Structure and assembly of bacterial surface layers composed of regular arrays of subunits

1974 ◽  
Vol 268 (891) ◽  
pp. 147-153 ◽  
Keyword(s):  
Self Assembly ◽  
Cell Walls ◽  
Surface Layers ◽  
Intact Cells ◽  
Bacterial Surface ◽  
Outer Membranes ◽  
And Function ◽  
Isolated Cell ◽  
Regular Arrays ◽  
Intact Bacterium

Regular arrays of subunits are observed on the surfaces of many bacteria, and the structure and function of such an array are being examined in a study of the Gram-negative bacterium Acinetobacter strain MJT/F5/199A. The subunits are on the surface of the outer membrane and are visible in electron micrographs of freeze-etched intact cells and of negatively stained preparations of isolated cell walls and outer membranes. The surface subunits can be detached from the membrane by various treatments and will then reassemble spontaneously to form the same regular pattern as that seen on the intact bacterium. The results of studies of the properties of the self-assembly system are described and its relevance to the formation of surface layers composed of regular arrays of subunits in intact bacteria discussed.

scholarly journals Ionic Relations of Cells of Ohara Australis I. Ion Exchange in the Cell Wall

1959 ◽  
Vol 12 (4) ◽  
pp. 395 ◽  
Author(s):  
J Dainty ◽  
AB Hope
Keyword(s):  
Cell Wall ◽  
Ion Exchange ◽  
Free Space ◽  
Cell Walls ◽  
Plant Cells ◽  
External Solution ◽  
Exchangeable Cations ◽  
Intact Cells ◽  
Donnan Free Space ◽  
Isolated Cell

Measurements of ion exchange were made between isolated cell walls of Ohara australis and an external solution. Comparison between intact cells and cell walls showed that nearly all the easily exchangeable cations are located in the cell wall. The wall is hown to consist of "water free space" (W.F.S.) and "Donnan free space" (D.F.S.); the concentration of in diffusible anions in the D.F.S. is about O� 6 equivjl. This finding is contrary to past suggestions that the D.F.S. is in the cytoplasm of plant cells.

Surface charge and morphogenesis of regular arrays of macromolecules on bacterial cell walls

1978 ◽  
Vol 36 (2) ◽  
pp. 346-347 ◽  
Author(s):  
U. B. Sleytr ◽  
G. P. Friers
Keyword(s):  
Cell Wall ◽  
Surface Charge ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Surface Layers ◽  
Regular Surface ◽  
Wide Range ◽  
Freeze Etching ◽  
Regular Arrays ◽  
Peptidoglycan Layer

Regular arrays of macromolecules can be demonstrated on the surface of a wide range of bacteria by negative staining and freeze-etching techniques. The isolated subunits of the regular surface layers (S-layers) examined in this study have shown to consist of protein or glycoprotein and to possess the ability to assemble spontaneously under certain conditions to form regular arrays with the same dimensions as those seen on intact bacteria. In appropriate conditions the isolated subunits reattach to the cell wall from which they have been removed. Analysis of the orientation of the reconstituted S-layers have shown that the pattern of the regular arrays seem to be determined only by the directional bonds between the subunits and not by any order in the underlying (peptidoglycan) layer.

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.

Formation of Tubes during Self-Assembly of Bacterial Surface Layers

Langmuir ◽  
2011 ◽  
Vol 27 (24) ◽  
pp. 15102-15111 ◽  
Author(s):  
Manfred Bobeth ◽  
Andreas Blecha ◽  
Anja Blüher ◽  
Michael Mertig ◽  
Nuriye Korkmaz ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Layers ◽  
Bacterial Surface

Morphological aspects of the shedding of surface layers from peanut roots

1997 ◽  
Vol 75 (4) ◽  
pp. 607-611 ◽  
Author(s):  
Eiji Uheda ◽  
Yoko Akasaka ◽  
Hiroyuki Daimon
Keyword(s):  
Arachis Hypogaea ◽  
Cell Separation ◽  
Cell Walls ◽  
Separation Process ◽  
Surface Layers ◽  
Outer Cortex ◽  
Electron Microscopic ◽  
Intact Cells ◽  
Morphological Aspects ◽  
Microscopic Studies

