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PubMed2026

A maize GT14 family glycosyltransferase affects cell wall composition and carbohydrate export from source leaves.

Sucrose translocation from photosynthetic leaves to distant parts of a plant, such as seeds and roots, is a critical aspect of plant growth and development and a major determinant of crop yield. To identify genes contributing to this process in maize (Zea mays), we isolated four allelic mutants, carbohydrate partitioning defective7, 48, 49 (cpd7, cpd48, cpd49) and a UniformMu insertion (mu1049954), all of which exhibited reduced growth and fertility and hyperaccumulation of starch and soluble sugars in mature leaves. Consistent with carbohydrate accumulation, cpd7 mutants exhibited reduced sucrose export from mature leaves. Cpd7 encodes a Golgi-resident glucuronosyltransferase belonging to the Glycosyltransferase14 (GT14) family, which is involved in decoration of type II arabinogalactan proteins. No previously described GT14 mutants exhibit reduced sucrose transport or carbohydrate partitioning defects. Additionally, we show that mature leaves of cpd7 mutants have reduced cellulose content and an altered cell wall composition. Further, cpd7 mutants exhibit ectopic phloem lignification likely as a compensatory mechanism for reduced cell wall integrity. Collectively, our data suggest that Cpd7 functions to facilitate cell wall development in the phloem, which is required for efficient sucrose export from mature maize leaves.

Zea mays↗
PubMed2005

SKG1, a suppressor gene of synthetic lethality of kex2Deltagas1Delta mutations, encodes a novel membrane protein that affects cell wall composition.

The fungal GAS1-related genes encode GPI-anchored beta-1,3-glucanosyltransferase, and their loss causes a defect in the assembly of the cell wall. The KEX2 gene encodes a processing protease in the late Golgi compartment and its loss also results in defects in the cell wall. Simultaneous mutations of these genes are lethal in Saccharomyces cerevisiae. To understand the basis of this synthetic lethality, we screened for multicopy suppressors and identified 13 SKG (suppressor of kex2 gas1 synthetic lethality) genes. SKG1 encodes a transmembrane protein that localizes on the inner surface of the plasma membrane at the bud and in the daughter cell. The multicopy SKG1 increases the sensitivity of cells to zymolyase, and the skg1Delta null mutation increases resistance to it. This zymolyase susceptibility corresponds to an increase of alkali-soluble beta-1,3-glucan and a decrease of chitin in the cell wall. Thus SKG1 encodes a novel protein that affects the cell wall polymer composition in the growing region of the cell.

Amino Acid Sequence↗
PubMed1970

Interaction of Gram-Negative Bacteria with the Lysosomal Fraction of Polymorphonuclear Leukocytes I. Role of Cell Wall Composition of Salmonella typhimurium.

Wild-type Salmonella typhimurium and cell wall mutants with sequential deficiencies in their cell wall polysaccharide were examined for sensitivity to the bactericidal action of the lysosomal fraction of polymorphonuclear leukocytes. The complete lipopolysaccharide basal core was essential for resistance to the bactericidal action. O-specific side chains of the wild type did not enhance the resistance. Absence of N-acetyl glucosamine considerably enhanced sensitivity, whereas absence of other core sugars did not; additional increase in sensitivity was obtained when the heptose phosphate was absent. Under conditions where appropriate supplementation of the medium permitted complete cell wall synthesis, the uridine diphosphate-gal-4-epimeraseless mutant regained resistance that was essentially equal to that of the wild type. Cells coated with specific antiserum and nongrowing cells were more resistant than normal growing cells.

Journal Article↗
PubMed2004

Soybean milk residue ensiled with peanut hulls: fermentation acids, cell wall composition, and silage utilization by mixed ruminal microorganisms.

