DOCSLIB.ORG

The Molecular Origins of Chiral Growth in Walled Cells

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Molecular Origins of Chiral Growth in Walled Cells COMICR-1050; NO. OF PAGES 8 Available online at www.sciencedirect.com The molecular origins of chiral growth in walled cells 1,2 3 4 Kerwyn Casey Huang , David W Ehrhardt and Joshua W Shaevitz Cells from all kingdoms of life adopt a dizzying array of In these walled cells, growth occurs through the spatially fascinating shapes that support cellular function. Amoeboid and regulated insertion of new material into the exoskeletal spherical shapes represent perhaps the simplest of geometries cell wall. Local insertion of material, performed by a host that may minimize the level of growth control required for of proteins, must be coordinated on the cellular scale so survival. Slightly more complex are rod-shaped cells, from that cell shape and the mechanical integrity of the wall are microscopic bacteria to macroscopic plants, which require maintained. While molecular experiments have led to the additional mechanisms to define a cell’s longitudinal axis, width, characterization of many of the players in this process, and length. Recent evidence suggests that many rod-shaped, understanding the regulation of shape requires walled cells achieve elongated growth through chiral insertion of approaches that can bridge the molecular and cellular cell-wall material that may be coupled to a twisting of the cell scales. Two key issues we address in this review are first, body. Inspired by these observations, biophysical mechanisms how individual molecules can organize into chiral fila- for twisting growth have been proposed that link the mechanics ments to generate a spatially coordinated pattern of of intracellular proteins to cell shape maintenance. In this review, growth, and second, the biophysical interactions required we highlight experimental and theoretical work that connects for robust, rod-shaped growth. molecular-scale organization and structure with the cellular- scale phenomena of rod-shaped growth. Cell-wall growth in bacteria Addresses Cell shape in nearly all bacteria is governed by the 1 Department of Bioengineering, Stanford University, Stanford, CA, USA peptidoglycan cell wall, a meshwork of glycan strands 2 Department of Microbiology and Immunology, Stanford University crosslinked by short peptides [2,3]. During growth and School of Medicine, Stanford, CA, USA 3 division, newly synthesized peptidoglycan subunits are Department of Plant Biology, Carnegie Institution, Stanford, CA, USA 4 incorporated into the wall through the concerted effort of Department of Physics, Princeton University, Princeton, NJ, USA a number of enzymes including the murein (Mur) and Corresponding authors: Huang, Kerwyn Casey ([email protected]), penicillin binding proteins (PBPs). These enzymes con- Shaevitz, Joshua W. ([email protected]) struct the cell wall through synthesis of new subunits, breakage of existing linkages in the wall, and insertion of new subunits to grow the peptidoglycan network. Current Opinion in Microbiology 2012, 15:xx–yy This review comes from a themed issue on Growth and development: While many of these enzymes have been characterized prokaryotes biochemically, several important biophysical questions Edited by Orna Amster-Choder and Taˆ m Mignot about their method of action remain unanswered. For example, severing individual linkages will promote the wall to expand under turgor, leading to a weakened state [4]. However, as new units are added, they can also have a 1369-5274/$ – see front matter, # 2012 Elsevier Ltd. All rights rigidifying effect on the wall if they are actively stressed reserved. before insertion in order to resist expansion [5]. It is not http://dx.doi.org/10.1016/j.mib.2012.11.002 currently known to what extent wall enzymes must coordinate their activities, in either space or time, in order for growth with a maintained shape to proceed. Introduction Biochemical measurements of in vitro peptidoglycan Cell shape is dictated physically by the balance of forces polymerization suggest that at least some of the enzymes on the cell envelope. Turgor pressure due to the high may be processive [6–9]; however, how this processivity concentration of osmotic solutes inside cells generates an manifests in vivo [10] and whether it is coupled between outward pressure on the envelope. To maintain a non- enzymes remain under current investigation. spherical shape, cells must surround themselves with an anisotropic elastic structure that expands to counterba- Rod-shaped growth lance this pressure. In animal cells, this is largely achieved Perhaps the simplest systems for studying complex cell through the construction of intracellular cortical networks growth are elongated rods, which must encode, at the of actin filaments, although other elastic filaments such as molecular level, a three-dimensional coordinate system spectrin can also be used. On the other hand, bacteria use that defines the longitudinal cell axis and division plane in a rigid, extracellular cell wall composed of a network of addition to the cell length and width. Rod-shaped cells peptidoglycan