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)

L-[4,5-3H]- or L-[U-14C]leucine was incorporated by Bacteroides thetaiotaomicron into acid-precipitable material even when the bacteria were treated with concentrations of tetracycline high enough to prevent growth. Similar results were obtained when L-[2,3,4-3H]valine or L-[4,5-3H]isoleucine was used instead of leucine. In bacteria which had been treated with tetracycline, the acid-precipitable label was not solubilized by treatment with protease, lysozyme, or deoxyribonuclease. However, virtually all of the label was extractable with chloroform-methanol, indicating that the label had been incorporated into membrane lipids. Since L-[1-14C]leucine was not incorporated into lipids, leucine was probably decarboxylated before incorporation. When a chloroform extract from bacteria which had been labeled with both [32P]phosphate and [3H]leucine was resolved into component phospholipids by two-dimensional thin-layer chromatography, 3H was incorporated into all of the phospholipids. When these phospholipids were deacylated, the 3H from leucine was associated with released fatty acids rather than with the head groups. Thus, it appears that B. thetaiotaomicron can utilize leucine and similar amino acids not only by incorporating them into protein but also by incorporating portions of these amino acids into membrane phospholipids.
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PMID:Incorporation of leucine into phospholipids of Bacteroides thetaiotaomicron. 746 55

Leuconostoc (Lc.) carnosum Ta11a, isolated from vacuum-packaged processed meats, produced a bacteriocin designated leucocin B-Ta11a. The crude bacteriocin was heat stable and sensitive to proteolytic enzymes, but not to catalase, lysozyme, or chloroform. It was active against Listeria monocytogenes and several lactic acid bacteria. Leucocin B-Ta11a was optimally produced at 25 degrees C in MRS broth at an initial pH of 6.0 or 6.5. An 8.9-MDa plasmid in Leuconostoc carnosum Ta11a hybridized to a 36-mer oligonucleotide probe (JF-1) that was homologous to leucocin A-UAL187. A 4.9-kb Sau3A fragment from a partial digest of the 8.9-MDa plasmid was cloned into pUC118. The 8.1-kb recombinant plasmid (pJF8.1) was used for sequencing and revealed the presence of two open reading frames (ORFs). ORF1 codes for a protein of 61 amino acids comprising a 37-amino-acid bacteriocin that was determined to be the leucocin B-Ta11a structural gene by virtue of its homology to leucocin A-UAL 187 (Hastings et al. 1991. J. Bacteriol 173:7491-7500). The 24-amino-acid N-terminal extension, however, differs from that of leucocin A-UAL187 by seven residues. The predicted protein of the ORF2 has 113 amino acids and is identical with the amino acid sequence of the cognate ORF of the leucocin A-UAL 187 operon.
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PMID:Characterization of leucocin B-Ta11a: a bacteriocin from Leuconostoc carnosum Ta11a isolated from meat. 776 96

The bacteriophage lambda R gene has been isolated into an Escherichia coli expression system and the R gene product, a lysozyme, has been overexpressed and purified to homogeneity using an efficient purification procedure. A turbidimetric assay utilizing chloroform-treated E. coli cells has been optimized to assess the bacteriolytic activity of the purified enzyme. Using this assay, oligomers of beta (1 --> 4) N-acetyl-D-glucosamine at high concentrations were shown to inhibit lysozyme but were not cleaved by the enzyme. Differential scanning calorimetry revealed that the thermal denaturation of lysozyme was found to increase in the presence of (GlcNAc)3 and (GlcNAc)5. The lysozyme was also expressed in an E. coli strain auxotrophic for methionine, allowing for the incorporation of [methyl-13C]methionine into the enzyme. An alteration of the [1H-13C]HMQC NMR spectra of the labelled enzyme was observed in the presence of (GlcNAc)5. Commercially available nitrophenyl glycosides did not act as substrates for lambda lysozyme. The results indicate that lambda lysozyme has specific interactions with oligosaccharides of N-acetylglucosamine, but is incapable of hydrolyzing these sugars. The relevance of the structure of peptidoglycan to the activity of lambda lysozyme is discussed.
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PMID:Investigations of the interactions of saccharides with the lysozyme from bacteriophage lambda. 787 85

