Structure, partial elemental composition, and size of Thiopedia rosea cells and platelets

1986 ◽  
Vol 32 (7) ◽  
pp. 607-610 ◽  
Author(s):  
René Scherrer ◽  
Vivion E. Shull
Keyword(s):  
Cell Envelope ◽  
Membrane Vesicles ◽  
Gas Vesicles ◽  
Intracytoplasmic Membrane ◽  
Purple Sulfur Bacterium ◽  
Large Size ◽  
Eutrophic Water ◽  
Flat Shape ◽  
Sulfur Globules ◽  
Gas Vacuole

The phototrophic purple sulfur bacterium Thiopedia rosea forms multicellular, gas-vacuolate, regular, flat aggregates (platelets, sheets) held together by slime. Platelets found in eutrophic water consisted of slime (85% of the total wet volume) and 16 cells, while the gas-filled vacuole occupied 44% of the volume of a single wet cell. Individual platelet cells contained central spindle-shaped gas vesicles (which together constitute the cell's gas vacuole), intracytoplasmic membrane vesicles (chromatophores), and peripheral sulfur globules. Cells were surrounded by a Gram-negative type cell envelope and were connected to neighboring cells of the same platelet by mostly unstructured slime. Cells contained detectable amounts of magnesium, phosphorus, sulfur, and potassium as determined by wavelength-dispersive X-ray microanalysis. The large size and relatively low slime density of the platelet, as well as the flat shape, could greatly decrease platelet sedimentation and so stabilize the position of T. rosea within its water column.

scholarly journals Antilisterial Activity of Peptide AS-48 and Study of Changes Induced in the Cell Envelope Properties of an AS-48-Adapted Strain ofListeria monocytogenes

1999 ◽  
Vol 65 (2) ◽  
pp. 618-625 ◽  
Author(s):  
Fátima Mendoza ◽  
Mercedes Maqueda ◽  
Antonio Gálvez ◽  
Manuel Martínez-Bueno ◽  
Eva Valdivia
Keyword(s):  
Cell Wall ◽  
Cell Envelope ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Wild Type ◽  
Intracytoplasmic Membrane ◽  
Highly Active ◽  
Bactericidal Effects ◽  
Cytoplasmic Content ◽  
Oflisteria Monocytogenes

ABSTRACT The peptide AS-48 is highly active on all Listeriaspecies. It has a bactericidal and bacteriolytic mode of action onListeria monocytogenes CECT 4032, causing depletion of the membrane electrical potential and pH gradient. The producer strainEnterococcus faecalis A-48-32, releases sufficient amounts of AS-48 into the growth medium to suppress L. monocytogenes in cocultures at enterococcus-to-listeria ratios above 1 at 37°C or above 10 at 15°C. As the temperature decreases, the bactericidal effects of AS-48 are less pronounced, but at 2.5 μg/ml it still can inhibit the growth of listeria at 6°C. AS-48 is highly active on liquid cultures, although concentrations above 0.2 μg/ml are required to avoid adaptation of listeria. AS-48-adapted cells can be selected at low (but still inhibitory) concentrations, and they can be inhibited completely by AS-48 at 0.5 μg/ml. The adaptation is lost gradually upon repeated subcultivation. AS48ad cells are cross-resistant to nisin and show an increased resistance to muramidases. Their fatty acid composition is modified: they show a much higher proportion of branched fatty acids as well as a higher C15:0 An-to-C17:0 An ratio. Resistance to AS-48 is also maintained by protoplasts from AS48ad cells. Electron microscopy observations show that the cell wall of AS48ad cells is thicker and less dense. The structure of wild-type cells is severely modified after AS-48 treatment: the cell wall and the cytoplasmic membrane are disorganized, and the cytoplasmic content is lost. Intracytoplasmic membrane vesicles are also observed when the wild-type strain is treated with high AS-48 concentrations.

scholarly journals Antibiotic action revealed by real-time imaging of the mycobacterial membrane

