DOCSLIB.ORG

Ftsz Filaments Have the Opposite Kinetic Polarity of Microtubules

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ftsz Filaments Have the Opposite Kinetic Polarity of Microtubules FtsZ filaments have the opposite kinetic polarity of microtubules Shishen Dua, Sebastien Pichoffa, Karsten Kruseb,c,d, and Joe Lutkenhausa,1 aDepartment of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160; bDepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland; cDepartment of Theoretical Physics, University of Geneva, 1211 Geneva, Switzerland; and dThe National Center of Competence in Research Chemical Biology, University of Geneva, 1211 Geneva, Switzerland Contributed by Joe Lutkenhaus, August 29, 2018 (sent for review July 11, 2018; reviewed by Jan Löwe and Jie Xiao) FtsZ is the ancestral homolog of tubulin and assembles into the Z Since FtsZ filaments treadmill, longitudinal interface mutants ring that organizes the division machinery to drive cell division of FtsZ should have different effects on assembly. Interface in most bacteria. In contrast to tubulin that assembles into 13 mutants that can add to the growing end but prevent further stranded microtubules that undergo dynamic instability, FtsZ growth should be toxic to assembly and thus cell division at assembles into single-stranded filaments that treadmill to distrib- substoichiometric levels, whereas interface mutants that cannot ute the peptidoglycan synthetic machinery at the septum. Here, add onto filaments should be much less toxic. Redick et al. (22) using longitudinal interface mutants of FtsZ, we demonstrate observed that some amino acid substitutions at the bottom end that the kinetic polarity of FtsZ filaments is opposite to that of of FtsZ were toxic, whereas substitutions at the top end were not. microtubules. A conformational switch accompanying the assem- – bly of FtsZ generates the kinetic polarity of FtsZ filaments, which Furthermore, expression of just the N-terminal domain (1 193, explains the toxicity of interface mutants that function as a capper top end), but not the C-terminal domain of FtsZ, showed some and reveals the mechanism of cooperative assembly. This ap- toxicity (23). Also, the N-terminal domain of FtsZ has been proach can also be employed to determine the kinetic polarity of shown to antagonize FtsZ polymerization in vitro (24). These other filament-forming proteins. observations suggest that FtsZ filaments have the opposite ki- netic polarity of microtubules; however, previous measurements FtsZ | capper | Z ring | treadmilling | tubulin showed that neither the bottom-face mutants nor the N-terminal domain of FtsZ was toxic at substoichiometric levels but needed rokaryotic cytoskeletons play essential roles in many funda- to be overexpressed three-to fivefold (22, 23), arguing against Pmental aspects of prokaryotic cell biology, including cytokinesis, this suggestion. Since the mutations examined in the prior study cell-shape maintenance, chromosome segregation, and other as- were made before the structure of an FtsZ filament was known, pects of cellular organization (1). FtsZ, a prokaryotic tubulin ho- and many of the mutants still assembled in vivo, we decided to molog, polymerizes into filaments that coalesce into the Z ring at reinvestigate the effect of interface mutants using known muta- – midcell (2 4). The ring functions as a scaffold for recruitment of the tions. Our findings demonstrate that the kinetic polarity of FtsZ machinery necessary to synthesize septal peptidoglycan (5, 6). Since filaments is the opposite of tubulin assembly into microtubules. formation of the Z ring is the first step in bacterial cytokinesis, Furthermore, we propose how the conformational switch cou- antagonism of FtsZ polymerization is a prominent mechanism for pled to assembly promotes polymerization. regulating cell division in bacteria (7–11). Like tubulin, FtsZ undergoes GTP-dependent, cooperative assembly with a critical concentration of about 1 μM (12, 13). Significance However, FtsZ differs from tubulin in several ways. Tubulin is present as an αβ-heterodimer that assembles into microtubules FtsZ is the founding member of the prokaryotic tubulin family. containing 13 protofilaments (14), whereas FtsZ is a monomer It assembles into single-stranded filaments that coalesce to that polymerizes into single-stranded filaments in vitro of about form