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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To obtain high yields of extracellular enzymes and toxins for immunological analysis, type culture collection strains of Clostridium perfringens types A to D and 28 fresh isolates of C. perfringens type A from humans were grown in fermenters under controlled conditions in a pre-reduced proteose peptone medium. The type culture collection strains all showed different characteristics with respect to growth rates and pH optima for growth. Production of phospholipase C (alpha-toxin), haemolysin and lethal activity varied considerably between the different types. Growth and extracellular protein production in fermenters with pH control and static or stirred cultures were compared. Production of all extracellular proteins measured was markedly improved by cultivation in fermenters with pH control. Strain ATCC13124 produced five times more phospholipase C than any of 28 freshly isolated strains of C. perfringens type A, grown under identical conditions. Haemolytic and lethal activities of the ATCC strain were equal or superior to the activities of any of the freshly isolated strains. There were no differences in the bacterial yields and in the production of extracellular toxins between type A strains isolated from clinical cases of gas gangrene and abdominal wounds, and those isolated from faecal samples from healthy persons.
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PMID:Production of phospholipase C (alpha-toxin), haemolysins and lethal toxins by Clostridium perfringens types A to D. 1 Mar 44

Prolonged cultivation of strain Wood 46 in fluid cultures resulted in a selection of mutants with low or no haemolytic activity. In one group of mutants, four out of five strains showed no production of alpha-toxin when examined by polyacrylamide gel electrophoresis and by double diffusion in agar. Two major extracellular proteins which have been identified by other methods as degradation products of alpha-toxin were also absent. The absence of alpha-toxin did not affect growth in fluid or solid media. Fibrinolysin was produced by these mutants but at a much lower rate than by the wild type. A second group of mutants was characterized by a slow rate of growth on rabbit blood agar and showed a heterogeneous extracellular protein pattern. These mutants had a high growth rate in fluid medium consisting of acid hydrolysed proteins. Production of fibrinolysin was absent or low in three out of four mutants in the second group. The slow growth and low production of alpha-haemolysin in rabbit blood agar probably was caused by deficient extracellular proteolytic activity of the mutants.
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PMID:Spontaneous alpha-toxin mutants of Staphylococcus aureus. 13 60

The progress of secretion of alpha-toxin and total extracellular protein by Staphylococcus aureus (Wood 46), grown aerobically at 37 degrees C, in a 3% (s/v) tryptone soya broth medium supplemented with vitamins was followed. Exoprotein was secreted at a high rate by intact bacteria during the exponential phase (to 9 h) and into the post-exponential phase. After 18 h, when exoprotein accounted for 33% of the total protein in the culture, no further exoprotein was secreted although the bacterial density continued to increase at a low rate beyond this time. During the phase of active secretion, alpha-toxin represented a constant proportion of total exoprotein, the differential rate of synthesis of which increased by a factor of four after the end of exponential growth. Concomitant with the increase in the differential rate of exoprotein formation there was a fourfold increase in the intracellular concentration of RNA precursor material.
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PMID:The characteristics of extracellular protein secretion by Staphylococcus aureus (Wood 46) and their relationship to the regulation of alpha-toxin formation. 87 52

A comparison has been made of total exoprotein formation by Staphylococcus aureus (Wood 46) in a tryptone soya broth (TSB) medium and a casein hydrolysate-yeast extract-containing (CCY) medium in which exponential growth occurred with doubling times of 3.0 and 1.3 h, respectively. It was found that the differential rate of exoprotein formation was biphasic in each case, increasing after the cessation of exponential growth by a factor of 4 in TSB and 7 in CCY medium. Although this relative change was greater in CCY medium, the maximum value of the differential rate was less than 40% of that achieved in TSB medium. It was further shown that throughout the growth cycle, and in both cultures, alpha-toxin accounted for the same proportion of total extracellular protein.
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PMID:Comparison of the patterns of increased in alpha-toxin and total extracellular protein by Staphylococcus aureus (Wood 46) grown in media supporting widely differing growth characteristics. 89 6

