Induced morphological changes in the stainable layers of the cell envelope of a gram-negative bacterium

1972 ◽  
Vol 18 (6) ◽  
pp. 937-940
Author(s):  
J. W. Costerton ◽  
J. Thompson
Keyword(s):  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Physical Nature ◽  
Ion Concentration ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Double Track ◽  
Peptidoglycan Layer

Manipulation of ion concentration can be used to produce profound changes in the morphology of both the cytoplasmic membrane and the outer double-track layer of the cell envelope of the marine pseudomonad studied here. The fact that these layers are deformable, without any changes in the morphology of the rigid peptidoglycan layer, suggests that both have a "plastic" physical nature.

Interaction of Gram-Negative Bacteria with the Lysosomal Fraction of Polymorphonuclear Leukocytes II. Changes in the Cell Envelope of Escherichia coli

1970 ◽  
Vol 1 (3) ◽  
pp. 311-318
Author(s):  
D. Friedberg ◽  
I. Friedberg ◽  
M. Shilo
Keyword(s):  
Escherichia Coli ◽  
Polymorphonuclear Leukocytes ◽  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Lysosomal Fraction ◽  
E Coli ◽  
Absorbing Material

Interaction of lysosomal fraction with Escherichia coli caused damage to the cell envelope of these intact cells and to the cytoplasmic membrane of E. coli spheroplasts. The damage to the cytoplasmic membrane was manifested in the release of 260-nm absorbing material and β-galactosidase from the spheroplasts, and by increased permeability of cryptic cells to O -nitrophenyl-β- d -galactopyranoside; damage to the cell wall was measured by release of alkaline phosphatase. Microscope observation showed morphological changes in the cell envelope.

Ultrastructure of the cell envelope and septation process in Caryophanon latum as revealed by thin section and freeze-etching techniques

1974 ◽  
Vol 20 (10) ◽  
pp. 1435-1442 ◽  
Author(s):  
W. C. Trentini ◽  
H. E. Gilleland Jr.
Keyword(s):  
Cytoplasmic Membrane ◽  
External Surface ◽  
Cell Envelope ◽  
Optimal Conditions ◽  
Structural Detail ◽  
Cross Sectional ◽  
External Wall ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
Peptidoglycan Layer

With optimal conditions of thin-sectioning and freeze-etching, the cell wall of Caryophanon latum was composed of a thick peptidoglycan layer plus two external wall layers. The freeze-etched appearance of the external surface of the outer layer was smooth and lacked structural detail. The numerous cross septa within a trichome were formed by the symmetrical and concurrent ingrowth of the cytoplasmic membrane and the peptidoglycan layer. The site of septum initiation was identifiable by a dart-shaped ingrowth of the peptidoglycan layer rather than by the presence of a mesosome. However, small simple mesosomes were occasionally seen associated with the developing septum. The peptidoglycan in the septum had thickened to at least double the thickness of the wall peptidoglycan layer by the time of septum completion. The external wall layers did not participate in septum formation but did participate in trichome separation. The separation of the septal peptidoglycan was completed during the early ingrowth of the external wall layers. A unique cross-sectional view of a developing septum closing like an iris diaphragm as seen in a freeze-etched preparation was observed.

The effects of phospholipid depletion on the cleavage pattern of the cell walls of frozen Gram-negative bacteria

1973 ◽  
Vol 19 (8) ◽  
pp. 1056-1057 ◽  
Author(s):  
A. Forge ◽  
J. W. Costerton
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Gram Negative Bacteria ◽  
Cleavage Pattern ◽  
Gram Negative ◽  
Whole Cells ◽  
The Cross ◽  
Double Track ◽  
Chloroform Methanol

Extraction of whole cells of the marine pseudomonad (B-16) with chloroform–methanol causes the disappearance of the cleavage planes, and the cross-sectioned profile of both the cytoplasmic membrane and the double-track layer of the cell wall.

scholarly journals The Rcs Phosphorelay Is a Cell Envelope Stress Response Activated by Peptidoglycan Stress and Contributes to Intrinsic Antibiotic Resistance

2008 ◽  
Vol 190 (6) ◽  
pp. 2065-2074 ◽  
Author(s):  
Mary E. Laubacher ◽  
Sarah E. Ades
Keyword(s):  
Outer Membrane ◽  
Single Molecule ◽  
Stress Responses ◽  
Structural Integrity ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
Envelope Stress ◽  
Peptidoglycan Layer

ABSTRACTGram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth, new peptidoglycan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identifyEscherichia colistress responses activated following inhibition of specific PBPs by the β-lactam antibiotics amdinocillin (mecillinam) and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance ofE. colito β-lactam antibiotics.

