores, or otherwise permeabilise the cytoplasmic membrane and, as a result, induce cell death by energy starvation. Here we show that this mode of action is not a conserved property of type I toxins. The analysis of the cellular toxicity caused by Bacillus subtilis prophage SPβ-encoded toxin BsrG revealed that, surprisingly, it neither dissipates membrane potential nor affects cellular ATP-levels. In contrast, BsrG strongly interferes with the cell envelope biosynthesis, causes membrane invaginations together with delocalisation of the cell wall synthesis machinery and triggers autolysis. Furthermore, efficient inhibition of protein biosynthesis is observed. These findings question the simplistic assumption that small membrane targeting toxins generally act by permeabilising the membrane.
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Affiliation(s)
- Natalie Jahn
- Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät, AG Bakteriengenetik, Philosophenweg 12, Jena, D-07743, Germany
| | - Sabine Brantl
- Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät, AG Bakteriengenetik, Philosophenweg 12, Jena, D-07743, Germany
| | - Henrik Strahl
- Newcastle University, Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
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26
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Matsumoto K, Hara H, Fishov I, Mileykovskaya E, Norris V. The membrane: transertion as an organizing principle in membrane heterogeneity. Front Microbiol 2015; 6:572. [PMID: 26124753 PMCID: PMC4464175 DOI: 10.3389/fmicb.2015.00572] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/25/2015] [Indexed: 01/05/2023] Open
Abstract
The bacterial membrane exhibits a significantly heterogeneous distribution of lipids and proteins. This heterogeneity results mainly from lipid-lipid, protein-protein, and lipid-protein associations which are orchestrated by the coupled transcription, translation and insertion of nascent proteins into and through membrane (transertion). Transertion is central not only to the individual assembly and disassembly of large physically linked groups of macromolecules (alias hyperstructures) but also to the interactions between these hyperstructures. We review here these interactions in the context of the processes in Bacillus subtilis and Escherichia coli of nutrient sensing, membrane synthesis, cytoskeletal dynamics, DNA replication, chromosome segregation, and cell division.
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Affiliation(s)
- Kouji Matsumoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, SaitamaJapan
| | - Hiroshi Hara
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, SaitamaJapan
| | - Itzhak Fishov
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-ShevaIsrael
| | - Eugenia Mileykovskaya
- Department of Biochemistry and Molecular Biology, University of Texas Medical School at HoustonHouston, TX, USA
| | - Vic Norris
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Department of Science, University of Rouen, Mont-Saint-AignanFrance
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27
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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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28
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Hol FJH, Dekker C. Zooming in to see the bigger picture: microfluidic and nanofabrication tools to study bacteria. Science 2014; 346:1251821. [PMID: 25342809 DOI: 10.1126/science.1251821] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The spatial structure of natural habitats strongly affects bacterial life, ranging from nanoscale structural features that individual cells exploit for surface attachment, to micro- and millimeter-scale chemical gradients that drive population-level processes. Nanofabrication and microfluidics are ideally suited to manipulate the environment at those scales and have emerged as powerful tools with which to study bacteria. Here, we review the new scientific insights gained by using a diverse set of nanofabrication and microfluidic techniques to study individual bacteria and multispecies communities. This toolbox is beginning to elucidate disparate bacterial phenomena-including aging, electron transport, and quorum sensing-and enables the dissection of environmental communities through single-cell genomics. A more intimate integration of microfluidics, nanofabrication, and microbiology will enable further exploration of bacterial life at the smallest scales.
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Affiliation(s)
- Felix J H Hol
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands.
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29
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Harris LK, Dye NA, Theriot JA. A Caulobacter MreB mutant with irregular cell shape exhibits compensatory widening to maintain a preferred surface area to volume ratio. Mol Microbiol 2014; 94:10.1111/mmi.12811. [PMID: 25266768 PMCID: PMC4379118 DOI: 10.1111/mmi.12811] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2014] [Indexed: 11/30/2022]
Abstract
Rod-shaped bacteria typically elongate at a uniform width. To investigate the genetic and physiological determinants involved in this process, we studied a mutation in the morphogenetic protein MreB in Caulobacter crescentus that gives rise to cells with a variable-width phenotype, where cells have regions that are both thinner and wider than wild-type. During growth, individual cells develop a balance of wide and thin regions, and mutant MreB dynamically localizes to poles and thin regions. Surprisingly, the surface area to volume ratio of these irregularly shaped cells is, on average, very similar to wild-type. We propose that, while mutant MreB localizes to thin regions and promotes rod-like growth there, wide regions develop as a compensatory mechanism, allowing cells to maintain a wild-type-like surface area to volume ratio. To support this model, we have shown that cell widening is abrogated in growth conditions that promote higher surface area to volume ratios, and we have observed individual cells with high ratios return to wild-type levels over several hours by developing wide regions, suggesting that compensation can take place at the level of individual cells.
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Affiliation(s)
- Leigh K. Harris
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Biochemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Natalie A. Dye
- Department of Biochemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Julie A. Theriot
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Biochemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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Santos TMA, Lin TY, Rajendran M, Anderson SM, Weibel DB. Polar localization of Escherichia coli chemoreceptors requires an intact Tol-Pal complex. Mol Microbiol 2014; 92:985-1004. [PMID: 24720726 DOI: 10.1111/mmi.12609] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2014] [Indexed: 11/29/2022]
Abstract
Subcellular biomolecular localization is critical for the metabolic and structural properties of the cell. The functional implications of the spatiotemporal distribution of protein complexes during the bacterial cell cycle have long been acknowledged; however, the molecular mechanisms for generating and maintaining their dynamic localization in bacteria are not completely understood. Here we demonstrate that the trans-envelope Tol-Pal complex, a widely conserved component of the cell envelope of Gram-negative bacteria, is required to maintain the polar positioning of chemoreceptor clusters in Escherichia coli. Localization of the chemoreceptors was independent of phospholipid composition of the membrane and the curvature of the cell wall. Instead, our data indicate that chemoreceptors interact with components of the Tol-Pal complex and that this interaction is required to polarly localize chemoreceptor clusters. We found that disruption of the Tol-Pal complex perturbs the polar localization of chemoreceptors, alters cell motility, and affects chemotaxis. We propose that the E. coli Tol-Pal complex restricts mobility of the chemoreceptor clusters at the cell poles and may be involved in regulatory mechanisms that co-ordinate cell division and segregation of the chemosensory machinery.
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Affiliation(s)
- Thiago M A Santos
- Department of Biochemistry, University of Wisconsin-Madison, 440 Henry Mall, Madison, WI, 53706, USA
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