Polarized epithelial cell monolayers contain two distinct plasma membrane domains as delineated by the presence of tight junctions--i.e., an apical surface that faces the external environment and a basolateral surface that functions both in cell-cell contact and cell-substrate attachment. Central to the understanding of epithelial cell polarity is the question of how such cell-surface specializations are generated. A different class of membrane glycoproteins has recently emerged that may yield new insight into the mechanism underlying the biogenesis of this polarity. Members of this class contain a large extracellular protein domain linked to the membrane via glycosyl-phosphatidylinositol. Using a polarized renal epithelial cell line (Madin-Darby canine kidney), we identified endogenous glycosyl-phosphatidylinositol-anchored proteins through release by a phosphatidylinositol-specific phospholipase C. Six glycosyl-phosphatidylinositol-anchored proteins of 110, 85, 70, 55, 38, and 35 kDa were identified and appeared to be restricted to the apical surface. Our data are consistent with the notion that the glycosyl-phosphatidylinositol membrane anchor may contain the necessary information for "targeting" to the apical surface.
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PMID:Polarized apical distribution of glycosyl-phosphatidylinositol-anchored proteins in a renal epithelial cell line. 297 57

The differential rates of formation of total extracellular protein and alpha-toxin by Staphylococcus aureus (Wood 46) were determined during aerobic growth, at 37 degrees C, in a complex medium containing 0.0, 0.25 or 1.0% (wt/vol) glucose. Different inocula were employed from 1% (vol/vol) of an overnight culture to 100% where bacterial cells were washed and resuspended in fresh medium without change in density. It was shown that under all conditions examined the differential rates of total extracellular protein formation exhibited a biphasic pattern characteristic of regulation based on 'competition'. This biphasic pattern was maintained even in the presence of a large inoculum and a high glucose concentration, conditions considered to favour the onset of catabolite repression. However, a lowering of the initial rate was observed with increasing glucose suggesting the superimposition of catabolite repression as a modulating effect under extreme conditions. In the case of the specific extracellular protein component, alpha-toxin, its differential rate of formation paralleled total exoprotein in all except the condition most favourable for catabolite accumulation when a deviation consistent with a pronounced catabolite repression of this component was demonstrated which was not pH-dependent.
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PMID:The effect of glucose on the differential rates of extracellular protein and alpha-toxin formation by Staphylococcus aureus (Wood 46). 661 25

Phospholipase C (heat-labile hemolysin) of Pseudomonas aeruginosa is a phosphate (P(i))-regulated extracellular protein which may be a significant virulence factor of this organism. The gene for this hemolytic enzyme was cloned on a 4.1-megadalton (Mdal) fragment from a BamHI digest of P. aeruginosa PAO1 genomic DNA and was inserted into the BamHI sites of the multicopy Escherichia coli(pBR322) and P. aeruginosa(pMW79) vectors. The E. coli and P. aeruginosa recombinant plasmids were designated pGV26 and pVB81, respectively. A restriction map of the 4.1-Mdal fragment from pGV26 was constructed, using double and single digestions with BamHI and EcoRI and several different restriction enzymes. Based on information from this map, a 2.4-Mdal BamHI/BglII fragment containing the gene for phospholipase C was subcloned to pBR322. The hybrid plasmids pGV26 and pVB81 direct the synthesis of enzymatically active phospholipase C, which is also hemolytic. The plasmid-directed synthesis of phospholipase C in E. coli or P. aeruginosa is not repressible by P(i) as is the chromosomally directed synthesis in P. aeruginosa. Data are presented which suggest that the synthesis of phospholipase C from pGV26 and pVB81 is directed from the tetracycline resistance gene promoter. The level of enzyme activity produced by E. coli(pGV26) is slightly higher than the levels produced by P. aeruginosa(pMW79) under repressed conditions. In contrast, the levels produced by P. aeruginosa(pVB81) are at least 600-fold higher than the levels produced by P. aeruginosa(pMW79) under repressed conditions and approximately 20-fold higher than those produced by P. aeruginosa(pMW79) under derepressed conditions. The majority (85%) of the enzyme produced by E. coli(pGV26) remained cell associated, whereas >95% of the enzyme produced by P. aeruginosa(pVB81) was extracellular. Analysis of extracellular proteins from cultures of P. aeruginosa(pMW79) and P. aeruginosa(pVB81) by high-performance liquid chromotography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the phospholipase C gene was cloned intact, and it is likely that several additional genes were cloned on the 4.1-Mdal fragment of DNA. It was also found that some of these genes encode proteins which are the same molecular weight as some previously described P(i)-repressible proteins of P. aeruginosa. The existence of a P(i) regulon of P. aeruginosa is proposed. It is likely that one of these genes also regulates the level of pyocyanin production by P. aeruginosa and that one or more play a role in transport or binding of P(i). The availability of the hybrid plasmids described herein will be useful in further studies on the role of this hemolysin in the virulence of P. aeruginosa and in the study of the genetics and physiology of P(i)-regulated proteins.
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PMID:Cloning of a phosphate-regulated hemolysin gene (phospholipase C) from Pseudomonas aeruginosa. 681 59

