scholarly journals A CYTOCHEMICAL LOCALIZATION OF REDUCTIVE SITES IN A GRAM-POSITIVE BACTERIUM

1964 ◽  
Vol 20 (3) ◽  
pp. 361-375 ◽  
Author(s):  
Woutera van Iterson ◽  
W. Leene
Keyword(s):  
Plasma Membrane ◽  
Cell Periphery ◽  
Gram Positive ◽  
Cytochemical Localization ◽  
Potassium Tellurite ◽  
Thin Sections ◽  
Gram Positive Bacteria ◽  
Cytoplasmic Membranes ◽  
Reducing Activity ◽  
The One

In bacteria the exact location of a respiratory enzyme system comparable to that of the mitochondria of other cells has remained uncertain. On the one hand, the existence of particulate "bacterial mitochondria" has been advocated (Mudd); on the other hand, important enzymes of the respiratory chain were recovered in the cytoplasmic membranes associated with some granular material (Weibull). In order to gain insight into this question, sites of reducing activity were localized in thin sections of bacteria using the reduction of potassium tellurite as an indicator. When this salt was added to the culture medium of Bacillus subtilis, it turned out that in this Gram-positive organism the reduced product is strictly bound at two sites, and that the plasma membrane does not materially gain in electron opacity through deposition of the reduced product. The reduction product is found on or in the membranes of particular organelles, which may possibly be regarded as the mitochondrial equivalents in Gram-positive bacteria, and which are sometimes seen connected to the plasma membrane. The second location is in thin rod-like elements at the cell periphery, possibly the sites from which the flagella emerge.

Microanatomy of the Periplasm of Bacillus Licheniformis

1971 ◽  
Vol 29 ◽  
pp. 262-263
Author(s):  
B.K. Ghosh
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacillus Licheniformis ◽  
External Environment ◽  
Permeability Barrier ◽  
Periplasmic Space ◽  
Modified Technique ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.

scholarly journals Granular Layer in the Periplasmic Space of Gram-Positive Bacteria and Fine Structures of Enterococcus gallinarum and Streptococcus gordonii Septa Revealed by Cryo-Electron Microscopy of Vitreous Sections

2006 ◽  
Vol 188 (18) ◽  
pp. 6652-6660 ◽  
Author(s):  
Benoît Zuber ◽  
Marisa Haenni ◽  
Tânia Ribeiro ◽  
Kathrin Minnig ◽  
Fátima Lopes ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Granular Layer ◽  
Streptococcus Gordonii ◽  
Periplasmic Space ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Cryo Electron Microscopy ◽  
Enterococcus Gallinarum ◽  
Peptidoglycan Layer

ABSTRACT High-resolution structural information on optimally preserved bacterial cells can be obtained with cryo-electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteria Bacillus subtilis and Staphylococcus aureus was recently shown. This raises questions about the mode of polymerization of peptidoglycan. In the present study, we report the structure of the cell envelope of three gram-positive bacteria (B. subtilis, Streptococcus gordonii, and Enterococcus gallinarum). In the three cases, a previously undescribed granular layer adjacent to the plasma membrane is found in the periplasmic space. In order to better understand how nascent peptidoglycan is incorporated into the mature peptidoglycan, we investigated cellular regions known to represent the sites of cell wall production. Each of these sites possesses a specific structure. We propose a hypothetic model of peptidoglycan polymerization that accommodates these differences: peptidoglycan precursors could be exported from the cytoplasm to the periplasmic space, where they could diffuse until they would interact with the interface between the granular layer and the thick peptidoglycan layer. They could then polymerize with mature peptidoglycan. We report cytoplasmic structures at the E. gallinarum septum that could be interpreted as cytoskeletal elements driving cell division (FtsZ ring). Although immunoelectron microscopy and fluorescence microscopy studies have demonstrated the septal and cytoplasmic localization of FtsZ, direct visualization of in situ FtsZ filaments has not been obtained in any electron microscopy study of fixed and dehydrated bacteria.

