scholarly journals Characterization of the Gene Encoding the Major Secreted Lysophospholipase A of Legionella pneumophila and Its Role in Detoxification of Lysophosphatidylcholine

2002 ◽  
Vol 70 (11) ◽  
pp. 6094-6106 ◽  
Author(s):  
Antje Flieger ◽  
Birgid Neumeister ◽  
Nicholas P. Cianciotto
Keyword(s):  
Fatty Acids ◽  
Legionella Pneumophila ◽  
Lipolytic Activity ◽  
Cholesterol Acyltransferase ◽  
Phospholipase A ◽  
Wild Type ◽  
Gene Encoding ◽  
Acyltransferase Activity ◽  
Lipolytic Enzymes ◽  
Cloned Gene

ABSTRACT We previously showed that Legionella pneumophila secretes, via its type II secretion system, phospholipase A activities that are distinguished by their specificity for certain phospholipids. In this study, we identified and characterized plaA, a gene encoding a phospholipase A that cleaves fatty acids from lysophospholipids. The plaA gene encoded a 309-amino-acid protein (PlaA) which had homology to a group of lipolytic enzymes containing the catalytic signature GDSL. In Escherichia coli, the cloned gene conferred trypsin-resistant hydrolysis of lysophosphatidylcholine and lysophosphatidylglycerol. An L. pneumophila plaA mutant was generated by allelic exchange. Although the mutant grew normally in standard buffered yeast extract broth, its culture supernatants lost greater than 80% of their ability to release fatty acids from lysophosphatidylcholine and lysophosphatidylglycerol, implying that PlaA is the major secreted lysophospholipase A of L. pneumophila. The mutant's reduced lipolytic activity was confirmed by growth on egg yolk agar and thin layer chromatography and was complemented by reintroduction of an intact copy of plaA. Overexpression of plaA completely protected L. pneumophila from the toxic effects of lysophosphatidylcholine, suggesting a role for PlaA in bacterial detoxification of lysophospholipids. The plaA mutant grew like the wild type in U937 cell macrophages and Hartmannella vermiformis amoebae, indicating that PlaA is not essential for intracellular infection of L. pneumophila. In the course of characterizing plaA, we discovered that wild-type legionellae secrete a phospholipid cholesterol acyltransferase activity, highlighting the spectrum of lipolytic enzymes produced by L. pneumophila.

scholarly journals Cloning and Characterization of the Gene Encoding the Major Cell-Associated Phospholipase A of Legionella pneumophila, plaB, Exhibiting Hemolytic Activity

2004 ◽  
Vol 72 (5) ◽  
pp. 2648-2658 ◽  
Author(s):  
Antje Flieger ◽  
Kerstin Rydzewski ◽  
Sangeeta Banerji ◽  
Markus Broich ◽  
Klaus Heuner
Keyword(s):  
Legionella Pneumophila ◽  
Hemolytic Activity ◽  
Genomic Library ◽  
Lipolytic Activity ◽  
Acanthamoeba Castellanii ◽  
Intracellular Survival ◽  
Phospholipase A ◽  
Wild Type ◽  
Gene Encoding ◽  
Human Red Blood Cells

ABSTRACT Legionella pneumophila, the causative agent of Legionnaires' disease, is an intracellular pathogen of amoebae, macrophages, and epithelial cells. The pathology of Legionella infections involves alveolar cell destruction, and several proteins of L. pneumophila are known to contribute to this ability. By screening a genomic library of L. pneumophila, we found an additional L. pneumophila gene, plaB, which coded for a hemolytic activity and contained a lipase consensus motif in its deduced protein sequence. Moreover, Escherichia coli harboring the L. pneumophila plaB gene showed increased activity in releasing fatty acids predominantly from diacylphospho- and lysophospholipids, demonstrating that it encodes a phospholipase A. It has been reported that culture supernatants and cell lysates of L. pneumophila possess phospholipase A activity; however, only the major secreted lysophospholipase A PlaA has been investigated on the molecular level. We therefore generated isogenic L. pneumophila plaB mutants and tested those for hemolysis, lipolytic activities, and intracellular survival in amoebae and macrophages. Compared to wild-type L. pneumophila, the plaB mutant showed reduced hemolysis of human red blood cells and almost completely lost its cell-associated lipolytic activity. We conclude that L. pneumophila plaB is the gene encoding the major cell-associated phospholipase A, possibly contributing to bacterial cytotoxicity due to its hemolytic activity. On the other hand, in view of the fact that the plaB mutant multiplied like the wild type both in U937 macrophages and in Acanthamoeba castellanii amoebae, plaB is not essential for intracellular survival of the pathogen.