Preservation of soybean milk residue (SMR) by ensiling with peanut hulls (PEH) and subsequent utilization of silage by mixed ruminal microorganisms were investigated. Treatments were combinations of SMR with PEH at the following ratios: 100:0, 78:22, 71:29, and 60:40 (fresh weight basis). After eight weeks of ensiling, silage lactic acid, crude protein, ether extract, and non-fiber carbohydrates were highest when SMR was ensiled alone and reduced as amounts of SMR decreased. Similar trends were observed for silage in vitro dry matter digestibility, and gas and volatile fatty acid production by ruminal microorganisms. Conversely, silage pH, dry matter, neutral detergent fiber, acid detergent fiber, cellulose, and lignin increased accordingly. The ensiling treatment appeared to alter silage cell wall composition. In particular, silage treated with PEH at the low level (78:22) resulted in reduced fiber contents and lignification. The silage (SMR:PEH=78:22) had enhanced efficiency of both silage fermentation and in vitro ruminal fermentation pattern.

Animals↗
PubMed1978

Effect of specific growth limitations on cell wall composition of Staphylococcus aureus H.

Conditions are described for the continuous culture of a derivative of Staphylococcus aureus H in a fully defined minimal medium in which cysteine is the sole amino acid. The effects of growth under various nutrient limitations on the composition and properties of the cell wall have been studied. The proportion of ribitol teichoic acid present in the wall, and the extent to which it is substituted with N-acetylglucosamine, varies in bacteria grown under different conditions as does the composition and extent of cross-linking of the peptidoglycan. Neither the derivative nor the original strain H produced teichuronic acid when grown under phosphate limitation.

Amino Acids↗
PubMed2003

A study of the yeast cell wall composition and structure in response to growth conditions and mode of cultivation.

AIM: The polysaccharide composition of the Saccharomyces cerevisiae cell wall was measured under various growth conditions and was compared with the cell wall structure. METHODS AND RESULTS: Chemical and enzymatic methods were used to determine levels of beta-1,3-glucan and 1,6-glucan, mannan and chitin of the yeast cell wall, whereas the structure/resistance of the wall was qualitatively assessed by the sensibility to the lytic action by zymolyase. It was found that the dry mass and polysaccharides content of the cell wall could vary by more than 50% with the nature of the carbon source, nitrogen limitation, pH, temperature and aeration, and with the mode of cell cultivation (shake flasks vs controlled fermentors). While no obvious correlation could be found between beta-glucan or mannan levels and the susceptibility of whole yeast cells to zymolyase, increase of beta-1,6-glucan levels, albeit modest with respect to the growth conditions investigated, and to a lesser extent that of chitin, was associated with decreased sensitivity of yeast cells to the lytic action by zymolyase. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results indicate that the cell wall structure is merely determined by cross-linking between cell wall polymers, pointed out the role of beta-1,6-glucan in this process. Hence, this study reinforces the idea that enzymes involved in these cross-linking reactions are potential targets for antifungal drugs.

Cell Wall↗
PubMed1975

Cell wall composition and incorporation of radio-labelled compounds by Veillonella alcalescens.

The cell wall of Veillonella alcalescens was shown to have a typically Gram-negative appearance and composition. The wall contains 24% lipid, 0.8% phosphorus, and 6.8% hexosamine. It is estimated to contain about 5% murein, unlike the 24% reported by other for Veillonella parvula. The amounts of 19 amino acids, including diaminopimelic acid, were determined. Though Veillonella sp. cannot metabolize sugars for energy, V. alcalescens incorporates ribose and fructose by separate, specific mechanisms and uses most of the incorporated sugar in nucleic acid synthesis. Large excesses of either sugar in the medium do not repress gluconeogenesis from the pyruvate level. We have been unable to detect phosphoglyceromutase (EC 2.7.5.3) by several assay methods but have no indication of a gluconeogenic pathway other than reverse glycolysis.

Amino Acids↗
PubMed1985

Bacterial cell wall composition, lysozyme resistance, and the induction of chronic arthritis in rats.