Bacteriophage PRD1 is a lipid-containing virus that infects a variety of Gram-negative bacteria, including Escherichia coli. The phage lyses its host by virtue of a virally-encoded lytic enzyme, the synthesis of which has been assigned to gene XV on the basis of complementation analysis and experiments with mutant phages. We report here the cloning of gene XV into an expression plasmid and the purification of its product, protein P15, to near homogeneity. The purified protein P15, identified by N-terminal sequence analysis, showed a strong lytic activity against chloroform-treated Gram-negative cells. No activity against Gram-positive bacterial species could be detected. The pH optimum of the enzyme was between 7.0-8.0. Protein P15 was readily inactivated at temperatures above 4 degrees C, as well as by increasing the ionic strength of the buffers. The analysis of cell wall digests indicated that P15 is a glycosidase that cleaves the beta (1-4) linkage between N-acetylmuramic acid and N-acetylglucosamine, thus displaying muramidase activity.
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PMID:Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity. 792 54

One hundred and fifty lactic acid bacteria (LAB) isolated from vacuum-packaged processed meats were screened for antagonistic activity against various food spoilage microorganisms and foodborne pathogens. Nineteen strains produced bacteriocins active against closely related LAB and Listeria strains. Leuconostoc carnosum (LA54a and TA26b) and Leuconostoc mesenteroides subspecies dextranicum (TA33a) produced bacteriocins that were susceptible to proteolytic enzymes, but not to catalase, lysozyme or chloroform. They were heat stable up to 100 degrees C for thirty minutes at pH 2 to 7, and exerted a bacteriolytic effect. Bacteriocin production by all Leuconostoc strains was growth associated, occurring at incubation temperatures of 0 degrees C to 30 degrees C and initial medium pH 4.5 to 7.5. Probing of plasmid DNA from the three Leuconostoc strains with an oligonucleotide probe homologous to the nucleotide sequence of leucocin A-UAL 187 indicated plasmid-mediated bacteriocin production. Homology of the three Leuconostoc bacteriocin-coding genes to the amino-terminal end of the leucocin A-UAL 187 gene from Leuconostoc gelidum UAL 187 is therefore suggested. This evidence implies that all three Leuconostoc strains produce type 2, Listeria active bacteriocins.
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PMID:Antibacterial activity of three Leuconostoc strains isolated from vacuum-packaged processed meats. 807 4

The X-PRESS, osmotic shock, chloroform treatment, lysozyme treatment and ultrasonic disruption methods to release five different plasmid-mediated beta-lactamases from Escherichia coli and one chromosomal beta-lactamase from Enterobacter cloacae were compared. The main activities of TEM-1, SHV-1, OXA-1, OXA-2, PSE-4 and chromosomal P99 beta-lactamases were found at the same isoelectric point irrespective of the method used. However, additional satellite bands were found with TEM-1, OXA-1, OXA-2 and PSE-4 beta-lactamases released by the lysozyme method. In addition, beta-lactamase released by osmotic shock treatment was found to be unstable during storage at -20 degrees C or during the 18 h period of iso-electric focusing at +4 degrees C. Chloroform treatment produced similar band patterns and at least as good an enzyme yield as ultrasonic disintegration and was equally simple and fast to perform.
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PMID:Evaluation of five different methods to prepare bacterial extracts for the identification of beta-lactamases by isoelectric focusing. 814 21

This study evaluated the Promega Magic Minipreps (MM) (Promega Corporation, Madison, WI) DNA purification system for use in plasmid analysis of common nosocomial bacterial pathogens. The MM system is a kit that includes lysis solutions and buffers and incorporates a minicolumn of DNA binding resin for recovery of plasmid DNA. The MM system was used according to the manufacturer's directions to recover plasmids for agarose gel electrophoresis from clinical isolates of Acinetobacter calcoaceticus, Enterobacter cloacae, and Klebsiella pneumoniae. For Salmonella enteritidis and Staphylococcus aureus, lysozyme and lysostaphin, respectively, were used for pretreatment. Plasmid DNA from ten isolates could be recovered in approximately one hour with very little manipulation and no phenol/chloroform extractions and was suitable for restriction endonuclease digestion. Compared with a standard miniprep protocol, the MM system was much easier to perform and resulted in significant cost savings due to a 50% reduction in technologist time. The authors conclude that the MM system is a convenient and cost-effective method for clinical microbiology laboratories for recovering plasmid DNA from nosocomial bacterial pathogens.
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PMID:Evaluation of a commercial DNA purification system for plasmid analysis of nosocomial bacterial pathogens. 837 41