2022 ◽  
Author(s):  
Michael G. Wuo ◽  
Charles L Dulberger ◽  
Robert A. Brown ◽  
Alexander Sturm ◽  
Eveline Ultee ◽  
...  
Keyword(s):  
Real Time ◽  
Immune Modulation ◽  
Cell Envelope ◽  
Membrane Vesicles ◽  
Time Lapse ◽  
Outer Membrane Vesicles ◽  
Imaging Data ◽  
Minimal Cell ◽  
Mycobacterial Cell ◽  
Cellular Phenotypes

The current understanding of mycobacterial cell envelope remodeling in response to antibiotics is limited. Chemical tools that report on phenotypic changes with minimal cell wall perturbation are critical to gaining insight into this time-dependent phenomenon. Herein we describe a fluorogenic chemical probe that reports on mycobacterial cell envelope assembly in real time. We used time-lapse microscopy to reveal distinct spatial and temporal changes in the mycobacterial membrane upon treatment with frontline antibiotics. Differential antibiotic treatment elicited unique cellular phenotypes, providing a platform for monitoring cell envelope construction and remodeling responses simultaneously. Analysis of the imaging data indicates a role for antibiotic-derived outer membrane vesicles in immune modulation.

scholarly journals Bacterial flagellar motor

2008 ◽  
Vol 41 (2) ◽  
pp. 103-132 ◽  
Author(s):  
Yoshiyuki Sowa ◽  
Richard M. Berry
Keyword(s):  
Single Molecule ◽  
Cell Envelope ◽  
Molecular Motor ◽  
Motive Force ◽  
Flagellar Motor ◽  
Large Size ◽  
Structural Details ◽  
Bacterial Flagellar Motor ◽  
And Function ◽  
Rotary Motor

AbstractThe bacterial flagellar motor is a reversible rotary nano-machine, about 45 nm in diameter, embedded in the bacterial cell envelope. It is powered by the flux of H+or Na+ions across the cytoplasmic membrane driven by an electrochemical gradient, the proton-motive force or the sodium-motive force. Each motor rotates a helical filament at several hundreds of revolutions per second (hertz). In many species, the motor switches direction stochastically, with the switching rates controlled by a network of sensory and signalling proteins. The bacterial flagellar motor was confirmed as a rotary motor in the early 1970s, the first direct observation of the function of a single molecular motor. However, because of the large size and complexity of the motor, much remains to be discovered, in particular, the structural details of the torque-generating mechanism. This review outlines what has been learned about the structure and function of the motor using a combination of genetics, single-molecule and biophysical techniques, with a focus on recent results and single-molecule techniques.

scholarly journals Immunocytochemical Localization of a Calmodulinlike Protein in Bacillus subtilis Cells

1999 ◽  
Vol 181 (15) ◽  
pp. 4605-4610 ◽  
Author(s):  
Delfina C. Dominguez ◽  
Hank Adams ◽  
James H. Hageman
Keyword(s):  
Bacillus Subtilis ◽  
Cellular Localization ◽  
Time Course ◽  
Cell Envelope ◽  
Membrane Vesicles ◽  
Cross Reactivity ◽  
Bovine Brain ◽  
Ruthenium Red ◽  
Thin Sections ◽  
Calcium Ion Transport

ABSTRACT To determine possible functions of the calmodulinlike protein ofBacillus subtilis, the time course of its expression during sporulation and its cellular localization were studied. The protein was expressed in a constitutive manner from the end of logarithmic growth through 8 h of sporulation as determined by antibody cross-reactivity immunoblots and enzyme-linked immunosorbent assays (ELISAs). In partially purified extracts, the immunopositive protein comigrated upon electrophoresis with a protein which selectively bound [45Ca]CaCl2, ruthenium red, and Stains-all. Previous studies showed increased extractability of the calmodulinlike protein from B. subtilis cells when urea and 2-mercaptoethanol were used in breakage buffers, implying that the protein might be partially associated with the membrane fraction. This was confirmed by demonstrating that isolated membrane vesicles ofB. subtilis also gave positive immunological tests with Western blotting and ELISAs. To more precisely locate the protein in cells, thin sections of late-log-phase cells, sporulating cells, and free spores were reacted first with bovine brain anticalmodulin specific antibodies and then with gold-conjugated secondary antibodies; the thin sections were examined by transmission electron microscopy. The calmodulinlike protein was found almost exclusively associated with the cell envelope of these fixed, sectioned cells. A possible function of the calmodulinlike protein in sensing calcium ions or regulating calcium ion transport is suggested.

