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 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 DivIVA Is Required for Polar Growth in the MreB-Lacking Rod-Shaped Actinomycete Corynebacterium glutamicum

2008 ◽  
Vol 190 (9) ◽  
pp. 3283-3292 ◽  
Author(s):  
Michal Letek ◽  
Efrén Ordóñez ◽  
José Vaquera ◽  
William Margolin ◽  
Klas Flärdh ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Streptococcus Pneumoniae ◽  
Corynebacterium Glutamicum ◽  
Chromosome Segregation ◽  
Polar Growth ◽  
Cell Wall Synthesis ◽  
Peptidoglycan Synthesis ◽  
Polarized Cell Growth

ABSTRACT The actinomycete Corynebacterium glutamicum grows as rod-shaped cells by zonal peptidoglycan synthesis at the cell poles. In this bacterium, experimental depletion of the polar DivIVA protein (DivIVACg) resulted in the inhibition of polar growth; consequently, these cells exhibited a coccoid morphology. This result demonstrated that DivIVA is required for cell elongation and the acquisition of a rod shape. DivIVA from Streptomyces or Mycobacterium localized to the cell poles of DivIVACg-depleted C. glutamicum and restored polar peptidoglycan synthesis, in contrast to DivIVA proteins from Bacillus subtilis or Streptococcus pneumoniae, which localized at the septum of C. glutamicum. This confirmed that DivIVAs from actinomycetes are involved in polarized cell growth. DivIVACg localized at the septum after cell wall synthesis had started and the nucleoids had already segregated, suggesting that in C. glutamicum DivIVA is not involved in cell division or chromosome segregation.

scholarly journals Bacteriophage SP01 Gene Product 56 Inhibits Bacillus subtilis Cell Division by Interacting with FtsL and Disrupting Pbp2B and FtsW Recruitment

2020 ◽  
Vol 203 (2) ◽  
pp. e00463-20
Author(s):  
Amit Bhambhani ◽  
Isabella Iadicicco ◽  
Jules Lee ◽  
Syed Ahmed ◽  
Max Belfatto ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Gene Product ◽  
Fluorescent Protein ◽  
Lytic Bacteriophage ◽  
Cell Wall Synthesis ◽  
Content Type ◽  
Ftsz Ring ◽  
Green Fluorescent

ABSTRACTPrevious work identified gene product 56 (gp56), encoded by the lytic bacteriophage SP01, as being responsible for inhibition of Bacillus subtilis cell division during its infection. Assembly of the essential tubulin-like protein FtsZ into a ring-shaped structure at the nascent site of cytokinesis determines the timing and position of division in most bacteria. This FtsZ ring serves as a scaffold for recruitment of other proteins into a mature division-competent structure permitting membrane constriction and septal cell wall synthesis. Here, we show that expression of the predicted 9.3-kDa gp56 of SP01 inhibits later stages of B. subtilis cell division without altering FtsZ ring assembly. Green fluorescent protein-tagged gp56 localizes to the membrane at the site of division. While its localization does not interfere with recruitment of early division proteins, gp56 interferes with the recruitment of late division proteins, including Pbp2b and FtsW. Imaging of cells with specific division components deleted or depleted and two-hybrid analyses suggest that gp56 localization and activity depend on its interaction with FtsL. Together, these data support a model in which gp56 interacts with a central part of the division machinery to disrupt late recruitment of the division proteins involved in septal cell wall synthesis.IMPORTANCE Studies over the past decades have identified bacteriophage-encoded factors that interfere with host cell shape or cytokinesis during viral infection. The phage factors causing cell filamentation that have been investigated to date all act by targeting FtsZ, the conserved prokaryotic tubulin homolog that composes the cytokinetic ring in most bacteria and some groups of archaea. However, the mechanisms of several phage factors that inhibit cytokinesis, including gp56 of bacteriophage SP01 of Bacillus subtilis, remain unexplored. Here, we show that, unlike other published examples of phage inhibition of cytokinesis, gp56 blocks B. subtilis cell division without targeting FtsZ. Rather, it utilizes the assembled FtsZ cytokinetic ring to localize to the division machinery and to block recruitment of proteins needed for septal cell wall synthesis.

scholarly journals Katanosin B and Plusbacin A3, Inhibitors of Peptidoglycan Synthesis in Methicillin-ResistantStaphylococcus aureus

2001 ◽  
Vol 45 (6) ◽  
pp. 1823-1827 ◽  
Author(s):  
Hideki Maki ◽  
Kenji Miura ◽  
Yoshinori Yamano
Keyword(s):  
Cell Wall ◽  
Antibacterial Activity ◽  
Whole Cells ◽  
Gram Positive Bacteria ◽  
Peptidoglycan Synthesis ◽  
Cyclic Depsipeptide ◽  
Naturally Occurring ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant

ABSTRACT Both katanosin B and plusbacin A3 are naturally occurring cyclic depsipeptide antibiotics containing a lactone linkage. They showed strong antibacterial activity against methicillin-resistantStaphylococcus aureus and VanA-type vancomycin-resistant enterococci, with MICs ranging from 0.39 to 3.13 μg/ml, as well as against other gram-positive bacteria. They inhibited the incorporation of N-acetylglucosamine, a precursor of cell wall synthesis, into peptidoglycan of S. aureus whole cells at concentrations close to their MICs. In vitro studies with a wall-membrane particulate fraction of S. aureus showed that katanosin B and plusbacin A3 inhibited the formation of lipid intermediates, with 50% inhibitory concentrations (IC50s) of 2.2 and 2.3 μg/ml, respectively, and inhibited the formation of nascent peptidoglycan, with IC50s of 0.8 and 0.4 μg/ml, respectively. Vancomycin, a well-known inhibitor of transglycosylation, did not inhibit the formation of lipid intermediates but did inhibit the formation of nascent peptidoglycan, with an IC50 of 4.1 μg/ml. Acetyl-Lys-d-Ala-d-Ala, an analog of the terminus of the lipid intermediates, effectively suppressed the inhibition of transglycosylation by vancomycin, but did not suppress those by katanosin B and plusbacin A3. These results indicate that the antibacterial activity of katanosin B and plusbacin A3 is due to blocking of transglycosylation and its foregoing steps of cell wall peptidoglycan synthesis via a mechanism differing from that of vancomycin.

scholarly journals A cell wall damage response mediated by a sensor kinase/response regulator pair enables beta-lactam tolerance

2015 ◽  
Vol 113 (2) ◽  
pp. 404-409 ◽  
Author(s):  
Tobias Dörr ◽  
Laura Alvarez ◽  
Fernanda Delgado ◽  
Brigid M. Davis ◽  
Felipe Cava ◽  
...  
Keyword(s):  
Cell Wall ◽  
Response Regulator ◽  
Cell Envelope ◽  
Normal Growth ◽  
Cell Diameter ◽  
Cell Wall Synthesis ◽  
Beta Lactam ◽  
Cell Wall Damage ◽  
A Cell

The bacterial cell wall is critical for maintenance of cell shape and survival. Following exposure to antibiotics that target enzymes required for cell wall synthesis, bacteria typically lyse. Although several cell envelope stress response systems have been well described, there is little knowledge of systems that modulate cell wall synthesis in response to cell wall damage, particularly in Gram-negative bacteria. Here we describe WigK/WigR, a histidine kinase/response regulator pair that enablesVibrio cholerae, the cholera pathogen, to survive exposure to antibiotics targeting cell wall synthesis in vitro and during infection. Unlike wild-typeV. cholerae, mutants lackingwigRfail to recover following exposure to cell-wall–acting antibiotics, and they exhibit a drastically increased cell diameter in the absence of such antibiotics. Conversely, overexpression ofwigRleads to cell slimming. Overexpression of activated WigR also results in increased expression of the full set of cell wall synthesis genes and to elevated cell wall content. WigKR-dependent expression of cell wall synthesis genes is induced by various cell-wall–acting antibiotics as well as by overexpression of an endogenous cell wall hydrolase. Thus, WigKR appears to monitor cell wall integrity and to enhance the capacity for increased cell wall production in response to damage. Taken together, these findings implicate WigKR as a regulator of cell wall synthesis that controls cell wall homeostasis in response to antibiotics and likely during normal growth as well.

Effets d'une plasmolyse prolongée sur les tubes polliniques angiospermiens en culture in vitro : étude ultrastructurale

1988 ◽  
Vol 66 (1) ◽  
pp. 108-115 ◽  
Author(s):  
Jean-Claude Pargney
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Pollen Tubes ◽  
Ultrastructural Changes ◽  
Cell Wall Synthesis ◽  
Culture In Vitro

In angiosperm plants subjected to plasmolysis, pollen tubes may undergo substantial ultrastructural changes accompanied by a gradual deterioration of those processes involved in cell syntheses. However, some tubes quickly regenerate a polysaccharide wall and thus ensure their extension. Others undergo fragmentation of their cytoplasm and a serious breakdown in processes involved in cell wall synthesis. In these extreme cases, the endoplasmic reticulum is the only compartment that is readily discernible.

scholarly journals Mutations of the YidC Insertase alleviate stress from σM-dependent membrane protein overproduction in Bacillus subtilis

