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PubMed1967

Structure and composition of the cell wall of Neurospora crassa.

The structure and composition of the cell walls of hyphae of Neurospora crassa were investigated by electron microscopy, chemical analysis, and X-ray diffraction both before and after progressive enzymatic degradation by snail gut enzymes, chitinase, and trypsin. The wall consists of two phases: randomly disposed skeletal microfibrils of chitin only and an amorphous matrix which contains both beta-glucans and protein. The protein contains a high percentage of the amides of aspartic and glutamic acid but no hydroxy-proline or cysteine. A portion of this protein is a component of or is associated with a system of pores which is embedded in the matrix of the wall. These pores, 40 to 70 A in outside diameter, sometimes branch and seem to provide a three-dimensional network from one side of the wall to the other. They may be a general system of transport across the walls.

Amino Acids↗
PubMed1975

[Isolation of new species of the genus Actinomadura on selective media with streptomycin and bruneomycin].

In the screening programme using selective media with streptomycin (25, 50 and 100 gamma/ml) and bruneomycin (0.5, 1 and 2 gamma/ml) 3 unusual actinomycetous cultures forming short, rarely long chains of straight, hook-like or spiral spores with 1 or rarely 2 turns were isolated. The study of the cell wall composition of the isolates showed that the walls contained meso-diaminopimelic acid and a sugar madurose. On the basis of the morphological structure and the cell wall composition the isolates were classified as belonging to Actinomadura. Comparison of the cultures with the Actinomadura species described in the literature showed that the isolates were new species of the genera, i. e. Am. coerulea sp. nov., Am. cremea sp. nov. and Am. salmonea sp. nov.

Actinomycetales↗
PubMed2001

Functional analysis of Streptococcus pneumoniae MurM reveals the region responsible for its specificity in the synthesis of branched cell wall peptides.

The recently identified murMN operon of Streptococcus pneumoniae encodes enzymes involved in the synthesis of branched structured muropeptides of the pneumococcal cell wall peptidoglycan. Its inactivation was shown to cause production of a peptidoglycan composed exclusively of linear muropeptides and a virtually complete loss of resistance in penicillin-resistant strains. The studies described in this communication follow up these observations in several directions. The substrate of the MurM-catalyzed reaction (addition of alanine or serine) was identified as the lipid-linked N-acetylglucosamine-muramyl pentapeptide. Different murM alleles from several penicillin-resistant S. pneumoniae strains, each with a characteristic branched peptide pattern, were cloned into pLS578, a pneumococcal plasmid capable of replicating in S. pneumoniae, and transformed into the penicillin-susceptible laboratory strain R36A. All transformants remained penicillin-susceptible; however, their cell wall composition changed in directions corresponding to the muropeptide pattern of the strain from which the murM allele was derived. This suggests that the muropeptide composition of the pneumococcal cell walls is determined by the particular murM allele carried by the cells. A 30-amino acid long sequence within the MurM protein was shown to be the main determinant of the specificity of the reaction (addition of alanine versus serine).

Alleles↗
PubMed2002

Altering the expression of two chitin synthase genes differentially affects the growth and morphology of Aspergillus oryzae.

In Aspergillus oryzae, one full-length chitin synthase (chsB) and fragments of two other chitin synthases (csmA and chsC) were identified. The deduced amino acid sequence of chsB was similar (87% identity) to chsB from Aspergillus nidulans, which encodes a class III chitin synthase. The sequence obtained for csmA indicated that it had high similarity to class V chitin synthases. chsB and csmA disruption strains and a strain in which chsB transcription was controlled were constructed using the nitrite reductase (niiA) promoter. The strains were examined during hyphal growth by Northern analysis, analysis of the cell-wall composition and growth in the presence of Calcofluor white (CFW). The chsB disrupted strain and the uninduced p(niiA)-chsB strain exhibited hyperbranching, they had a lower level of conidiation than the wild-type and were sensitive to CFW at 50 mg l(-1). When chsB transcription was induced in the strain containing the p(niiA)-chsB construct, the strain displayed wild-type morphology on solid medium and at sub-maximum growth rates but the wild-type morphology was not fully restored during rapid growth in batch cultivation. The csmA disruption strain displayed morphological abnormalities, such as ballooning cells, intrahyphal hyphae and conidial scars. The growth was severely inhibited in the presence of 10 mg CFW l(-1). In none of the constructed strains did the cell-wall composition differ from the wild-type. Northern analysis indicated no change in the transcription of the chitin synthase genes csmA and chsC when chsB expression was altered, and there was no change in the transcription of chsB and chsC when csmA was disrupted.

