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At least 19 recordsLinked to original sources
PubMed1978

Immunotherapy of a guinea pig hepatoma with mycobacterial vaccines: comparison of BCG cell walls and cell wall skeletons.

BCG cell wall skeletons (SK) derived from BCG cell walls (CW) by treatment with proteolytic enzymes and organic solvents were tested for their potency to cause regression of a transplanted guinea pig hepatoma. On a weight basic, SK were as effective as CW in causing tumor regression, and they, as well as purified protein derivative of mycobacteria, provoked delayed cutaneous hypersensitivity reactions in animals immunized with CW or with SK. On a weight basis, CW were more active than SK in eliciting delayed cutaneous hypersensitivity in sensitized guinea pigs whether the animals were immunized with CW or with SK. In unimmunized animals the inflammatory response to intradermally administered CW was greater than that evoked by SK. CW and SK provoked delayed cutaneous hypersensitivity reactions of similar strength in animals immunized with living BCG. This study provided no compelling reasons for using SK instead of CW in clinical trials of cancer treatment by mycobacterial vaccines.

Animals↗
PubMed1977

Preparation of arthritogenic hydrosoluble peptidoglycans from both arthritogenic and non-arthritogenic bacterial cell walls.

Cell wall lytic enzyme (Kyowa lytic no. 2 enzyme) liberated arthritogenic hydrosoluble peptidoglycans from both arthritogenic and non-arthritogenic bacterial cell walls. From these cell walls, mutanolysin (peptidoglycan-degrading enzyme) also liberated hydrosoluble peptidoglycans which, however, lacked arthritogenicity. Based on the chemical composition of these peptidoglycans, it was suggested that their arthritis-inducing ability depends on a relatively long chain of glycan units that consists of repeated units of N-acetylglucosaminyl-N-acetylmuramic acid. However, the glycan chain lengths on these peptidoglycans appeared to be related to their adjuvancy rather than to an antigen(s) responsible for development of arthritis in rats.

Animals↗
PubMed1979

Thermal activation of peroxidase from tobacco leaf mesophyll cell walls.

Cell wall-bound peroxidase isolated from tobacco leaf mesophyll cell walls was found to consist of two isoenzymes (P1 and P2). Each exists in the form of a single subunit with the same molecular weight (35 000) as determined by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Both isoenzymes exhibited maximum activities at 70 degrees. P1 increased to 265% and P2 to 140% of the activities assayed at 27 degrees; below this temperature the two isoenzymes had the same specific activity. On hydrolysis, P1 showed a carbohydrate content of 26.22% when the monosaccharides were analyzed by gas liquid chromatography; P2 gave 21.45%.

Carbohydrates↗
PubMed1992

Role of Kupffer cells in developing streptococcal cell wall granulomas. Streptococcal cell wall induction of inflammatory cytokines and mediators.

Hepatic granulomas are induced by intraperitoneal injection of streptococcal cell walls (SCW) into Lewis rats. Kupffer cells rapidly clear SCW from the blood, and the authors examined Kupffer cells further for a role in SCW-hepatic inflammation. Isolated Kupffer cells cultured with SCW secreted high levels of tumor necrosis factor alpha (TNF alpha), interleukin-1 (IL-1), transforming growth factor beta (TGF beta), and prostaglandin E2 (PGE2). SCW transiently induced increased steady-state levels of IL-1 beta and TNF alpha mRNA; in contrast, constitutive expression of TGF beta 1 mRNA in Kupffer cells was not affected by SCW. Low concentrations of SCW induced the accumulation of intracellular IL-1 and TGF beta bioactivity, with intracellular IL-1 bioactivity remaining high through at least 72 hours of culture. Kupffer cells isolated 1, 7, and 21 days after SCW injection did not express IL-1 beta or TNF alpha mRNA greater than control levels and exhibited marked hyporesponsiveness to secondary in vitro stimulation with SCW or LPS. SCW transiently induces Kupffer cells to secrete a variety of soluble mediators that contribute to hepatic inflammation by inducing leukocyte recruitment and activation and fibroproliferation. The transient nature of the Kupffer cell response and the hyporesponsiveness to secondary stimulation may be a mechanism by which the hepatic inflammation is negatively regulated.

Animals↗
PubMed2025

Nitrate modulates pectin metabolism and cell wall mechanics during cell expansion in Arabidopsis.

