scholarly journals THE FINE STRUCTURE OF STALKED BACTERIA BELONGING TO THE FAMILY CAULOBACTERACEAE

1964 ◽  
Vol 23 (3) ◽  
pp. 587-607 ◽  
Author(s):  
Jeanne L. Stove Poindexter ◽  
Germaine Cohen-Bazire
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Cell Membrane ◽  
Multilayered Structure ◽  
Gram Negative Bacteria ◽  
Thin Sections ◽  
Gram Negative ◽  
Cytoplasmic Region ◽  
The Core ◽  
The Family

The fine structure of a series of stalked bacteria belonging to the genera Caulobacter and Asticcacaulis has been examined in thin sections. The cell wall has the multilayered structure typical of many Gram-negative bacteria, and continues without interruption throughout the length of the stalk. The core of the stalk, continuous with the cytoplasmic region of the cell, is enclosed in an extension of the cell membrane, and contains a system of internal membranes: it is devoid of ribosomes and nucleoplasm. A membranous organelle occupies the juncture of stalk and cell, separating the ribosomal region from the core of the stalk. Typical mesosomes also occur in the cell, being particularly frequent at the plane of division. The secreted holdfast is located at the tip of the stalk in Caulobacter, and at the pole of the cell adjacent to the stalk in Asticcacaulis.

Fine Structure and Radiation Resistance in Acinetobacter: Studies on a Resistant Strain

1968 ◽  
Vol 3 (2) ◽  
pp. 273-294
Author(s):  
MARGARET J. THORNLEY ◽  
AUDREY M. GLAUERT
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Radiation Resistance ◽  
Cell Walls ◽  
Proteolytic Enzymes ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Isolated Cell

An electron-microscope study of thin sections and negatively stained preparations of intact cells and isolated cell walls of a bacterium which is moderately resistant to ionizing radiation, Acinetobacter strain 199A, showed that it is similar to other Gram-negative bacteria except for its mode of division and for the fine structure of some of the surface layers. During division the cells form a fairly thick septum similar to those observed in Gram-positive bacteria. An examination of the appearance and chemical composition of isolated cell walls before and after treatment with enzymes, detergents and lipid solvents revealed that three layers, each with a characteristic fine structure, are present in the cell wall: (1) an outer membrane with an array of peg-like subunits; (2) a layer of wrinkled material which is digested by proteolytic enzymes; and (3) a smooth, rigid layer, which contains the mucopeptide components of the cell wall. These observations are compared with the results of other workers for various Gram-negative bacteria. From comparisons with the structure of more radiation-sensitive strains of Acinetobacter, it appears that layer (2) may be associated with the radiation resistance of the organism.

LYSOZYME SENSITIVITY OF THE CELL WALL OF PSEUDO-MONAS AERUGINOSA: FURTHER EVIDENCE FOR THE ROLE OF THE NON-PEPTIDOGLYCAN COMPONENTS IN CELL WALL RIGIDITY

1966 ◽  
Vol 12 (1) ◽  
pp. 105-108 ◽  
Author(s):  
K. Jane Carson ◽  
R. G. Eagon
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Gram Negative Bacteria ◽  
Normal Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Cell Wall Rigidity

Electron micrographs of thin sections of normal cells of Pseudomonas aeruginosa showed the cell walls to be convoluted and to be composed of two distinct layers. Electron micrographs of thin sections of lysozyme-treated cells of P. aeruginosa showed (a) that the cell walls lost much of their convoluted nature; (b) that the layers of the cell walls became diffuse and less distinct; and (c) that the cell walls became separated from the protoplasts over extensive cellular areas. These results suggest that the peptidoglycan component of the unaltered cell walls of P. aeruginosa is sensitive to lysozyme. Furthermore, it appears that the peptidoglycan component is not solely responsible for the rigidity of the cell walls of Gram-negative bacteria.