while plants use a wall composed of cellu- are common in both bacteria and plants. Prokaryotic rods lose and other polysaccharides [1]. are thought to possess several biophysical advantages over www.sciencedirect.com Current Opinion in Microbiology 2012, 15:1–8 Please cite this article in press as: Huang KC, et al.: The molecular origins of chiral growth in walled cells, Curr Opin Microbiol (2012), http://dx.doi.org/10.1016/j.mib.2012.11.002 COMICR-1050; NO. OF PAGES 8 2 Growth and development: prokaryotes Figure 1 non-elongated cells for functions such as motility and in certain environmental niches [11–13]. In plants, rod- shaped cell growth is coupled directly to the elongation (a) (b) of roots, stems, and other tissues. Because of their small size and the fast speed of diffusion α γ within the cytoplasm, it is difficult for a bacterial cell to establish precise cytoplasmic gradients with which to β define a cellular coordinate system [14,15]. Instead, it has been proposed that geometric cues such as curvature may provide information about orientation within the cell that can be processed through local binding interactions between inherently curved polymers and a curved surface (c)(d) (e) [16–18]. The determination and maintenance of cell shape are governed by the cellular-scale pattern of wall insertion and the balance of forces on the cell wall [19,20]. To query whether local geometric cues can guide cellular-scale patterning that robustly generates the correct cell shape requires experimental and computational tools to quantify and connect molecular organization to wall patterning. While some rod-shaped bacteria insert material at the poles or mid-cell, most model bacteria with a rod shape Current Opinion in Microbiology appear to insert material in a roughly uniform distribution along the cylindrical portion of the cell wall. However, (a) Three angles, often referred to as Euler angles, are needed to computational simulations studying the consequences of describe an arbitrary rotation between adjacent monomers in a polymer. random insertion predict a loss of both cell shape and (b) Different combinations of the Euler angles a, b, and g yield different filament geometries including straight rods, helices, and rings. (c) X-ray mechanical integrity [5], suggesting that the orchestration crystallography has revealed that MreB monomers polymerize into linear of growth is required for rod-shape maintenance. In protofilaments (adapted from [61]). (d) MreB binds directly to lipid elongating bacteria, recent evidence suggests that fila- membranes in a double-protofilament geometry (adapted from [33]). (e) ments with chiral (left- or right-handed) positioning along In live cells, MreB labeled with YFP at the N-terminus forms polymeric the membrane are used to coordinate insertion, producing structures with a left-handed chirality. both a rod-like shape and a robustly cross-linked cell wall that twists as it grows [21]. particularly interesting property of these filaments in a Protein filaments are inherently chiral biological context is that resultant shapes can have features Biopolymer filaments such as actin, microtubules, and on length scales much larger than the size of an individual bacterial flagellar filaments are linear assemblies of indi- monomer. Examples of these include the radius of vidual monomeric units. The molecular binding inter- curvature for a ring and the pitch of a helix, both of actions between protein monomers define the spatial which can be arbitrarily large compared to the scale of relationship between adjacent monomers in a filament. the proteins themselves. These features are independent In general, three angles that encapsulate the relative of the chemical kinetics that affect the length of filaments orientation of neighboring monomers along the filament through assembly and disassembly. Thus, polymeriz- define this relationship (Figure 1a). Different combi- ation of filaments can generate cellular-scale ‘order’ nations of angles between monomer subunits lead to a independent of the monomer size or chemical kinetics. variety of beautiful and complex filament shapes Outstanding questions surrounding this topic are the (Figure 1b) whose geometry has been the subject of extent to which this order is established for filaments study as far back as Euler. A common feature of all of in living cells, and the mechanisms through which this these shapes is their helicity, due to the fact that a order can be maintained and utilized for cellular-scale constant bend and twist per monomer leads to chiral phenomena such as growth. backbones [22–24]. Indeed, as early as 1950, the helical nature of biological chains was recognized, with a pres- In bacteria, a number of cytoskeletal polymers have been cient focus on biological growth [24]. described as helical. Filament bundles of the tubulin homolog FtsZ form tightly wound circumferential rings Of the observed classes of filaments, simplified shapes at the division plane in nearly all prokaryotes, and have such as straight lines and rings are extreme limits in which been observed to form helical structures away from the some of the relative orientation angles are zero.