the Z ring that drives bacterial cell division in most bac- 120–200 nm in length (30–50 subunits) under conditions that teria. FtsZ filaments undergo cooperative assembly and display best mimic in vivo conditions (5, 15). In vivo, FtsZ assembles into treadmilling behavior. Here we investigate the kinetic polarity small clusters of filaments of unknown structure that together of FtsZ filaments by studying the toxicity of longitudinal in- compose the Z ring (16, 17). Furthermore, microtubules undergo terface mutants of FtsZ and find that bottom-face mutants are dynamic instability (18), whereas FtsZ filaments treadmill (16, extremely toxic. This toxicity combined with a conformational 19). FtsZ filaments form the scaffold for the divisome, and the switch induced during assembly reveals the kinetic polarity of treadmilling distributes this peptidoglycan synthetic machinery FtsZ filaments, the basis for cooperative assembly, and explains around the septum (16, 20). FtsZ exists in two conformations: an the basis for other inhibitors of FtsZ assembly. It is likely that all open conformation observed in filaments and a closed conforma- members of the FtsZ/tubulin superfamily employ an assembly- tion in the monomer (21). The basis of treadmilling is an assembly- induced conformational switch to generate kinetic polarity, which could be revealed by the same approach used here. associated conformational switch that promotes polymerization along with the assembly-associated GTP hydrolysis that weakens Author contributions: S.D. and J.L. designed research; S.D., S.P., and K.K. performed re- intersubunit interactions (21). However, the kinetic polarity of these search; S.P. contributed new reagents/analytic tools; S.D., K.K., and J.L. analyzed data; and FtsZ filaments, or how it is achieved, is not known (5). S.D. and J.L. wrote the paper. Dynamic filaments have structural and kinetic polarity. The Reviewers: J.L., Medical Research Council Laboratory of Molecular Biology; and J.X., Johns growing end is referred to as the “plus” end and the other end is Hopkins University School of Medicine. referred to as the “minus” end. When tubulin assembles into The authors declare no conflict of interest. microtubules, the bound GTP (top end) is exposed at the plus Published under the PNAS license. end, and incoming subunits interact with this end through their 1To whom correspondence should be addressed. Email: [email protected]. T7 loop (bottom end) (14). Like tubulin, FtsZ assembles in a This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. head-to-tail manner, however, there are several indications that 1073/pnas.1811919115/-/DCSupplemental. the polarity of FtsZ assembly is opposite to that of microtubules. Published online October 1, 2018. 10768–10773 | PNAS | October 16, 2018 | vol. 115 | no. 42 www.pnas.org/cgi/doi/10.1073/pnas.1811919115 Downloaded by guest on September 25, 2021 Results Although arabinose-inducible vectors offer some advantages Strategy for Determining Polarity of FtsZ Filaments. The expected (tighter off regulation), they have some disadvantages (variable effect of top and bottom interface mutants on treadmilling of cell-to-cell induction) (28). To better assess the toxicity of ftsZL272E FtsZ is outlined in Fig. 1A. In the first scenario, FtsZ polymer- , we attempted to clone it into an IPTG-inducible vec- izes in the same direction as tubulin (top-end growth), and a top tor; however, we were unsuccessful. Since this was likely due interface mutant would add to the growing or plus end blocking the to toxicity from leaky expression, we modified the ribosome ftsZ growth of the filament, resulting in disassembly. Such a mutant binding site for on the plasmid to reduce expression (from CGGAGA to CGCAGA). Following this change, we were able would be expected to be dominant-negative and inhibit cell division, ftsZ whereas a bottom interface mutant would not affect polymerization to clone all alleles into the IPTG-inducible vector. Induction ftsZL272E ftsZ360 ftsZL272E and thus would be nontoxic. In the second scenario, FtsZ poly- of and from this plasmid was toxic with A ftsZL272E merizes in the opposite direction of tubulin (bottom-end growth), being much more toxic (Fig. 2 ). Induction of in a WT and the effects of the top- and bottom-face mutants on polymeri- strain caused filamentation and blocked colony formation at μ A B ftsZ zation