Nitrate is a key nutrient and one of the most important nitrogen sources for land plants. Besides its nutritional role, nitrate is a signal molecule that regulates plant gene expression, metabolism, physiology, growth, and development. In cotyledons and true leaves, nitrate promotes growth by inducing cell expansion. Plant cell expansion requires changes in the cell wall. However, there is scant information on the influence of nitrate on cell wall metabolism and properties during cell expansion and growth. Here, we demonstrate that nitrate availability modulates pectin metabolism, a major polysaccharide of the primary cell wall. Using colorimetric assays, immunohistochemistry, and confocal microscopy, we show that nitrate enhances methylesterified pectin during cotyledon cell expansion. This is achieved by increasing galacturonic acid (GalA) deposition as homogalacturonan (HG) and by decreasing global PME activity. We further show that this regulation is dependent on nitrate signaling pathway components, including NRT1.1 and NLP7. Pectin methylesterification state impacts the mechanical properties of the cell wall. We characterized cell wall elasticity changes during nitrate-induced expansion using atomic force microscopy (AFM) and automatic confocal microextensometry (ACME). We found that nitrate induces cell wall softening at both cellular and whole-tissue levels during this expansion process. Our results indicate pectin metabolism plays an important role in nitrate-induced cell expansion and cotyledon growth in Arabidopsis. We provide insights into the interplay between nitrate signaling, cell wall metabolism, and biomechanical properties for cell expansion. Our results contribute to our understanding of how plants sense and respond to environmental cues for growth.

Pectins↗
PubMed1978

Regulation of bacterial cell walls: correlation between autolytic activity and cell wall turnover in Staphylococcus aureus.

Cell wall turnover was examined in parent and mutant strains of Staphylococcus aureus. Peptidoglycan and teichoic acid were observed to undergo turnover in the wild-type strain during exponential growth; however, the rate of turnover did not decrease when the growth rate slowed, as the culture entered stationary phase. Isolated native cell walls and crude soluble autolytic enzyme were prepared from cells harvested during exponential and postexponential phases of growth. Native cell walls from both phases of growth autolyzed in buffer at identical rates; similarily, crude soluble enzyme from both preparations degraded radioactive cell walls at the same rate. Therefore, the activity of the autolysin in both exponential and postexponential cells was similar. The autolysis of whole cells of a mutant tar-1 was enhanced by 1.0 M NaCl. When 1.0 M NaCl was present under growing conditions, the rate of cell wall turnover was greatly increased. The presence of chloramphenicol, which inhibits whole-cell autolysis, also inhibited turnover. Analysis of the cell wall material recovered from spent medium revealed products consistent with the known mode of action of the endogenous autolysin. It is concluded that cell wall turnover in S. aureus is independent of the stage of culture growth but is dependent instead on the activity of the autolysin.

Bacteriolysis↗
PubMed1977

Relation between cell wall turnover and cell growth in Bacillus subtilis.

The kinetics of cell wall turnover in Bacillus subtilis have been examined in detail. After pulse labeling of the peptidoglycan with N-acetylglucosamine, the newly formed peptidoglycan is stable for approximately three-quarters of a generation and is then degraded by a process that follows first-order kinetics. Deprivation of an auxotroph of amino acids required for protein synthesis results in a cessation of turnover. If a period of amino acid starvation occurs during the lag phase of turnover, then the initiation of turnover is delayed for a period of time equivalent to the starvation period. During amino acid starvation, new cell wall peptidoglycan is synthesized and added to preexisting cell wall. This peptidoglycan after resumption of growth is also subject to degradation (turnover). It is suggested that cell wall turnover is dependent on cell growth and elongation. Several possible control mechanisms for cell wall autolytic enzymes are discussed in light of these observations.

Acetylglucosamine↗
PubMed1975

Immunochemical characterization of cell wall protein antigen purified from the cell wall autolysate of Clostridium botulinum type A.

The cell wall protein antigen was solubilized from the isolated cell walls of Clostridium botulinum type A by autolysis and purified by diethylaminoethyl-cellulose column chromatography followed by gel filtration on Sephadex G-150. The two fractions showed a high degree of the serological activity and produced a main fused precipitin line in immunodiffusion tests against the homologous antiserum. The fact that antigenic fractions contained various kinds of amino acids but no detectable amounts of amino sugars or carbohydrates suggests that the antigens were principally composed of proteins. The protein antigen possessed multiple antigenic components in immunoelectrophoresis. As serological activity, the antigen was heat-stable and resistant to tryptic digestion but sensitive to the actions of pronase, nagarse or pepsin. The protein antigen appeared to be responsible for the common antigenicity among the proteolytic strains of C. botulinum.

