Multiple phospholipid substrates of phospholipase C/sphingomyelinase HR 2 from Pseudomonas aeruginosa (original) (raw)
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Enzymatic Hydrolysis of Immobilized Sphingomyelin by Three Bacterial Phospholipases C
Acta Pathologica Microbiologica Scandinavica Section B Microbiology, 1981
Through hydrophobic interaction, sphingomyelin was adsorbed to agarose beads containing octyl groups by a stepwise dilution procedure. This immobilized lipid was used as a substrate for three bacterial phospholipases C (E.C. 3. I. 4. 3.). The degradation with time of this substrate showed two different fractions of the substrate according to hydrolysing velocity in the early part of the time-curve when phospholipases C from Bacillus cereus and Closrridium perfringens were used. The early fractions could be predigested by the enzymes, a procedure which resulted in linear time-curves. The corresponding early part of the time-curve for phospholipase C from Siaphylococcus aureus was linear, indicating a comparatively large early fraction of the substrate for this enzyme. The stock gel of the immobilized lipid substrate could be stored for months. It was easily and reproducibly handled as a water suspension. After enzymatic hydrolysis the substrate was rapidly separated from enzyme and product by filtration. The enzyme assay presented thus represents a convenient way to avoid the difficulties connected with the use of temporary sonicated suspensions as substrate for bacterial phospholipases C.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2007
PlcHR 2 is the paradigm member of a novel phospholipase C/phosphatase superfamily, with members in a variety of bacterial species. This paper describes the phospholipase C and sphingomyelinase activities of PlcHR 2 when the substrate is in the form of large unilamellar vesicles, and the subsequent effects of lipid hydrolysis on vesicle and bilayer stability, including vesicle fusion. PlcHR 2 cleaves phosphatidylcholine and sphingomyelin at equal rates, but is inactive on phospholipids that lack choline head groups. Calcium in the millimolar range does not modify in any significant way the hydrolytic activity of PlcHR 2 on choline-containing phospholipids. The catalytic activity of the enzyme induces vesicle fusion, as demonstrated by the concomitant observation of intervesicular total lipid mixing, inner monolayer-lipid mixing, and aqueous contents mixing. No release of vesicular contents is detected under these conditions. The presence of phosphatidylserine in the vesicle composition does not modify significantly PlcHR 2 -induced liposome aggregation, as long as Ca 2+ is present, but completely abolishes fusion, even in the presence of the cation. Each of the various enzyme-induced phenomena have their characteristic latency periods, that increase in the order lipid hydrolysis b vesicle aggregation b total lipid mixing b inner lipid mixing b contents mixing. Concomitant measurements of the threshold diacylglyceride + ceramide concentrations in the bilayer show that late events, e.g. lipid mixing, require a higher concentration of PlcHR 2 products than early ones, e.g. aggregation. When the above results are examined in the context of the membrane effects of other phospholipid phosphocholine hydrolases it can be concluded that aggregation is necessary, but not sufficient for membrane fusion to occur, that diacylglycerol is far more fusogenic than ceramide, and that vesicle membrane permeabilization occurs independently from vesicle fusion.
Phospholipase A activity in Pseudomonas aeruginosa
Zentralblatt für Bakteriologie : international journal of medical microbiology, 1995
Our study describes the production, purification and properties of an enzyme from Pseudomonas aeruginosa displaying the properties of phospholipase A. Maximal amounts of enzyme could be detected in the culture supernatant when the bacterium was grown for 3 to 5 days at 37 degrees C in stirred flask cultures containing brain heart infusion. The enzyme was purified by polyethylenimine precipitation and ammonium sulfate precipitation followed by gel filtration. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme preparation exhibited two bands with molecular weights of 13.5 and 60 kD, respectively. Correspondingly, two peaks of the same molecular weight could be demonstrated by high performance size exclusion chromatography. The activity toward the sn-2 ester binding of phospholipids was characterized and found to be highest towards phosphatidylcholine. Enzymatic activity was not influenced by the addition of calcium or EDTA while magnesium and strontium caused a d...
Bacterial Sphingomyelinases and Phospholipases as Virulence Factors
Microbiology and molecular biology reviews : MMBR, 2016
Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural...