Physiological and morphological effects of phenethyl alcohol upon a gram-negative marine pseudomonad

1972 ◽  
Vol 18 (6) ◽  
pp. 841-852 ◽  
Author(s):  
J. Thompson ◽  
I. W. DeVoe
Keyword(s):  
Structural Changes ◽  
Cytoplasmic Membrane ◽  
Cell Envelope ◽  
Gram Negative ◽  
Phenethyl Alcohol ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Uptake Medium ◽  
Subsequent Addition ◽  
Acid Exchange

Phenethyl alcohol (PEA) at 0.15% (v/v) inhibited the growth of a gram-negative marine pseudomonad. After removal of the alcohol, the cells remained viable even when pre-exposed to PEA concentrations as high as 0.25% (v/v). Phenethyl alcohol inhibited uptake of α-aminoisobutyric acid (AIB) and also prevented amino acid exchange. At PEA concentrations of 0.25% or less, inhibition of AIB uptake was completely reversible and, provided K+ was added to the uptake medium, the treated cells could accumulate AIB to the same extent as control cells. If K+ was omitted from the medium, the capacity of the cells to accumulate AIB was found to be proportional to the length of time that the cells had been exposed to the alcohol. Phenethyl alcohol caused a rapid efflux of intracellular K+ and AIB-14C from previously loaded cells, and such cells were noticeably smaller than normal cells and had a plasmolyzed or irregular outline when observed by phase contrast. Thin section electron microscopy, and freeze-etch studies, showed that the plasmolyzed appearance of these cells was due to local invagination of the cytoplasmic membrane. After removal of the alcohol, the subsequent addition of K+ to the incubation medium caused the cells to become deplasmolyzed. It seems likely that the inhibition of cell growth by PEA is due to two major causes: (1) direct interference of the compound with the normal physiological functions of the cytoplasmic membrane and, (2) PEA induced structural changes occurring within the cell envelope.

scholarly journals Mechanical penetration of β-lactam–resistant Gram-negative bacteria by programmable nanowires

2020 ◽  
Vol 6 (27) ◽  
pp. eabb9593 ◽  
Author(s):  
Lizhi Liu ◽  
Sheng Chen ◽  
Xu Zhang ◽  
Zhenjie Xue ◽  
Shengjie Cui ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Cell Envelope ◽  
Treatment Strategies ◽  
Physical Nature ◽  
Cell Stiffness ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Peptidoglycan Biosynthesis ◽  
Poor Understanding ◽  
Novel Treatment Strategies

β-Lactam–resistant (BLR) Gram-negative bacteria that are difficult or impossible to treat are causing a global health threat. However, the development of effective nanoantibiotics is limited by the poor understanding of changes in the physical nature of BLR Gram-negative bacteria. Here, we systematically explored the nanomechanical properties of a range of Gram-negative bacteria (Salmonella, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) with different degrees of β-lactam resistance. Our observations indicated that the BLR bacteria had cell stiffness values almost 10× lower than that of β-lactam–susceptible bacteria, caused by reduced peptidoglycan biosynthesis. With the aid of numerical modeling and experimental measurements, we demonstrated that these stiffness findings can be used to develop programmable, stiffness-mediated antimicrobial nanowires that mechanically penetrate the BLR bacterial cell envelope. We anticipate that these stiffness-related findings will aid in the discovery and development of novel treatment strategies for BLR Gram-negative bacterial infections.

Preparation and chemical properties of the outer membrane of a moderately halophilic gram-negative bacterium

1976 ◽  
Vol 22 (5) ◽  
pp. 731-740 ◽  
Author(s):  
T. Hiramatsu ◽  
T. Yokoyama ◽  
Y. Ohno ◽  
I. Yano ◽  
M. Masui ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Sucrose Solution ◽  
Cell Envelope ◽  
Buoyant Density ◽  
Chemical Properties ◽  
Negative Bacterium ◽  
Unidentified Phospholipid ◽  
Gram Negative ◽  
Moderately Halophilic ◽  
Ethanolamine Phosphatidyl

Outer membranes, almost free from peptidoglycan components, were prepared from a moderately halophilic gram-negative bacterium grown in a medium containing 2 M NaCl. The outer membrane was easily released, leaving mureinoplasts, by mild desalting in a 20% sucrose solution containing 50 mM tris(hydroxymethyl)aminomethane-HCl buffer, pH 7.8. The membrane was recovered by treatment with DNase I and CsCl buoyant density centrifugation.Chemical analyses revealed that the outer membrane was mainly composed of 31% protein, about 20% extractable lipids (mainly phospholipids), and lipopolysaccharides. The proteins had about 18 mol% excess of acidic over basic amino acids. The phospholipids comprised phosphatidyl ethanolamine, phosphatidyl glycerol, cardiolipin, and an unidentified phospholipid containing glucose, which seemed mainly associated with the outer membrane. The content of lipopolysaccharides in the outer membrane was calculated arbitrarily as 30% from the heptose content. A unique feature of these lipopolysaccharides seemed to be a higher lipid content than found in lipopolysaccharides of other gram-negative bacteria. The major fatty acids of bound lipids of the outer membrane resembled those of the lipopolysaccharides obtained from cell envelope preparation and contained high concentrations of 3-hydroxy lauric acid.