scholarly journals Alanyl-Phosphatidylglycerol and Lysyl-Phosphatidylglycerol Are Translocated by the Same MprF Flippases and Have Similar Capacities To Protect against the Antibiotic Daptomycin in Staphylococcus aureus

2012 ◽  
Vol 56 (7) ◽  
pp. 3492-3497 ◽  
Author(s):  
Christoph J. Slavetinsky ◽  
Andreas Peschel ◽  
Christoph M. Ernst
Keyword(s):  
Staphylococcus Aureus ◽  
Deletion Mutant ◽  
Wild Type ◽  
Gram Positive ◽  
Content Type ◽  
Wild Type Level ◽  
Bacterial Membranes ◽  
Gram Positive Bacteria ◽  
Cytoplasmic Membranes ◽  
Simultaneous Expression

ABSTRACTThe lysinylation of negatively charged phosphatidylglycerol by MprF proteins reduces the affinity of cationic antimicrobial peptides (CAMPs) for bacterial cytoplasmic membranes and reduces the susceptibility of several Gram-positive bacterial pathogens to CAMPs. MprF ofStaphylococcus aureusencompasses a lysyl-phosphatidylglycerol (Lys-PG) synthase and a Lys-PG flippase domain. In contrast,Clostridium perfringensencodes two MprF homologs which specifically synthesize alanyl-phosphatidylglycerol (Ala-PG) or Lys-PG, while only the Lys-PG synthase is fused to a putative flippase domain. It remains unknown whether cationic Lys-PG and zwitterionic Ala-PG differ in their capacities to be translocated by MprF flippases and if both can reduce CAMP susceptibility in Gram-positive bacteria. By expressing the MprF proteins ofC. perfringensin anS. aureus mprFdeletion mutant, we found that both lipids can be efficiently produced inS. aureus. Simultaneous expression of the Lys-PG and Ala-PG synthases led to the production of both lipids and slightly increased the overall amounts of aminoacyl phospholipids. Ala-PG production by the correspondingC. perfringensenzyme did not affect susceptibility to CAMPs such as nisin and gallidermin or to the CAMP-like antibiotic daptomycin. However, coexpression of the Ala-PG synthase with flippase domains of Lys-PG synthesizing MprF proteins led to a wild-type level of daptomycin susceptibility, indicating that Ala-PG can also protect bacterial membranes against daptomycin and suggesting that Lys-PG flippases can also translocate the related lipid Ala-PG. Thus, bacterial aminoacyl phospholipid flippases exhibit more relaxed substrate specificity and Ala-PG and Lys-PG are more similar in their capacities to modulate membrane functions than anticipated.

scholarly journals Physicochemical Properties That Enhance Discriminative Antibacterial Activity of Short Dermaseptin Derivatives

2006 ◽  
Vol 50 (8) ◽  
pp. 2666-2672 ◽  
Author(s):  
Shahar Rotem ◽  
Inna Radzishevsky ◽  
Amram Mor
Keyword(s):  
Antimicrobial Peptides ◽  
Physicochemical Properties ◽  
Culture Media ◽  
Gram Negative Bacteria ◽  
Terminal Sequence ◽  
Binding Properties ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Cytoplasmic Membranes

ABSTRACT Antimicrobial peptides are widely believed to exert their effects by nonspecific mechanisms. We assessed the extent to which physicochemical properties can be exploited to promote discriminative activity by manipulating the N-terminal sequence of the 13-mer dermaseptin derivative K4-S4(1-13) (P). Inhibitory activity determined in culture media against 16 strains of bacteria showed that when its hydrophobicity and charge were changed, P became predominantly active against either gram-positive or gram-negative bacteria. Thus, conjugation of various aminoacyl-lysin moieties (e.g., aminohexyl-K-P) led to inactivity against gram-positive bacteria (MIC50 > 50 μM) but potent activity against gram-negative bacteria (MIC50, 6.2 μM). Conversely, conjugation of equivalent acyls to the substituted analog M4-S4(1-13) (e.g., hexyl-M4-P) led to inactivity against gram-negative bacteria (MIC50 > 50 μM) but potent activity against gram-positive bacteria (MIC50, 3.1 μM). Surface plasmon resonance experiments, used to investigate peptides' binding properties to lipopolysaccharide-containing idealized phospholipid membranes, suggest that although the acylated derivatives have increased lipophilic properties with parallel antibacterial behavior, hydrophobic derivatives are prevented from reaching the cytoplasmic membranes of gram-negative bacteria. Moreover, unlike modifications that enhanced the activity against gram-positive bacteria, which also enhanced hemolysis, we found that modifications that enhanced activity against gram-negative bacteria generally reduced hemolysis. Thus, compared with the clinically tested peptides MSI-78 and IB-367, the dermaseptin derivative aminohexyl-K-P performed similarly in terms of potency and bactericidal kinetics but was significantly more selective in terms of discrimination between bacteria and human erythrocytes. Overall, the data suggest that similar strategies maybe useful to derive potent and safe compounds from known antimicrobial peptides.

