Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “cell wall composition”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed2001

Cellulose in algal cell wall: an "in situ" localization.

In order to ascertain the presence and the in muro localization of cellulose, the enzyme-gold affinity test was applied to algal cell walls. The high specificity of affinity cytochemistry allowed us, by using the enzyme cellulase, to confirm the available biochemical data and to give a map of the cellulose localization in different algal groups. Taking into account the complex skeletal polysaccharide structure and composition of the algal cell walls, this method proved to be a reliable tool in this field.

Cell Wall↗
PubMed2000

What determines arthritogenicity of bacterial cell wall? A study on Eubacterium cell wall-induced arthritis.

OBJECTIVE: To study what determines the arthritogenicity of the bacterial cell wall (CW) using Eubacterium CW-induced arthritis in the rat. METHODS: Eubacterium aerofaciens, previously reported as arthritogenic, and E. limosum and E. alactolyticum, known as non-arthritogenic, were used. Gas chromatography-mass spectrometry (GC-MS) was applied to analyse the chemical composition of the bacterial cell wall. Cellular immune response was measured by concanavalin A (Con A) stimulation and FACScan analysis. Also, serum antibodies against the injected cell wall were determined. RESULTS: Unexpectedly, from the two strains of E. aerofaciens used only one proved to be arthritogenic (with a CW inducing chronic arthritis after a single intraperitoneal injection), even though these two strains were 100% identical by 16S rDNA analysis. CW of the other E. aerofaciens strain induced only transient acute arthritis; CW of E. limosum and E. alactolyticum induced weak signs of acute arthritis. Based on the GC-MS analysis and on the results published previously, putative structures of peptidoglycan (PG) in the four CW preparations are presented. It is apparent that the presence of lysine in position 3 of the PG stem peptide contributes to arthritogenicity but is alone not decisive. Both strains of E. aerofaciens were immunosuppressive, when tested by Con A response at 2 weeks after CW injection. Such an immunosuppression was not observed after injection of CW from E. limosum or E. alactolyticum. FACScan analysis for six T cell markers and studies on serum antibody responses did not reveal any differences in the effect of the four bacterial strains used. CONCLUSIONS: The results obtained suggest that the chemical structure of PG present in the bacterial CW is decisive in determining arthritogenicity/non-arthritogenicity. Therefore, from two bacterial strains belonging to normal human intestinal flora and 100% identical by 16S rDNA analysis, one proved to be arthritogenic and the other non-arthritogenic.

Acute Disease↗
PubMed2002

Natural and acquired macrolide resistance in mycobacteria.

The genus Mycobacterium contains two of the most important human pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, the etiologic agents of tuberculosis and leprosy, respectively. Other mycobacteria are mostly saprophytic organisms, living in soil and water, but some of them can cause opportunistic infections. The increasing incidence of tuberculosis as well as infections with non-tuberculous mycobacteria (NTM) in AIDS patients has renewed interest in molecular mechanisms of drug resistance in these pathogens. Mycobacteria show a high degree of intrinsic resistance to most common antibiotics. For instance, species from the M. tuberculosis complex (MTC) are intrinsically resistant to macrolides. Nevertheless, some semi-synthetic macrolides as the erythromycin derivatives clarithromycin, azithromycin and most recently the ketolides, are active against NTM, particularly Mycobacterium avium, and some of them are widely used for infection treatment. However, shortly after the introduction of these new drugs, resistant strains appeared due to mutations in the macrolide target, the ribosome. The mycobacterial cell wall with its specific composition and structure is considered to be a major factor in promoting the natural resistance of mycobacteria to various antibiotics. However, to explain the difference in macrolide sensitivity between the MTC and NTM, the synergistic contribution of a specific resistance mechanism might be required, in addition to possible differences in cell wall permeability. This mini-review summarizes the current knowledge on the natural and acquired macrolide resistance in mycobacteria, gives an overview of potential mechanisms implicated in the intrinsic resistance and brings recent data concerning a macrolide resistance determinant in the MTC.

