scholarly journals Tuning spherical cells into kinking helices in wall-less bacteria

2021 ◽  
Author(s):  
Carole Lartigue ◽  
Bastien Lambert ◽  
Fabien Rideau ◽  
Marion Decossas ◽  
Mélanie Hillion ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Cell Movement ◽  
Membrane Curvature ◽  
Special Role ◽  
Spiroplasma Citri ◽  
Cytoplasmic Filaments ◽  
Peptidoglycan Cell Wall ◽  
A Cell ◽  
Spherical Cells

In bacteria, cell shape is determined and maintained through a complex interplay between the peptidoglycan cell wall and cytoplasmic filaments made of polymerized MreB. Spiroplasma species, members of the Mollicutes class, challenge this general understanding because they are characterized by a helical cell shape and motility without a cell wall. This specificity is thought to rely on five MreB isoforms and a specific fibril protein. In this study, combinations of these five MreBs and of the fibril from Spiroplasma citri were expressed in another Mollicutes, Mycoplasma capricolum. Mycoplasma cells that were initially pleomorphic, mostly spherical, turned into helices when MreBs and fibrils were expressed in this heterologous host. The fibril protein was essential neither for helicity nor for cell movements. The isoform MreB5 had a special role as it was sufficient to confer helicity and motility to the mycoplasma cells. Cryo-electron microscopy confirmed the association of MreBs and fibril-based cytoskeleton with the plasma membrane, suggesting a direct effect on the membrane curvature. Finally, the heterologous expression of these proteins, MreBs and fibril, made it possible to reproduce the kink-like motility of spiroplasmas without providing the ability of cell movement in liquid broth. We suggest that other Spiroplasma components, not yet identified, are required for swimming, a hypothesis that could be evaluated in future studies using the same model.

scholarly journals Bacterial Cell Wall Quality Control during Environmental Stress

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Elizabeth A. Mueller ◽  
Petra Anne Levin
Keyword(s):  
Quality Control ◽  
Cell Wall ◽  
Cell Surface ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Bacterial Cell ◽  
Cell Shape ◽  
Bacterial Cell Wall ◽  
Peptidoglycan Synthesis ◽  
Peptidoglycan Cell Wall

ABSTRACT Single-celled organisms must adapt their physiology to persist and propagate across a wide range of environmental conditions. The growth and division of bacterial cells depend on continuous synthesis of an essential extracellular barrier: the peptidoglycan cell wall, a polysaccharide matrix that counteracts turgor pressure and confers cell shape. Unlike many other essential processes and structures within the bacterial cell, the peptidoglycan cell wall and its synthesis machinery reside at the cell surface and are thus uniquely vulnerable to the physicochemical environment and exogenous threats. In addition to the diversity of stressors endangering cell wall integrity, defects in peptidoglycan metabolism require rapid repair in order to prevent osmotic lysis, which can occur within minutes. Here, we review recent work that illuminates mechanisms that ensure robust peptidoglycan metabolism in response to persistent and acute environmental stress. Advances in our understanding of bacterial cell wall quality control promise to inform the development and use of antimicrobial agents that target the synthesis and remodeling of this essential macromolecule. IMPORTANCE Nearly all bacteria are encased in a peptidoglycan cell wall, an essential polysaccharide structure that protects the cell from osmotic rupture and reinforces cell shape. The integrity of this protective barrier must be maintained across the diversity of environmental conditions wherein bacteria replicate. However, at the cell surface, the cell wall and its synthesis machinery face unique challenges that threaten their integrity. Directly exposed to the extracellular environment, the peptidoglycan synthesis machinery encounters dynamic and extreme physicochemical conditions, which may impair enzymatic activity and critical protein-protein interactions. Biotic and abiotic stressors—including host defenses, cell wall active antibiotics, and predatory bacteria and phage—also jeopardize peptidoglycan integrity by introducing lesions, which must be rapidly repaired to prevent cell lysis. Here, we review recently discovered mechanisms that promote robust peptidoglycan synthesis during environmental and acute stress and highlight the opportunities and challenges for the development of cell wall active therapeutics.

scholarly journals Bacterial Cell Wall Synthesis: New Insights from Localization Studies

2005 ◽  
Vol 69 (4) ◽  
pp. 585-607 ◽  
Author(s):  
Dirk-Jan Scheffers ◽  
Mariana G. Pinho
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Cell Shape ◽  
Fluorescent Protein ◽  
Model Organisms ◽  
Live Cells ◽  
Cell Wall Synthesis ◽  
A Cell ◽  
Green Fluorescent ◽  
Bacterial Cell Shape

