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)

Morphological mon mutants and a chain-forming envC mutant of Escherichia coli K12 are hypersensitive to detergents and to various other antibacterial agents. Electron microscopy shows that the cytoplasmic membrane of growing mon and envC cells is dissolved by detergents, and that the cytoplasm dissociates into two parts of unequal density. The mutant envC is sensitive to actinomycin D and to rifampicin, is lysed by lysozyme in the absence of EDTA, and releases alkaline phosphatase in the absence of osomotic shock, indicating a gross perturbation of its outer membrane.
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PMID:Morphological mutants of Escherichia coli: nature of the permeability barrier in mon and envC cells. 35 22

Exposure of E. coli K12 W1485 to the cytolytic alternative pathway assembled from the 11 isolated pathway proteins resulted in killing of the bacteria, as evidenced by loss of viability. Lysis of the bacteria required introduction of lysozyme into the reaction mixture. The time-course and dose dependency of bacteriolysis in the isolated system were identical to those in C4-depleted serum. The bacteriolytic activity of the pathway was highly dependent on the concentration of the pathway proteins and became insignificant at 1:16 physiological concentration. Electron microscopic visualization of killed and of lysed bacteria revealed numerous complement membrane lesions and partial disintegration of the outer phospholipid membrane. Scanning electron microscopy showed that killed bacteria were enlarged, partially collapsed and exhibited irregular surface protrusions. Lysed bacteria were fragmented and appeared polymorphic. This study demonstrates that the alternative pathway, in absence of immunoglobulins, has the potential or eradicating gram-negative bacteria.
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PMID:Bactericidal activity of the alternative complement pathway generated from 11 isolated plasma proteins. 37 83

Mutants of Escherichia coli K12, deficient in up to three major outer membrane proteins b, c and d have been constructed. Mutants that lack the lipopolysaccharide sugar heptose are deficient in protein b. All heptose-deficient strains are supersensitive to lysozyme, various antibiotics and detergents. They excrete the periplasmic enzyme ribonuclease I. Mutants deficient in proteins c and/or d have the same sensitivity towards these compounds as the parent strain. Cells of single, double and triple mutants are all rod-shaped. Electrophoretic analysis of cell envelope proteins indicates that in some mutants the protein deficiency is partially compensated for by increased amounts of one or two of the other major outer membrane proteins. Heptose-deficient strains have an increased amount of 2-keto-3-deoxyoctonate.
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PMID:Heptose-deficient mutants of Escherichia coli K12 deficient in up to three major outer membrane proteins. 78 63

Escherichia coli B/SM, strain 1-1, was killed dose dependently by human hereditary C9-deficient serum (C9DHS), which was shown to contain no C9 Ag by an ELISA method. On the other hand, human hereditary C7-deficient serum did not kill the bacteria under similar conditions. The bactericidal activity of C9DHS was inhibited by rabbit anti-C5 antibody but not by murine anti-C9 mAb. The anti-C9 antibody decreased the bactericidal activity of normal human serum (NHS) to the level of that with C9DHS. Sheep anti-human lysozyme antibody did not affect the bactericidal activity of C9DHS or NHS even when added at more than twice the concentration required to block the serum lysozyme activity on Micrococcus luteus. After treatment with C9DHS and washing, surviving Escherichia coli were killed by C9, but not by lysozyme, transferrin, or both. Other strains of E. coli (K12 W3110, C600, and NIHJ) and Salmonella typhimurium (strain NCTC 74), all maintained in the laboratory, were also killed by C9DHS. However, pathogenic strains recently isolated from patients with traveler's diarrhea and some strains of S. typhimurium were resistant to both C9DHS and NHS, at least at the serum concentration tested. A concentration of 0.1 M Tris did not increase the susceptibility of serum-resistant strains of bacteria to C9DHS, but made one strain of S. typhimurium tested susceptible to NHS, but not to C9DHS. These results clearly showed that C9DHS kills bacteria that are sensitive to NHS through activation of C up to the step of C8 in the same way that C9-deficient C serum lyzed sensitized erythrocytes.
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PMID:Bactericidal activity of C9-deficient human serum. 173 Aug 76

Larvae of the cabbage white butterfly, Pieris brassicae, were reared on a semisynthetic diet with or without 20 ppm of the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and using three assays the sera were subsequently tested for natural antibacterial activity against Bacillus cereus, Escherichia coli K12, and Micrococcus luteus. These assays showed that exposure of larvae to 2,4,5-T lowered the antibacterial activity of the serum against E. coli and M. luteus compared with control animals. Spectrophotometric tests for the presence of a lysozyme-like principle in the serum also revealed similar trends with a significant loss of enzyme activity in 2,4,5-T-treated insects. Overall total serum protein levels of control and 2,4,5-T-treated insects were similar, suggesting a specific effect of the herbicide on certain serum components such as lysozyme. The possible mode of action of the herbicide on production of antibacterial factors is discussed.
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PMID:Effect of exposure of Pieris brassicae larvae to 2,4,5-trichlorophenoxyacetic acid on the natural antibacterial activity of serum. 273 19