and cell division would be reversed. Li et al. (25) described 30 M IPTG (Fig. 2 and ). Since induction of with 1 mM interface mutants that are unable to assemble including top IPTG from this plasmid does not provide enough FtsZ to fully ftsZ SI Appendix [FtsZL178E(top)] and bottom-face mutants [FtsZL272E(bottom)]. These complement a -depletion strain ( ,Fig.S3), we con- clude that FtsZL272E is inhibitory at substoichiometric levels. If mutants do not assemble because charged residues would be forced L272E into hydrophobic pockets formed between subunits in the filament the toxicity of FtsZ is due to incorporation into filaments, (Fig. 1B). then addition of the L178E substitution to disrupt the other longitudinal interface should prevent incorporation into the The Bottom Interface Mutant Is Toxic at Substoichiometric Levels. polymer and alleviate the
Load more

Recommended publications
  • The Cytoskeleton in Cell-Autonomous Immunity: Structural Determinants of Host Defence
    Mostowy & Shenoy, Nat Rev Immunol, doi:10.1038/nri3877 The cytoskeleton in cell-autonomous immunity: structural determinants of host defence Serge Mostowy and Avinash R. Shenoy Medical Research Council Centre of Molecular Bacteriology and Infection (CMBI), Imperial College London, Armstrong Road, London SW7 2AZ, UK. e‑mails: [email protected] ; [email protected] doi:10.1038/nri3877 Published online 21 August 2015 Abstract Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton — actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement — have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence. 1 Mostowy & Shenoy, Nat Rev Immunol, doi:10.1038/nri3877 Cell-autonomous immunity, which is defined as the ability of a host cell to eliminate an invasive infectious agent, is a first line of defence against microbial pathogens 1 . It relies on antimicrobial proteins, specialized degradative compartments and programmed host cell death 1–3 . Cell- autonomous immunity is mediated by tiered innate immune signalling networks that sense microbial pathogens and stimulate downstream pathogen elimination programmes. Recent studies on host– microorganism interactions show that components of the host cell cytoskeleton are integral to the detection of bacterial pathogens as well as to the mobilization of antibacterial responses (FIG.
    [Show full text]
  • Essential for Protein Regulation
    CYTOSKELETON NEWS NEWS FROM CYTOSKELETON INC. Rac GTP Rho GTPases Control Cell Migration P-Rex1 Related Publications Fli2 Rac Research Tools January GDP 2020 Tiam1 Rac GTP v Rho GTPases Control Cell Migration Meetings Directed cell migration depends upon integrin-containing deposition of the ECM protein fibronectin which supports Cold Spring Harbor focal adhesions connecting the cell’s actin cytoskeleton nascent lamellipodia formation. The fibronectin binds to Conference - Systems with the extracellular matrix (ECM) and transmitting integrin and serves as an ECM substrate for Rac1-dependent 18 Biology: Global Regulation of mechanical force. Focal adhesion formation and subsequent directional migration . N e Gene Expression migration require dynamic re-organization of actin-based w contractile fibers and protrusions at a cell’s trailing and Cell Directionality s March 11-14th leading edges, respectively, in response to extracellular Cold Spring Harbor, NY guidance cues. Migration is essential for healthy cell Rho-family-mediated remodeling of the actin cytoskeleton is Cytoskeleton Supported (and organism) development, growth, maturation, and necessary for the cell’s directional response to extracellular physiological responses to diseases, injuries, and/or immune guidance cues (e.g., chemokines, matrix-released molecules, system challenges. Various pathophysiological conditions growth factors, etc). The response is either a migration Cold Spring Harbor (e.g., cancer, fibrosis, infections, chronic inflammation) usurp toward or away from environmental cues and this directional Conference -Neuronal and/or compromise the dynamic physiological processes response requires dynamic reorganization of the actin Circuts underlying migration1-5. cytoskeleton. A central question is the identity of the March 18-21st signaling molecule (or molecules) that relays the extracellular 1-4 Cold Spring Harbor, NY Rho-family GTPases (e.g., RhoA, Rac1, Cdc42, and RhoJ) act information to the actin cytoskeleton .
