Early Changes in the Ultrastructure of
            <i>Streptococcus faecalis</i>
            After Amino Acid Starvation

Higgins, M. L.; Shockman, Gérald D.

doi:10.1128/jb.103.1.244-253.1970

Cited by 66 publications

(43 citation statements)

References 26 publications

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“…Ultrastructural studies of thin-section walls on intact cells and in isolated wall preparations before and after TCA extraction. The structure of the cell walls of S. faecalis observed in thin sections has been reported (18,19). Typically for gram-positive bacteria in axial section, walls in sectioned cells appear as a "sandwich" made up of two electron-dense layers enclosing a central, less dense region (Fig.…”

Section: Resultsmentioning

confidence: 88%

“…Walls to be sectioned were similarly initially fixed by adding glutaraldehyde (final concentration, 2%) to 10 to 20 mg of walls in 20 ml of 10 mM phosphate, pH 7.2. After 2 h of glutaraldehyde fixation at 25°C, both walls and cells were postfixed in osmium tetroxide, embedded in Epon 812, and stained with uranyl acetate-lead citrate as previously described (17,19).…”

mentioning

confidence: 99%

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Structural arrangement of polymers within the wall of Streptococcus faecalis

Tsien¹,

Shockman²,

Higgins³

1978

J Bacteriol

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The structure of the cell wall of Streptococcus faecalis was studied in thin sections and freeze fractures of whole cells and partially purified wall fractions. Also, the structures of wall preparations treated with hot trichloroacetic acid to remove non-peptidoglycan wall polymers were compared with wall preparations that possess a full complement of accessory polymers. The appearance of the wall varied with the degree of hydration of preparations and physical removal of the cell membrane from the wall before study. Seen in freeze fractures of whole cells, the fully hydrated wall seemed to be a thick, largely amorphic layer. Breaking cells with beads caused the cell membrane to separate from the wall and transforned the wall from a predominantly. amorphic layer to a structure seemingly made up of two rows of "cobblestones" enclosing a central channel of lower density. Dehydration of walls seemingly caused the cobblestones to be transformed into two bands which continued to be separated by a channel. This channel was also observed in isolated wall preparations treated with hot trichloroacetic acid to remove non-peptidoglycan polymers. These observations are consistent with the interpretation that both peptidoglycan and non-peptidoglycan polymers are concentrated at the outer and inner surfaces of cell walls. These observations are discussed in relation to possible models of wall structure and assembly.Walls of gram-positive bacteria are composed of peptidoglycan to which is covalently linked one or more non-peptidoglycan polymers, such as anionic, teichoic, or teichuronic acids, and neutral polysaccharides. Currently, little, is known about the exact topological localization of the various wall polymers. The question of exclusive or enriched domains within walls remains open.Several kinds of evidence have been used to promote the idea that various polymers in walls are enriched in specific wall areas. First is the appearance of walls of a variety of gram-positive species in thin sections. Frequently, two electron-dense bands enclosing a less dense central zone are seen (16). This appearance has led to the idea that the outer and inner dense bands might be enriched in anionic polymers which would bind larger amounts of the heavy metal stains used to improve the contrast of these preparations. Although phosphate groups in the teichoic acid of Streptococcus faecalis have a high affinity for uranyl acetate, this affinity was greatly reduced after exposure of walls to osmium tetroxide (14). Since fixation with osmium almost invariably precedes uranyl acetate staining of thin sections, it seems unlikely that the tribanded appearance is due solely to selective binding of uranyl ions by phosphate groups.However, in support of the idea that anions are concentrated at wall surfaces are studies of sectiots of Bacillus subtilis in which tribanded walls were visualized in sections that had never been exposed to either heavy metal stains or osmium tetroxide (29). The tribanded image observed was interpreted as indicating an ac...

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Section: Resultsmentioning

confidence: 88%

mentioning

confidence: 99%

Structural arrangement of polymers within the wall of Streptococcus faecalis

Tsien¹,

Shockman²,

Higgins³

1978

J Bacteriol

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“…It may be that cell wall synthesis, known to occur in portions of the cell wall other than the region of septation (16,22,31), occurs in the absence of lipoteichoic acid and is dependent on the local magnesium ion concentration.…”