Anti-Bacterial Agents↗
PubMed2006

A cortical band of gelatinous fibers causes the coiling of redvine tendrils: a model based upon cytochemical and immunocytochemical studies.

A cortical band of fiber cells originate de novo in tendrils of redvine [Brunnichia ovata (Walt.) Shiners] when these convert from straight, supple young filaments to stiffened coiled structures in response to touch stimulation. We have analyzed the cell walls of these fibers by in situ localization techniques to determine their composition and possible role(s) in the coiling process. The fiber cell wall consists of a primary cell wall and two lignified secondary wall layers (S(1) and S(2)) and a less lignified gelatinous (G) layer proximal to the plasmalemma. Compositionally, the fibers are sharply distinct from surrounding parenchyma as determined by antibody and affinity probes. The fiber cell walls are highly enriched in cellulose, callose and xylan but contain no homogalacturonan, either esterified or de-esterified. Rhamnogalacturonan-I (RG-I) epitopes are not detected in the S layers, although they are in both the gelatinous layer and primary wall, indicating a further restriction of RG-I in the fiber cells. Lignin is concentrated in the secondary wall layers of the fiber and the compound middle lamellae/primary cell wall but is absent from the gelatinous layer. Our observations indicate that these fibers play a central role in tendril function, not only in stabilizing its final shape after coiling but also generating the tensile strength responsible for the coiling. This theory is further substantiated by the absence of gelatinous layers in the fibers of the rare tendrils that fail to coil. These data indicate that gelatinous-type fibers are responsible for the coiling of redvine tendrils and a number of other tendrils and vines.

Cell Wall↗
PubMed2001

Unravelling cell wall formation in the woody dicot stem.

Populus is presented as a model system for the study of wood formation (xylogenesis). The formation of wood (secondary xylem) is an ordered developmental process involving cell division, cell expansion, secondary wall deposition, lignification and programmed cell death. Because wood is formed in a variable environment and subject to developmental control, xylem cells are produced that differ in size, shape, cell wall structure, texture and composition. Hormones mediate some of the variability observed and control the process of xylogenesis. High-resolution analysis of auxin distribution across cambial region tissues, combined with the analysis of transgenic plants with modified auxin distribution, suggests that auxin provides positional information for the exit of cells from the meristem and probably also for the duration of cell expansion. Poplar sequencing projects have provided access to genes involved in cell wall formation. Genes involved in the biosynthesis of the carbohydrate skeleton of the cell wall are briefly reviewed. Most progress has been made in characterizing pectin methyl esterases that modify pectins in the cambial region. Specific expression patterns have also been found for expansins, xyloglucan endotransglycosylases and cellulose synthases, pointing to their role in wood cell wall formation and modification. Finally, by studying transgenic plants modified in various steps of the monolignol biosynthetic pathway and by localizing the expression of various enzymes, new insight into the lignin biosynthesis in planta has been gained.

Cell Wall↗
PubMed1989

The characterization and ultrastructure of two new strains of Butyrivibrio.

Strains B-385-1 and 2-33 are numerically important components rumen bacterial populations , but they have remained (taxonomically) undefined. In spite of some resemblance to Selenomonas ruminantium in their cell size and in their formation of tufts of flagella, they more closely resemble Butyrivibrio fibrisolvens in the subpolar location of their flagella, in their guanine + cytosine content, and in most biochemical characteristics, including butyrate formation. Cells of these strains stain Gram negative, as do both Selenomonas and Butyrivibrio, but their cell walls closely resemble those of Butyrivibrio in their Gram-positive type of molecular architecture and in their cleavage pattern in freeze-etching. Cells of these strains and of B. fibrisolvens have a very thin (ca. 12 nm) peptidoglycan cell wall; thus, they fail to retain the crystal violet complex of the Gram stain and stain Gram negative. This important structural characteristic of their cell walls places strains B-385-1 and 2-33 within the genus Butyrivibrio and certain morphological and biochemical characteristics distinguish them from B. fibrisolvens.