An L-form isolated from Escherichia coli K12 by sequential treatment with N-methyl-N'-nitro-N-nitrosoguanidine and lysozyme was adapted to grow in hyperosmolar liquid cultures. It was stable in the absence of antibiotic when cultured in brain heart infusion (BHI) broth containing NaCl and CaCl2, the optimal concentrations being 0.34 M and 1 mM, respectively. No growth of the L-form was observed when CaCl2 was not added to BHI medium containing 0.34 M-NaCl. On the other hand, when KCl replaced NaCl as the osmotic stabilizer, growth of the L-form was repressed in the presence of CaCl2. Electron microscopy of the L-form confirmed the absence of a cell wall. A revertant strain derived from the L-form grew as a stable bacillary form in BHI medium without osmotic stabilizer. The growth characteristics of the revertant strain resembled those of the parent strain. The revertant strain produced L-forms in the presence of NaCl.
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PMID:Morphology, growth and reversion in a stable L-form of Escherichia coli K12. 330 59

Mutation of Escherichia coli K12 HfrH to resistance to fluorophenylalanine resulted in changes in the plaque morphology of bacteriophage MS2 on this strain and led to an increased efficiency of propagation of the phage in liquid cultures. Evidence was obtained that the mutation resulted in inhibition of early lysis in infected cells and that lysis involved the production of a lysozyme. Genetic studies suggested that the observed pleiotropy of the resistance mutation was due to informational suppression.
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PMID:Male-specific bacteriophage MS2 propagation in fluorophenylalanine-resistant Escherichia coli K12. 459 9

The locations of the periplasmic proteins of Escherichia coli on standard two-dimensional gel patterns are described. The periplasmic fractions were prepared by osmotic shock of plasmolyzed whole cells and by release during EDTA-lysozyme treatment of whole cells. Within this fraction of proteins, we identify nine binding proteins (leucine-specific, glutamate-aspartate, glutamine, cystine, galactose, maltose, xylose, ribose, and arabinose) in addition to leucine-isoleucine-valine binding protein, which has been previously identified (Bloch, P. L., Phillips, T. A., and Neidhardt, F. C. (1980) J. Bacteriol. 141, 1409-1420). The identifications are based upon genetic criteria, protein induction, and comigration with purified protein. The levels of these proteins are compared in strains K12, B, and HA12 (a derivative of W). A technique was developed for renaturation of the ligand binding sites of periplasmic binding proteins in denaturing two-dimensional gels. This technique was used to demonstrate that leucine-specific and cystine binding proteins both have different isoelectric points in different strains. Renaturation was also used to demonstrate that there are two different charged forms for glutamine binding protein.
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PMID:Renaturation and identification of periplasmic proteins in two-dimensional gels of Escherichia coli. 675 51

1. The outer membrane of a phospholipase A-deficient mutant of Escherichia coli K12, isolated without the use of EDTA and lysozyme, showed the same freeze-fracture morphology as that seen in cells and remained stable for hours as observed by 31P-NMR. 2. 31P-NMR spectroscopy of the isolated outer membranes revealed that the lipopolysaccharide exists in the same physical state as in phospholipid-lipopolysaccharide liposomes and is most probably arranged in a bilayer at 37 degrees C. The outer membrane contains most or all of the phospholipids at 37 degrees C, and all the phospholipids at 20 degrees C, as a bilayer. 3. The 31P-NMR spectroscopy of the outer membranes from a mutant strain lacking the major outer membrane protein b, c and d (60% of the total outer membrane protein) yields virtually the same spectrum as the wild-type outer membranes, although most of the particles and pits which were observed in wild-type outer membranes in freeze-fracture electron microscopy were absent. 4. Whereas treatment of wild-type outer membranes with calcium ions has no effect on the 31P-NMR spectrum, treatment with EDTA results in more motion of the lipopolysaccharide.
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PMID:31P nuclear magnetic resonance and freeze-fracture electron microscopy studies on Escherichia coli. III. The outer membrane. 676 82

Examination of the localization of the dicarboxylate binding protein (DBP) in the cell envelope of Escherichia coli K12 reveals that this protein is present on the cell surface, and also in the inner and outer regions of the periplasmic space. The cell surface DBP is release by treating the cells with EDTA. This protein can be surface labeled by lactoperoxidase radioiodination, and by diazo[125I]iodosulfanilic acid in whole cells. It also binds tightly, but not covalently, to lipopolysaccharide. The DBP located in the outer region of the periplasmic space is released when the outer membrane is dissociated by EDTA-osmotic shock treatment. The DBP located in the inner region of the periplasmic space is released only when the EDTA-osmotic shocked cells are subjected to lysozyme treatment. At the moment, it is not certain whether this protein is bound to or trapped by the peptidoglycan network. This protein cannot be surface labeled in whole cells or in EDTA-osmotic shock treated cells; and it is not associated with lipopolysaccharide. Analysis of transport mutants indicates that these DBP are coded by the same gene.
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PMID:Localization of the dicarboxylate binding protein in the cell envelope of Escherichia coli K12. 678 Jan 68


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