Molecular and genetic analysis of the gene encoding the Saccharomyces cerevisiae strand exchange protein Sep1

1991 ◽  
Vol 11 (5) ◽  
pp. 2593-2608 ◽  
Author(s):  
D X Tishkoff ◽  
A W Johnson ◽  
R D Kolodner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Open Reading Frame ◽  
Strand Exchange ◽  
Wild Type ◽  
Homologous Pairing ◽  
Gene Encoding ◽  
Reading Frame ◽  
Cloned Gene ◽  
Diploid Cells ◽  
Exchange Protein

Vegetatively grown Saccharomyces cerevisiae cells contain an activity that promotes a number of homologous pairing reactions. A major portion of this activity is due to strand exchange protein 1 (Sep1), which was originally purified as a 132,000-Mr species (R. Kolodner, D. H. Evans, and P. T. Morrison, Proc. Natl. Acad. Sci. USA 84:5560-5564, 1987). The gene encoding Sep1 was cloned, and analysis of the cloned gene revealed a 4,587-bp open reading frame capable of encoding a 175,000-Mr protein. The protein encoded by this open reading frame was overproduced and purified and had a relative molecular weight of approximately 160,000. The 160,000-Mr protein was at least as active in promoting homologous pairing as the original 132,000-Mr species, which has been shown to be a fragment of the intact 160,000-Mr Sep1 protein. The SEP1 gene mapped to chromosome VII within 20 kbp of RAD54. Three Tn10LUK insertion mutations in the SEP1 gene were characterized. sep1 mutants grew more slowly than wild-type cells, showed a two- to fivefold decrease in the rate of spontaneous mitotic recombination between his4 heteroalleles, and were delayed in their ability to return to growth after UV or gamma irradiation. Sporulation of sep1/sep1 diploids was defective, as indicated by both a 10- to 40-fold reduction in spore formation and reduced spore viability of approximately 50%. The majority of sep1/sep1 diploid cells arrested in meiosis after commitment to recombination but prior to the meiosis I cell division. Return-to-growth experiments showed that sep1/sep1 his4X/his4B diploids exhibited a five- to sixfold greater meiotic induction of His+ recombinants than did isogenic SEP1/SEP1 strains. sep1/sep1 mutants also showed an increased frequency of exchange between HIS4, LEU2, and MAT and a lack of positive interference between these markers compared with wild-type controls. The interaction between sep1, rad50, and spo13 mutations suggested that SEP1 acts in meiosis in a pathway that is parallel to the RAD50 pathway.

scholarly journals Molecular and genetic analysis of the gene encoding the Saccharomyces cerevisiae strand exchange protein Sep1.

1991 ◽  
Vol 11 (5) ◽  
pp. 2593-2608 ◽  
Author(s):  
D X Tishkoff ◽  
A W Johnson ◽  
R D Kolodner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Open Reading Frame ◽  
Strand Exchange ◽  
Wild Type ◽  
Homologous Pairing ◽  
Gene Encoding ◽  
Reading Frame ◽  
Cloned Gene ◽  
Diploid Cells ◽  
Exchange Protein