Animals↗
PubMed1980

Characterization of the cell wall and cell wall proteins of Chromatium vinosum.

Highly purified cell walls of Chromatium vinosum were isolated by differential centrifugation, with or without Triton X-100 extraction. The isolated material had a protein composition similar to that of cell walls obtained by sucrose density gradient centrifugation. Twenty-two proteins were reproducibly detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A 42-kilodalton protein was shown to account for 65% of the total cell wall protein. The majority of cell wall proteins were solubilized in sodium dodecyl sulfate at room temperature; however, they existed as high-molecular-weight complexes unless heated to 45 degrees C or above. The cell wall contained one heat-modifiable protein which migrated with an apparent molecular weight of 37,400 when solubilized at 70 degrees C or below, but which migrated with an apparent molecular weight of 52,500 if solubilized at 100 degrees C. The electrophoretic mobility of three proteins was modified by 2-mercaptoethanol. The majority of C. vinosum cell wall proteins had isoelectric points between pH 4.5 and 5.5, and the 42-kilodalton protein focused at pH 4.9. No proteins were detected which were analogous to the lipoprotein or peptidoglycan-associated proteins of the Enterobacteriaceae. Nearest-neighbor analysis with a reducible, cross-linking reagent indicated that three proteins, including the 42-kilodalton protein, associated with themselves. Most of the cell wall proteins were partially accessible to proteases in both intact cells and isolated cell walls. Protease treatment of the whole cell or isolated cell wall digested approximately an 11,000-molecular-weight portion of the 42-kilodalton protein.

Bacterial Proteins↗
PubMed1995

A new interpretation of the structure of the mycolyl-arabinogalactan complex of Mycobacterium tuberculosis as revealed through characterization of oligoglycosylalditol fragments by fast-atom bombardment mass spectrometry and 1H nuclear magnetic resonance spectroscopy.

Previous structural analysis of small oligosaccharide fragments had allowed the recognition of several small structural motifs within arabinogalactan, the dominant cell was structural polysaccharide of Mycobacterium tuberculosis. To determine how these motifs are connected to one another to form the complete polymer, oligosaccharide fragments containing up to 26 glycosyl residues were released by gentle acid hydrolysis of the per-O-methylated arabinogalactan, converted to fully per-O-alkylated oligoglycosylalditols, and purified by high-performance liquid chromatography, and the molecular weights and alkylation patterns of the resultant oligoglycosyl fragments were determined by fast atom bombardment mass spectrometry. The results, combined with previous studies, allowed further understanding of the intricate structural features of the nonreducing ends of arabinogalactan. Thus, the extended nonreducing ends of the arabinan were shown to consist of a tricosaarabinoside (23-mer). We reason that three such arabinan motifs are attached to the homogalactan component or arabinogalactan, which was previously shown to consist of alternating 5- and 6-linked beta-D-galactofuranosyl residues. Using the same approach as applied to the arabinan branches, an extended stretch of the galactan was isolated that consisted of at least 23 alternating beta-1,6 and beta-1,5 D-Galf residues, devoid of any branching, demonstrating that the points of attachment of the arabinan chains to galactan are close to the reducing end of galactan, which itself is linked to peptidoglycan via the linker disaccharide phosphate L-Rhap-(1-->3)-alpha-D-GlcNAc-P. By nuclear magnetic resonance analysis, the L-Rhap was shown to be in the alpha configuration. The long-chain alpha-alkyl-beta-hydroxy mycolic acids, known to occupy the 5-positions of both the terminal beta-D-Araf and internal 2-alpha-D-Araf residues of the terminal branched pentaarabinosyl motif, are now shown to be nonacylated at the beta-hydroxy function. Lack of acylation points to intramolecular hydrogen bonding between the beta-hydroxyl and carbonyl functions of the mycolic acid, providing a highly ordered arrangement of mycolic acids in accord with evolving models of the orientation of the cell wall polymers in mycobacterial cell walls. A revised model is proposed for the composition and orientation of the mycolyl-arabinogalactan in the cell walls of M. tuberculosis, which should increase our understanding of cell wall hydrophobicity, impermeability, and role in disease pathogenesis.

