Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rate of individual ribosomal protein synthesis relative to total protein synthesis has been determined in Escherichia coli rel+ and rel- cells, under valyltRNA deprivation. These strains have a temperature-sensitive valyl-tRNA synthetase. Starvation was obtained following transfer to the cells to non-permissive temperature. Ribosomal proteins were obtained by treatment of either total lysates of freeze-thawed lysozyme spheroplasts or ammonium sulphate precipitate of ribosomes, with acetic acid. Differential labelling of the ribosomal proteins was observed in both strains: proteins from the rel+ strain appear more labelled than those from the rel- strain, the rate of labelling of individual proteins being about the same in both strains. Moreover ribosomal proteins were found as stable during starvation as total protein. It is thus concluded that in starving cells individual ribosomal proteins are not synthesized at equal rates. This indicates that the synthesis of ribosomal proteins is not only under the control of the rel gene.
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PMID:On the control of ribosomal protein biosynthesis in Escherichia coli. I. Studies on ribosomal protein biosynthesis in amino acid-starved cells. 32 Oct 26

Bdellovibrio peptidoglycan is of typical gram-negative composition. The molar ratios of alanine:glutamic acid:diaminopimelic acid:muramic acid:glucosamine were about 2:1:1:1:1. Nascent, nongrowing Bdellovibrio bacteriovorus 109J were converted from highly motile vibrios to highly motile spheres when shaken in dilute buffer plus penicillin, cephalothin, bacitracin, or D-cycloserine. The spherical forms contained essentially no sedimentable peptidoglycan; i.e., they were spheroplasts. Spheroplasts induced by penicillin, D-cycloserine, and lysozyme were stable in dilute buffer and did not lyse when subjected to osmotic shock. Normal Bdellovibrio suspended in buffer turned over their peptidoglycan at a rate of approximately 30% h during the initial 120 min of starvation. Chloramphenicol and sodium azide strongly inhibited Bdellovibrio peptidoglycan turnover and the induction of spheroplasts by penicillin. The data indicate that nongrowing B. bacteriovorus are sensitive to penicillin and other antibiotics affecting cell walls because of their high rate of peptidoglycan turnover. It is also concluded that an intact peptidoglycan layer is required for maintaining cell shape, but is not required for osmotic stability of B. bacteriovorus.
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PMID:Penicillin-induced formation of osmotically stable spheroplasts in nongrowing Bdellovibrio bacteriovorus. 64 Oct 13

1. Folded chromosomes from amino-acid-starved Escherichia coli DG 75 cells are to a large extent released as envelope-bound complexes which sediment more rapidly than envelope-bound complexes from exponentially growth cells. A minor fraction (about 3%) represents relatively slow sedimenting envelope-free nucleoids. 2. Morphological analysis of the sensitivity of amino-acid-starved cells to the action of lysozyme and/or detergents indicates that these cells are less susceptible to lysis than exponentially grown cells. This results in the production of fast sedimenting envelope-bound complexes from non-dividing cells. We infer that it is not the amount of DNA, as suggested by Ryder and Smith (1974), but the low degree of envelope fragmentation that causes the high sedimentation rate. 3. After prolonged periods of starvation about 3% of cells in the process of division persist in the population. The results indicate that these cells release their (terminated) chromosomes in the envelope-free form. At this stage it is impossible to conclude whether these chromosomes are released because of their detachment from the membrane in situ (cf. Worcel and Burgi, 1974) or because of an enhanced susceptibility of dividing cells to lysis.
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PMID:Significance of folded chromosomes released from amino-acid-starved Escherichia coli cells. 78 Jan 6