    [Show full text]
  • Structure and Mechanics of Proteins from Single Molecules to Cells
    University of Pennsylvania ScholarlyCommons Publicly Accessible Penn Dissertations Summer 2009 Structure and Mechanics of Proteins from Single Molecules to Cells Andre E. Brown University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/edissertations Part of the Biological and Chemical Physics Commons Recommended Citation Brown, Andre E., "Structure and Mechanics of Proteins from Single Molecules to Cells" (2009). Publicly Accessible Penn Dissertations. 9. https://repository.upenn.edu/edissertations/9 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/edissertations/9 For more information, please contact [email protected]. Structure and Mechanics of Proteins from Single Molecules to Cells Abstract Physical factors drive evolution and play important roles in motility and attachment as well as in differentiation. As animal cells adhere to survive, they generate force and “feel” various mechanical features of their surroundings and respond to externally applied forces. This mechanosensitivity requires a substrate for cells to adhere to and a mechanism for cells to apply force, followed by a cellular response to the mechanical properties of the substrate. We have taken an outside-in approach to characterize several aspects of cellular mechanosensitivity. First, we used single molecule force spectroscopy to measure how fibrinogen, an extracellular matrix protein that forms the scaffold of blood clots, responds to applied force and found that it rapidly unfolds in 23 nm steps at forces around 100 pN. Second, we used tensile testing to measure the force-extension behavior of fibrin gels and found that they behave almost linearly to strains of over 100%, have extensibilities of 170 ± 15 %, and undergo a large volume decrease that corresponds to a large and negative peak in compressibility at low strain, which indicates a structural transition.
    [Show full text]
  • ERIN D. GOLEY, Ph.D. Curriculum Vitae
    Curriculum vitae Goley, Erin D. ERIN D. GOLEY, Ph.D. Curriculum Vitae DEMOGRAPHIC INFORMATION: Professional Appointment Assistant Professor, Department of Biological Chemistry Johns Hopkins University School of Medicine 08/2011 – current Personal Data Laboratory address: 725 N. Wolfe Street, 520 WBSB Baltimore, MD 21205 Office Phone: 410-502-4931 Lab Phone: 410-955-2361 FAX: 410-955-5759 e-mail: [email protected] Education and Training 1994-1998 BA/Hood College, Frederick, MD Biochemistry and Maths 2000-2006 PhD/University of California, Berkeley, CA Molecular and Cell Biology 2006-2011 Postdoc/Stanford University, Stanford, CA Bacterial Cell Biology Professional Experience 1997-2000 Laboratory Technician USDA, Ft Detrick, MD 1997 NSF Undergrad Fellow University of Utah, Salt Lake City, UT RESEARCH ACTIVITIES: Peer Reviewed Publications 1) Tooley PW, Goley ED, Carras MM, Frederick RD, Weber EL, Kuldau GA. (2001) Characterization of Claviceps species pathogenic on sorghum by sequence analysis of the beta- tubulin gene intron 3 region and EF-1alpha gene intron 4. Mycologia. 93: 541-551. 2) Skoble J, Auerbuch V, Goley ED, Welch MD, Portnoy DA. (2001) Pivotal role of VASP in Arp2/3 complex-mediated actin nucleation, actin branch-formation, and Listeria monocytogenes motility. J Cell Biol. 155:89-100. 3) Gournier H, Goley ED, Niederstrasser H, Trinh T, Welch MD. (2001) Reconstitution of human Arp2/3 complex reveals critical roles of individual subunits in complex structure and activity. Mol Cell. 8:1041-52. 4) Tooley PW, Goley ED, Carras MM, O'Neill NR. (2002) AFLP comparisons among Claviceps africana isolates from the United States, Mexico, Africa, Australia, India, and Japan.