scholarly journals THE FINE STRUCTURE AND MODE OF ATTACHMENT OF THE SHEATHED FLAGELLUM OF VIBRIO METCHNIKOVII

1963 ◽  
Vol 18 (2) ◽  
pp. 327-336 ◽  
Author(s):  
Audrey M. Glauert ◽  
D. Kerridge ◽  
R. W. Horne
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Thin Sections ◽  
Basal Disc ◽  
The Core ◽  
Thin Sectioning ◽  
Potassium Phosphotungstate ◽  
Mode Of Attachment

The sheathed flagellum of Vibrio metchnikovii was chosen for a study of the attachment of the flagellum to the bacterial cell. Normal and autolysed organisms and isolated flagella were studied by electron microscopy using the techniques of thin sectioning and negative staining. The sheath of the flagellum has the same layered structure as the cell wall of the bacterium, and in favourable thin sections it appears that the sheath is a continuation of the cell wall. After autolysis the sheath is usually absent and the core of the flagellum has a diameter of 120 A. Electron micrographs of autolysed bacteria negatively stained with potassium phosphotungstate show that the core ends in a basal disc just inside the plasma membrane. The basal disc is about 350 A in diameter and is thus considerably smaller than the "basal granules" described previously by other workers.

scholarly journals Gram-positive bacteria cell wall-derived lipoteichoic acid induces inflammatory alveolar bone loss through prostaglandin E production in osteoblasts

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tsukasa Tominari ◽  
Ayumi Sanada ◽  
Ryota Ichimaru ◽  
Chiho Matsumoto ◽  
Michiko Hirata ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bone Loss ◽  
Alveolar Bone ◽  
Osteoclast Differentiation ◽  
Lipoteichoic Acid ◽  
Alveolar Bone Loss ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

AbstractPeriodontitis is an inflammatory disease associated with severe alveolar bone loss and is dominantly induced by lipopolysaccharide from Gram-negative bacteria; however, the role of Gram-positive bacteria in periodontal bone resorption remains unclear. In this study, we examined the effects of lipoteichoic acid (LTA), a major cell-wall factor of Gram-positive bacteria, on the progression of inflammatory alveolar bone loss in a model of periodontitis. In coculture of mouse primary osteoblasts and bone marrow cells, LTA induced osteoclast differentiation in a dose-dependent manner. LTA enhanced the production of PGE2 accompanying the upregulation of the mRNA expression of mPGES-1, COX-2 and RANKL in osteoblasts. The addition of indomethacin effectively blocked the LTA-induced osteoclast differentiation by suppressing the production of PGE2. Using ex vivo organ cultures of mouse alveolar bone, we found that LTA induced alveolar bone resorption and that this was suppressed by indomethacin. In an experimental model of periodontitis, LTA was locally injected into the mouse lower gingiva, and we clearly detected alveolar bone destruction using 3D-μCT. We herein demonstrate a new concept indicating that Gram-positive bacteria in addition to Gram-negative bacteria are associated with the progression of periodontal bone loss.

scholarly journals FINE STRUCTURE OF THE GRAM-NEGATIVE BACTERIUM ACETOBACTER SUBOXYDANS

1964 ◽  
Vol 20 (2) ◽  
pp. 217-233 ◽  
Author(s):  
G. W. Claus ◽  
L. E. Roth
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Walls ◽  
Negative Staining ◽  
Homogeneous Layer ◽  
Physical Treatment ◽  
Thin Sections ◽  
Gram Negative ◽  
Acetobacter Suboxydans ◽  
Negative Cell

