Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We recently described a Tn551 insertion in the chromosome of Staphylococcus aureus S6C that resulted in drastically reduced expression of extracellular lipase (M. S. Smeltzer, S. R. Gill, and J. J. Iandolo, J. Bacteriol. 174:4000-4006, 1992). The insertion was localized to a chromosomal site (designated omega 1058) distinct from the lipase structural gene (geh) and the accessory gene regulator (agr), both of which were structurally intact in the lipase-negative (Lip-) mutants. In this report, we describe a phenotypic comparison between strains S6C, a hyperproducer of enterotoxin B; KSI9051, a derivative of S6C carrying the Tn551 insertion at omega 1058; ISP546, an 8325-4 strain that carries a Tn551 insertion in the agr locus; and ISP479C, the parent strain of ISP546 cured of the Tn551 delivery plasmid pI258repA36. Compared with their respective parent strains, ISP546 and KSI9051 produced greatly reduced amounts of lipase, alpha-toxin, delta-toxin, protease, and nuclease. KSI9051 also produced reduced amounts of staphylococcal enterotoxin B. Coagulase production was increased in ISP546 but not in KSI9051. Using a mouse model, we also demonstrated that ISP546 and KSI9051 were far less virulent than ISP479C and S6C. We have designated the genetic element defined by the Tn551 insertion at omega 1058 xpr to denote its role as a regulator of extracellular protein synthesis. We conclude that xpr and agr are similar and possibly interactive regulatory genes that play an important role in pathogenesis of staphylococcal disease.
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PMID:Phenotypic characterization of xpr, a global regulator of extracellular virulence factors in Staphylococcus aureus. 843 12

Ninety-four Staphylococcus aureus strains isolated from chronic and recurrent skin and respiratory tract infections were investigated for several virulence factor expressions. Production of protein A was noticed in all of the tested strains in amounts from less than 0.1 to more than 2.5 ng per 10(6) bacterial cells. The percentage of the extracellularly produced protein A was found to lie between 4.5 and 27.8%. Two strains (both from the respiratory tract) produced more than 50% of protein A in the extracellular form and one strain did not produce any detectable amount of the extracellular protein A; 99% of the tested strains produced the clumping factor, 96% staphylocoagulase, 79% staphylokinase and 90% gelatinolytic activity; 79% produced alpha-toxin exclusively or in combination with delta- or beta-toxin; 8% of strains produced beta-toxin. There were differences in beta-toxin production between strains from the respiratory tract (5%) and skin infections (25%). delta-Toxin was produced by 53% of the strains. In each of the tested strains a complex of virulence factors was detected. The importance of inactivated extracellular products (especially alpha- and delta-toxin and in the case of skin infections also beta-toxin) as components of staphylococcal whole-cell vaccine was suggested.
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PMID:Staphylococcus aureus in chronic and recurrent infections. 876 57

Variants of a parent culture of Listeria monocytogenes were prepared by passaging it several times through rabbits. The resulting isolates (V1 to V6) were investigated and compared with the parent culture with particular emphasis on their phenotypic characters and their pathogenicity for rabbits. The variants maintained the morphological, cultural, biochemical and serological features of the parent strain. Although no significant decrease was noted in the total extracellular protein produced, 10 mg/ml of a 6-day culture broth grown at 34 degrees C for V6 as compared to 12.3 mg/ml for the parent culture, the phosphocholine-specific phospholipase C (PC-PLC) activity diminished with passaging. Pathogenicity for rabbits, as determined by viable count of the organism per gram of the infected organ, increased at each passage. Animals infected with V6 revealed a mean of 2.2 x 10(9) CFU/g of spleen as compared to the parent culture which had a count of 5.0 x 10(6) CFU/g. These observations indicate a lack of direct correlation between in vitro production of PC-PLC and virulence of L. monocytogenes for rabbits.
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PMID:A comparative study of unpassaged and animal passaged cultures of Listeria monocytogenes in rabbits. 877 34