Membrane vesicles, nanopods and/or nanotubes produced by hyperthermophilic archaea of the genus Thermococcus

2013 ◽  
Vol 41 (1) ◽  
pp. 436-442 ◽  
Author(s):  
Evelyne Marguet ◽  
Marie Gaudin ◽  
Emilie Gauliard ◽  
Isabelle Fourquaux ◽  
Stephane le Blond du Plouy ◽  
...  
Keyword(s):  
Cellular Networks ◽  
Culture Medium ◽  
Cell Envelope ◽  
Protein A ◽  
Peptide Binding ◽  
Membrane Vesicles ◽  
Hyperthermophilic Archaea ◽  
Eukaryotic Cells ◽  
Major Protein ◽  
Tubular Structures

Thermococcus species produce MVs (membrane vesicles) into their culture medium. These MVs are formed by a budding process from the cell envelope, similar to ectosome formation in eukaryotic cells. The major protein present in MVs of Thermococci is a peptide-binding receptor of the OppA (oligopeptide-binding protein A) family. In addition, some of them contain a homologue of stomatin, a universal membrane protein involved in vesiculation. MVs produced by Thermococcus species can recruit endogenous or exogenous plasmids and plasmid transfer through MVs has been demonstrated in Thermococcus kodakaraensis. MVs are frequently secreted in clusters surrounded by S-layer, producing either big protuberances (nanosphere) or tubular structures (nanotubes). Thermococcus gammatolerans and T. kodakaraensis produce nanotubes containing strings of MVs, resembling the recently described nanopods in bacteria, whereas Thermococcus sp. 5-4 produces filaments whose internal membrane is continuous. These nanotubes can bridge neighbouring cells, forming cellular networks somehow resembling nanotubes recently observed in Firmicutes. As suggested for bacteria, archaeal nanopods and/or nanotubes could be used to expand the metabolic sphere around cells and/or to promote intercellular communication.

scholarly journals The Mechanism behind Bacterial Lipoprotein Release: Phenol-Soluble Modulins Mediate Toll-Like Receptor 2 Activation via Extracellular Vesicle Release from Staphylococcus aureus

mBio ◽  
2018 ◽  
Vol 9 (6) ◽  
Author(s):  
Katja Schlatterer ◽  
Christian Beck ◽  
Dennis Hanzelmann ◽  
Marco Lebtig ◽  
Birgit Fehrenbacher ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cytoplasmic Membrane ◽  
Cell Envelope ◽  
Membrane Vesicles ◽  
Extracellular Vesicle ◽  
Host Cells ◽  
Bacterial Cells ◽  
Toll Like Receptor ◽  
Vesicle Release ◽  
Content Type