Alkylation↗
PubMed1975

Structural and biochemical alterations of Nocardia asteroides cell walls during its growth cycle.

Analysis of Nocardia asteroides 14759 cell walls were done to determine the chemical and structural composition during the growth cycle. It was found that the ultrastructural profiles of the cell wall become altered as the cultures aged. Chemical analysis revealed corresponding shifts in cell wall components as the culture went from lag to logarithmic to stationary phases of growth. The peptidoglycan from lag-phase cells (5 h) represented 15% of the total cell wall weight, and the percentage of peptidoglycan progressively increased so that, in 1-week stationary-phase cells, it represented approximately 40% of the total wall weight. In lag-phase cells it was found that 36% of the cell wall weight was lipid in nature, whereas stationary-phase cells had only 7% lipid in their wall. The overall sugar composition of the walls remained relatively constant at about 28 to 31% however, the arabinose to galactose ratio changed from approximately 1:1 in lag-phase to 2:1 in stationary-phase cells. Gas-liquid chromatography demonstrated that the fatty acids making up the cell wall lipids changed relative to one another as the cells aged. Based upon the removal of lipids by ethanol-ether, chloroform, and alkaline methanol extraction, it was shown that the classes of loosely and firmly associated lipids changed as the cells aged. Further, it was found that a carotenoid-like pigment associated to a C22 fatty acid increased in the cell wall as the culture stopped growing. Peptidolipid or lipoprotein was found to make up a significant part of the cell wall. This component increased in amount and varied in amino acid content as the culture aged. Analysis of the totally extracted basal layer of the cell wall (peptidoglycan plus arabinogalactan) showed that it too changed as the cells grew and fragmented. The data presented established that the cell wall of N. asteroides was structurally and chemically complex and that a progression of chemical and physical processes occurred within the wall as the cells developed through their growth cycle.

Amino Acids↗
PubMed2000

A proteomic approach for the study of Saccharomyces cerevisiae cell wall biogenesis.

In fungi, cell shape is determined by the presence of a rigid cell wall which separates the cell from the extracellular medium. This highly dynamic structure is essential for the maintenance of cell integrity and is involved in several phenomena such as flocculation, adherence and pathogenicity. The composition of the fungal cell wall is well known, but issues such as the assembly and remodeling of its components remain poorly understood. In an attempt to study the de novo construction of the yeast cell wall, we have undertaken a large-scale proteomic approach to analyze the proteins secreted by regenerating protoplasts. Upon incubation of protoplasts in regenerating conditions, numerous proteins are secreted into the culture medium. These presumably include proteins destined for the cell wall, comprising both structural proteins as well as enzymes involved in cell wall biogenesis. This work reports the establishment of a reference map of proteins secreted by regenerating protoplasts by means of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and their identification by mass spectrometry. Thirty-two different proteins have been identified, including known cell wall proteins, glycolytic enzymes, heat shock proteins, and proteins involved in several other processes. Using this approach, novel proteins possibly involved in cell wall construction have also been identified. This reference map will allow comparative analyses to be carried out on a selected collection of mutants affected in the cell wall.

Amino Acid Sequence↗
PubMed1987

Changes in peptidoglycan composition and penicillin-binding proteins in slowly growing Escherichia coli.