2019 ◽  
Author(s):  
Heng Zhao ◽  
Ankita J. Sachla ◽  
John D. Helmann
Keyword(s):  
Oxidative Stress ◽  
Cell Wall ◽  
Bacillus Subtilis ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Substrate Binding ◽  
Single Amino Acid ◽  
Cell Wall Synthesis ◽  
Intrinsic Resistance ◽  
Σ Factor

AbstractIn Bacillus subtilis, the extracytoplasmic function σ factor σM regulates cell wall synthesis and is critical for intrinsic resistance to cell wall targeting antibiotics. The anti-σ factors YhdL and YhdK form a complex that restricts the basal activity of σM, and the absence of YhdL leads to runaway expression of the σM regulon and cell death. Here, we report that this lethality can be suppressed by gain-of-function mutations in spoIIIJ, which encodes the major YidC membrane protein insertase in B. subtilis. B. subtilis PY79 SpoIIIJ contains a single amino acid substitution in the substrate-binding channel (Q140K), and this allele suppresses the lethality of high SigM. Analysis of a library of YidC variants reveals that increased charge (+2 or +3) in the substrate-binding channel can compensate for high expression of the σM regulon. Derepression of the σM regulon induces secretion stress, oxidative stress and DNA damage responses, all of which can be alleviated by the YidCQ140K substitution. We further show that the fitness defect caused by high σM activity is exacerbated in the absence of SecDF protein translocase or σM-dependent induction of the Spx oxidative stress regulon. Conversely, cell growth is improved by mutation of specific σM-dependent promoters controlling operons encoding integral membrane proteins. Collectively, these results reveal how the σM regulon has evolved to up-regulate membrane-localized complexes involved in cell wall synthesis, and to simultaneously counter the resulting stresses imposed by regulon induction.Author SummaryBacteria frequently produce antibiotics that inhibit the growth of competitors, and many naturally occurring antibiotics target cell wall synthesis. In Bacillus subtilis, the alternative σ factor σM is induced by cell wall antibiotics, and upregulates genes for peptidoglycan and cell envelope synthesis. However, dysregulation of the σM regulon, resulting from loss of the YhdL anti-σM protein, is lethal. We here identify charge variants of the SpoIIIJ(YidC) membrane protein insertase that suppress the lethal effects of high σM activity. Further analyses reveal that induction of the σM regulon leads to high level expression of membrane proteins that trigger envelope stress, and this stress is countered by specific genes in the σM regulon.

scholarly journals Staphylococcus aureus Cell Wall Biosynthesis Modulates Bone Invasion and Osteomyelitis Pathogenesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Elysia A. Masters ◽  
Gowrishankar Muthukrishnan ◽  
Lananh Ho ◽  
Ann Lindley Gill ◽  
Karen L. de Mesy Bentley ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Surface Protein ◽  
Implant Loosening ◽  
Penicillin Binding Protein ◽  
Cell Wall Synthesis ◽  
Transmission Electron ◽  
Surface Adhesins

Staphylococcus aureus invasion of the osteocyte lacuno-canalicular network (OLCN) is a novel mechanism of bacterial persistence and immune evasion in chronic osteomyelitis. Previous work highlighted S. aureus cell wall transpeptidase, penicillin binding protein 4 (PBP4), and surface adhesin, S. aureus surface protein C (SasC), as critical factors for bacterial deformation and propagation through nanopores in vitro, representative of the confined canaliculi in vivo. Given these findings, we hypothesized that cell wall synthesis machinery and surface adhesins enable durotaxis- and haptotaxis-guided invasion of the OLCN, respectively. Here, we investigated select S. aureus cell wall synthesis mutants (Δpbp3, Δatl, and ΔmreC) and surface adhesin mutants (ΔclfA and ΔsasC) for nanopore propagation in vitro and osteomyelitis pathogenesis in vivo. In vitro evaluation in the microfluidic silicon membrane-canalicular array (μSiM-CA) showed pbp3, atl, clfA, and sasC deletion reduced nanopore propagation. Using a murine model for implant-associated osteomyelitis, S. aureus cell wall synthesis proteins were found to be key modulators of S. aureus osteomyelitis pathogenesis, while surface adhesins had minimal effects. Specifically, deletion of pbp3 and atl decreased septic implant loosening and S. aureus abscess formation in the medullary cavity, while deletion of surface adhesins showed no significant differences. Further, peri-implant osteolysis, osteoclast activity, and receptor activator of nuclear factor kappa-B ligand (RANKL) production were decreased following pbp3 deletion. Most notably, transmission electron microscopy (TEM) imaging of infected bone showed that pbp3 was the only gene herein associated with decreased submicron invasion of canaliculi in vivo. Together, these results demonstrate that S. aureus cell wall synthesis enzymes are critical for OLCN invasion and osteomyelitis pathogenesis in vivo.

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.

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