ABSTRACT The innate immune system uses Toll-like receptor (TLR) 2 to detect conserved bacterial lipoproteins of invading pathogens. The lipid anchor attaches lipoproteins to the cytoplasmic membrane and prevents their release from the bacterial cell envelope. How bacteria release lipoproteins and how these molecules reach TLR2 remain unknown. Staphylococcus aureus has been described to liberate membrane vesicles. The composition, mode of release, and relevance for microbe-host interaction of such membrane vesicles have remained ambiguous. We recently reported that S. aureus can release lipoproteins only when surfactant-like small peptides, the phenol-soluble modulins (PSMs), are expressed. Here we demonstrate that PSM peptides promote the release of membrane vesicles from the cytoplasmic membrane of S. aureus via an increase in membrane fluidity, and we provide evidence that the bacterial turgor is the driving force for vesicle budding under hypotonic osmotic conditions. Intriguingly, the majority of lipoproteins are released by S. aureus as components of membrane vesicles, and this process depends on surfactant-like molecules such as PSMs. Vesicle disruption at high detergent concentrations promotes the capacity of lipoproteins to activate TLR2. These results reveal that vesicle release by bacterium-derived surfactants is required for TLR2-mediated inflammation. IMPORTANCE Our study highlights the roles of surfactant-like molecules in bacterial inflammation with important implications for the prevention and therapy of inflammatory disorders. It describes a potential pathway for the transfer of hydrophobic bacterial lipoproteins, the major TLR2 agonists, from the cytoplasmic membrane of Gram-positive bacteria to the TLR2 receptor at the surface of host cells. Moreover, our study reveals a molecular mechanism that explains how cytoplasmic and membrane-embedded bacterial proteins can be released by bacterial cells without using any of the typical protein secretion routes, thereby contributing to our understanding of the processes used by bacteria to communicate with host organisms and the environment.

Properties of Membrane Fractions Prepared by Chromatophore-Liposome Fusion

1984 ◽  
Vol 39 (11-12) ◽  
pp. 1112-1119 ◽  
Author(s):  
Augusto F. Garcia ◽  
Gerhart Drews
Keyword(s):  
Electron Transport ◽  
Continuous Light ◽  
Membrane Vesicles ◽  
Rhodopseudomonas Capsulata ◽  
Intracytoplasmic Membrane ◽  
Band Shift ◽  
Liposome Fusion ◽  
Ubiquinone 10 ◽  
Kinetics Of ◽  
Transition Procedure

Abstract Intracytoplasmic membrane vesicles (chromatophores) isolated from Rhodopseudomonas capsulata cells were fused with liposomes by a pH transition procedure. Vesicles of lower density and higher lipid contents and larger diameter than chromatophores were obtained. Similar results were observed by Ca2+ induced fusion and by the freeze-thawing method. Respiratory and light-induced electron transport were measured in chromatophores and fused vesicles. Light-induced reaction center bleaching was observed in all types of vesicles, whereas repiratory electron transport was substantially diminished by lipid incorporation. Ubiquinone 10 restored to some extent respiratory electron transport and oxidative phosphorylation and it modified the photophosphorylation kinetics under continuous light. Electrochromic carotenoid band-shift and the 9-aminoacridine fluorescence quenching indicate that the capacity of the fused vesicles to maintain an electrochemical proton gradient has not been substantially diminished. From the kinetics of 9-aminoacridine quenching an increased K+-permeability seems to be apparent.

scholarly journals Halochromatium roseum sp. nov., a non-motile phototrophic gammaproteobacterium with gas vesicles, and emended description of the genus Halochromatium

2007 ◽  
Vol 57 (9) ◽  
pp. 2110-2113 ◽  
Author(s):  
P. Anil Kumar ◽  
T. N. R. Srinivas ◽  
Ch. Sasikala ◽  
Ch. V. Ramana
Keyword(s):  
Novel Species ◽  
Rrna Gene ◽  
Solar Saltern ◽  
Gas Vesicles ◽  
16S Rrna Gene Sequences ◽  
Marine Solar Saltern ◽  
Purple Sulfur Bacterium ◽  
Absolute Requirement ◽  
Intracytoplasmic Membranes ◽  
Emended Description

A rod-shaped, marine, phototrophic, purple sulfur bacterium containing gas vesicles was isolated from a marine solar saltern at Kakinada, India. Cells of strain JA134T are Gram-negative, non-motile rods, with vesicular intracytoplasmic membranes, and the strain has an absolute requirement for NaCl for growth. Bacteriochlorophyll a and the carotenoid okenone are present as photosynthetic pigments. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA134T clusters with members of the genus Halochromatium, but is distinctly separated from the species reported so far. The morphological and physiological differences of strain JA134T from other Halochromatium species support the description of strain JA134T (=ATCC BAA-1363T =DSM 18859T =JCM 14151T) as the type strain of a novel species, Halochromatium roseum sp. nov.