During endospore formation in Bacillus subtilis, approximately a dozen proteins are synthesized and assembled around the prespore to form a protective coat. Little is known about the assembly process, but several of the genes encoding these coat proteins are expressed in the mother cell compartment, where the proteins accumulate on the outer side of the developing endospore. Transcription of these genes is directed by the mother cell-specific sigma factor, sigma K, during the later stages of endospore development. sigma E may direct expression of the genes that encode proteins that function in the earliest stages of coat assembly. By screening for sigma E-dependent promoters, we cloned a gene, designated spoVID, required for assembly of a normal spore coat. Expression of spoVID was initiated at about the second hour of sporulation and continued throughout development from a sigma E-dependent promoter. The spoVID gene was located on the B. subtilis chromosome just downstream of the previously characterized hemAXCDBL operon and is predicted to encode an extremely acidic protein with 575 residues. Insertion mutants of spoVID produced refractile spores that were resistant to heat and to chloroform but were sensitive to lysozyme. Electron microscopic examination of sporulating spoVID mutant cells revealed normal morphological development up to about the third hour of sporulation. However, during the later stages of development the coat proteins assembled into aberrant structures that occurred freely in the mother cell cytoplasm and that consisted of reiterations of the single inner and outer layers that normally make up the spore coat.
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PMID:Cloning and characterization of a gene required for assembly of the Bacillus subtilis spore coat. 844 78

The phage lambda lysozyme (lambda L) contains four tryptophans. These have been efficiently replaced by 7-azatryptophan (7aW) through biosynthetic incorporation into the overexpressed protein. Comparative analysis of the effect of temperature or pH on the fluorescence of the wild-type lambda L and 7aWs-containing protein (a lambda L) shows that the stability of the protein is only mildly reduced by 7aW incorporation above pH 5 but that it is strongly decreased below pH 4 on protonation of inaccessible 7aWs. The a lambda L fluorescence depends on pH as a consequence of its effect on the denaturation equilibrium, on the state of protonation of accessible 7aWs in the native state and of all 7aWs in the denatured state. The pH dependence of the fluorescence is used to estimate the number of accessible tryptophans in the protein. The result agrees with that derived from tryptophan NH exchange measurements by 1H-NMR. The acid limb of the activity-pH profile is characterized by a sharp drop that might arise from a cooperative acid-induced denaturation. The difference in acid stability of a lambda L versus lambda L is used to rule out this acid denaturation hypothesis as tryptophan replacement does not affect the lytic activity on chloroform-sensitized Escherichia coli cells or its pH profile.
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PMID:Biosynthetic incorporation of 7-azatryptophan into the phage lambda lysozyme: estimation of tryptophan accessibility, effect on enzymatic activity and protein stability. 853 66

Endospores of Bacillus subtilis are encased in a protein shell, known as the spore coat, composed of a lamella-like inner layer and an electron-dense outer layer. We report the identification and characterization of a gene, herein called cotH, located at 300 degrees on the B. subtilis genetic map between two divergent cot genes, cotB and cotG. The cotH open reading frame extended for 1,086 bp and corresponded to a polypeptide of 42.8 kDa. Spores of a cotH null mutant were normally heat, lysozyme, and chloroform resistant but were impaired in germination. The mutant spores were also pleiotropically deficient in several coat proteins, including the products of the previously cloned cotB, -C, and -G genes. On the basis of the analysis of a cotE cotH double mutant, we infer that CotH is probably localized in the inner coat and is involved in the assembly of several proteins in the outer layer of the coat.
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PMID:Bacillus subtilis spore coat assembly requires cotH gene expression. 899 97


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