Load more

Recommended publications
  • The Bacterial Actin Mreb Rotates, and Rotation Depends on Cell-Wall Assembly
    The bacterial actin MreB rotates, and rotation depends on cell-wall assembly Sven van Teeffelena,1, Siyuan Wanga,b, Leon Furchtgottc,d, Kerwyn Casey Huangd, Ned S. Wingreena,b, Joshua W. Shaevitzb,e,1, and Zemer Gitaia,1 aDepartment of Molecular Biology, Princeton University, Princeton, NJ 08544; bLewis–Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544; cBiophysics Program, Harvard University, Cambridge, MA 02138; dDepartment of Bioengineering, Stanford University, Stanford, CA 94305; and eDepartment of Physics, Princeton University, Princeton, NJ 08854 Edited by Lucy Shapiro, Stanford University School of Medicine, Palo Alto, CA, and approved July 27, 2011 (received for review June 3, 2011) Bacterial cells possess multiple cytoskeletal proteins involved in a tently in a nearly circumferential direction. Interestingly, this wide range of cellular processes. These cytoskeletal proteins are MreB rotation is not driven by its own polymerization, but rather dynamic, but the driving forces and cellular functions of these requires cell-wall synthesis. These findings indicate that a motor dynamics remain poorly understood. Eukaryotic cytoskeletal dy- whose activity depends on cell-wall assembly rotates MreB. namics are often driven by motor proteins, but in bacteria no mo- Furthermore, the coupling of MreB rotation to cell-wall synthesis tors that drive cytoskeletal motion have been identified to date. suggests that MreB may not merely act upstream of cell-wall Here, we quantitatively study the dynamics of the Escherichia coli assembly. Indeed, computational simulations suggest that cou- actin homolog MreB, which is essential for the maintenance of pling MreB rotation to cell-wall synthesis can help cells maintain rod-like cell shape in bacteria.
    [Show full text]
  • Bacterial Actin Mreb Forms Antiparallel Double Filaments Fusinita Van Den Ent1*†, Thierry Izoré1†, Tanmay AM Bharat1, Christopher M Johnson2, Jan Löwe1
    RESEARCH ARTICLE elifesciences.org Bacterial actin MreB forms antiparallel double filaments Fusinita van den Ent1*†, Thierry Izoré1†, Tanmay AM Bharat1, Christopher M Johnson2, Jan Löwe1 1Structural Studies Division, Medical Research Council - Laboratory of Molecular Biology, Cambridge, United Kingdom; 2Protein and Nucleic Acid Chemistry Division, Medical Research Council - Laboratory of Molecular Biology, Cambridge, United Kingdom Abstract Filaments of all actin-like proteins known to date are assembled from pairs of protofilaments that are arranged in a parallel fashion, generating polarity. In this study, we show that the prokaryotic actin homologue MreB forms pairs of protofilaments that adopt an antiparallel arrangement in vitro and in vivo. We provide an atomic view of antiparallel protofilaments of Caulobacter MreB as apparent from crystal structures. We show that a protofilament doublet is essential for MreB's function in cell shape maintenance and demonstrate by in vivo site-specific cross-linking the antiparallel orientation of MreB protofilaments in E. coli. 3D cryo-EM shows that pairs of protofilaments ofCaulobacter MreB tightly bind to membranes. Crystal structures of different nucleotide and polymerisation states of Caulobacter MreB reveal conserved conformational changes accompanying antiparallel filament formation. Finally, the antimicrobial agents A22/MP265 are shown to bind close to the bound nucleotide of MreB, presumably preventing nucleotide hydrolysis and destabilising double protofilaments. DOI: 10.7554/eLife.02634.001 *For correspondence: fent@mrc- lmb.cam.ac.uk Introduction †These authors contributed Cell shape is a characteristic and hereditary feature that is crucial for existence and its regulation is a equally to this work common challenge for organisms across all biological kingdoms.