Aspergillus oryzae↗
PubMed1976

Variations in surface polymers of Streptococcus mutans.

The cell wall composition of strains of S mutans with respect to sugars and proteins appears to be correlated to the serological grouping although groups c and E are rather similar. There also appear to be similarities in the structure of the polysaccharide formed by the glycosyltransferases from organisms of serological groups b and d. However, the activity of these enzymes appears to be variable in these groups. The most noteworthy difference found was that between the three Ingbritt strains. All three strains gave identical results with regard to their cell wall composition, and presumably this would mean that they were identical serologically. However, Ingbritt LH differed considerably from both the others in the types of polysaccharide formed by their glycosyltransferases from sucrose. Ingbritt B was a reisolate from monkeys, whereas Ingbritt LH was maintained in laboratory culture, and this may explain the difference. Clearly, more work will be required to explain this difference and as c strains are commonly isolated from plaque, it would seem desirable to clear up this point.

Cell Wall↗
PubMed1963

Mycobacterial cell walls. II. Chemical composition of the "basal layer".

Takeya, Kenji (Kyushu University, Fukuoka, Japan), Kazuhito Hisatsune, and Yasuko Inoue. Mycobacterial cell walls. II. Chemical composition of the "basal layer." J. Bacteriol. 85:24-30. 1963.-Chemical composition of the "basal layer" of the mycobacterial cell wall was determined. The layer contained 35% amino acids, 41.5% reducing sugars (mainly composed of arabinose and galactose), 13.8% amino sugars (glucosamine and muramic acid, 2:1), and 7.7% lipid. The main amino acids were alanine, glutamic acid, and diaminopimelic acid. Their molar ratio was approximately 2:2:1. The main difference in chemical composition between the cell wall and the basal layer was found in lipid content. According to the chemical composition, the basal layer resembles the walls of gram-positive bacteria, while the mycobacterial cell wall resembles the walls of gram-negative bacteria. The basal layer was thoroughly disintegrated by lysozyme digestion, and was considered to be an inner layer of the wall, conferring shape and rigidity on the mycobacterial cell wall.

Alanine↗
PubMed2001

Spontaneous nisin-resistant Listeria monocytogenes mutants with increased expression of a putative penicillin-binding protein and their sensitivity to various antibiotics.

A concern regarding the use of bacteriocins, as for example the lantibiotic nisin, for biopreservation of certain food products is the possibility of resistance development and potential cross-resistance to antibiotics in the target organism. The genetic basis for nisin resistance development is as yet unknown. We analyzed changes in gene expression following nisin resistance development in Listeria monocytogenes 412 by restriction fragment differential display. The mutant had increased expression of a protein with strong homology to the glycosyltransferase domain of high-molecular-weight penicillin-binding proteins (PBPs), a histidine protein kinase, a protein of unknown function, and ClpB (putative functions from homology). The three former proteins had increased expression in a total of six out of 10 independent mutants originating from five different wild-type strains, indicating a prevalent nisin resistance mechanism under the employed isolation conditions. Increased expression of the putative PBP may affect the cell wall composition and thereby alter the sensitivity to cell wall-targeting compounds. The mutants had an isolate-specific increase in sensitivity to different beta-lactams and a slight decrease in sensitivity to another lantibiotic, mersacidin. A model incorporating these observations is proposed based on current knowledge of nisin's mode of action.

Anti-Bacterial Agents↗
PubMed1996

Staphylococcus saprophyticus subsp. bovis subsp. nov., isolated from bovine nostrils.

A new coagulase-negative subspecies, Staphylococcus saprophyticus subsp. bovis, is described on the basis of a study of five strains isolated from the anterior nares of cows. This subspecies is differentiated from the other novobiocin-resistant staphylococci by its phenotypic properties, cell wall composition, and levels of genetic relatedness. The type strain of the new subspecies is KV 12 (=CCM 4410).

Animals↗
PubMed1978

[Peptidoglycan type and cell wall polysaccharide composition of Cellulomonas cartalyticum and some coryneform organisms (author's transl)].

Cellulomonas cartalyticum was found to contain a peptidoglycan type different from that of the other species of Cellulomonas. The diamino acid is lysin instead of ornithine and the interpeptide bridge consists of D-Asp-D-Ser. The same peptidoglycan type occurs in Corynebacterium manihot, Brevibacterium liticum and Arthrobacter luteus. These non cellulolytic organisms are most likely not closely related with Cellulomonas cartalyticum, as indicated by the very different G +C content of their DNA, although they formed a narrow cluster including C. cartalyticum when numeric taxonomical methods were applied.