The morphological features of the cell wall, plasma membrane, protoplasmic constituents, and flagella of Acetobacter suboxydans (ATCC 621) were studied by thin sectioning and negative staining. Thin sections of the cell wall demonstrate an outer membrane and an inner, more homogeneous layer. These observations are consistent with those of isolated, gram-negative cell-wall ghosts and the chemical analyses of gram-negative cell walls. Certain functional attributes of the cell-wall inner layer and the structural comparisons of gram-negative and gram-positive cell walls are considered. The plasma membrane is similar in appearance to the membrane of the cell wall and is occasionally found to be folded into the cytoplasm. Certain features of the protoplasm are described and discussed, including the diffuse states of the chromatinic material that appear to be correlated with the length of the cell and a polar differentiation in the area of expected flagellar attachment. Although the flagella appear hollow in thin sections, negative staining of isolated flagella does not substantiate this finding. Severe physical treatment occasionally produces a localized penetration into the central region of the flagellum, the diameter of which is much smaller then that expected from sections. A possible explanation of this apparent discrepancy is discussed.

scholarly journals General principles for the formation and proliferation of a wall-free (L-form) state in bacteria

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Romain Mercier ◽  
Yoshikazu Kawai ◽  
Jeff Errington
Keyword(s):  
Cell Wall ◽  
Molecular Biology ◽  
Gram Negative Bacteria ◽  
Systematic Analysis ◽  
Gram Negative ◽  
Membrane Blebbing ◽  
Precursor Synthesis ◽  
Peptidoglycan Cell Wall ◽  
Synthetic Cells ◽  
Opening Up

The peptidoglycan cell wall is a defining structural feature of the bacterial kingdom. Curiously, some bacteria have the ability to switch to a wall-free or ‘L-form’ state. Although known for decades, the general properties of L-forms are poorly understood, largely due to the lack of systematic analysis of L-forms in the molecular biology era. Here we show that inhibition of peptidoglycan precursor synthesis promotes the generation of L-forms from both Gram-positive and Gram-negative bacteria. We show that the L-forms generated have in common a mechanism of proliferation involving membrane blebbing and tubulation, which is dependent on an altered rate of membrane synthesis. Crucially, this mode of proliferation is independent of the essential FtsZ based division machinery. Our results suggest that the L-form mode of proliferation is conserved across the bacterial kingdom, reinforcing the idea that it could have been used in primitive cells, and opening up its use in the generation of synthetic cells.

scholarly journals Conformational changes in the peptidoglycan synthase activator LpoA are likely important for maintaining a viable cell wall in Gram-negative bacteria

2018 ◽  
Vol 74 (a1) ◽  
pp. a20-a20
Author(s):  
Mark A. Saper ◽  
Karthik Sathiyamoorthy ◽  
J Vijayalakshmi ◽  
Bhramara Tirupati ◽  
Lixin Fan
Keyword(s):  
Cell Wall ◽  
Conformational Changes ◽  
Viable Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals Lipopolysaccharide-Trap-Fc, a Multifunctional Agent To Battle Gram-Negative Bacteria

2009 ◽  
Vol 77 (7) ◽  
pp. 2925-2931 ◽  
Author(s):  
Philipp Groß ◽  
Katharina Brandl ◽  
Christine Dierkes ◽  
Jürgen Schölmerich ◽  
Bernd Salzberger ◽  
...  
Keyword(s):  
Myeloid Differentiation ◽  
Gram Negative Bacteria ◽  
Bacterial Sepsis ◽  
Tlr Signaling ◽  
Monocytic Cells ◽  
Gram Negative ◽  
The Family ◽  
Myeloid Differentiation Factor ◽  
Lps Treatment