The composition of peptidoglycan of chemostat-grown cultures of Escherichia coli was investigated as a function of growth rate. As the generation time was lengthened from 0.8 to 13.8 h, there was a decrease in the major monomer (disaccharide tetrapeptide) and dimer (bis-disaccharide tetrapeptide), while disaccharide tripeptide moieties increased to greater than 50% of the total wall. The average chain length became much shorter; lipoprotein density tripled, and the number of unusual diaminopimelyl-diaminopimelic acid crossbridges increased fivefold. As cells grew more slowly, amounts of penicillin-binding proteins (PBPs) 1a-1b complex and 4 decreased, while amounts of PBPs 3 and the 5-6 complex increased. We propose that the chemical composition of E. coli cell walls changes with growth rate in a manner consistent with alterations in the activities of PBPs and cell shape.

Bacterial Proteins↗
PubMed1976

Isolation and composition of an alkali-soluble glucan from the cell walls of Saccharomyces cerevisiae.

An alkali-soluble glucan was obtained from the cell walls of Saccharomyces cerevisiae NCYC1109 and baker's yeast by extraction with cold, dilute sodium hydroxide under nitrogen. The glucan, which represented approximately 20% of purified glucan was homogeneous and was shown to be free from contamination by other cell-wall polysaccharides by ultracentrifuging, gel filtration and electrophoresis. In addition to glucose, the glucan contained traces of mannose and nitrogen, but no hexosamine. Structural analyses revealed the presence of 80-85% (1 leads to 3)-beta-D linkages, 8-12% (1 leads to 6)-beta-D linkages and 3-4% branched residues linked through C-1, C-3 and C-6. The molecular weight of the glucan was estimated to be about 250000. Electron-microscopic examination of the cell walls after alkali extraction showed that an amorphous surface layer had been removed revealing numerous bud scar structures.

Cell Fractionation↗
PubMed1975

Amino-acid composition of the covalent rigid-layer lipoprotein in cell walls of Proteus mirabilis.

Cell walls of Proteus mirabilis in the stationary phase of growth contain a lipoprotein in covalent linkage to peptidoglycan and probably also in free form in the outer membrane. The protein moiety of this lipoprotein is composed of about 50 amino acids and has an approximate molecular weight of 5500. The Proteus lipoprotein has glycine and phenylalanine as specific components which are not present in lipoproteins of other enteric bacteria. Treatment of the peptidoglycan-lipoprotein complex of Proteus with trypsin leaves lysine as the only lipoprotein amino acid attached to the peptidoglycan. This suggests that in P. mirabilis, as in Escherichia coli, the lipoprotein is linked to the peptidoglycan by its C-terminal lysine residue.

Amino Acids↗
PubMed1972

Chemical composition and immunological specificity of the streptococcal group O cell wall polysaccharide antigen.

The group O streptococcal group antigen was shown to be a polysaccharide located in the cell wall of the organism. The antigen could be extracted by one of several methods: (i) 0.5 n NaOH at 37 C, (ii) phenol-water (50:50) at 68 C, (iii) 0.2 n HCl at 100 C, or (iv) 10% trichloroacetic acid at 4 C. The last method yielded more polysaccharide with less protein contamination. The polysaccharide was purified on diethylaminoethyl-Sephadex A-25 and Sephadex G-200. It was composed of two-thirds glucosamine and galactosamine, and the remainder glucose plus galactose. Rhamnose, glycerol, ribitol, and muramic acid were absent. Total phosphorus and amino acids were each less than 0.1%. N-Acetyl-beta-d-glucosamine exerted a strong inhibition of the precipitin reaction and is considered the immunodominant sugar. Glucosamine and glucose possessed a partial inhibitory activity. Galactose and galactosamine were essentially negative. No evidence of cross-reactivity was found between the O polysaccharide and group A and L polysaccharides, and group A and Staphylococcus aureus teichoic acids, which posesss N-acetylglucosamine specificity. The release of limited quantities of N-acetyl-glucosamine from its terminal location by enzyme, and glucose by acid hydrolysis, indicates a limited number of side chains in the O antigen. The glucosamine is in acid-stable linkage in the polysaccharide. Glucose was not released by beta-glucosidase and probably does not occupy a terminal position. The O antigen is the only known streptococcal polysaccharide antigen which does not contain rhamnose. The effect of these factors on the immunological specificity is discussed. O serum, after adsorption with the purified polysaccharide, was used to demonstrate the presence of protein antigens in acid extracts of cells from each of the nine strains examined. These antigens may represent type antigens. Two of these strains, originally described as group O, did not contain the O polysaccharide.