    [Show full text]
  • Investigating the Actin Regulatory Activities of Las17, the Wasp Homologue in S. Cerevisiae Liemya E. Abugharsa
    Investigating the actin regulatory activities of Las17, the WASp homologue in S. cerevisiae A thesis submitted for the degree of Doctor of Philosophy By Liemya E. Abugharsa Department of Molecular Biology and Biotechnology University of Sheffield March 2015 Abstract Investigating the actin regulatory activities of Las17, the WASp homologue in S. cerevisiae Clathrin mediated endocytosis (CME) in S. cerevisiae requires the dynamic interplay between many proteins at the plasma membrane. Actin polymerisation provides force to drive membrane invagination and vesicle scission. The WASp homologue in yeast, Las17 plays a major role in stimulating actin filament assembly during endocytosis. The actin nucleation ability of WASP family members is attributed to their WCA domain [WH2 (WASP homology2) domain, C central, and A (acidic) domains] which provides binding sites for both actin monomers and the Arp2/3 complex. In addition, the central poly-proline repeat region of Las17 is able to bind and nucleate actin filaments independently of the Arp2/3 complex. While Las17 is a key regulator of endocytic progression and has been found to be phosphorylated in global studies, the mechanism behind regulation of Las17 actin-based function is unclear. Therefore, the aims of this study were to investigate the post-translation modification of Las17 by phosphorylation, and to determine how this modification impacts on Las17 function both in vivo and in vitro. Mass Spec analysis was employed and allowed identification of further phosphorylation sites in Las17. Through the studies described here I was able to demonstrate that Las17 is phosphorylated, and that one specific phosphorylation event was of importance in endocytosis.
    [Show full text]
  • Interrogating the Escherichia Coli Cell Cycle by Cell Dimension Perturbations
    Interrogating the Escherichia coli cell cycle by cell dimension perturbations Hai Zhenga,b, Po-Yi Hoc, Meiling Jianga, Bin Tangd, Weirong Liua,b, Dengjin Lia, Xuefeng Yue, Nancy E. Klecknerf, Ariel Amirc,1, and Chenli Liua,b,1 aCenter for Synthetic Biology Engineering Research, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People’s Republic of China; bUniversity of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China; cSchool of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; dDepartment of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People’s Republic of China; eInstitute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People’s Republic of China; and fDepartment of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 Edited by Kiyoshi Mizuuchi, National Institutes of Health, Bethesda, MD, and approved November 14, 2016 (received for review September 30, 2016) Bacteria tightly regulate and coordinate the various events in by a phenomenological size variable, with no explicit reference to their cell cycles to duplicate themselves accurately and to control DNA replication. their cell sizes. Growth of Escherichia coli, in particular, follows a A second class of models for control of cell division postulates relation known as Schaechter’s growth law. This law says that the that cell division is governed by the process of DNA replica- average cell volume scales exponentially with growth rate, with tion, which can be described as follows. The time from a repli- a scaling exponent equal to the time from initiation of a round cation initiation event to the cell division that segregates the of DNA replication to the cell division at which the corresponding corresponding sister chromosomes can be split into the C period, sister chromosomes segregate.
    [Show full text]
  • Actin Homolog Mreb and RNA Polymerase Interact and Are Both Required for Chromosome Segregation in Escherichia Coli
    Downloaded from genesdev.cshlp.org on September 27, 2021 - Published by Cold Spring Harbor Laboratory Press Actin homolog MreB and RNA polymerase interact and are both required for chromosome segregation in Escherichia coli Thomas Kruse,1 Blagoy Blagoev,1 Anders Løbner-Olesen,2 Masaaki Wachi,3 Kumi Sasaki,3 Noritaka Iwai,3 Matthias Mann,1,4 and Kenn Gerdes1,5 1Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, DK-5230 Odense M, Denmark; 2Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark; 3Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan; 4Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany The actin-like MreB cytoskeletal protein and RNA polymerase (RNAP) have both been suggested to provide the force for chromosome segregation. Here, we identify MreB and RNAP as in vivo interaction partners. The interaction was confirmed using in vitro purified components. We also present convincing evidence that MreB and RNAP are both required for chromosome segregation in Escherichia coli. MreB is required for origin and bulk DNA segregation, whereas RNAP is required for bulk DNA, terminus, and possibly also for origin segregation. Furthermore, flow cytometric analyses show that MreB depletion and inactivation of RNAP confer virtually identical and highly unusual chromosome segregation defects. Thus, our results raise the possibility that the MreB–RNAP interaction is functionally important for chromosome segregation. [Keywords: MreB; actin; RNA polymerase (RNAP); chromosome segregation; oriC; terC] Supplemental material is available at http://www.genesdev.org. Received September 20, 2005; revised version accepted November 2, 2005. In eukaryotic cells, the mitotic spindle apparatus segre- chromosome segregation.