Bactericidal effect of gentamicin-induced membrane vesicles derived fromPseudomonas aeruginosaPAO1 on gram-positive bacteria

2002 ◽  
Vol 48 (9) ◽  
pp. 810-820 ◽  
Author(s):  
Kelly L MacDonald ◽  
Terry J Beveridge
Keyword(s):  
Electron Microscopy ◽  
Therapeutic Potential ◽  
Hydrophobic Interaction Chromatography ◽  
Membrane Vesicles ◽  
Bactericidal Effect ◽  
Gram Positive ◽  
Thin Sections ◽  
Gram Negative ◽  
Induced Membrane ◽  
Gram Positive Bacteria

Previous studies have shown that gentamicin-induced membrane vesicles (g-MVs) from Pseudomonas aeruginosa PAO1 possess both the antibiotic (gentamicin) and a potent peptidoglycan hydrolase (PGase; autolysin) that is effective in killing gram-negative pathogens. This present study evaluated the therapeutic potential of g-MVs against four gram-positive bacteria. Bactericidal assays and electron microscopy of thin sections revealed that Bacillus subtilis 168 and Staphylococcus aureus D2C were susceptible to killing mediated by g-MVs, Listeria monocytogenes ATCC 19113 was slightly susceptible, whereas Enterococcus hirae ATCC 9790 was unaffected. g-MVs were generally more effective against the bacteria than was soluble gentamicin, suggesting they could have more killing power than natural membrane vesicles containing no antibiotic. Electron microscopy and hydrophobic interaction chromatography showed that more membrane vesicles (MVs) initially attached to B. subtilis (hydrophilic) than to predominantly hydrophobic E. hirae, L. monocytogenes, and S. aureus. Zymograms containing murein sacculi as an enzyme substrate illustrated that all organisms except E. hirae were sensitive to the 26-kDa autolysin to varying degrees. Peptidoglycan O-acetylation did not influence susceptibility to MV-mediated lysis. Though not universally effective, the g-MV delivery system remains a promising therapeutic alternative for specific gram-positive infections.Key words: gram-negative membrane vesicles, gentamicin, autolysin.

scholarly journals A CYTOCHEMICAL LOCALIZATION OF REDUCTIVE SITES IN A GRAM-NEGATIVE BACTERIUM

1964 ◽  
Vol 20 (3) ◽  
pp. 377-387 ◽  
Author(s):  
Woutera van Iterson ◽  
W. Leene
Keyword(s):  
Plasma Membrane ◽  
Electron Scattering ◽  
Gram Negative Bacteria ◽  
Proteus Vulgaris ◽  
Electron Microscopic ◽  
Cytochemical Localization ◽  
Gram Negative ◽  
Living State ◽  
Granular Matrix ◽  
Reducing Activity

In order to obtain information on the exact location of the respiratory enzyme chain in Gram-negative bacteria, an electron microscopic study was made of the sites of reducing activity of cells that had, in the living state, incorporated tellurite. In the test object Proteus vulgaris, the reduced tellurite was found to be deposited in bodies contiguous with the plasma membrane but different in structure from those described in the Gram-positive Bacillus subtilis (2). In fact, the bodies proved to consist of a conglomerate of elements which contained the strongly electron-scattering reduced tellurite and a delicately granular "matrix." A limiting membrane was not observed around these complexes. In serial sections details of the complexes are illustrated. Reduced tellurite was not deposited in the plasma membrane to any important degree. Since no other sites of deposition of the reduced product were revealed, it is assumed that the complexes represent the mitochondrial equivalents in the investigated organism. In addition, the bodies might function as the basal granules of the flagella.