    [Show full text]
  • Of the Bacterial Cytoskeleton
    30 Apr 2004 18:9 AR AR214-BB33-09.tex AR214-BB33-09.sgm LaTeX2e(2002/01/18) P1: FHD 10.1146/annurev.biophys.33.110502.132647 Annu. Rev. Biophys. Biomol. Struct. 2004. 33:177–98 doi: 10.1146/annurev.biophys.33.110502.132647 Copyright c 2004 by Annual Reviews. All rights reserved First published online as a Review in Advance on January 7, 2004 MOLECULES OF THE BACTERIAL CYTOSKELETON Jan Lowe,¨ Fusinita van den Ent, and Linda A. Amos MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom; email: [email protected]; [email protected]; [email protected] Key Words FtsZ, MreB, ParM, tubulin, actin ■ Abstract The structural elucidation of clear but distant homologs of actin and tubulin in bacteria and GFP labeling of these proteins promises to reinvigorate the field of prokaryotic cell biology. FtsZ (the tubulin homolog) and MreB/ParM (the actin ho- mologs) are indispensable for cellular tasks that require the cell to accurately position molecules, similar to the function of the eukaryotic cytoskeleton. FtsZ is the organizing molecule of bacterial cell division and forms a filamentous ring around the middle of the cell. Many molecules, including MinCDE, SulA, ZipA, and FtsA, assist with this process directly. Recently, genes much more similar to tubulin than to FtsZ have been identified in Verrucomicrobia. MreB forms helices underneath the inner membrane and probably defines the shape of the cell by positioning transmembrane and periplas- mic cell wall–synthesizing enzymes. Currently, no interacting proteins are known for MreB and its relatives that help these proteins polymerize or depolymerize at certain times and places inside the cell.
    [Show full text]
  • Post-Translational Modifications of Β-Catenin and TFC/LEF-1 Regulate Canonical Wnt Signaling Related Publications MARCH Research Tools 2018
    CYTOSKELETON NEWS NEWS FROM CYTOSKELETON INC. Post-translational Modifications of β-catenin and TFC/LEF-1 Regulate Canonical Wnt Signaling Related Publications MARCH Research Tools 2018 v Meetings Post-translational Modifications of β-catenin and TCF/LEF-1 Regulate Canonical Wnt Signaling Boston Area Mitosis and Protein post-translational modifications (PTMs) such as consisting of the scaffolding/tumor suppressor proteins Axin News Meiosis Meeting phosphorylation, acetylation, ubiquitination, and SUMOylation, and adenomatous polyposis coli (APC), and the serine/threonine May 12 to name but a few, have evolved to diversify the functions of kinases casein kinase 1α (CK-1α) and glycogen synthase kinase 3 Boston MA a single protein and account for the vast increase in proteome (GSK3) mediates phosphorylation of β-catenin2,3,9. Under these Cytoskeleton Supported complexity and functional diversity1. A prime example of the quiescent conditions, β-cateinin is sequentially phosphorylated complex and dynamic regulatory power PTMs confer is the on Ser45 by CK-1α, followed by phosphorylation of Ser33, Ser37, GRC Phosphorylation Wnt/β-catenin signaling pathway2,3. This pathway regulates and Thr41 by GSK312 (Fig. 1). Upon phosphorylation, the E3 and G-Protein Mediated cellular proliferation, differentiation, and migration during ubiquitin ligase β-transducin repeats containing protein (β-TrCP) 4-6 13,14 Signaling Networks embryonic development and adult cell homeostasis . In ubiquitinates phospho-β-catenin on Lys19 and Lys49 , which addition, dysregulation of Wnt/β-catenin signaling is implicated leads to proteasomal destruction and low β-catenin levels June 3-8 in multiple pathological conditions, including carcinogenesis and and activity15,16. Conversely, in the presence of Wnt binding, Biddeford, ME degenerative diseases5,7.