A method was developed to label specifically the glycan chains of the cell wall peptidoglycan of Streptococcus faecalis ATCC 9790 with [14C]acetate. The formation of peptide cross-links (a) during exponential growth, (b) after valine starvation and wall thickening, and (c) during regrowth after 2 hours of valine starvation, was studied using continuous, pulse and pulse-chase labeling of the peptidoglycan with both [14C]acetate and [3H]lysine. After labeling, walls were isolated, digested with the muramidase of Chalaropsis B, and the "free" peptidoglycan fragments (75 to 90% of the total peptidoglycan) were then fractionated on columns of Sephadex G-50, G-50, and G-25 in series into disaccharide-peptide monomer and peptide cross-linked bisdisaccharide-peptide dimer, trisdisaccharide-peptide trimer, and higher oligomer fractions. Peptidoglycan made during valine starvation and wall thickening was found to be slightly more cross-linked than peptidoglycan made during exponential growth. Pulse and pulse-chase experiments indicated that peptide cross-linking continued for an unexpectedly long time after incorporation of precursors into insoluble peptidoglycan.
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PMID:Studies of the formation of peptide cross-links in the cell wall peptidoglycan of Streptococcus faecalis. 80 47

An enzyme capable of hydrolyzing the substrate L-alanine p-nitroanilide has been found in the various Escherichia coli strains tested. This enzyme has been called aminoendopeptidase since it shows both activities (see accompanying paper). It is released from the cells by osmotic shock and by lysozyme -- EDTA spheroplasting treatment, and 50% of the total activity is directly detectable with suspensions of intact cells. However, the release by osmotic shock or spheroplasting is not as efficient as it is for alkaline phosphatase. This periplasmic aminoendopeptidase is constitutively produced but the differential rate of synthesis is increased 4-fold when the cell growth is limited by Pi. The occurrence of this 'derepression' is simultaneous with that of alkaline phosphatase. Increasing the concentration of inorganic phosphate in the medium has no effect on the constitutive aminoendopeptidase synthesis. The effect of phosphate starvation is specific since starvation for neither nitrogen nor carbon and energy source are effective in derepressing aminoendopeptidase.
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PMID:Evidence for an aminoendopeptidase localized near the cell surface of Escherichia coli. Regulation of synthesis by inorganic phosphate. 110 39

The R gene coding for phage lambda lysozyme (lambda L), cloned under the control of the PL promoter on a multicopy vector, is expressed in an Escherichia coli strain auxotrophic for tryptophan. Induction by a thermal shift after tryptophan supplementation in a culture initially brought into stationary phase by tryptophan starvation leads to highly increased expression. A thermally unstable mutant protein, difficult to obtain under standard conditions, can be easily produced by post-stationary-phase expression. It is shown that this is due to a drastic decrease in the heat-shock-induced proteolysis normally observed on thermal induction. These data are discussed in relation to our present knowledge of stringent and heat-shock responses.
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PMID:A large decrease in heat-shock-induced proteolysis after tryptophan starvation leads to increased expression of phage lambda lysozyme cloned in Escherichia coli. 138 88

The knowledge about the differentiation of basophilic leukocytes is fragmentary. This report discusses a detailed phenotypic characterization of molecular markers for hematopoietic differentiation in a basophilic leukemia cell line, KU812. The expression of markers for lymphoid, erythroid, neutrophil, eosinophil, monocytic, megakaryocytic, mast cell and basophil differentiation was analyzed at the mRNA level by Northern blots in the KU812 cells, and for reference, in a panel of human cell lines representative of the different hematopoietic differentiation lineages. KU812 was found to express a number of mast cell and basophil-related proteins, i.e. mast cell tryptase, mast cell carboxypeptidase A, high-affinity immunoglobulin (IgE) receptor alpha and gamma chains and the core protein for heparin and chondroitin sulphate synthesis. We found no expression of a number of monocyte/-macrophage or neutrophil leukocyte markers except for lysozyme. From earlier studies, it has been shown that lysozyme is not expressed in murine mucosal mast cell lines. This finding, together with the expression of the mast cell carboxypeptidase in KU812 might distinguish the phenotype of this cell line from that typical of mucosal mast cell lines in rodents. We found a low level of expression of the eosinophil and basophil marker, major basic protein, which might indicate a relationship between basophils and eosinophils. No expression is, however, detected with the eosinophil-specific markers eosinophil cationic protein, eosinophil-derived neurotoxin or eosinophil peroxidase. We also report an extensive screening for inducers of basophilic differentiation of the KU812 cells. The most efficient protocol of induction included serum starvation which led to a dramatic increase in a number of markers specific for mast cells and basophils such as tryptase, carboxypeptidase A and the heparin core protein. Finally, diisopropylfluorophosphate analysis of total protein extracts from KU812 show four labeled protein bands with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that this cell line expresses at least three previously undescribed serine proteases of which one or more could be a potential basophil-specific marker(s).
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PMID:Phenotypic characterization of KU812, a cell line identified as an immature human basophilic leukocyte. 163 3