Vegetatively grown Saccharomyces cerevisiae cells contain an activity that promotes a number of homologous pairing reactions. A major portion of this activity is due to strand exchange protein 1 (Sep1), which was originally purified as a 132,000-Mr species (R. Kolodner, D. H. Evans, and P. T. Morrison, Proc. Natl. Acad. Sci. USA 84:5560-5564, 1987). The gene encoding Sep1 was cloned, and analysis of the cloned gene revealed a 4,587-bp open reading frame capable of encoding a 175,000-Mr protein. The protein encoded by this open reading frame was overproduced and purified and had a relative molecular weight of approximately 160,000. The 160,000-Mr protein was at least as active in promoting homologous pairing as the original 132,000-Mr species, which has been shown to be a fragment of the intact 160,000-Mr Sep1 protein. The SEP1 gene mapped to chromosome VII within 20 kbp of RAD54. Three Tn10LUK insertion mutations in the SEP1 gene were characterized. sep1 mutants grew more slowly than wild-type cells, showed a two- to fivefold decrease in the rate of spontaneous mitotic recombination between his4 heteroalleles, and were delayed in their ability to return to growth after UV or gamma irradiation. Sporulation of sep1/sep1 diploids was defective, as indicated by both a 10- to 40-fold reduction in spore formation and reduced spore viability of approximately 50%. The majority of sep1/sep1 diploid cells arrested in meiosis after commitment to recombination but prior to the meiosis I cell division. Return-to-growth experiments showed that sep1/sep1 his4X/his4B diploids exhibited a five- to sixfold greater meiotic induction of His+ recombinants than did isogenic SEP1/SEP1 strains. sep1/sep1 mutants also showed an increased frequency of exchange between HIS4, LEU2, and MAT and a lack of positive interference between these markers compared with wild-type controls. The interaction between sep1, rad50, and spo13 mutations suggested that SEP1 acts in meiosis in a pathway that is parallel to the RAD50 pathway.

Compared Effect of n-3 and n-6 Dietary Fatty Acids on Rat Intestinal Acyl-CoA: Cholesterol Acyltransferase Activity

1989 ◽  
Vol 24 (5) ◽  
pp. 632-640 ◽  
Author(s):  
M. Chautan ◽  
E. Termine ◽  
N. Amirayan ◽  
J. Leonardi ◽  
A.-M. Pauli ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Cholesterol Acyltransferase ◽  
Dietary Fatty Acids ◽  
Acyltransferase Activity

scholarly journals The Secreted Esterase of Propionibacterium freudenreichii Has a Major Role in Cheese Lipolysis

2013 ◽  
Vol 80 (2) ◽  
pp. 751-756 ◽  
Author(s):  
María Claudia Abeijón Mukdsi ◽  
Hélène Falentin ◽  
Marie-Bernadette Maillard ◽  
Victoria Chuat ◽  
Roxana Beatriz Medina ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Type Strain ◽  
Wild Type Strain ◽  
Lipolytic Activity ◽  
Premature Stop Codon ◽  
Propionibacterium Freudenreichii ◽  
Wild Type ◽  
Swiss Cheese ◽  
Content Type ◽  
Type Strains

ABSTRACTFree fatty acids are important flavor compounds in cheese.Propionibacterium freudenreichiiis the main agent of their release through lipolysis in Swiss cheese. Our aim was to identify the esterase(s) involved in lipolysis byP. freudenreichii. We targeted two previously identified esterases: one secreted esterase, PF#279, and one putative cell wall-anchored esterase, PF#774. To evaluate their role in lipolysis, we constructed overexpression and knockout mutants ofP. freudenreichiiCIRM-BIA1Tfor each corresponding gene. The sequences of both genes were also compared in 21 wild-type strains. All strains were assessed for their lipolytic activity on milk fat. The lipolytic activity observed matched data previously reported in cheese, thus validating the relevance of the method used. The mutants overexpressing PF#279 or PF#774 released four times more fatty acids than the wild-type strain, demonstrating that both enzymes are lipolytic esterases. However, inactivation of thepf279gene induced a 75% reduction in the lipolytic activity compared to that of the wild-type strain, whereas inactivation of thepf774gene did not modify the phenotype. Two of the 21 wild-type strains tested did not display any detectable lipolytic activity. Interestingly, these two strains exhibited the same single-nucleotide deletion at the beginning of thepf279gene sequence, leading to a premature stop codon, whereas they harbored apf774gene highly similar to that of the other strains. Taken together, these results clearly demonstrate that PF#279 is the main lipolytic esterase inP. freudenreichiiand a key agent of Swiss cheese lipolysis.

