Structural Research on Surface Layers: A Focus on Stability, Surface Layer Homology Domains, and Surface Layer–Cell Wall Interactions

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

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Cell-wall composition and viomycin resistance in Rhizobium meliloti

Canadian Journal of Microbiology ◽

10.1139/m72-181 ◽

1972 ◽

Vol 18 (7) ◽

pp. 1168-1170 ◽

Cited By ~ 2

Author(s):

C. R. MacKenzie ◽

D. C. Jordan

Keyword(s):

Cell Wall ◽

Cell Surface ◽

Rhizobium Meliloti ◽

Cell Wall Composition ◽

Surface Layers ◽

Mechanism Of Resistance ◽

Resistant Cells

Mutation to viomycin-resistance in Rhizobium meliloti R21 resulted in an accumulation of phosphatidylcholine and phosphatidylethanolamine in the cell wall. Resistance to viomycin decreased when the excess lipid was removed by EDTA or when its synthesis was prevented by growth of normally resistant cells at 40 °C. Microelectrophoretic data showed binding of viomycin to the cell surface and it is proposed that the mechanism of resistance to viomycin is an immobilization of the antibiotic in the surface layers of the cell as a result of combination with phospholipid.

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Electrokinetics, Adsorption and Colloid Study of Simulated Nuclear Waste Glasses Leached in Aqueous Solutions

MRS Proceedings ◽

10.1557/proc-44-221 ◽

1984 ◽

Vol 44 ◽

Cited By ~ 2

Author(s):

Cheng T. Lee ◽

D. E. Clark

Keyword(s):

Surface Layer ◽

Nuclear Waste ◽

Glass Surface ◽

Charged Particles ◽

Electrostatic Repulsion ◽

Surface Layers ◽

Short Term ◽

Chloride Solutions ◽

Zeta Potentials ◽

Glass Surfaces

AbstractZeta potentials of SRL-131-29.8% TOS simulated nuclear waste glasses leached in D.I. water, Al, Ca, Mg, and Zn chloride solutions at 90°C were measured as a function of leaching time. For short term leaching, the adsorption of Ca, Mg, Zn and Al reverses the glass surface potential from negative to positive. Colloids were found to be stable in D.I. water and AICl3 solutions after leaching, presumably due to the electrostatic repulsion between the glass surface and similarly charged particles. Colloids were not found in Mg, Zn or Ca chloride solutions after leaching; instead, a relatively thick metasilicate surface layer was formed on glass surfaces leached in these solutions. The concentration of Si in solution is reduced by the formation of these surface layers.

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Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.225.131 ◽

2014 ◽

Vol 225 ◽

pp. 131-138

Author(s):

Jarosław Chmiel ◽

Jolanta Baranowska ◽

Roman Jędrzejewski ◽

Arkadiusz Rzeczycki

Keyword(s):

Surface Layer ◽

Stress State ◽

Hydrogen Absorption ◽

Surface Layers ◽

Fem Modeling ◽

And Diffusion

Cavitation attack in liquids generated a various states of stresses in surface layers of metals. Differences in stress state effects on hydrogen absorption activated by the cavitation implosion. Results of XRD investigation and FEM modeling shows on inhomogenity of process.

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Novel Combinations of Vancomycin plus Ceftaroline or Oxacillin against Methicillin-Resistant Vancomycin-Intermediate Staphylococcus aureus (VISA) and Heterogeneous VISA

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02354-12 ◽

2013 ◽

Vol 57 (5) ◽

pp. 2376-2379 ◽

Cited By ~ 45

Author(s):

B. J. Werth ◽

C. Vidaillac ◽

K. P. Murray ◽

K. L. Newton ◽

G. Sakoulas ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Inverse Correlation ◽

Fluorescent Dye ◽

Beta Lactam ◽

Significant Inverse Correlation ◽

Methicillin Resistant ◽

Content Type ◽

Time Kill ◽

Wall Interactions

ABSTRACTWe demonstrated a significant inverse correlation between vancomycin and beta-lactam susceptibilities in vancomycin-intermediateStaphylococcus aureus(VISA) and heterogeneous VISA (hVISA) isolates. Using time-kill assays, vancomycin plus oxacillin or ceftaroline was synergistic against 3 of 5 VISA and 1 of 5 hVISA isolates or 5 of 5 VISA and 4 of 5 hVISA isolates, respectively. Beta-lactam exposure reduced overall vancomycin-Bodipy (dipyrrometheneboron difluoride [4,4-difluoro-4-bora-3a,4a-diaza-s-indacene] fluorescent dye) binding but may have improved vancomycin-cell wall interactions to improve vancomycin activity. Further research is warranted to elucidate the mechanism behind vancomycin and beta-lactam synergy.