The quantitative relations of various groups of microbes, the biological properties of lactobacilli in the luminal and mucosal microfloras of the gastrointestine of rats after having received kanamycin and after starvation, of conventional and germfree mice after irradiation and of piglets of different ages were compared. It was revealed that there exists a positive correlation between the mucosal and the lumenal microfloras which remains considerably stable under different conditions. Nevertheless, in case of irradiation or starvation influencing the gastrointestine microflora, the mucosal microflora gets more changed and the translocation of microbes through the mucosa into blood circulation takes place. The mucosal lactoflora of piglets is formed during the first (1-5) days of life on account of microbes with well-expressed antagonistic activity and lysozyme resistance.
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PMID:Interrelations between mucosal and luminal microflora of gastrointestine. 365 20

Group B streptococci treated with cell wall synthesis inhibitors (penicillin or vancomycin) or by a variety of membrane-acting agents are sensitized to the lytic action of exogenous M1 muramidase. Muramidase without a sensitizing agent caused rupture of bacterial chains only, accompanied by the release of a small amount of cell wall peptidoglycan label and an increase of the number of colony-forming units. In combination with sensitizing agents the exogenous muramidase appeared to initiate hydrolysis of biosynthetically new peptidoglycan. Treatment of the cells with chloramphenicol or starvation for nutritionally required amino acids suppressed the rate of cell lysis and peptidoglycan hydrolysis during subsequent sensitization and muramidase treatment of the bacteria. Purified cell walls prepared from the amino acid starved cells were also hydrolyzed with a slower rate by muramidase. It is suggested that agents sensitizing the bacteria to the exogenous muramidase act by perturbing or removing some nonmurein components of the cell envelope which protect the peptidoglycan from the activity of exogenous enzyme. Agents increasing resistance against exogenous muramidase may also cause some alteration in peptidoglycan structure.
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PMID:Factors affecting sensitivity of group B streptococci to an exogenous murein hydrolase. 389 Oct 54

The induction of beta-lactamase in Pseudomonas aeruginosa 1822s was studied using benzylpenicillin as inducer. The specific rate of beta-lactamase formation was constant throughout an induction experiment. Above a threshold (20 mug/ml), the specific activity increased linearly with the concentration of the inducer. Removal of the inducer resulted in a rapid cessation of beta-lactamase biosynthesis. Inhibition of protein synthesis by starvation for a required amino acid or by the addition of chloramphenicol also led to an instantaneous arrest in enzyme formation. In the absence of inducer, a basal beta-lactamase activity was formed. The basal and the induced enzymes seem to be identical since they had the same substrate profile, electrophoretic mobility, and molecular weight. In all these respects, induction of beta-lactamase in Pseudomonas aeruginosa is analogous to induction of the lac operon in Escherichia coli. However, there was a long, concentration-dependent lag before beta-lactamase was induced. This can be explained by the outer penetration barrier decreasing the rate of inducer uptake. The lag was significantly shorter for lysozyme-ethylenediaminetetraacetic acid-produced spheroplasts than for intact cells. Induction was obtained with all beta-lactam antibiotics tested, but not with other agents affecting the cell envelope.
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PMID:Induction kinetics of beta-lactamase biosynthesis in Pseudomonas aeruginosa. 421 83


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