Bacterial cell wall induced arthritis is an experimental model of chronic erosive synovitis in which arthritis is induced in rats by a single injection of an aqueous suspension of cell wall fragments from selected Gram-positive bacteria. To understand better the Gram-positive bacterial cell wall characteristics necessary for the induction of chronic arthritis we tested the arthritogenicity of five Gram-positive bacteria which were (1) lysozyme resistant and contained a polyrhamnose peptidoglycan side chain moiety, (2) lysozyme resistant, but had little or no rhamnose in the peptidoglycan, polysaccharide, or (3) neither lysozyme resistant, nor contained rhamnose in their peptidoglycan, polysaccharide. All of the lysozyme resistant cell walls tested induced acute arthritis, but only those cell walls which were both lysozyme resistant and contained rhamnose in their polysaccharide side chain were able to induce chronic arthritis. Cell walls which were neither lysozyme resistant nor contained rhamnose were not arthritogenic. These data suggest that both lysozyme resistance and the rhamnose moiety in the peptidoglycan, polysaccharide side chain play an important role in the induction of chronic arthritis by Gram-positive bacterial cell walls in aqueous suspension.

Animals↗
PubMed1982

Group B, type III streptococcal cell wall: composition and structural aspects revealed through endo-N-acetylmuramidase-catalyzed hydrolysis.

Cell walls from a group B, type III streptococcus strain were prepared, purified by extraction with sodium dodecyl sulfate, and solubilized by the M-1 fraction of mutanolysin, an endo-N-acetylmuramidase obtained from Streptomyces globisporus. The lysate was resolved into three fractions by ion-exchange chromatography: a fraction containing peptidoglycan (PG) fragments, free of neutral and acidic sugars and of phosphate; a complex of PG fragments and group B-specific polysaccharide; and a complex of PG fragments and group B-specific polysaccharide and type III-specific polysaccharide. The PG-polysaccharide complexes were large and heterogeneous in molecular size. When subjected to base-catalyzed beta-elimination, both complexes were disintegrated, and polysaccharides and low-molecular-weight PG fragments could then be separated by gel filtration. The low-molecular-weight PG fragment-containing fraction contained muramic acid, glucosamine, alanine, lysine, glutamic acid, and serine in molar ratios (to lysine) of 0.92:0.98:3.01:1.00:1.00:0.05. Wall-derived, purified group polysaccharide contained rhamnose, galactose, glucosamine, and phosphorus in molar ratios (to galactose) of 5.03:1.00:1.00:1.05. It also contained an unidentified sugar. Wall-derived, purified type III polysaccharide contained galactose, glucosamine, glucose, and N-acetylneuraminic acid in molar ratios (to glucose) of 1.94:0.85:1.00:1.39. On a dry-weight basis, the whole wall lysate contained 19.8 and 20.6% of group and type polysaccharide, respectively. Neither glycerol nor ribitol was found, and all of the cell wall phosphorus was accounted for as polysaccharide, indicating the absence of a wall teichoic acid.

Amino Acids↗
PubMed1976

Cell-wall composition and taxonomy of Cephaloascus fragrans and some Ophiostomataceae.

Carbohydrates of intact cells and cell walls were studied by gas-liquid chromatographical analysis after acid hydrolysis. Isolated cellulose was determined by infrared spectrophotometry, pyrolysis mass spectrometry and histochemistry. Biochemical characters do not support an assumed relationship between Ophiostoma (including Europhium) and Cephaloascus fragrans. Cephaloascus fragrans differs from Ophiostoma by a high mannose content and by the absence of cellulose and rhamnose. A relationship between Cephaloascus fragrans and Ceratocystis cannot be excluded on the basis of the biochemical characters, although there is a marked difference in conidiogenesis. Saprolegnia ferax (Oomycetes) was included as a cellulose-containing fungus for comparison.

Ascomycota↗
PubMed1972

Cell wall composition of two strains of Blastomyces dermatitidis exhibiting differences in virulence for mice.

Cell walls isolated from two strains of Blastomyces dermatitidis were examined. Whereas strain Ga-1 was practically avirulent for mice, strain KL-1 produced death by 21 days in 50% of the mice inoculated. Analyses of the trypsin-treated cell walls of the two strains revealed a higher chitin and protein content in strain KL-1, whereas a higher polysaccharide content was observed in the cell walls of strain Ga-1. Extraction of the walls with 1 n NaOH revealed a threefold difference in the amount of alkali-soluble cell wall material present. The alkali-soluble material could be further fractionated into a water-soluble and a water-insoluble fraction. Previous reports have indicated that the water-insoluble fraction of B. dermatitidis consists of an alpha-linked glucan; however, we report that in addition a phospholipid moiety is covalently bound to the polysaccharide. Furthermore, on the basis of organic phosphorus content, considerably more phospholipid is associated with the alpha-linked glucan of the more virulent KL-1 strain. These results suggest that this cell wall constituent might be one of the factors related to the virulence of this fungus.