It is now generally accepted that adherence of microorganisms to various components of cardiac valve surfaces or vegetation lodging on the heart valves is an important early event in the pathogenesis of infective endocarditis. 120 clinical isolates of S. aureus obtained from patients with endocarditis and wound infections and from nasopharyngeal carriers were quantitatively analysed in vitro for their ability to bind to fibronectin and to produce protein A and alpha-toxin. Both cell-bound and extracellular protein A were measured and alpha-toxin was determined as antigen and as haemolytic activity. The highest fibronectin binding ability was found in carrier strains while no significant differences between strains were observed regarding the production of protein A. Strains isolated from patients with endocarditis produced significantly lower amounts of alpha-toxin than did strains from the other two groups. An inverse relationship between the production of protein A and of alpha-toxin was noticed in the material. Animal passage of five strains in an experimental endocarditis model showed a good reproducibility of the test systems and one strain was upregulated in its fibronectin binding ability and in alpha-toxin production. These in vitro results indicate that the fibronectin binding ability is not the decisive adherence factor and question the role of alpha-toxin as a virulence factor in endocarditis.
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PMID:Virulence factors of Staphylococcus aureus in the pathogenesis of endocarditis. A comparative study of clinical isolates. 963 73

We produced monoclonal antibodies (MAbs) to the extracellular proteins of Listeria monocytogenes EGD grown in Chelex-treated improved minimal medium. Ten of the positive hybridomas generated were chosen for further characterization. Seven of the MAbs reacted with a protein having a molecular mass of 60 kDa. These MAbs inhibited listeriolysin (LLO)-mediated hemolysis, and two of them were specific for LLO and none of the other thiol-activated toxins tested. In an enzyme-linked immunosorbent assay and Western blot analysis, five of the anti-LLO MAbs reacted with ivanolysin from Listeria ivanovii. Three of the 10 MAbs reacted with a 29-kDa protein on Western blots and neutralized the phosphatidylcholine-specific phospholipase C (PC-PLC) activity of L. monocytogenes. These three anti-PC-PLC MAbs did not react with phospholipases from five different gram-positive bacteria. However, the anti-PC-PLC MAbs recognized a 27-kDa extracellular protein from L. ivanovii and neutralized sphingomyelinase activity in a hemolysis test that demonstrates the antigenic relatedness of listerial phospholipases. These data indicate that listerial thiol-activated toxins possess species-specific epitopes and share group-specific epitopes. This is the first description of MAbs that neutralize listerial PC-PLC, and the data suggest that there is antigenic similarity between L. monocytogenes PC-PLC and L. ivanovii sphingomyelinase. The reactions of the MAbs with catfish isolates of L. monocytogenes suggested that some of the isolates examined lack the LLO and/or PC-PLC required for pathogenicity. The MAbs described here differentiated some catfish isolates from previously described type strain-pathogenic isolates and could be useful for detecting and determining the virulence of L. monocytogenes in food and clinical samples and for detecting L. ivanovii in veterinary clinical samples.
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PMID:Production of monoclonal antibodies to Listeria monocytogenes and their application to determine the virulence of isolates from channel catfish. 1038 71

