Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase C from the Dallas 1E strain of Legionella pneumophila serogroup 5 was purified from buffered yeast extract culture supernate by ion-exchange chromatography followed by fractionation by manganous chloride and ammonium sulphate precipitation steps. Enzyme activity was assayed by hydrolysis of p-nitrophenylphosphorylcholine and confirmed by release of radioactivity from tritiated L-alpha-dipalmitoylphosphatidylcholine labelled in the methyl groups of choline. After SDS-PAGE, the purified preparation yielded a single band upon Coomassie-blue staining. This protein migrated with an apparent Mr of 50,000-54,000. Phospholipase C activity was maximal at pH greater than or equal to 8.4 and was enhanced in the presence of sorbitol and of several nonionic detergents but was eliminated by SDS. EDTA, Cu2+, Fe2+ and Zn2+ inhibited enzyme activity, whereas Ba2+, Ca2+, Co2+, Mg2+ and Mn2+ restored activity to EDTA-treated material. No haemolytic activity was demonstrated with the purified enzyme.
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PMID:A phospholipase C from the Dallas 1E strain of Legionella pneumophila serogroup 5: purification and characterization of conditions for optimal activity with an artificial substrate. 317 47

An extracellular proteolytic enzyme of Legionella pneumophila was purified by sequential batch separation with DEAE-cellulose, hydrophobic interaction chromatography with octyl-Sepharose, and ion-exchange chromatography with DEAE-Bio-Gel A (Bio-Rad Laboratories, Richmond, Calif.). The resulting protease preparation was determined to be homogeneous by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. Although free of contaminating proteins, the purified protease separated into two antigenically indistinguishable proteins both of which possessed proteolytic activity. The apparent masses of the proteins were 38 and 40 kilodaltons (kDa) as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate, whereas gel filtration chromatography revealed a single mass of 34 kDa. Immunoblot analysis indicated that the 38-kDa protein probably originated from the 40-kDa protein during purification. The isoelectric points of the two protease species were 4.20 and 4.42. Enzyme activity, which was optimum between pH 5.5 and 7.5, was inhibited by various metal chelators; however, no effect was observed after treatment with phenylmethylsulfonyl fluoride, chymostatin, trypsin inhibitor, or dithiothreitol. Enzyme activity inhibited by metal chelators was restored upon the addition of various metal ions, including Zn2+, Fe2+, Mn2+, Cu2+, and Fe3+, but was not restored by Mg2+ or Ca2+. Atomic absorption analysis of the purified protease revealed a single gram-atom of zinc per mole of enzyme. Our findings indicate that the L. pneumophila protease resembles neutral zinc-containing metalloproteases similar to those found in other bacterial species.
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PMID:Purification and characterization of an extracellular protease of Legionella pneumophila. 351 31

Lactoferrin, an iron-binding protein found in mucosal secretions and in specific granules of polymorphonuclear leukocytes, has been shown to be bactericidal for a variety of organisms. In this study, the effect of lactoferrin on Legionella pneumophila was investigated. Purified human apolactoferrin was bactericidal for the Knoxville 1 strain (serogroup 1), with a 4-log decrease in viability within 2 h at 37 degrees C. Killing was dependent on the iron-free state since iron-saturated lactoferrin had no activity. Guinea pig passage of this strain did not affect its sensitivity to lactoferrin. Treatment of the cells with dilutions of the lactoferrin resulted in correspondingly reduced killing. Activity was temperature dependent; there was no loss of viability at 1 or 22 degrees C and slightly enhanced killing at 41 degrees C. Addition of Mg2+ blocked bactericidal activity. In addition, mature human milk, a lactoferrin-containing mucosal secretion, was also bactericidal for L. pneumophila. As demonstrated with the purified lactoferrin, bactericidal activity was lost when the milk was iron saturated.
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PMID:Bactericidal effect of lactoferrin on Legionella pneumophila. 394 91

The bacterium Legionella pneumophila is the responsible agent for Legionnaires' disease and has recently been shown to harbor a gene encoding a kinase that confers resistance to the aminoglycoside antibiotic spectinomycin (Suter, T. M., Viswanathan, V. K., and Cianciotto, N. P. (1997) Antimicrob. Agents Chemother. 41, 1385-1388). We report the overproduction, purification, and characterization of this spectinomycin kinase from an expressing system in Escherichia coli. The purified protein shows stringent substrate specificity for spectinomycin with Km = 21.5 microM and kcat = 24.2 s-1 and does not bind other aminoglycosides including kanamycin, amikacin, neomycin, butirosin, streptomycin, or apramycin. Purification of spectinomycin phosphate followed by characterization by mass spectrometry and 1H, 13C, and 31P NMR established the site of phosphorylation to be at the hydroxyl group at position 9. Thus this enzyme is designated APH(9)-Ia (where APH is aminoglycoside kinase). The enzyme was inactivated by the electrophilic ATP analogue 5'-[p-(fluorosulfonyl)benzoyl]adenosine, consistent with a nucleophilic residue such as Lys lining the nucleotide binding pocket. Site-directed mutagenesis of Lys-52 and Asp-212 to Ala confirmed that these residues were important for catalysis, with Lys-52 playing a potential role in ATP binding and Asp-212 in phosphoryl transfer. Thio and solvent isotope effect experiments in the presence of either Mg2+ or Mn2+ were consistent with a kinetic mechanism in which phosphate transfer does not contribute significantly to the rate-limiting step. These results establish that APH(9)-Ia is a highly specific antibiotic resistance kinase and provides the requisite mechanistic information for future structural studies.
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PMID:Spectinomycin kinase from Legionella pneumophila. Characterization of substrate specificity and identification of catalytically important residues. 961 79

Copper-silver (Cu-Ag) ionization has effectively controlled Legionella spp. in the hot water systems of numerous hospitals. However, it was ineffective at controlling Legionella in one Ohio hospital despite the confirmation of adequate total concentrations of copper and silver ions. The pH of the water at this hospital was found to be 8.5 to 9.0. The purpose of this study was to investigate the impact of pH and other water quality parameters, including alkalinity (HCO3-), hardness (Ca2+ and Mg2+), and amount of dissolved organic carbon (DOC), on the control of Legionella by Cu-Ag ionization. Initial concentrations of Legionella and copper and silver ions used in batch experiments were 3 x 10(6) CFU/ml and 0.4 and 0.08 mg/liter, respectively. Changes in bicarbonate ion concentration (50, 100, and 150 mg/liter), water hardness (Ca2+ at 50 and 100 mg/liter; Mg2+ at 40 and 80 mg/liter), and level of DOC (0.5 and 2 mg/liter) had no significant impact on the efficacy of copper and silver ions in killing Legionella at a neutral pH. When the pH was elevated to 9 in these experiments, copper ions achieved only a 10-fold reduction in the number of Legionella organisms in 24 h, compared to a millionfold decrease at pH 7.0. Silver ions were able to achieve a millionfold reduction in 24 h at all ranges of water quality parameters tested. Precipitation of insoluble copper complexes was observed at a pH above 6.0. These results suggest that pH may be an important factor in the efficacy of copper-silver ionization in controlling Legionella in water systems.
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PMID:Negative effect of high pH on biocidal efficacy of copper and silver ions in controlling Legionella pneumophila. 1203 24