Amino Acids↗
PubMed2003

Variations in the cell wall composition of maize brown midrib mutants.

Most studies published thus far on the four brown midrib (bm) mutants (bm1, bm2, bm3, and bm4) in maize (Zea mays L.) have focused on one or two individual mutants, and comparisons between studies have been difficult because of variation in genetic backgrounds, maturity, and source of tissue. Detailed analyses of the stalks of the four bm single mutants and a bm1-bm2 double mutant in a common genetic background (inbred A619) revealed structural and compositional changes in their isolated cell walls and lignins compared to the wild-type inbred. 2D-NMR revealed a significant presence of benzodioxane units in the bm3 isolated lignin. 1D (13)C NMR revealed increased aldehyde levels in the bm1 and bm1-bm2 mutants compared to the wild-type inbred. The bm3 and bm1-bm2 mutants contained less Klason lignin in the isolated cell walls. The bm1, bm3, and bm1-bm2 mutants contained approximately 50% less esterified p-coumaric acid with noticeably elevated levels of ferulate in the bm3 mutant. A difference among bm mutants in the solubility of p-coumaric acid-lignin complexes during cellulase enzyme treatment was also discovered, suggesting that the bm mutations might also differ in the structural organization of lignin.

Aldehydes↗
PubMed1969

Cell wall composition of the yeast and mycelial forms of Paracoccidioides brasiliensis.

Isolation and chemical analyses of the cell walls of the yeast (Y form) and mycelial forms (M form) of Paracoccidioides brasiliensis and Blastomyces dermatitidis revealed that their chemical composition is similar and depends on the form. Lipids, chitin, glucans, and proteins are the main constituents of the cell walls of both forms of these fungi. There is no significant difference in the amount of lipids (5 to 10%) and glucans (36 to 47%) contained by the two forms. In both fungi, the Y form has a larger amount of chitin (37 to 48%) than the M form (7 to 18%), whereas the M form has a larger amount of proteins (24 to 41%) than the Y form (7 to 14%). Several properties of the glucan of P. brasiliensis were studied. Almost all of the glucan in the Y form was soluble in 1 n NaOH, was weakly positive in the periodic acid-Schiff reaction, was not hydrolyzed by snail digestive juice, and had alpha-glycosidic linkage. Glucans of the M form were divided into alkali-soluble (60 to 65%) and alkali-insoluble (35 to 40%) types. The alkali-soluble glucan was similar to that of the Y form; the alkali-insoluble glucan was positive in the periodic acid-Schiff reaction and was hydrolyzed by snail digestive juice.

Amino Acids↗
PubMed1980

Effects of carbon source and growth rate on cell wall composition of Bacillus subtilis subsp. niger.

A study was made to determine whether factors other than the availability of phosphorus were involved in the regulation of synthesis of teichoic and teichuronic acids in Bacillus subtilis subsp. niger WM. First, the nature of the carbon source was varied while the dilution rate was maintained at about 0.3 h-1. Irrespective of whether the carbon source was glucose, glycerol, galactose, or malate, teichoic acid was the main anionic wall polymer whenever phosphorus was present in excess of the growth requirement, and teichuronic acid predominated in the walls of phosphate-limited cells. The effect of growth rate was studied by varying the dilution rate. However, only under phosphate limitation did the wall composition change with the growth rate: walls prepared from cells grown at dilution rates above 0.5 h-1 contained teichoic as well as teichuronic acid, despite the culture still being phosphate limited. The wall content of the cells did not vary with the nature of the growth limitation, but a correlation was observed between the growth rate and wall content. No indications were obtained that the composition of the peptidoglycan of B. subtilis subsp. niger WM was phenotypically variable.