scholarly journals Tellurite reduction test to aid in the recognition of Corynebacterium vaginale

1977 ◽  
Vol 5 (3) ◽  
pp. 375-377
Author(s):  
R F Smith ◽  
J L Voss ◽  
R K Bailey
Keyword(s):  
Aqueous Solution ◽  
Vaginal Discharge ◽  
Gram Positive ◽  
Potassium Tellurite ◽  
Gram Positive Bacteria ◽  
Reduction Test ◽  
Presumptive Identification ◽  
Fermenting Bacteria ◽  
Tellurite Reduction ◽  
Starch Agar

Corynebacterium vaginale (Haemophilus vaginalis) does not reduce potassium tellurite. When a 1% aqueous solution of tellurite is added to starch agar plates previously inoculated with vaginal discharge material, other starch-fermenting and most non-starch-fermenting bacteria rapidly reduce tellurite to produce black or gray colonies. This test is a useful adjunct to methods for rapid presumptive identification of C. vaginale. C. vaginale is more susceptible to tellurite inhibition than a variety of other gram-positive bacteria.

Mesosome-like Structures in a Blue-green Alga, Phormidium Luridum

1970 ◽  
Vol 28 ◽  
pp. 180-181
Author(s):  
Mercedes R. Edwards
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Dna Replication ◽  
Green Alga ◽  
Photosynthetic Bacteria ◽  
Blue Green Alga ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Lamellar Structures ◽  
Septum Formation

The invagination of the plasma membrane (plasmalemma) to form vesicular or lamellar structures, usually called mesosomes (l) or plasmalemmosomes (2), has been extensively documented in bacteria (3) and more recently also in lower eucaryotes (e.g., the fungi, 4). Such structures have “been implicated in septum formation (i.e., cell division of gram-positive bacteria), in respiratory reactions, and in DNA replication.In photosynthetic bacteria, such as Rhodospirilium rubrum, vesicular structures derived from the plasma membrane were shown by Drews and Giesbrecht (5) to give rise to thylakoids (photosynthetic vesicles or chromatophores). Continuation between the plasma and thylakoidal membranes is readily seen in R. rubrum (6).

Fate of the plasma membrane of Saccharomyces cerevisiae during cell rupture

1973 ◽  
Vol 19 (2) ◽  
pp. 285-290 ◽  
Author(s):  
J. Dubé ◽  
G. Setterfield ◽  
G. Kiss ◽  
C. V. Lusena
Keyword(s):  
Plasma Membrane ◽  
Polyacrylamide Gel Electrophoresis ◽  
Outer Wall ◽  
Yeast Cells ◽  
Wall Material ◽  
Physical Damage ◽  
Intact Cells ◽  
Thin Sections ◽  
Cytoplasmic Membranes ◽  
Mitochondrial Origin

Intact and homogenized yeast cells were studied in thin sections in the electron microscope to determine the fate of the plasma membrane during fractionation. Intact cells possess a unit-membrane plasma membrane closely appressed to the cell wall. After even slight physical damage following limited homogenization in dilute buffer, the plasma membrane collapses away from the wall while the intra-cytoplasmic membranes (ER, vacuolar, nuclear, mitochondrial) dilate and vesiculate. With prolonged homogenization, the plasma membrane fragments and vesiculates and becomes indistinguishable from the remains of the other membranes. Washed wall fractions consist of wall fragments with entrapped vesicles derived from all cellular membranes. Exhaustive digestion of the wall fraction with snail gut enzymes liberates some of the trapped vesicles and results in an undigested, non-membranous, inner layer of wall partially contaminated with outer wall material. Polyacrylamide gel electrophoresis indicates that proteins of the wall "membranes" are partially of mitochondrial origin.

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