    [Show full text]
  • Effect of A22 on the Conformation of Bacterial Actin Mreb
    International Journal of Molecular Sciences Article Effect of A22 on the Conformation of Bacterial Actin MreB Elvis Awuni 1 and Yuguang Mu 2,* 1 Department of Biochemistry, School of Biological Sciences, CANS, University of Cape Coast, Cape Coast 00233, Ghana; [email protected] 2 School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore * Correspondence: [email protected]; Tel.: +65-63162885 Received: 23 January 2019; Accepted: 25 February 2019; Published: 15 March 2019 Abstract: The mechanism of the antibiotic molecule A22 is yet to be clearly understood. In a previous study, we carried out molecular dynamics simulations of a monomer of the bacterial actin-like MreB in complex with different nucleotides and A22, and suggested that A22 impedes the release of Pi from the active site of MreB after the hydrolysis of ATP, resulting in filament instability. On the basis of the suggestion that Pi release occurs on a similar timescale to polymerization and that polymerization can occur in the absence of nucleotides, we sought in this study to investigate a hypothesis that A22 impedes the conformational change in MreB that is required for polymerization through molecular dynamics simulations of the MreB protofilament in the apo, ATP+, and ATP-A22+ states. We suggest that A22 inhibits MreB in part by antagonizing the ATP-induced structural changes required for polymerization. Our data give further insight into the polymerization/depolymerization dynamics of MreB and the mechanism of A22. Keywords: molecular dynamics; simulations; actin-like MreB; conformational change; polymerization; depolymerization 1. Introduction The bacterial actin-like MreB forms the cytoskeleton network, and is involved in several life processes of rod-shaped bacteria [1–10].
    [Show full text]
  • Dynamic Gradients of an Intermediate Filament-Like Cytoskeleton Are
    Dynamic gradients of an intermediate filament-like PNAS PLUS cytoskeleton are recruited by a polarity landmark during apical growth Katsuya Fuchinoa, Sonchita Bagchib,1, Stuart Cantlaya,1, Linda Sandbladc,DiWud, Jessica Bergmanb, Masood Kamali-Moghaddamd, Klas Flärdha, and Nora Ausmeesa,2 aDepartment of Biology, Lund University, 22362 Lund, Sweden; bDepartment of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden; cDepartment of Molecular Biology, Umeå University, 901 87 Umeå, Sweden; and dDepartment of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden Edited by Richard Losick, Harvard University, Cambridge, MA, and approved April 8, 2013 (received for review March 21, 2013) Intermediate filament (IF)-like cytoskeleton emerges as a versatile in several species of the Gram-positive phylum Actinobacteria tool for cellular organization in all kingdoms of life, underscoring the (see below and ref. 8). importance of mechanistically understanding its diverse manifesta- Although most of the distantly related bacterial IF-like proteins tions. We showed previously that, in Streptomyces (a bacterium do not share obvious conserved sequence motifs with each other or with a mycelial lifestyle similar to that of filamentous fungi, includ- with eukaryotic IF proteins, we refer to them as “IF-like,” based on ing extreme cell and growth polarity), the IF protein FilP confers their structural, biochemical, and functional analogy to eukaryotic rigidity to the hyphae by an unknown mechanism. Here, we provide IF proteins. In addition to their similar coiled-coil domain archi- a possible explanation for the IF-like function of FilP by demonstrat- tecture, most of the above mentioned bacterial proteins also share ing its ability to self-assemble into a cis-interconnected regular net- a fundamental biochemical property with the eukaryotic IF pro- work in vitro and its localization into structures consistent with teins, which is to spontaneously self-assemble into ordered fila- a cytoskeletal network in vivo.