    [Show full text]
  • Lessons from Bacterial Homolog of Tubulin, Ftsz for Microtubule Dynamics
    249 R R Battaje and D Panda Assembly dynamics of FtsZ and 24:9 T1–T21 Thematic Review microtubules Lessons from bacterial homolog of tubulin, FtsZ for microtubule dynamics Correspondence Rachana Rao Battaje and Dulal Panda should be addressed to D Panda Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India Email [email protected] Abstract FtsZ, a homolog of tubulin, is found in almost all bacteria and archaea where it has a Key Words primary role in cytokinesis. Evidence for structural homology between FtsZ and tubulin f FtsZ assembly came from their crystal structures and identification of the GTP box. Tubulin and FtsZ f microtubules constitute a distinct family of GTPases and show striking similarities in many of their f cell division polymerization properties. The differences between them, more so, the complexities f anticancer drugs of microtubule dynamic behavior in comparison to that of FtsZ, indicate that the f antibacterial drugs evolution to tubulin is attributable to the incorporation of the complex functionalities in higher organisms. FtsZ and microtubules function as polymers in cell division but their roles differ in the division process. The structural and partial functional homology has made the study of their dynamic properties more interesting. In this review, we focus on the application of the information derived from studies on FtsZ dynamics to study Endocrine-Related Cancer Endocrine-Related microtubule dynamics and vice versa. The structural and functional aspects that led to the establishment of the homology between the two proteins are explained to emphasize the network of FtsZ and microtubule studies and how they are connected.
    [Show full text]
  • The Bacterial Cell Division Protein Ftsz Assembles Into Cytoplasmic Rings in Fission Yeast
    Downloaded from genesdev.cshlp.org on October 4, 2021 - Published by Cold Spring Harbor Laboratory Press RESEARCH COMMUNICATION posed to exist as short polymers of 25–30 subunits The bacterial cell division (Anderson et al. 2004). These observations have been protein FtsZ assembles supported recently by cryo-electron tomography images in Caulobacter crescentus (Li et al. 2007). Although a into cytoplasmic rings major understanding of the polymerization process of in fission yeast FtsZ has come from in vitro studies (Lu and Erickson 1998; Mukherjee and Lutkenhaus 1998; Romberg et al. Ramanujam Srinivasan,1,4 Mithilesh Mishra,1,4 2001; Scheffers et al. 2002; Romberg and Levin 2003; 2 2 Chen and Erickson 2005; Mingorance et al. 2005), stud- Lifang Wu, Zhongchao Yin, ies over the past decade have identified several molecu- 1,3,5 and Mohan K. Balasubramanian lar regulators of FtsZ in vivo (Romberg and Levin 2003; Weiss 2004; Goehring and Beckwith 2005; Margolin 1Cell Division Laboratory, Temasek Life Sciences Laboratory, 2005), and models for FtsZ ring positioning and assembly The National University of Singapore, Singapore 117604; have been established. One model predicts a nucleation 2Molecular Plant Pathology, Temasek Life Sciences point at the mid-cell site for the initial assembly of FtsZ, Laboratory, The National University of Singapore, Singapore from which FtsZ polymerizes into a ring-like structure, 117604; 3Department of Biological Sciences, The National and has been called the membrane nucleation model (Bi University of Singapore, Singapore 117604 and Lutkenhaus 1991; Addinall and Lutkenhaus 1996; During cytokinesis, most bacteria assemble a ring-like Addinall et al. 1997).
