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 killing of Staphylococcus aureus strain 1030 and derived variants of it by lysozyme increased with increased lysozyme concentrations or decreased concentrations of sodium chloride. beta-Lactamase-producing and non-producing derivatives of strain 1030 were constructed. The former were less susceptible to lysozyme. Induction of beta-lactamase synthesis with 2-2'carboxyphenyl-benzoyl-6-penicillanic acid increased the resistance of producer strains to lysozyme. These results are discussed in relation to the spread of beta-lactamase-producing strains of S. aureus.
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PMID:The susceptibility to lysozyme of beta-lactamase-producing and non-producing derivatives of Staphylococcus aureus strain 1030. 349 26

The growth of Alcaligenes eutrophus in the presence of benzylpenicillin under heterotrophic and autotrophic conditions was studied. The drug induced a penicillinase in the cells, which can be readily released and extracted from the cells after a lysozyme and EDTA treatment in the course of spheroplast formation. The isoelectric point of the enzyme is 8.1 and the molar mass was estimated to be nearly 25 kg/mol. Phenoxypenicillin is hydrolyzed in the presence of the enzyme at a higher relative rate than benzylpenicillin, ampicillin, amoxycillin and azlocillin. The cephalosporins tested, i.e. cephalosporin C, cefalexin, cefotaxime and 7-aminocephalosporanic acid, were hydrolyzed at a substantially lower relative rate than the penicillins, indicating that the enzyme is a penicillinase.
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PMID:Identification of an inducible penicillinase of the lithoautotrophic hydrogen-oxidizing bacterium Alcaligenes eutrophus. 350 Sep 1

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

A penetration barrier operating outside the periplasmic enzyme penicillinase was studied in an ampicillin-resistant mutant of Escherichia coli K-12. Growth in the presence of lysozyme and sublethal concentrations of ampicillin partially opened the barrier. This could be recorded as an increased penetration of penicillin G, sodium cholate, and rifampin to their respective targets. Brief treatments with tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid and sodium cholate effectively impaired the barrier against penicillin and also caused leakage of penicillinase. Wild-type E. coli K-12, Proteus mirabilis, and Pseudomonas aeruginosa also showed an increased sensitivity to cholate after treatment with penicillins. Electron micrographs showed that lysis by cholate was due to a distortion of the cytoplasmic membrane causing a leakage of protein and RNA from the cells to the medium. Physiological data indicated that the increased sensitivity to cholate induced by growth in the presence of ampicillin or lysozyme was due to effects upon the murein. This was supported by measurement of the incorporation of (3)H-diaminopimelic acid. These results indicate that the murein sacculus either is a part of the penetration barrier or is responsible for holding the structure of the outer membrane together.
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PMID:Murein and the outer penetration barrier of Escherichia coli K-12, Proteus mirabilis, and Pseudomonas aeruginosa. 462 57

1. The permeability barrier against benzylpenicillin has been found to be passive in four strains of penicillinase-producing Gram-negative bacteria (three of Klebsiella aerogenes and one of Escherichia coli). 2. If the three K. aerogenes strains are grown in the presence of sub-inhibitory concentrations of benzylpenicillin, ampicillin or phenethicillin the resultant bacterial cells have deficient permeability barriers. Concentrations of ampicillin or benzylpenicillin less than one-tenth of those required to inhibit growth cause destruction of more than half the permeability barrier in these strains. 3. Benzylpenicillin, ampicillin and phenethicillin have no effect upon the permeability barriers of resting cells from the three K. aerogenes strains. 4. Treatment of resting cells with trisodium EDTA, although failing to sensitize K. aerogenes to lysozyme, severely damages permeability barriers in this species. 5. The magnesium and calcium salts of EDTA do not have the same capacity as the sodium salt for causing damage to permeability barriers in K. aerogenes and E. coli. Damage caused by trisodium EDTA can be at least partially reversed by treatment with Ca(2+) or Mg(2+) ions. It is suggested that EDTA damage is caused by removal of either Ca(2+) or Mg(2+) ions, or both, from the bacterial cell envelope. 6. Bacterial cells with deficient permeability barriers as a result of either growth in the presence of a penicillin or treatment with EDTA remain viable, and revert to their usual permeability after growth in nutrient broth.
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PMID:Damaging effects of ethylenediaminetetra-acetate and penicillins on permeability barriers in Gram-negative bacteria. 496 52

Hydrolysis of the chromogenic beta-lactam nitrocefin by periplasmic beta-lactamase in intact Pseudomonas aeruginosa cells was used to assess the influence of various compounds on the permeability of the P. aeruginosa outer membrane. In addition to the five previously described outer membrane-active compounds EDTA, polymyxin B, gentamicin, poly-L-lysine, and Tris, seven other compounds were shown to increase outer membrane permeability to nitrocefin by 14- to 63-fold. These other compounds included poly-L-ornithine, neomycin, cetyltrimethylammonium bromide, nitrilotriacetate, L-ascorbate, and acetylsalicylate. In each case, Mg2+ ions antagonized, to different extents, the enhancement of outer membrane permeability. The same compounds increased the permeability of the outer membrane to the protein lysozyme and to the hydrophobic fluorescent probe 1-N-phenylnaphthylamine, although L-ascorbate and acetylsalicylate showed only very weak enhancement of uptake in these assays. In this report, we discuss the possibility that these compounds act at a common outer membrane site at which divalent cations noncovalently cross-bridge adjacent lipopolysaccharide molecules.
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PMID:Compounds which increase the permeability of the Pseudomonas aeruginosa outer membrane. 643 88