In Staphylococcus aureus infection hemolysis caused by the extracellular protein alpha-toxin encoded by hla is thought to contribute significantly to its multifactorial virulence. In vitro, subinhibitory concentrations of beta-lactam antibiotics and fluoroquinolones increase the levels of hla and alpha-toxin expression, whereas aminoglycosides decrease the levels of hla and alpha-toxin expression. In the present study we investigated the effects of subinhibitory concentrations of amoxicillin, gentamicin, and moxifloxacin on hla and alpha-toxin expression and total hemolysis of S. aureus strain 8325-4, a high-level alpha-toxin producer, and its alpha-toxin-negative mutant, DU 1090, in vitro and in a rat model of chronic S. aureus infection. The levels of expression of hla and alpha-toxin and total hemolysis did not differ significantly when amoxicillin, gentamicin, or moxifloxacin was added to cultures of S. aureus strain 8325-4. In vivo, strain 8325-4 induced a significantly increased level of hemolysis in infected pouches compared to that in uninfected control pouches, but the hemolysis was reduced to control levels by treatment with doses of amoxicillin, gentamicin, or moxifloxacin that reduced bacterial numbers by 2 orders of magnitude. Additionally, the effects of subinhibitory concentrations of the three antibiotics on total hemolysis of four methicillin-resistant S. aureus and three methicillin-sensitive S. aureus (MSSA) clinical isolates were assessed in vitro. A significant increase in total hemolysis was observed for only one MSSA strain when it was treated with amoxicillin but not when it was treated with moxifloxacin or gentamicin. When purified alpha-toxin was incubated with purified human neutrophil elastase, alpha-toxin was cleaved nearly completely. The results suggest that the penicillin-induced increases in S. aureus alpha-toxin expression are strain dependent, that reduction of bacterial numbers in vivo counteracts this phenomenon effectively, and finally, that in localized S. aureus infections alpha-toxin activity is controlled by neutrophil elastase.
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PMID:Effects of amoxicillin, gentamicin, and moxifloxacin on the hemolytic activity of Staphylococcus aureus in vitro and in vivo. 1112 Sep 65

Successful infection by Listeria monocytogenes is dependent upon a range of bacterial extracellular proteins including a cytolysin termed listeriolysin O and phosphatidylcholine-specific phospholipase C. Five plant essential oils--bay, clove, cinnamon, nutmeg and thyme--significantly reduced the production of listeriolysin O by L. monocytogenes. The greatest change was observed after culture with oil of thyme, which reduced haemolysis to 52.1 haemolytic units (HU)/ml compared with 99.8 HU/ml observed with the control. Oil of clove was the only oil that also significantly reduced phosphatidylcholine-specific phospholipase C activity. These changes were observed despite the oils causing no change to the final bacterial concentration or total extracellular protein concentration.
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PMID:Inhibition of listeriolysin O and phosphatidylcholine-specific production in Listeria monocytogenes by subinhibitory concentrations of plant essential oils. 1213 73

The virulence determinants of Staphylococcus aureus are coordinately controlled by several unlinked chromosomal loci. Here, we report the identification of CYL5614, derived from strain Becker, with a mutation that affects the expression of type 8 capsular polysaccharide (CP8), nuclease, alpha-toxin, coagulase, protease, and protein A. This novel locus, named mgr, was linked by transposon Tn917 and mapped by three-factorial transduction crosses. The region containing the mgr locus was cloned and sequenced. Deletion mutagenesis and genetic complementation showed that the locus consisted of one gene, mgrA. Interestingly, mgrA-null mutants exhibited a phenotype opposite to that of CYL5614. This was due to a T-to-C mutation upstream of mgrA that resulted in a four- to eightfold increase in mgrA transcription in strain CYL5614. Thus, these results indicate that mgrA is an activator of CP8 and nuclease but a repressor of alpha-toxin, coagulase, protease, and protein A. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed that the mgr locus profoundly affected extracellular protein production, suggesting that the locus may regulate many other genes as well. The translated MgrA protein has a region of significant homology, which includes the helix-turn-helix DNA-binding motif, with the Escherichia coli MarR family of transcriptional regulators. Northern slot blot analyses suggested that mgr affected CP8, alpha-toxin, nuclease, and protein A at the transcriptional level.
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PMID:Mgr, a novel global regulator in Staphylococcus aureus. 1281 62

The data presented show the ability of subinhibitory concentrations of plant essential oils to influence the production of enterotoxins A and B and alpha-toxin by Staphylococcus aureus. Subinhibitory concentrations of the oils of bay, clove, cinnamon, nutmeg and thyme had no significant effect on the overall quantity of extracellular protein produced. Haemolysis due to alpha-toxin was significantly reduced after culture with all five plant essential oils. This reduction was greatest with the oils of bay, cinnamon and clove. These three oils also significantly decreased the production of enterotoxin A; the oils of clove and cinnamon also significantly decreased the production of enterotoxin B.
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PMID:Influence of subinhibitory concentrations of plant essential oils on the production of enterotoxins A and B and alpha-toxin by Staphylococcus aureus. 1535 26


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