scholarly journals Interrupting Biosynthesis of O Antigen or the Lipopolysaccharide Core Produces Morphological Defects in Escherichia coli by Sequestering Undecaprenyl Phosphate

2016 ◽  
Vol 198 (22) ◽  
pp. 3070-3079 ◽  
Author(s):  
Matthew A. Jorgenson ◽  
Kevin D. Young
Keyword(s):  
Escherichia Coli ◽  
Cell Envelope ◽  
Negative Bacterium ◽  
Core Oligosaccharide ◽  
Gram Negative ◽  
Content Type ◽  
O Antigen ◽  
Dead End ◽  
Morphological Defects ◽  
Undecaprenyl Phosphate

ABSTRACTUndecaprenyl phosphate (Und-P) is a member of the family of essential polyprenyl phosphate lipid carriers and in the Gram-negative bacteriumEscherichia coliis required for synthesizing the peptidoglycan (PG) cell wall, enterobacterial common antigen (ECA), O antigen, and colanic acid. Previously, we found that interruption of ECA biosynthesis indirectly alters PG synthesis by sequestering Und-P via dead-end intermediates, causing morphological defects. To determine if competition for Und-P was a more general phenomenon, we determined if O-antigen intermediates caused similar effects. Indeed, disrupting the synthesis of O antigen or the lipopolysaccharide core oligosaccharide induced cell shape deformities, which were suppressed by preventing the initiation of O-antigen biosynthesis or by manipulating Und-P metabolism. We conclude that accumulation of O-antigen intermediates alters PG synthesis by sequestering Und-P. Importantly, many previous experiments addressed the physiological functions of various oligosaccharides and glycoconjugates, but these studies employed mutants that accumulate deleterious intermediates. Thus, conclusions based on these experiments must be reevaluated to account for possible indirect effects of Und-P sequestration.IMPORTANCEBacteria use long-chain isoprenoids like undecaprenyl phosphate (Und-P) as lipid carriers to assemble numerous glycan polymers that comprise the cell envelope. In any one bacterium, multiple oligosaccharide biosynthetic pathways compete for a common pool of Und-P, which means that disruptions in one pathway may produce secondary consequences that affect the others. Using the Gram-negative bacteriumEscherichia colias a model, we demonstrate that interruption of the biogenesis of O antigen, a major outer membrane component, indirectly impairs peptidoglycan synthesis by sequestering Und-P into dead-end intermediates. These results strongly argue that the functions of many Und-P-utilizing pathways must be reevaluated, because much of our current understanding is based on experiments that did not control for these unintended secondary effects.

The isolation and characterisation of cytoplasmic and outer membranes from Micrococcus cryophilus

1984 ◽  
Vol 30 (11) ◽  
pp. 1357-1366 ◽  
Author(s):  
Geoffrey M. Lloyd ◽  
Nicholas J. Russell
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Outer Membrane ◽  
Cytoplasmic Membrane ◽  
Phospholipid Composition ◽  
Marker Enzymes ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Outer Membranes ◽  
Phospholipid Classes

The cytoplasmic and outer membranes of the Gram-negative bacterium, Micrococcus cryophilus, have been separated and purified. Both membrane preparations consist of a mixture of closed and apparently open vesicles, which vary in size but those of the outer membrane are on average 1.5 times the diameter of those of the cytoplasmic membrane. The membranes were characterised by their 2-keto-3-deoxyoctonate content and the activity of marker enzymes. There are gross differences in the protein and phospholipid composition of the two membranes. The outer membrane contains three major polypeptides, whereas the cytoplasmic membrane has many more. In addition the outer membrane is enriched in cardiolipin, at the expense of phosphatidylglycerol and phosphatidylethanolamine, relative to the cytoplasmic membrane. There are no significant differences in the fatty acid composition of the phospholipid classes, but all phospholipids of the outer membrane were slightly more saturated than those of the cytoplasmic membrane. Wax esters are present in both cytoplasmic and outer membranes. The significance of these findings is discussed in relation to known differences in the fluidity of the cytoplasmic and outer membranes in M. cryophilus and the specialized roles these membranes play.

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