Polymyxin-resistant pmrA mutants of Salmonella typhimurium differed from their parents in that they were resistant to tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-lysozyme, tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-deoxycholate, and tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-bacitracin. Tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate released about 50% less lipopolysaccharide from the pmrA strains than from the parental strains when the bacteria were grown in L-broth containing 2 mM Ca2+. Protamine, polylysine, octapeptin, benzalkonium chloride, cold NaCl, cold MgCl2, or cold tris(hydroxymethyl)aminomethane hydrochloride (pH 7.2) caused no leakage or markedly less leakage of periplasmic beta-lactamase from a pmrA mutant than from its parent strain. pmrA mutants were more resistant than their parent strains to protamine and polylysine but not to octapeptin or benzalkonium chloride, as measured by the ability of these agents to kill the bacteria or to sensitize them to deoxycholate-induced lysis. The pmrA strains did not differ from their parent strains in sensitivity to several antibiotics, in porin function (as measured by cephaloridine diffusion across the outer membrane), or in outer membrane-associated phospholipase A activity.
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PMID:Increased outer membrane resistance to ethylenediaminetetraacetate and cations in novel lipid A mutants. 679 77

Spheroplasts of Mycobacterium smegmatis LM15, strain 607, were prepared by a combined treatment with glycine and lysozyme. The spheroplasts were tested for ability to take up and express purified mycobacteriophage DNA. Exposure of 1.0 x 10(8) to 1.0 x 10(9) spheroplasts to saturating DNA (1 microgram) for 15 min at 5 degrees C resulted in a transfection efficiency of approximately 0.009% . The transfer of the beta-lactamase marker with DNA purified from strain LM15 to spheroplasts of a beta-lactamase-negative mutant, strain LM144, was achieved. The DNA-treated cultures, after reversion to the bacillary form, contained 20-fold more penicillin-resistant cells than the nontreated control culture. Approximately 80% of the penicillin-resistant colonies from the DNA-treated cells were positive for beta-lactamase Cell-free extracts of penicillin-resistant transformants contained beta-lactamase activity that ranged from 0.046 to 0.134 micromol of benzylpenicillin hydrolyzed/min per mg protein. This low temperature procedure is recommended for high efficiency transformation of M. smegmatis.
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PMID:Low temperature protocol for efficient transformation of Mycobacterium smegmatis spheroplasts. 776 35

The interaction between divalent cations and quinolones and the mechanism by which the former antagonizes the antimicrobial activities of the latter were investigated. In the presence of either magnesium or calcium chloride, the MICs of 18 quinolones for Gram-positive and Gram-negative bacteria increased. Accumulation of and inhibition of DNA synthesis by quinolones were decreased in the presence of magnesium chloride while, in the presence of EDTA, there was no increase in the concentration of accumulated quinolone for any of the agents tested. Only with nalidixic acid was there enhancement of the inhibition of DNA synthesis. Chelation of selected quinolones by magnesium was demonstrated with a fluorescence assay which showed that the extent to which fluorescence (consistent with chelation) was enhanced varied with the quinolone. Assessment of the strength of the magnesium-quinolone complexes with the chelating agent EDTA demonstrated that some of the complexes could be broken. Thin layer chromatography of quinolones and quinolone-magnesium complexes provided evidence that the components of the complex were probably combined in a ratio of 1:1 and that reduced intracellular accumulation of the quinolones in the presence of magnesium was unlikely to be due to a complex being too bulky to be taken through the porin channels. In contrast with permeabilizers which are known to utilize the self-promoted uptake pathway, none of the quinolones studied permeabilized Gram-negative bacteria to lysozyme, caused enhanced fluorescence to 1-N-phenyl-naphthylamine (NPN) or increased the leakage of periplasmic beta-lactamase into the culture medium. The reduced activities of the quinolones in the presence of divalent cations may be the result of the chelation of exogenous ions and, possibly, lipopolysaccharide- or lipoteichoic acid-associated magnesium ions, thereby resulting in less drug being available to enter the bacterium. Alternatively, reduced activity may be due to a fundamental effect on the interaction between quinolones and their target DNA gyrase.
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PMID:Interaction of divalent cations, quinolones and bacteria. 786 2

An inducible hemolysin with antibacterial properties was isolated from the hemolymph of immune Galleria mellonella larvae. The Galleria-derived lysin, named Gallysin-1, was shown to have an apparent molecular weight of 75,000 and to be relatively heat stable at 56 degrees C. Although Gallysin alone was not bactericidal it caused sufficient damage of the outer cell membranes of Pseudomonas aeruginosa RP4 and Escherichia coli K176 to release beta-lactamase from the periplasm. In the presence of either purified Galleria lysozyme or egg white lysozyme Gallysin-1 had potent antibacterial activity against gram-negative bacteria. Gallysin-1 killed osmotically shocked P. aeruginosa and E. coli that suggests that it can also attack exposed inner cell membranes of gram-negative bacteria. The identification of Gallysin-1 recognizes another distinct member of the bactericidins involved in insect immunity.
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PMID:Gallysin-1, an antibacterial protein isolated from hemolymph of Galleria mellonella. 805 Jun 12


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