Antibodies, Bacterial↗
PubMed1974

The Structure of Plant Cell Walls: VI. A Survey of the Walls of Suspension-cultured Monocots.

The primary cell walls of six suspension-cultured monocots and of a single suspension-cultured gymnosperm have been investigated with the following results: (a) the compositions of all six monocot cell walls are remarkably similar, despite the fact that the cell cultures were derived from diverse tissues; (b) the cell walls of suspension-cultured monocots differ substantially from those of suspension-cultured dicots and from the suspension-cultured gymnosperm; (c) an arabinoxylan is a major component (40% or more by weight) of monocot primary cell walls; (d) mixed beta-1,3; beta-1,4-glucans were found only in the cell wall preparations of rye grass endosperm cells, and not in the cell walls of any of the other five monocot cell cultures nor in the walls of suspension-cultured Douglas fir cells; (e) the monocot primary cell walls studied contain from 9 to 14% cellulose, 7 to 18% uronic acids, and 7 to 17% protein; (f) hydroxyproline accounts for less than 0.2% of the cell walls of monocots. Similar data on the soluble extracellular polysaccharides secreted by these cells are included.

Journal Article↗
PubMed1986

Immunogold localization of xyloglucan and rhamnogalacturonan I in the cell walls of suspension-cultured sycamore cells.

PLANT CELL WALLS SERVE SEVERAL FUNCTIONS: they impart rigidity to the plant, provide a physical and chemical barrier between the cell and its environment, and regulate the size and shape of each cell. Chemical studies have provided information on the biochemical composition of the plant cell walls as well as detailed knowledge of individual cell wall molecules. In contrast, very little is known about the distribution of specific cell wall components around individual cells and throughout tissues. To address this problem, we have produced polyclonal antibodies against two cell wall matrix components; rhamnogalacturonan I (RG-I), a pectic polysaccharide, and xyloglucan (XG), a hemicellulose. By using the antibiodies as specific markers we have been able to localize these polymers on thin sections of suspension-cultured sycamore cells (Acer pseudoplatanus). Our results reveal that each molecule has a unique distribution. XG is localized throughout the entire wall and middle lamella. RG-I is restricted to the middle lamella and is especially evident in the junctions between cells. These observations indicate that plant cell walls may have more distinct chemical (and functional?) domains than previously envisaged.

Journal Article↗
PubMed2006

Inhibitory activity of 1-farnesylpyridinium on the spatial control over the assembly of cell wall polysaccharides in Schizosaccharomyces pombe.

The modes of actions of 1-farnesylpyridinium (FPy) on yeast cell growth were investigated on the basis of its effects on cell cycle progression, morphogenesis and the related events for construction of cell wall architecture in Schizosacchromyces pombe. FPy predominantly inhibited the growth of the yeast cells after various cycles of cell division so that cells were arrested at the phase of separation into daughter cells accompanying morphological changes to swollen spherical cells at 24 h of incubation. FPy-treated cells were osmotically stable but were susceptible to the lytic action of (1, 3) beta-D-glucanases, and characterized by serious damages to the cell wall architecture as represented by a rough and irregular surface outlook. The isolated cell wall fraction gave a similar hexose composition with or without FPy treatment, suggesting that FPy did not inhibit the synthesis of each cell wall polysaccharide. FPy was permissive for the extracellular accumulation of amorphous cell wall materials and septum development in protoplasts, but absolutely interfered with the following morphogenetic process for construction of the rod-shaped cell wall architecture. Our results suggest the inhibitory activity of FPy on the spatial control over the assembly of cell wall polysaccharides.

Cell Wall↗