Bacillus subtilis↗
PubMed1968

Cell wall composition and virulence in Escherichia coli.

Uridine diphosphate galactose 4-epimerase and phosphomannose isomerase-deficient mutants of Escherichia coli O111:B4 were studied to test the hypothesis that in E. coli a specific relationship exists between O antigenicity, virulence, and capacity to resist phagocytosis. The first mutant, designated J-5, produces a cell wall lipopolysaccharide, the side chains of which do not contain galactose, glucose, N-acetylglucosamine, or colitose. The second mutant produces a cell wall lipopolysaccharide which lacks only colitose. The capacity of these various organisms to kill mice was strikingly different. E. coli O111 was 1000 times as virulent as J-5, and 100 times as virulent as L-2. The capacity of the organisms to kill mice was correlated with their ability to resist phagocytosis and to persist in the peritoneal cavity. The parent strain of O111 resisted phagocytosis by macrophages in vivo and polymorphonuclear leukocytes in vitro. The mutants did not, and the organism most deficient in the saccharide component of its LPS was most susceptible to phagocytosis and least virulent. These results were corroborated by growing the mutants in appropriately supplemented media which permitted the synthesis of complete LPS, reversed the susceptibility to phagocytosis, and restored virulence. Finally, serological reactivity was consistent with previous observations which had demonstrated that the O antigenicity of E. coli is determined by the saccharide composition of its cell wall lipopolysaccharide. Despite the difference in the capacity of the various log-phase organisms to kill mice when injected intraperitoneally, purified lipopolysaccharides extracted from them did not differ significantly in their capacity to kill or produce fever. Thus virulence was shown to be independent of endotoxin activity which in turn seemed to be unrelated to the saccharide composition of the cell wall LPS. Collectively, these data provide at least a partial molecular definition of virulence in E. coli by demonstrating that the presence or absence of specific sugars in its cell wall lipopolysaccharide is a determinant of its antiphagocytic capacity and its virulence.

Agglutination Tests↗
PubMed1971

Cell wall composition of the yeastlike and mycelial forms of Blastomyces dermatitidis.

The thermally induced changes in the cell wall polysaccharides of Blastomyces dermatitidis strain BD64, which produces a yeastlike form (Y form) at 37 C and a mycelial form (M form) at 20 C, were examined. The cell walls of the Y and M forms contained 36 and 51% of hexoses, respectively. The M-form cell wall contained glucose, galactose, and mannose in a molar ratio of 1:0.1:0.2. The Y-form cell wall contained mainly glucose and a very small amount of galactose and mannose. The glucans of the cell wall of the Y form consisted of about 95% alpha-glucan and 5% beta-glucan, whereas those of the M-form cell wall consisted of about 60% alpha-glucan and 40% beta-glucan.

Blastomyces↗
PubMed1976

Relationship of the cell wall composition of group H streptococci and Streptococcus sanguis to their serological properties.

Previous studies indicated the a antigen was widely distributed among strains of Streptococcus sanguis and the group H streptococci. The cell walls of strains containing this antigen had moderate to large quantities of rhamnose, small amounts of phosphorus, and little to no ribitol. The molar ratios of the peptidoglycan amino acids and hexosamines suggested a di-alanyl cross bridge. The homogeneity of the walls of these strains suggested that serological group H can be considered synonymous with S. sanguis. In contrast those strains that did not contain the a antigen had only small amounts of rhamnose in their cell walls, galactosamine and ribitol were always detected, and large quantitites of phosphorus were present. The molar ratios of peptidoglycan components in the latter strains suggested a direct alanyl-lysl cross bridge. Although many of these strains had been classified either as S. sanguis or group H streptococci because of minor serological cross-reactions and similar biochemical properties, the distinct differences between the composition of their cell walls and those of S. sanguis and group H streptococci indicate that they do not belong in this species or group. The cell walls of strains containing the a antigen are relatively homogeneous and therefore it is suggested that cells containing this antigen be considered Lancefield serological group H.

Amino Acids↗