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Elemental composition of the surface layers formed on titanium at the cathodic treatment in chitosan-containing aqueous-dimethyl sulfoxide solutions of phosphate-molybdate electrolyte

Electrochemical Energetics ◽

10.18500/1608-4039-2021-21-1-32-48 ◽

2021 ◽

Vol 21 (1) ◽

pp. 32-48

Author(s):

Svetlana S. Popova ◽

◽

Hussein Ali Hussein ◽

Lyubov’ N. Olshanskaya ◽

Sergei V. Arzamastsev ◽

...

Keyword(s):

Surface Layer ◽

Phosphoric Acid ◽

Organic Solvent ◽

Dimethyl Sulfoxide ◽

Electrolyte Solution ◽

Aqueous Electrolyte ◽

Sodium Molybdate ◽

Volume Ratio ◽

Surface Layers ◽

Potentiostatic Mode

It was established that at the cathodic treatment of titanium in aqueous dimethyl sulfoxide solutions of sodium molybdate, containing phosphoric acid, at the potential of the cathodic incorporation of sodium (Ec = −2.6 V) in the potentiostatic mode, the composition formed on the electrode surface layer depended not only on the composition of the solution, but also on the volume ratio of the aqueous electrolyte solution and the organic solvent (dimethyl sulfoxide).

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The structure and associations of the double S layer on the cell wall of Aquaspirillum sinuosum

Canadian Journal of Microbiology ◽

10.1139/m90-057 ◽

1990 ◽

Vol 36 (5) ◽

pp. 327-335 ◽

Cited By ~ 18

Author(s):

Stephen H. Smith ◽

Robert G. E. Murray

Keyword(s):

Cell Wall ◽

Outer Membrane ◽

Outer Layer ◽

Peptide Mapping ◽

Periodic Acid ◽

Minor Component ◽

Membrane Resistance ◽

Surface Layers ◽

Periodic Acid Schiff ◽

Bacterial Surface

Aquaspirillum sinuosum cell walls bear two paracrystalline, proteinaceous surface layers (S layers). Each shows a different symmetry: the inner layer is closely apposed to the outer membrane and is a tetragonal array (90° axes; 5-nm units; repeat frequency 8 nm); the outer layer is a hexagonal array on the external surface (14-nm units; repeat frequency 18 nm) and, although the units have a six-pointed stellate form, the linkage between units is not resolved. The outer layer consists of a major 130-kDa protein and a 180-kDa minor component; these co-extract, co-assemble, and are inseparable by hydroxylapatite chromatography or by recrystallization. The solubilizing effects of reagents suggest stabilization by hydrogen bonding and Ca2+. The two outer layer proteins are serologically related and show partial identity by peptide mapping. Periodic acid – Schiff staining of the 180-kDa band suggests that this may be a glycosylated form of the 130-kDa component. The inner layer components form a doublet of 75- and 80-kDa polypeptides with extreme resistance to extraction. Close apposition to the outer membrane, resistance to chaotropes, aqueous insolubility, and behaviour in charge-shift electrophoresis suggest hydrophobic interaction between subunits and an integral association with the outer membrane. Key words: bacterial surface, cell wall, surface layers, cell-wall proteins, cell-wall assembly.