    [Show full text]
  • Reconstitution of Contractile Actomyosin Rings in Vesicles
    ARTICLE https://doi.org/10.1038/s41467-021-22422-7 OPEN Reconstitution of contractile actomyosin rings in vesicles Thomas Litschel 1, Charlotte F. Kelley 1,2, Danielle Holz3, Maral Adeli Koudehi3, Sven K. Vogel1, ✉ Laura Burbaum1, Naoko Mizuno 2, Dimitrios Vavylonis3 & Petra Schwille 1 One of the grand challenges of bottom-up synthetic biology is the development of minimal machineries for cell division. The mechanical transformation of large-scale compartments, 1234567890():,; such as Giant Unilamellar Vesicles (GUVs), requires the geometry-specific coordination of active elements, several orders of magnitude larger than the molecular scale. Of all cytos- keletal structures, large-scale actomyosin rings appear to be the most promising cellular elements to accomplish this task. Here, we have adopted advanced encapsulation methods to study bundled actin filaments in GUVs and compare our results with theoretical modeling. By changing few key parameters, actin polymerization can be differentiated to resemble various types of networks in living cells. Importantly, we find membrane binding to be crucial for the robust condensation into a single actin ring in spherical vesicles, as predicted by theoretical considerations. Upon force generation by ATP-driven myosin motors, these ring-like actin structures contract and locally constrict the vesicle, forming furrow-like deformations. On the other hand, cortex-like actin networks are shown to induce and stabilize deformations from spherical shapes. 1 Department of Cellular and Molecular Biophysics,
    [Show full text]
  • Two Dynamin-Like Proteins Stabilize Ftsz Rings During Streptomyces
    Two dynamin-like proteins stabilize FtsZ rings during PNAS PLUS Streptomyces sporulation Susan Schlimperta, Sebastian Wasserstromb, Govind Chandraa, Maureen J. Bibba, Kim C. Findlayc, Klas Flärdhb,1, and Mark J. Buttnera,1 aDepartment of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, United Kingdom; bDepartment of Biology, Lund University, 223 62 Lund, Sweden; and cDepartment of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom Edited by Susan S. Golden, University of California, San Diego, La Jolla, CA, and approved June 13, 2017 (received for review March 21, 2017) During sporulation, the filamentous bacteria Streptomyces undergo bacterial dynamins have remained largely unclear. Recent reports a massive cell division event in which the synthesis of ladders of suggest that dynamins might function in diverse cellular processes in sporulation septa convert multigenomic hyphae into chains of unige- bacteria, including chromosome replication (8), membrane stress nomic spores. This process requires cytokinetic Z-rings formed by the responses (9, 10), and outer membrane vesicle release (7), indi- bacterial tubulin homolog FtsZ, and the stabilization of the newly cating that they have perhaps evolved to fulfill a range of different formed Z-rings is crucial for completion of septum synthesis. Here we functions in bacteria. show that two dynamin-like proteins, DynA and DynB, play critical Here we show that two bacterial dynamin-like proteins play an roles in this process. Dynamins are a family of large, multidomain important role in sporulation-specific cell division in Streptomyces GTPases involved in key cellular processes in eukaryotes, including venezuelae. Streptomycetes are filamentous, antibiotic-producing vesicle trafficking and organelle division.
    [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]
  • Tubulin Family: Kinship of Key Proteins Across Phylogenetic Domains Edward H
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE R288 Dispatch provided by Elsevier - Publisher Connector Tubulin family: Kinship of key proteins across phylogenetic domains Edward H. Egelman Atomic structures obtained by electron microscopy for Numerous attempts to obtain ordered three-dimensional tubulin, and by X-ray crystallography for bacterial FtsZ, crystals of tubulin had failed, in large part because the show that the two proteins are highly homologous. The high salt, high protein concentrations needed for crystal complementarity between such high-resolution studies formation cause tubulin to polymerize into helical micro- and low-resolution reconstructions of microtubule tubules. Such polymerization is incompatible with crystal complexes is clear, but controversy still abounds. packing and will disrupt attempts to form highly-ordered three-dimensional crystals. To surmount this problem, Address: Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, 321 Church Street SE, Minneapolis, Downing and colleagues [1] used highly-ordered, two- Minnesota 55455, USA. dimensional zinc-induced sheets of tubulin that contain E-mail: [email protected] protofilaments of α and β tubulin heterodimers. These sheets were ideal candidates for high-resolution electron Current Biology 1998, 8:R288–R290 http://biomednet.com/elecref/09609822008R0288 microscopy and served to generate the first structure of a non-membrane protein to be solved by electron © Current Biology Ltd ISSN 0960-9822 microscopy. While the determination of an atomic struc- ture by electron microscopy might come as a surprise to The simultaneous elucidation of the atomic structures of many in the field of cytoskeletal proteins, workers in the eukaryotic tubulin [1] and bacterial FtsZ [2] is momentous field of integral membrane proteins have been much more for several reasons.
    [Show full text]