ABSTRACT The family of Toll-like receptors (TLRs) plays a pivotal role in host defense against pathogens. However, overstimulation of these receptors may lead to uncontrolled general inflammation and eventually to systemic organ dysfunction or failure. With the intent to control overwhelming inflammation during gram-negative bacterial sepsis, we constructed soluble fusion proteins of the lipopolysaccharide (LPS)-receptor complex to modulate TLR signaling in multiple ways. The extracellular domain of mouse TLR4 and mouse myeloid differentiation factor 2 (MD-2) fusions (LPS-Trap) were linked to human immunoglobulin G Fc domains (LPS-Trap-Fc). In addition to the ability to bind LPS or gram-negative bacteria and to inhibit interleukin-6 secretion of monocytic cells after LPS treatment, LPS-Trap-Fc was able to opsonize fluorescent Escherichia coli particles. This led to enhancement of phagocytosis by monocytic cells which was strictly dependent on the presence of the Fc region. Moreover, only LPS-Trap-Fc- and not LPS-Trap-coated bacteria were sensitized to complement killing. Therefore, LPS-Trap-Fc not only neutralizes LPS but also, after binding to bacteria, enhances phagocytosis and complement-mediated killing and could thus act as a multifunctional agent to fight gram-negative bacteria in vivo.

Select Gram-negative Aerobic Bacteria

2012 ◽  
pp. 90-101
Author(s):  
David R. McNamara ◽  
Franklin R. Cockerill
Keyword(s):  
Cell Wall ◽  
Sepsis Syndrome ◽  
Vital Role ◽  
Klebsiella Pneumonia ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Neisseria Meningitides ◽  
A Cell ◽  
Normal Human ◽  
Specific Species

Gram-negative bacteria may be rod-shaped (bacilli), spherical (cocci), oval, helical, or filamentous. Cytoplasmic membrane is surrounded by a cell wall consisting of a peptidoglycan layer and an outer cell membrane. Gram-negative bacteria are widely distributed in the natural environment. They are commensals with many animals and play a vital role in normal human physiology as intestinal commensals. Gram-negative bacteria are the cause of various human illnesses. The gram-negative bacterial cell wall contains various lipopolysaccharide endotoxins. Endotoxins trigger intense inflammation and the sepsis syndrome during infection. Specific species of gram-negative bacteria such as Neisseria meningitides, Moraxella catarrhalis, Acinetobacter, Vibrio, Klebsiella pneumonia, Salmonella, Pseudomonas aeruginosa, and Haemophilus influenza are reviewed.

scholarly journals How the assembly and protection of the bacterial cell envelope depend on cysteine residues

2020 ◽  
Vol 295 (34) ◽  
pp. 11984-11994 ◽  
Author(s):  
Jean-François Collet ◽  
Seung-Hyun Cho ◽  
Bogdan I. Iorga ◽  
Camille V. Goemans
Keyword(s):  
Amino Acid ◽  
Cell Envelope ◽  
Multilayered Structure ◽  
Cysteine Residues ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Amino Acid Residues ◽  
Gram Negative ◽  
Oxidative Inactivation ◽  
Peptidoglycan Cell Wall

The cell envelope of Gram-negative bacteria is a multilayered structure essential for bacterial viability; the peptidoglycan cell wall provides shape and osmotic protection to the cell, and the outer membrane serves as a permeability barrier against noxious compounds in the external environment. Assembling the envelope properly and maintaining its integrity are matters of life and death for bacteria. Our understanding of the mechanisms of envelope assembly and maintenance has increased tremendously over the past two decades. Here, we review the major achievements made during this time, giving central stage to the amino acid cysteine, one of the least abundant amino acid residues in proteins, whose unique chemical and physical properties often critically support biological processes. First, we review how cysteines contribute to envelope homeostasis by forming stabilizing disulfides in crucial bacterial assembly factors (LptD, BamA, and FtsN) and stress sensors (RcsF and NlpE). Second, we highlight the emerging role of enzymes that use cysteine residues to catalyze reactions that are necessary for proper envelope assembly, and we also explain how these enzymes are protected from oxidative inactivation. Finally, we suggest future areas of investigation, including a discussion of how cysteine residues could contribute to envelope homeostasis by functioning as redox switches. By highlighting the redox pathways that are active in the envelope of Escherichia coli, we provide a timely overview of the assembly of a cellular compartment that is the hallmark of Gram-negative bacteria.

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