Epidermal cells and cells originating in the outer cortex form the surface layers of peanut (Arachis hypogaea) roots, the outermost of which separate and shed from the periphery. Shedding takes place continuously and over the whole surface of the root. Light and electron microscopic studies revealed that the shedding of surface layers involves modification of cell walls and separation of intact cells. Wall breakdown, as well as the expansion of cells resulting from wall breakdown, might facilitate the separation of intact cells. Examination of enzymes revealed that cellulase showed much higher activity in the shedding layers than in the remaining tissues. The results suggest that the cell separation process in peanut roots involves a wall-degrading enzyme-mediated mechanism. Key words: Arachis hypogaea, morphology, root, shedding, surface layers, wall breakdown.

The structure of the yeast cell wall - I. Identification of charged groups at the surface

1958 ◽  
Vol 148 (932) ◽  
pp. 419-432 ◽  
Keyword(s):  
Cell Wall ◽  
Electrophoretic Mobility ◽  
Cell Walls ◽  
Phosphorus Content ◽  
Negative Charge ◽  
Alkaline Solutions ◽  
Type I ◽  
Intact Cells ◽  
Fixed Structure ◽  
Isolated Cell

The electrophoretic mobility of various strains of Saccharomyces cerevisiae and S. carlsbergensis over the range pH 2 to 9 and at constant ionic strength ( I = 0.005) varies from about + 0·5 to — 1·5 µ , s -1 (V /cm ) -1 , values of an order indicating that the fraction of the cell surface occupied by ions is probably rather small. Both intact cells and the cell walls isolated from them behave similarly on electrophoresis and in a manner varying with the strain of yeast. It is the composition of the wall therefore which determines the electrophoretic properties. Two general effects (I and II) of change of pH on electrophoretic mobility were distinguished as characterizing certain strains of yeast, although in other cases they were encountered together. In the first type (I), the mobility was nearly independent of the pH and corresponded to a negative charge. As such charges were lacking from yeasts grown in media deficient in phosphate, and as the mobility of the isolated cell wall appeared to be directly related to its phosphorus content, the negative charge may be attributed to combined phosphate forming part of the fixed structure of the cell wall. In the second form of behaviour (II) the mobility varied continuously between pH 3 and 6, with an alteration in charge from positive to negative at about pH 4. In this case the charged groups are tentatively attributed to protein, as material of this nature was removed together, apparently, with the groups themselves when cell walls were treated with alkaline solutions.

scholarly journals Mitochondrial Processes during Early Development of Dictyostelium discoideum: From Bioenergetic to Proteomic Studies

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 638
Author(s):  
Monika Mazur ◽  
Daria Wojciechowska ◽  
Ewa Sitkiewicz ◽  
Agata Malinowska ◽  
Bianka Świderska ◽  
...  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Coupling Efficiency ◽  
Slime Mold ◽  
Intact Cells ◽  
Life Cycle Stages ◽  
Early Developmental Stages ◽  
Proteomic Study ◽  
And Function ◽  
Early Developmental

The slime mold Dictyostelium discoideum’s life cycle includes different unicellular and multicellular stages that provide a convenient model for research concerning intracellular and intercellular mechanisms influencing mitochondria’s structure and function. We aim to determine the differences between the mitochondria isolated from the slime mold regarding its early developmental stages induced by starvation, namely the unicellular (U), aggregation (A) and streams (S) stages, at the bioenergetic and proteome levels. We measured the oxygen consumption of intact cells using the Clarke electrode and observed a distinct decrease in mitochondrial coupling capacity for stage S cells and a decrease in mitochondrial coupling efficiency for stage A and S cells. We also found changes in spare respiratory capacity. We performed a wide comparative proteomic study. During the transition from the unicellular stage to the multicellular stage, important proteomic differences occurred in stages A and S relating to the proteins of the main mitochondrial functional groups, showing characteristic tendencies that could be associated with their ongoing adaptation to starvation following cell reprogramming during the switch to gluconeogenesis. We suggest that the main mitochondrial processes are downregulated during the early developmental stages, although this needs to be verified by extending analogous studies to the next slime mold life cycle stages.

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