Antigens, Bacterial↗
PubMed1977

Comparison of Coccidioides immitis arthrospore, mycelium, and spherule cell walls, and influence of growth medium on mycelial cell wall composition.

Comparative lipid content, cell wall yield, neutral monosaccharide, glucosamine, and protein (amino acid) contents of arthrospores, mycelia, and spherules of Coccidioides immitis Cash were studied. Cellular lipid contents were found in the decreasing order: spherules, arthrospores, mycelia. Lipid content of mycelia did not reach the level of arthrospores or spherules even when mycelia were grown on relatively rich media. Cell wall yields of spherules were lower than for mycelia when grown on comparable media. Cell walls of arthrospores, mycelia, spherules, and spherule culture filtrate all contained 3-O-methylmannose, mannose, and glucose, but in varying amounts. Cell wall yield and cell wall glucose content increased in mycelia grown in increasingly rich media, whereas mannose content either decreased or remained constant.

Acetylglucosamine↗
PubMed1990

Cell wall regeneration in Chlamydomonas: accumulation of mRNAs encoding cell wall hydroxyproline-rich glycoproteins.

The unicellular alga Chlamydomonas reinhardtii is surrounded by a cell wall composed entirely of hydroxyproline-rich glycoproteins (HRGPs). When the walls of vegetative cells are removed with the enzyme gamete autolysin (g-lysin), they regenerate a matrix within 3-4 hr. In vitro translation of mRNAs isolated from g-lysin-treated cells showed significant increases and decreases in abundance of several mRNAs encoding proline-rich polypeptides. Because the population of up-regulated mRNAs is likely to include species encoding cell wall components, expression of genes for two outer wall HRGPs (GP1 and GP2) was analyzed during wall regeneration by using cDNAs isolated from a C. reinhardtii lambda gt11 library. Transcripts encoding GP1 and GP2 were elevated severalfold within the first hour or regeneration, suggesting that upregulation of HRGP mRNAs is a primary response to cell wall removal by g-lysin. Cell wall regeneration in Chlamydomonas provides an accessible system to study HRGP gene expression during matrix development.

Amino Acid Sequence↗
PubMed2023

Proteomics from compartment-specific APEX2 labeling in Mycobacterium tuberculosis reveals Type VII secretion substrates in the cell wall.

The cell wall of mycobacteria plays a key role in interactions with the environment. Its ability to act as a selective filter is crucial to bacterial survival. Proteins in the cell wall enable this function by mediating the import and export of diverse metabolites, from ions to lipids to proteins. Identifying cell wall proteins is an important step in assigning function, especially as many mycobacterial proteins lack functionally characterized homologues. Current methods for protein localization have inherent limitations that reduce accuracy. Here we showed that although chemical labeling of live cells did not exclusively label surface proteins, protein tagging by the engineered peroxidase APEX2 within live Mycobacterium tuberculosis accurately identified the cytosolic and cell wall proteomes. Our data indicate that substrates of the virulence-associated Type VII ESX secretion system are exposed to the periplasm, providing insight into the currently unknown mechanism by which these proteins cross the mycobacterial cell envelope.

Mycobacterium tuberculosis↗
PubMed1979

Bacteriophage T4D receptors and the Escherichia coli cell wall structure: role of spherical particles and protein b of the cell wall in bacteriophage infection.

The nature of the interaction of bacteriophage T4D and the outer cell wall of its host, Escherichia coli B, has been investigated. Bacteria with altered or modified cell walls have been obtained by two different growth procedures: (i) growth in high osmolarity medium or (ii) growth in broth in the presence of divalent heavy metal ions. When these altered host cells were washed and subsequently added to regular growth medium, they interacted with added phage particles, but successful infection did not occur. Most of the phage particles released from these treated cells were observed to have full heads and an altered tail structure. The altered phage tails had contracted sheaths and unusual pieces of the bacterial cell wall attached to the distal portion of the exposed phage tail tube. Phage released from bacteria grown in the high osmolarity medium had attached cell wall pieces of two major types, these pieces being either 40 or 21 nm in diameter. The smaller-type cell wall pieces (21 nm) were formed by three spheres each measuring 7 nm in diameter. Phage particles released from cells previously exposed to the divalent metal ions had only one 7-nm cell wall sphere attached to the distal end of the tail tube. It was found that these 7-nm spheres (i) are normal components of the cell wall and are morphologically similar to endotoxin, (ii) are held in place on the cell wall by a component of the cell wall called protein b, and (iii) are most likely the site of penetration of the phage tail tube through which the phage DNA enters the host cell.