SUMMARY In order to maintain shape and withstand intracellular pressure, most bacteria are surrounded by a cell wall that consists mainly of the cross-linked polymer peptidoglycan (PG). The importance of PG for the maintenance of bacterial cell shape is underscored by the fact that, for various bacteria, several mutations affecting PG synthesis are associated with cell shape defects. In recent years, the application of fluorescence microscopy to the field of PG synthesis has led to an enormous increase in data on the relationship between cell wall synthesis and bacterial cell shape. First, a novel staining method enabled the visualization of PG precursor incorporation in live cells. Second, penicillin-binding proteins (PBPs), which mediate the final stages of PG synthesis, have been localized in various model organisms by means of immunofluorescence microscopy or green fluorescent protein fusions. In this review, we integrate the knowledge on the last stages of PG synthesis obtained in previous studies with the new data available on localization of PG synthesis and PBPs, in both rod-shaped and coccoid cells. We discuss a model in which, at least for a subset of PBPs, the presence of substrate is a major factor in determining PBP localization.

scholarly journals Cell-wall synthases contribute to bacterial cell-envelope integrity by actively repairing defects

2019 ◽  
Author(s):  
Antoine Vigouroux ◽  
Baptiste Cordier ◽  
Andrey Aristov ◽  
Enno Oldewurtel ◽  
Gizem Özbaykal ◽  
...  
Keyword(s):  
Cell Wall ◽  
Single Molecule ◽  
Cell Shape ◽  
Mechanical Stability ◽  
Cell Envelope ◽  
Cylindrical Part ◽  
Single Molecule Level ◽  
Class A ◽  
Wall Stiffness ◽  
Peptidoglycan Cell Wall

AbstracCell shape and cell-envelope integrity of bacteria are determined by the peptidoglycan cell wall. In rod-shaped Escherichia coli, two conserved sets of machinery are essential for cell-wall insertion in the cylindrical part of the cell, the Rod complex and the class-A penicillin-binding proteins (aPBPs). While the Rod complex governs rod-like cell shape, aPBP function is less well understood. aPBPs were previously hypothesized to either work in concert with the Rod complex or to independently repair cell-wall defects. First, we demonstrate through modulation of enzyme levels that class-A PBPs do not contribute to rod-like cell shape but are required for mechanical stability, supporting their independent activity. By combining measurements of cell-wall stiffness, cell-wall insertion, and PBP1b motion at the single-molecule level we then demonstrate that PBP1b, the major class-A PBP, contributes to cell-wall integrity by localizing and inserting peptidoglycan in direct response to local cell-wall defects.

scholarly journals FtsW is a peptidoglycan polymerase that is activated by its cognate penicillin-binding protein

2018 ◽  
Author(s):  
Atsushi Taguchi ◽  
Michael A. Welsh ◽  
Lindsey S. Marmont ◽  
Wonsik Lee ◽  
Daniel Kahne ◽  
...  
Keyword(s):  
Cell Wall ◽  
Side Wall ◽  
Polymerase Activity ◽  
Cell Wall Assembly ◽  
Peptidoglycan Synthesis ◽  
Lipid Ii ◽  
Peptidoglycan Cell Wall ◽  
Class B ◽  
A Cell

AbstractThe peptidoglycan cell wall is essential for the survival and shape maintenance ofbacteria.1 For decades it was thought that only penicillin-binding proteins (PBPs) effected peptidoglycan synthesis. Recently, it was shown that RodA, a member of the Rod complex involved in side wall peptidoglycan synthesis, acts as a peptidoglycan polymerase.2–4 RodA is absent or dispensable in many bacteria that contain a cell wall; however, all of these bacteria have a RodA homologue, FtsW, which is a core member of the divisome complex that is essential for septal cell wall assembly.5,6 FtsW was previously proposed flip the peptidoglycan precursor Lipid II to the peripasm,7,8 but we report here that FtsW polymerizes Lipid II. We show that FtsW polymerase activity depends on the presence of the class B PBP (bPBP) that it recruits to the septum. We also demonstrate that the polymerase activity of FtsW is required for its function in vivo. Our findings establish FtsW as a peptidoglycan polymerase that works with its cognate bPBP to produce septal peptidoglycan during cell division.

scholarly journals MreB Filaments Create Rod Shape By Aligning Along Principal Membrane Curvature

2017 ◽  
Author(s):  
Saman Hussain ◽  
Carl N. Wivagg ◽  
Piotr Szwedziak ◽  
Felix Wong ◽  
Kaitlin Schaefer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Radial Direction ◽  
Membrane Curvature ◽  
Biophysical Modeling ◽  
Peptidoglycan Synthesis ◽  
Stable Maintenance ◽  
Spherical Cells ◽  
Self Organizing

AbstractMreB 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 ofBacillus 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 liposomesin 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 and increased glycan crosslinking. 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.

scholarly journals MreB filaments align along greatest principal membrane curvature to orient cell wall synthesis

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Saman Hussain ◽  
Carl N Wivagg ◽  
Piotr Szwedziak ◽  
Felix Wong ◽  
Kaitlin Schaefer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Radial Direction ◽  
Membrane Curvature ◽  
Biophysical Modeling ◽  
Cell Wall Synthesis ◽  
Peptidoglycan Synthesis ◽  
Stable Maintenance ◽  
Spherical Cells