Acta pathologica et microbiologica Scandinavica. Section B, Microbiology, 1981
An assay system for phospholipases C has been described with sphingomyelin immobilized to octyl-Sepharose CL-4B as substrate. The immobilization procedure was further developed and used with [14 C-choline]-sphingomyelin and [14C-choline] phosphatidylcholine (lecithin). These immobilized radioactive phospholipids made the enzymatic assays easier to perform and made it possible to increase the sensitivity. Furthermore, since release of the choline part instead of the phosphate part of the substrate molecule was measured, it was possible to use this assay for phospholipase D as well. The enzyme characteristics of phospholipase D from Corynebacterium ovis were compared in this test system with those of three phospholipases C (from Clostridium perfringens, Bacillus cereus and Staphylococcus aureus) with respect to hydrolysing capacities and optimal ion concentrations.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2010
A phospholipase C/ sphingomyelinase from Pseudomonas aeruginosa has been assayed on vesicles containing phosphatidylcholine, sphingomyelin, phosphatidylethanolamine and cholesterol, at equimolar ratios. The enzyme activity modifies the bilayer chemical composition giving rise to diacylglycerol (DAG) and ceramide (Cer). Assays of enzyme activity, enzyme-induced aggregation and fusion have been performed. Ultrastructural evidence of vesicle fusion at various stages of the process is presented, based on cryo-EM observations. The two enzyme lipidic end-products, DAG and Cer, have opposite effects on the bilayer physical properties, the former abolishes lateral phase separation, while the latter generates a new gel phase [Sot et al., FEBS Lett. 582, 3230-3236 (2008)]. Addition of either DAG, or Cer, or both to the liposome mixture causes an increase in enzyme binding to the bilayers and a decrease in lag time of hydrolysis. These two lipids also have different effects on the enzyme activity, DAG enhancing enzyme-induced vesicle aggregation and fusion, Cer inhibiting the hydrolytic activity. These effects are explained in terms of the different physical properties of the two lipids. DAG increases bilayers fluidity and decreases lateral separation of lipids, thus increasing enzyme activity and substrate accessibility to the enzyme. Cer has the opposite effect mainly because of its tendency to sequester sphingomyelin, an enzyme substrate, into rigid domains, presumably less accessible to the enzyme.
Sphingomyelinases: enzymology and membrane activity
Febs Letters, 2002
This paper reviews our present knowledge of sphingomyelinases as enzymes, and as enzymes acting on a membrane constituent lipid, sphingomyelin. Six types of sphingomyelinases are considered, namely acidic, secretory, Mg2+-dependent neutral, Mg2+-independent neutral, alkaline, and bacterial enzymes with both phospholipase C and sphingomyelinase activity. Sphingomyelinase assay methods and specific inhibitors are reviewed. Kinetic and mechanistic studies are summarized, a kinetic model and a general-base catalytic mechanism are proposed. Sphingomyelinase–membrane interactions are considered from the point of view of the influence of lipids on the enzyme activity. Moreover, effects of sphingomyelinase activity on membrane architecture (increased membrane permeability, membrane aggregation and fusion) are described. Finally, a number of open questions on the above topics are enunciated.
PLoS pathogens, 2009
The hemolytic phospholipase C (PlcHR) expressed by Pseudomonas aeruginosa is the original member of a Phosphoesterase Superfamily, which includes phosphorylcholine-specific phospholipases C (PC-PLC) produced by frank and opportunistic pathogens. PlcHR, but not all its family members, is also a potent sphingomyelinase (SMase). Data presented herein indicate that picomolar (pM) concentrations of PlcHR are selectively lethal to endothelial cells (EC). An RGD motif of PlcHR contributes to this selectivity. Peptides containing an RGD motif (i.e., GRGDS), but not control peptides (i.e., GDGRS), block the effects of PlcHR on calcium signaling and cytotoxicity to EC. Moreover, RGD variants of PlcHR (e.g., RGE, KGD) are significantly reduced in their binding and toxicity, but retain the enzymatic activity of the wild type PlcHR. PlcHR also inhibits several EC-dependent in vitro assays (i.e., EC migration, EC invasion, and EC tubule formation), which represent key processes involved in angiog...
The Journal of Lipid Research, 2011
Phospholipases are essential enzymes in maintaining membrane homeostasis and in the generation of metabolic signals. They are also powerful tools that bacteria use to infect and eventually destroy eukaryotic cells by helping in the degradation of the target cell membranes. Phospholipase C (PLC) enzymes cleave the phosphodiester bond between the diacylglycerol moiety and the phosphoryl base (phosphorylcholine, phosphorylethanolamine, and others), characteristic of each phospholipid class. Most sphingomyelinases hydrolyze the equivalent bond between ceramide (Cer) and phosphorylcholine in sphingomyelin (SM). From the point of view of their enzyme activities, phospholipases and lipases in general are rather unique among enzymes in that their substrates and end products do not occur freely in solution but are instead found to make up part of the cell membrane.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2011
a b s t r a c t Cholesterol Lipid curvature Lipid negative charge Lysosomal lipids Clostridium perfringens α-Toxin, a major determinant of Clostridium perfringens toxicity, exhibits both phospholipase C and sphingomyelinase activities. Our studies with large unilamellar vesicles containing a variety of lipid mixtures reveal that both lipase activities are enhanced by cholesterol and by lipids with an intrinsic negative curvature, e.g. phosphatidylethanolamine. Conversely lysophospholipids, that possess a positive intrinsic curvature, inhibit the α-toxin lipase activities. Phospholipids with a net negative charge do not exert any major effect on the lipase activities, and the same lack of effect is seen with the lysosomal lipid bis (monoacylglycero) phosphate. Ganglioside GT1b has a clear inhibitory effect, while the monosialic ganglioside GM3 is virtually ineffectual even when incorporated at 6 mol % in the vesicles. The length of the lag periods appears to be inversely related to the maximum (post-lag) enzyme activities. Moreover, and particularly in the presence of cholesterol, lag times increase with pH. Both lipase activities are sensitive to vesicle size, but in opposite ways: while phospholipase C is higher with larger vesicles, sphingomyelinase activity is lower. The combination of our results with previous structural studies suggests that α-toxin lipase activities have distinct, but partially overlapping and interacting active sites.