The changes in bacterial density, total extracellular protein and haemolysin produced by bacteria from overnight cultures of Staphylococcus aureus (Wood 46) and a low alpha-toxin-producing variant suspended in fresh medium were followed at 37 degrees C. Although five extracellular proteins were produced at a reduced level by the variant (alpha-toxin formation was reduced more than tenfold), the differential rates of total extracellular protein formation by the two organisms were identical. The results are consistent with a common regulatory mechanism for extracellular protein formation in which a pleiotropic compensation may occur in order to saturate the extracellular protein-producing capability.
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PMID:Pleiotropic compensation in the regulation of extracellular protein formation by a low alpha-toxin-producing variant of Staphylococcus aureus (Wood 46). 732 Jun 91

The mechanism of in vitro synergistic lysis of sheep erythrocytes by Corynebacterium ovis and Corynebacterium equi was investigated. Hemolysis required (i) the action of phospholipase D from C. ovis, (ii) the action of an extracellular protein of C. equi, and (iii) Mg2+. Maximum lysis required imposition on the system of a fourth condition (step iv), such as chilling. Steps i, ii, and iv occur sequentially and in that order. Mg2+ functions in steps i and ii. The extracellular protein C. equi was purified to homogeneity and found to be a phospholipase C capable of hydrolyzing ceramide phosphate, phosphatidic acid, and all of the isolated major phospholipids of mammalian erythrocyte membranes. The principal features of the synergistic hemolytic system could be reproduced in experiments involving liposomes containing either sphingomyelin or ceramide phosphate and trapped [14C]glucose. We inferred that sphingomyelin of sheep erythrocytes is first converted to ceramide phosphate by C. ovis phospholipase D. On the basis of results with liposomes, we propose that the ceramide phosphate is then converted to ceramide by C. equi phospholipase C. We believe that the resulting in situ ceramide then undergoes dislocation by chilling and perhaps also by virtue of an affinity between ceramide and C. equi phospholipase C. The dislocation of ceramide presumably disorganizes the lipid bilayer sufficiently to result in cell lysis.
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PMID:Stepwise degradation of membrane sphingomyelin by corynebacterial phospholipases. 739

Exoenzyme S is an ADP-ribosyltransferase produced by Pseudomonas aeruginosa. Synthesis of exoenzyme S depends on an intact trans-regulatory locus encoding three protein products, ExsC, ExsB, and ExsA. To identify the phenotype of ExsC, -B, and -A mutants in exoenzyme S production, specific insertional mutations with the streptomycin resistance-encoding omega interposon were introduced into cloned DNA and returned to the chromosomes of P. aeruginosa PA103, PAO1, and PAK. Southern blot analysis was used to confirm insertion of omega and resolution of vector sequences. Exoenzyme S expression was measured in parental and mutant derivatives by Western blot (immunoblot) analysis and ADP-ribosyltransferase activity measurement. A complete set of mutations were obtained in strains PAK and PAO1, but in strain PA103, only an insertion in the exsA coding region was identified. Southern blot analysis demonstrated that extensive duplication and rearrangement of the PA103 chromosomal trans-regulatory locus occurred when exsC::omega or exsB::omega recombination events were attempted. Exoenzyme S antigen was not detectable in the supernatant or lysate fractions of mutant strains by Western blot analysis. ADP-ribosyltransferase activity was detected in the lysate but not in the supernatant fractions of mutant derivatives. The general secretion pathway appeared to function normally in mutant strains, as elastase, exotoxin A, and phospholipase C were measured in the supernatants of parental and mutant strains. Several differences were noted when the extracellular protein profiles of parental strains were compared with similar samples from the insertional mutant strains. Some of these differences appeared to be unrelated to exoenzyme S. These data suggest that insertional inactivation of the exoenzyme S trans-regulatory locus may affect a subset of other extracellular proteins.
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PMID:Construction and characterization of chromosomal insertional mutations of the Pseudomonas aeruginosa exoenzyme S trans-regulatory locus. 830 Feb 13


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