scholarly journals Outer Membrane Vesicle Production by Escherichia coli Is Independent of Membrane Instability

2006 ◽  
Vol 188 (15) ◽  
pp. 5385-5392 ◽  
Author(s):  
Amanda J. McBroom ◽  
Alexandra P. Johnson ◽  
Sreekanth Vemulapalli ◽  
Meta J. Kuehn
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Fold Increase ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Physiological Basis ◽  
Gram Negative

ABSTRACT It has been long noted that gram-negative bacteria produce outer membrane vesicles, and recent data demonstrate that vesicles released by pathogenic strains can transmit virulence factors to host cells. However, the mechanism of vesicle release has remained undetermined. This genetic study addresses whether these structures are merely a result of membrane instability or are formed by a more directed process. To elucidate the regulatory mechanisms and physiological basis of vesiculation, we conducted a screen in Escherichia coli to identify gene disruptions that caused vesicle over- or underproduction. Only a few low-vesiculation mutants and no null mutants were recovered, suggesting that vesiculation may be a fundamental characteristic of gram-negative bacterial growth. Gene disruptions were identified that caused differences in vesicle production ranging from a 5-fold decrease to a 200-fold increase relative to wild-type levels. These disruptions included loci governing outer membrane components and peptidoglycan synthesis as well as the σE cell envelope stress response. Mutations causing vesicle overproduction did not result in upregulation of the ompC gene encoding a major outer membrane protein. Detergent sensitivity, leakiness, and growth characteristics of the novel vesiculation mutant strains did not correlate with vesiculation levels, demonstrating that vesicle production is not predictive of envelope instability.

scholarly journals Motility of Marichromatium gracilein Response to Light, Oxygen, and Sulfide

2001 ◽  
Vol 67 (12) ◽  
pp. 5410-5419 ◽  
Author(s):  
Roland Thar ◽  
Michael Kühl
Keyword(s):  
Cell Tracking ◽  
Tracking System ◽  
Sulfide Oxidation ◽  
Purple Sulfur Bacterium ◽  
Light Regimes ◽  
Chemical Gradients ◽  
Protection Strategies ◽  
Oxic Zone ◽  
Sulfur Globules ◽  
Oxygen Concentrations

ABSTRACT The motility of the purple sulfur bacterium Marichromatium gracile was investigated under different light regimes in a gradient capillary setup with opposing oxygen and sulfide gradients. The gradients were quantified with microsensors, while the behavior of swimming cells was studied by video microscopy in combination with a computerized cell tracking system. M. gracile exhibited photokinesis, photophobic responses, and phobic responses toward oxygen and sulfide. The observed migration patterns could be explained solely by the various phobic responses. In the dark, M. gracileformed an ∼500-μm-thick band at the oxic-anoxic interface, with a sharp border toward the oxic zone always positioned at ∼10 μM O2. Flux calculations yielded a molar conversion ratio Stot/O2 of 2.03:1 (Stot = [H2S] + [HS−] + [S2−]) for the sulfide oxidation within the band, indicating that in darkness the bacteria oxidized sulfide incompletely to sulfur stored in intracellular sulfur globules. In the light, M. gracilespread into the anoxic zone while still avoiding regions with >10 μM O2. The cells also preferred low sulfide concentrations if the oxygen was replaced by nitrogen. A light-dark transition experiment demonstrated a dynamic interaction between the chemical gradients and the cell's metabolism. In darkness and anoxia, M. gracile lost its motility after ca. 1 h. In contrast, at oxygen concentrations of >100 μM with no sulfide present the cells remained viable and motile for ca. 3 days both in light and darkness. Oxygen was respired also in the light, but respiration rates were lower than in the dark. Observed aggregation patterns are interpreted as effective protection strategies against high oxygen concentrations and might represent first stages of biofilm formation.

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