Bacterial Proteins↗
PubMedDate not supplied

[Enzymatic degradation of cell walls of yeast cells at different growth phases].

The enzymes of Actinomyces cellulosae were fractionated by precipitation with ammonium sulphate and gel filtration on Sephadex G-75. Fractionation yielded protease, beta-1,3-glucanase and an enzyme of a low molecular weight and unknown nature involved in lysis by 70% of yeast cells at early exponential growth phase without the participation of the other two enzymes. The protease did not accomplish lysis of the cells; beta-1,3-glucanase was involved in degradation of the cell walls of old yeast cells.

Actinomyces↗
PubMed1978

Mineral components of plant cell walls.

Plant cell walls that are secondarily thickened contain silicon and metal cations. The silicon occurs predominantly as silica (SiO2.nH2O) deposited in intimate association with the organic components of the walls and, according to recent evidence, as an integral constituent of polyuronides. Relatively large amounts of deposited (i.e., solid) silica are found in rice and other cereals and in grasses. When ingested by ruminant animals, practically all the solid silica may be recovered in the feces. However, microscopic particles of silica from plants are, to a small extent, absorbed as such through the gastrointestinal wall in both man and ruminant animals. It has now been shown that silicon is essential for animals, and that it is a constituent of certain mucopolysaccharides, thereby contribution to the architecture of connective tissues. The acidic silanol group of solid silica in plant cell walls may be involved in binding metal cations, but carboxyl and phenolic hydroxyl groups of the organic components of the walls are probably mainly responsible. Binding of metal cations by these components of plant cell walls, and possibly by silica, is likely to reduce availability of the cations for intestinal absorption.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Pectin methylesterase, metal ions and plant cell-wall extension. The role of metal ions in plant cell-wall extension.

The study of pectin methylesterase and wall-loosening enzyme activities in situ, as well as the estimation of the electrostatic potential of the cell wall, suggest a coherent picture of the role played by metal ions and pH in cell-wall extension. Cell-wall growth brings about a decrease of local proton concentration because the electrostatic potential difference (delta psi) of the wall decreases. This in turn activates pectin methylesterase, which restores the initial delta psi value. This process is amplified by the attraction of metal ions in the polyanionic cell-wall matrix. The amplification process is basically due to the release of enzyme molecules that were initially bound to 'blocks' of carboxy groups. This increase of metal-ion concentration also results in the activation of wall-loosening enzymes. Moreover, the apparent 'inhibition' of pectin methylesterase by high salt concentrations may be considered as a device which prevents the electrostatic potential from becoming too high.

Carboxylic Ester Hydrolases↗
PubMed1992

Pythium aphanidermatum: culture, cell-wall composition, and isolation and structure of antitumour storage and solubilised cell-wall (1----3),(1----6)-beta-D-glucans.

Under optimal conditions for the culture of the fungus Phytium aphanidermatum, no polysaccharides were excreted into the medium. The mycelium contained up to 38% of a slightly branched, storage (1----3),(1----6)-beta-D-glucan with a MW of 20,000. The cell-wall polysaccharides of the mycelium comprised 18% of cellulose and 82% of (1----3),(1----6)-beta-D-glucans. Of the non-cellulosic glucans, approximately 33% could be solubilised by extraction with water at 121 degrees, and they had a MW of 10,000, were highly branched, and contained 6% of (1----6) linkages. Treatment of the cell wall with 0.1 M trifluoroacetic acid released approximately 50% of the non-cellulosic glucans. The acid-soluble cell-wall (1----3),-(1----6)-beta-D-glucans of lower MW (6000) were still highly branched and contained 14% of (1----6) and 8% of (1----4) linkages. The storage glucan and the hot-water-soluble cell-wall glucan exhibited strong activity against the Sarcoma 180 in CD-1 mice, whereas the acid-soluble cell-wall glucans were inactive. The hot-water-soluble cell-wall glucan was also active against the DBA/2-MC.SC-1 fibrosarcoma in DBA/2 mice.

Animals↗