Actinomycetales↗
PubMed1997

Colony variation of Helicobacter pylori: pathogenic potential is correlated to cell wall lipid composition.

BACKGROUND: Differences in expression of disease after infection with Helicobacter pylori have so far been connected with host factors and bacterial interstrain variation. In this study, spontaneous and ecology-mediated intrastrain variation was examined. METHODS: Four clinical isolates of H. pylori were shown to give rise to two colony forms. Bacterial morphology was examined by electron microscopy. Bacterial fractions were examined for proteins using ion exchange chromatography and SDS-PAGE; for lipids using thin-layer chromatography, lipid anion-exchange chromatography, column chromatography on silica gel, 31P-NMR, gas chromatography and mass spectrometry. Bacterial in vitro invasiveness and adhesiveness were examined in two different systems, and urease and VacA toxin were assayed by Western blot analysis. RESULTS: H. pylori was shown to give rise to two colony forms: at normal pH the population was dominated by L colonies. One strain was chosen for further studies. Bacteria from L colonies retained VacA toxin and urease, did not invade or adhere to epithelial cells, and contained normal quantities of phosphatidylethanolamine. In a small frequency, spontaneous S colonies were formed. Bacteria from these colonies released VacA and urease, adhered to and invaded epithelial cells and contained increased amounts of lysophosphatidyl ethanolamine and phosphatidyl serine. After addition of HCl to the culture medium (pH6), almost only S colonies were formed. The results demonstrate that environmental factors, such as HCl, can change the bacterial cell wall, and thereby enhance expression of virulence factors of H. pylori in vitro. A similar in vivo variation would have implications for our understanding of the interaction between HCl secretion in the gastric mucosa and H. pylori in the development of peptic ulcer disease.

Bacterial Adhesion↗
PubMed1989

[Comparative study of cell walls of group A Streptococcus and its non-adhesive phosphomycin-resistant mutant].

The cell wall composition of nonadhesive fosfomycin-resistant mutant of group A streptococcus and highly adhesive wild strain have been studied. The cell wall of the mutant nonadhesive strain contained significantly reduced amounts of lipoteichoic acid and surface proteins as compared to the wild strain, did not contain surface lipoteichoic acid, and, possibly, differed in peptidoglycan-polysaccharide bonding. No differences in the qualitative carbohydrate composition of the cell walls were found. The amino acid composition of the cell walls of these microorganisms differed only in alanine content, which correlates with the reduction of lipoteichoic acid content in the mutant strain. The structural similarity of peptidoglycans of the two strains is demonstrated.

Amino Acids↗
PubMed2002

Changes in the cell wall network during the thermal dehydration of alfalfa stems.

The effects of heat treatments used to dry alfalfa stems were investigated. Heating at 70 or 100 degrees C caused no major change in the cell wall composition, but xylanase had lower activity on the cell wall of heated material and the amount of xylose released varied with the temperature used. Chemical fractionation of cell wall carbohydrates showed that the main changes occurring during stem dehydration concerned pectic polymers and probably hemicelluloses. There was less material soluble in ammonium oxalate from alfalfa heated at 100 degrees C than from fresh alfalfa. The results suggest that heat processing causes some changes in the cell wall network. Environmental scanning electron microscopy was used to examine fully hydrated tissues at high resolution. There was cell distortion without disruption of cell walls as water was lost.

Carbohydrates↗
PubMed1999

Alterations in macromolecular composition and cell wall integrity by ciprofloxacin in Mycobacterium smegmatis.

The present study has been undertaken to explore the biochemical mechanism of antimycobacterial action of a potent fluoroquinolone i.e. ciprofloxacin in Mycobacterium smegmatis. Cells grown in the presence of a subinhibitory concentration (IC50) of ciprofloxacin had a significantly lower content of all the major macromolecules i.e. DNA, RNA, proteins and lipids with maximum inhibition in DNA concentration as compared to control. Significant quantitative changes were also observed in the various chemical constituents of cell wall of ciprofloxacin grown cells. A decrease in the number of binding sites for a fluorescent probe L-anilinonapthalene-8-sulphonate (ANS) in ciprofloxacin grown cells suggested structural changes on the cell surface. Significant changes were also observed in the morphology of cells grown in the presence of ciprofloxacin by scanning electron microscopy (SEM). Our results suggest that ciprofloxacin exerts its antimycobacterial activity by affecting the cell wall as well as various macromolecules, particular DNA, the vital component for cell survival and growth.

Anilino Naphthalenesulfonates↗