Section: Resultsmentioning

confidence: 99%

Lipoteichoic Acid Localization in Mesosomal Vesicles of Staphylococcus aureus

1974

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Mesosomal vesicles and plasma membranes of Staphylococcus aureus ATCC 6538P have been prepared and examined for the presence of lipoteichoic acid. Lipids were first removed by treatment with pyridine-acetic acid-butanol (22:31:100, vol/vol/vol) and chloroform-methanol (2:1, vol/vol). Subsequently, lipoteichoic acid was removed with 40%o phenol in water. The lipoteichoic acid from mesosomal vesicles was characterized by (i) equimolar glycerol and phosphate, (ii) alanine upon hydrolysis (2 N NH,OH, 18 h, 22 C), and (iii) fatty acids, diglycerol triphosphate, glycerol monophosphate, and glycerol diphosphate upon alkaline hydrolysis (1 N NaOH, 3h, 100 C). The plasma membranes contained no lipoteichoic acid. The presence in mesosomal vesicles of 18% of the dry weight as lipoteichoic acid and its absence from plasma membranes provide the first major chemical differences between these organelles. A study of the lipoteichoic acid content in various fractions of the cell showed that the mesosomal vesicles were the major and probably the sole site for the localization of the lipoteichoic acid in these organisms. A new method for the preparation of mesosomes in increased yields is reported. A theory for the control of cell division involving lipoteichoic acid and the mesosome is proposed. This paper describes the isolation of lipoteichoic acid from mesosomal vesicles of S. aureus 209P (ATCC 6538P). Plasma membranes from this bacterium are shown to lack lipoteichoic acid. The data demonstrate a major qualitative chemical difference between mesosomal vesicles and plasma membranes and show further that most and probably all of the intracellular teichoic acid (membrane or lipoteichoic acid) is 273 on July 31, 2020 by guest http://jb.asm.org/ Downloaded from 274

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“…Electron microscopy. Cells were fixed with glutaraldehyde-osmium, embedded in Epon 812, sectioned, and poststained with uranylacetate-lead citrate as previously described (7,9).…”

Section: Methodsmentioning

confidence: 99%

Some Properties of Two Autolytic-Defective Mutants of Streptococcus faecalis ATCC 9790

et al. 1972

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The isolation and some properties of two mutants of Streptococcus faecalis ATCC 9790 (S. faecium) which autolyze at a much slower rate than the wild type are described. Compared with the wild type, mutant E71 autolyzed more slowly, contained less active but more latent autolysin in the isolated wall fraction, and possessed a wall of very similar chemical composition and degree of cross-bridging. Ultrastructural studies of exponential phase cells showed that cells of E71 were on the average slightly longer and had slightly thickened walls compared to the wild type. Mutant E81 autolyzed much more slowly, grew exponentially in long chains (8 to 40 cells compared with mainly diplococci), contained much less active and latent autolysin in the wall, and possessed a wall of very similar chemical composition but with about twice the content of N-terminal groups. Mutant E81 walls were more susceptible to isolated autolysin but possessed an autolysin of the same specificity as the wild type. Ultrastructurally E81 cells were, on the average, significantly longer and had thicker walls than the wild type. Mutant E71 may be partially blocked at either transport of autolysin to the wall or in conversion of latent to active autolysin. The pleitropic effects noted in mutant E81 have been taken to suggest a possible membrane defect and to support the role of the autolysin in cell separation.A number of biological roles for peptidoglycan hydrolases have been proposed. These include participation in (i) the process of cell wall growth (13,17,24); (ii) cell separation (10, 23); (iii) peptidoglycan turnover (1, 12); and (iv) providing gaps or holes in the cell surface large enough to admit large macromolecules which cannot pass through the spaces in the cell wall (25).The cleavage of the polysaccharide backbone of the rigid peptidoglycan polymer of the cell wall by N-acetylmuramidases could allow for the insertion of new disaccharide units resulting in cell wall growth. The autolysin of Streptococcus faecalis could perform such a role, although it is difficult to imagine how this role could be achieved by autolytic activities cleaving certain other bonds in the cell wall (20; M. L. Higgins and G. D. Shockman, CRC Crit. Rev. Microbiol, in press). Support for the involvement of the S. faecalis autolysin in the cell wall growth comes from the association of I Present address:

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Early Changes in the Ultrastructure of Streptococcus faecalis After Amino Acid Starvation

Cited by 66 publications

References 26 publications

Structural arrangement of polymers within the wall of Streptococcus faecalis

Structural arrangement of polymers within the wall of Streptococcus faecalis

Lipoteichoic Acid Localization in Mesosomal Vesicles of Staphylococcus aureus

Some Properties of Two Autolytic-Defective Mutants of Streptococcus faecalis ATCC 9790

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