    [Show full text]
  • Functional Analysis of Actin-Like Protein Mreb and Alternative Sigma Factor Rpon in Chlamydial Developmental Cycle by Namita
    Functional analysis of actin-like protein MreB and alternative sigma factor RpoN in chlamydial developmental cycle By Namita Balwalli Submitted to the graduate degree program in Molecular Biosciences and Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Master of Arts __________________________ Chairperson (Scott Hefty, Ph.D.) __________________________* (Susan Egan, Ph.D.) __________________________* (David Davido, Ph.D.) *Committee members Date Defended 03/29/13 i The Thesis Committee for Namita Balwalli certifies that this is the approved version of the following thesis: Functional analysis of actin-like protein MreB and alternative sigma factor RpoN in chlamydial developmental cycle Committee: __________________________________ Chairperson (P. Scott Hefty, Ph.D.) Date approved: 04/22/13 ii Abstract Chlamydia trachomatis is an obligate intracellular pathogen of immense public health impact and is responsible for diverse disease states leading to blindness, sterility, atherosclerosis etc. in humans. Its unique biphasic developmental cycle is essentially linked to its pathogenesis. MreB, an actin-like protein, is known to be present in most rod-shaped organisms as a part of the cell elongation machinery. The role of MreB in Chlamydia is unknown, even though this gene is conserved. Recent studies have attributed diverse roles to MreB in different organisms. Our study focusses on the possible role of MreB in Chlamydia trachomatis using different approaches and techniques. To understand the functional role of MreB, we sought two strategies, in vitro and in vivo analysis. Purified recombinant chlamydial MreB was subjected to a polymerization reactions using ATP and Mg2+ ions in the presence and absence of a known inhibitor of MreB polymerization i.e.
    [Show full text]
  • Mreb, the Cell Shape-Determining Bacterial Actin Homologue, Co-Ordinates Cell Wall Morphogenesis in Caulobacter Crescentus
    Blackwell Science, LtdOxford, UKMMIMolecular Microbiology0950-382XBlackwell Publishing Ltd, 2004? 200451513211332Original ArticleMreB-dependent regulation of cell shapeR. M. Figge, A. V. Divakaruni and J. W. Gober Molecular Microbiology (2004) 51(5), 1321–1332 doi:10.1046/j.1365-2958.2003.03936.x MreB, the cell shape-determining bacterial actin homologue, co-ordinates cell wall morphogenesis in Caulobacter crescentus Rainer M. Figge, Arun V. Divakaruni and distinct shape on the intact cell (Holtje, 1998). For rod- James W. Gober* shaped bacteria, morphogenesis occurs in two distinct Department of Chemistry and Biochemistry and the phases, cell elongation followed by septation (cell divi- Molecular Biology Institute, University of California, Los sion) (Wientjes and Nanninga, 1989; Nanninga, 1991; Angeles, CA 90095-1569, USA. de Pedro et al., 1997). During the elongation phase, the cells grow along the longitudinal axis with little increase in width. Once a critical cell length is Summary attained, cell wall synthesis switches direction at the The bacterial actin homologue, MreB, is required for mid-cell, turning inward, thus forming a cell division the maintenance of a rod-shaped cell and has been septum. The regulation of these two phases in cell shown to form spirals that traverse along the longitu- wall morphogenesis is co-ordinated with other cell dinal axis of Bacillus subtilis and Escherichia coli cycle-related events such as DNA replication and chro- cells. The depletion of MreB in Caulobacter crescen- mosome partitioning. tus resulted in lemon-shaped cells that possessed The structure and composition of peptidoglycan has defects in the integrity of the cell wall. MreB localiza- been determined in detail, and many enzymes involved tion appeared as bands or spirals that encircled the in its synthesis have been characterized (Holtje, 1998).
    [Show full text]
  • Biochimica Et Biophysica Acta 1833 (2013) 2334–2347
    Biochimica et Biophysica Acta 1833 (2013) 2334–2347 Contents lists available at SciVerse ScienceDirect Biochimica et Biophysica Acta journal homepage: www.elsevier.com/locate/bbamcr Stimulation of in vivo nuclear transport dynamics of actin and its co-factors IQGAP1 and Rac1 in response to DNA replication stress Michael A. Johnson 1, Manisha Sharma, Myth T.S. Mok 2, Beric R. Henderson ⁎ Westmead Institute for Cancer Research, The University of Sydney, Westmead Millennium Institute at Westmead Hospital, Westmead, NSW 2145, Australia article info abstract Article history: Actin, a constituent of the cytoskeleton, is now recognized to function in the nucleus in gene transcription, Received 21 November 2012 chromatin remodeling and DNA replication/repair. Actin shuttles in and out of the nucleus through the action of Received in revised form 31 May 2013 transport receptors importin-9 and exportin-6. Here we have addressed the impact of cell cycle progression and Accepted 4 June 2013 DNA replication stress on actin nuclear localization, through study of actin dynamics in living cells. First, we Available online 13 June 2013 showed that thymidine-induced G1/S phase cell cycle arrest increased the nuclear levels of actin and of two factors that stimulate actin polymerization: IQGAP1 and Rac1 GTPase. When cells were exposed to hydroxyurea to induce Keywords: Nuclear actin DNA replication stress, the nuclear localization of actin and its regulators was further enhanced. We employed live IQGAP1 cell photobleaching assays and discovered that in response to DNA replication stress, GFP-actin nuclear import and Rac1 export rates increased by up to 250%. The rate of import was twice as fast as export, accounting for actin nuclear Nuclear transport accumulation.