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.

scholarly journals The evolution of spherical cell shape; progress and perspective

2019 ◽  
Vol 47 (6) ◽  
pp. 1621-1634 ◽  
Author(s):  
Paul Richard Jesena Yulo ◽  
Heather Lyn Hendrickson
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Cell Shape ◽  
Shape Change ◽  
Spherical Cell ◽  
Shape Evolution ◽  
Penicillin Binding Proteins ◽  
Cell Shape Change ◽  
Peptidoglycan Cell Wall ◽  
Bacterial Cell Shape

Bacterial cell shape is a key trait governing the extracellular and intracellular factors of bacterial life. Rod-like cell shape appears to be original which implies that the cell wall, division, and rod-like shape came together in ancient bacteria and that the myriad of shapes observed in extant bacteria have evolved from this ancestral shape. In order to understand its evolution, we must first understand how this trait is actively maintained through the construction and maintenance of the peptidoglycan cell wall. The proteins that are primarily responsible for cell shape are therefore the elements of the bacterial cytoskeleton, principally FtsZ, MreB, and the penicillin-binding proteins. MreB is particularly relevant in the transition between rod-like and spherical cell shape as it is often (but not always) lost early in the process. Here we will highlight what is known of this particular transition in cell shape and how it affects fitness before giving a brief perspective on what will be required in order to progress the field of cell shape evolution from a purely mechanistic discipline to one that has the perspective to both propose and to test reasonable hypotheses regarding the ecological drivers of cell shape change.

scholarly journals FERONIA’s sensing of cell wall pectin activates ROP GTPase signaling in Arabidopsis

2018 ◽  
Author(s):  
Wenwei Lin ◽  
Wenxin Tang ◽  
Charles T. Anderson ◽  
Zhenbiao Yang
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Cell Surface Receptor ◽  
Pavement Cell ◽  
Signaling Mechanism ◽  
Rop Gtpase ◽  
Surface Receptor ◽  
A Cell

ABSTRACTPlant cells need to monitor the cell wall dynamic to control the wall homeostasis required for a myriad of processes in plants, but the mechanisms underpinning cell wall sensing and signaling in regulating these processes remain largely elusive. Here, we demonstrate that receptor-like kinase FERONIA senses the cell wall pectin polymer to directly activate the ROP6 GTPase signaling pathway that regulates the formation of the cell shape in the Arabidopsis leaf epidermis. The extracellular malectin domain of FER directly interacts with de-methylesterified pectin in vivo and in vitro. Both loss-of-FER mutations and defects in the pectin biosynthesis and de-methylesterification caused changes in pavement cell shape and ROP6 signaling. FER is required for the activation of ROP6 by de-methylesterified pectin, and physically and genetically interacts with the ROP6 activator, RopGEF14. Thus, our findings elucidate a cell wall sensing and signaling mechanism that connects the cell wall to cellular morphogenesis via the cell surface receptor FER.

scholarly journals An Actin Homolog of the Archaeon Thermoplasma acidophilum That Retains the Ancient Characteristics of Eukaryotic Actin

2006 ◽  
Vol 189 (5) ◽  
pp. 2039-2045 ◽  
Author(s):  
Futoshi Hara ◽  
Kan Yamashiro ◽  
Naoki Nemoto ◽  
Yoshinori Ohta ◽  
Shin-ichi Yokobori ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cell Wall ◽  
Crucial Role ◽  
Cell Shape ◽  
Critical Concentration ◽  
Central Component ◽  
Unit Size ◽  
Thermoplasma Acidophilum ◽  
Nucleotide Triphosphates ◽  
A Cell

ABSTRACT Actin, a central component of the eukaryotic cytoskeleton, plays a crucial role in determining cell shape in addition to several other functions. Recently, the structure of the archaeal actin homolog Ta0583, isolated from the archaeon Thermoplasma acidophilum, which lacks a cell wall, was reported by Roeben et al. (J. Mol. Biol. 358:145-156, 2006). Here we show that Ta0583 assembles into bundles of filaments similar to those formed by eukaryotic actin. Specifically, Ta0583 forms a helix with a filament width of 5.5 nm and an axial repeating unit of 5.5 nm, both of which are comparable to those of eukaryotic actin. Eukaryotic actin shows a greater resemblance to Ta0583 than to bacterial MreB and ParM in terms of polymerization characteristics, such as the requirement for Mg2+, critical concentration, and repeating unit size. Furthermore, phylogenetic analysis also showed a closer relationship between Ta0583 and eukaryotic actin than between MreB or ParM and actin. However, the low specificity of Ta0583 for nucleotide triphosphates indicates that Ta0583 is more primitive than eukaryotic actin. Taken together, our results suggest that Ta0583 retains the ancient characteristics of eukaryotic actin.

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