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Features of damage and modification of surface layers of Al and its alloys by powerful energy flows in a plasma focus device

Perspektivnye Materialy ◽

10.30791/1028-978x-2021-9-34-52 ◽

2021 ◽

Vol 9 ◽

pp. 34-52

Author(s):

V. N. Pimenov ◽

◽

S.A. Maslyaev ◽

Keyword(s):

Surface Layer ◽

Plasma Focus ◽

Phase State ◽

Structural Phase ◽

Pulsed Laser ◽

Plasma Focus Device ◽

Deuterium Plasma ◽

Surface Layers ◽

Pulsed Laser Radiation ◽

Structural Phase State

The results of the analysis of damageability and modification of the structural-phase state of the surface layers of aluminum and its alloys by powerful flows of fast high-energy ions and high-temperature plasma in Plasma focus devices, as well as using pulsed laser radiation. Pure Al, an alloy of the Al – Mg – Li system, a duralumin alloy, and a composition of a ceramic coating Al2O3 on an Al substrate are considered. It is shown that in the regime of Al irradiation with a power density of q ≈ 106 – 107 W/cm2 in the nano- and microsecond range of pulse durations, ultrafast crystallization of melted surface layer occurs with the formation of a wavy surface relief and the structural fragments of sub-microcrystalline and nanoscale size. After the action of deuterium plasma flows on a duralumin alloy tube located along the axis of the Plasma focus device a modification of the structural-phase state of the alloy is observed: the initial two-phase state of an αAl-solid solution of copper in aluminum and inclusions of the second phase of CuAl2 became fine-grained and single-phase due to the dissolution of CuAl2 particles in the melt. Irradiation of an alloy of the Al – Mg – Li system containing (wt %) 2 % Li and 5 % Mg at q = 5·106 W/cm2, t = 50 – 100 ns after four pulsed impacts of fast ions and deuterium plasma led to the modification the structural-phase state of the surface layer of the alloy, associated with an increase in the content of magnesium oxide and a decrease in the crystal lattice parameter of the Al-based solid solution. The formation of spherical cavities due to the evaporation of lithium into the internal micropores of the surface layer was also found. The low damage and structural stability of Al2O3 ceramics on an Al substrate under beam-plasma impacts in plasma focus device with a radiation power density q ≤ 108 – 109 W/cm2 in the nano- and microsecond range of pulse duration is noted. At the same time, the Al2O3/Al composition was unstable to pulsed laser radiation in the free-running mode (q = 105 – 106 W/cm2, t = 0.7 ms) and Q-switch mode (q = 107 – 108 W/cm2, t = 80 ns). In both cases the coating peeled off from the substrate.

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Structure of the freshened surface layer in the Eastern Arctic during ice-free periods

10.5194/egusphere-egu21-255 ◽

2021 ◽

Author(s):

Alexander Osadchiev ◽

Dmitry Frey

Keyword(s):

Surface Layer ◽

Sea Water ◽

Discharge Rate ◽

World Ocean ◽

Kara Sea ◽

Surface Layers ◽

Narrow Channels ◽

Lena River ◽

Annual Variability ◽

The World

Discharges from the largest rivers of the World to coastal sea form sea-wide freshened surface layers which areas have order of hundred thousands of square kilometers. Large freshened surface layers (which are among the largest in the World Ocean) are located in the Kara, Laptev, and East-Siberian seas in the Eastern Arctic. This work is focused on the structure and inter-annual variability of these freshened water masses during ice-free periods. The freshened surface layer in the Laptev and East-Siberian seas is formed mainly by deltaic rives among which the Lena River contributes about two thirds of the inflowing freshwater volume. Based on in situ measurements, we show that the area of this freshened surface layer is much greater than the area of the freshened surface layer in the neighboring Kara Sea, while the total annual freshwater discharge to the Laptev and East-Siberian seas is 1.5 times less than to the Kara Sea (mainly from the estuaries of the Ob and Yenisei rivers). This feature is caused by differences in morphology of the estuaries and deltas. Shallow and narrow channels of the Lena Delta are limitedly affected by sea water. As a result, undiluted Lena discharge inflows to sea from multiple channels and forms relatively shallow plume, as compared to the Ob-Yenisei plumes which mix with subjacent saline sea water in deep and wide estuaries. The shallow Lena plume spreads over wide area (up to 500 000 km2) in the Laptev and East-Siberian seas during and shortly after freshet period in summer and then transforms to the Laptev/East-Siberian ROFI in autumn. Area and position of the relatively shallow freshened surface layer in the Laptev and East-Siberian seas have large inter-annual variability governed by local wind forcing conditions, however, do not show any dependence on significant variability of the annual volume of discharge rate from the Lena River. The deep freshened surface layer in the Kara Sea also has distinct seasonal varability of area and position, however, is stable on inter-annual time scale.

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