    [Show full text]
  • Ftsz Exhibits Rapid Movement and Oscillation Waves in Helix-Like Patterns in Escherichia Coli
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Current Biology, Vol. 14, 1167–1173, July 13, 2004, 2004 Elsevier Ltd. All rights reserved. DOI 10.1016/j.cub.2004.06.048 FtsZ Exhibits Rapid Movement and Oscillation Waves in Helix-like Patterns in Escherichia coli Swapna Thanedar and William Margolin* viously observed for FtsZ outside of Z rings under spe- Department of Microbiology and Molecular cialized conditions, such as FtsZ overproduction in E. coli Genetics [5] or sporulation in B. subtilis [13]. University of Texas Medical School 6431 Fannin Street Houston, Texas 77030 FtsZ Moves Rapidly within a Helix-like Structure Apart from the Z Ring To monitor the localization and movement of FtsZ, we used a green fluorescent protein (GFP) fusion to FtsZ, Summary FtsZ-GFP, which is generally not capable of fully replac- ing native FtsZ for function. Nevertheless, FtsZ-GFP can Prokaryotes contain cytoskeletal proteins such as the localize like FtsZ and, when expressed at levels equiva- tubulin-like FtsZ, which forms the Z ring at the cell lent to or lower than those of native FtsZ, it acts as an center for cytokinesis [1], and the actin-like MreB, accurate tracer for FtsZ localization and dynamics [5, which forms a helix along the long axis of the cell and 12–14]. E. coli EC448 expresses a single copy of FtsZ- is required for shape maintenance [2]. Using time- GFP under IPTG control as well as wild-type FtsZ under lapse analysis of Escherichia coli cells expressing control of its native promoter.
    [Show full text]
  • The Role of Cytoskeletal Elements in Shaping Bacterial Cells Hongbaek Cho*
    J. Microbiol. Biotechnol. (2015), 25(3), 307–316 http://dx.doi.org/10.4014/jmb.1409.09047 Research Article Review jmb The Role of Cytoskeletal Elements in Shaping Bacterial Cells Hongbaek Cho* Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA Received: September 16, 2014 Revised: September 26, 2014 Beginning from the recognition of FtsZ as a bacterial tubulin homolog in the early 1990s, many Accepted: September 26, 2014 bacterial cytoskeletal elements have been identified, including homologs to the major eukaryotic cytoskeletal elements (tubulin, actin, and intermediate filament) and the elements unique in prokaryotes (ParA/MinD family and bactofilins). The discovery and functional First published online characterization of the bacterial cytoskeleton have revolutionized our understanding of September 29, 2014 bacterial cells, revealing their elaborate and dynamic subcellular organization. As in *Corresponding author eukaryotic systems, the bacterial cytoskeleton participates in cell division, cell morphogenesis, Phone: +1-617-432-6970; DNA segregation, and other important cellular processes. However, in accordance with the Fax: +1-617-432-6970; vast difference between bacterial and eukaryotic cells, many bacterial cytoskeletal proteins E-mail: hongbaek_cho@hms. harvard.edu play distinct roles from their eukaryotic counterparts; for example, control of cell wall synthesis for cell division and morphogenesis. This review is aimed at providing an overview of the bacterial cytoskeleton, and discussing the roles and assembly dynamics of bacterial cytoskeletal proteins in more detail in relation to their most widely conserved functions, DNA pISSN 1017-7825, eISSN 1738-8872 segregation and coordination of cell wall synthesis. Copyright© 2015 by The Korean Society for Microbiology Keywords: Bacterial cytoskeleton, DNA segregation, FtsZ, MreB, ParA, peptidoglycan and Biotechnology Introduction cytokinesis, and cell morphogenesis.
    [Show full text]