scholarly journals Secreted Enzymatic Activities of Wild-Type andpilD-Deficient Legionella pneumophila

2000 ◽  
Vol 68 (4) ◽  
pp. 1855-1863 ◽  
Author(s):  
Virginia Aragon ◽  
Sherry Kurtz ◽  
Antje Flieger ◽  
Birgid Neumeister ◽  
Nicholas P. Cianciotto
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Legionella Pneumophila ◽  
Wild Type ◽  
Intracellular Infection ◽  
Type Iv ◽  
Nitrophenyl Phosphate ◽  
Pilus Biogenesis ◽  
Legionnaires Disease

ABSTRACT Legionella pneumophila, the agent of Legionnaires' disease, is an intracellular pathogen of protozoa and macrophages. Previously, we had determined that the Legionella pilD gene is involved in type IV pilus biogenesis, type II protein secretion, intracellular infection, and virulence. Since the loss of pili and a protease do not account for the infection defect exhibited by apilD-deficient strain, we sought to define other secreted proteins absent in the mutant. Based upon the release ofp-nitrophenol (pNP) from p-nitrophenyl phosphate, acid phosphatase activity was detected in wild-type but not in pilD mutant supernatants. Mutant supernatants also did not release either pNP from p-nitrophenyl caprylate and palmitate or free fatty acid from 1-monopalmitoylglycerol, suggesting that they lack a lipase-like activity. However, since wild-type samples failed to release free fatty acids from 1,2-dipalmitoylglycerol or to cleave a triglyceride derivative, this secreted activity should be viewed as an esterase-monoacylglycerol lipase. The mutant supernatants were defective for both release of free fatty acids from phosphatidylcholine and degradation of RNA, indicating that PilD-negative bacteria lack a secreted phospholipase A (PLA) and nuclease. Finally, wild-type but not mutant supernatants liberated pNP from p-nitrophenylphosphorylcholine (pNPPC). Characterization of a new set of mutants defective for pNPPC-hydrolysis indicated that this wild-type activity is due to a novel enzyme, as opposed to a PLC or another known enzyme. Some, but not all, of these mutants were greatly impaired for intracellular infection, suggesting that a second regulator or processor of the pNPPC hydrolase is critical for L. pneumophila virulence.

scholarly journals Characterization of the Major Secreted Zinc Metalloprotease- Dependent Glycerophospholipid:Cholesterol Acyltransferase, PlaC, of Legionella pneumophila

2005 ◽  
Vol 73 (5) ◽  
pp. 2899-2909 ◽  
Author(s):  
Sangeeta Banerji ◽  
Mayte Bewersdorff ◽  
Björn Hermes ◽  
Nicholas P. Cianciotto ◽  
Antje Flieger
Keyword(s):  
Legionella Pneumophila ◽  
Hydrolytic Enzymes ◽  
Acanthamoeba Castellanii ◽  
Severe Pneumonia ◽  
Phospholipase A ◽  
Type Ii Secretion ◽  
Lipolytic Enzyme ◽  
Acyltransferase Activity ◽  
Zinc Metalloprotease ◽  
Bacterial Culture Supernatant

ABSTRACT Legionella pneumophila, an intracellular pathogen causing a severe pneumonia, possesses distinct lipolytic activities which have not been completely assigned to specific enzymes so far. We cloned and characterized a gene, plaC, encoding a protein with high homology to PlaA, the major secreted lysophospholipase A of L. pneumophila and to other hydrolytic enzymes belonging to the GDSL family. Here we show that L. pneumophila plaC mutants possessed reduced phospholipase A and lysophospholipase A activities and lacked glycerophospholipid:cholesterol acyltransferase activity in their culture supernatants. The mutants' reduced phospholipase A and acyltransferase activities were complemented by reintroduction of an intact copy of plaC. Additionally, plaC conferred increased lysophospholipase A and glycerophospholipid:cholesterol acytransferase activities to recombinant Escherichia coli. Furthermore, PlaC was shown to be another candidate exported by the L. pneumophila type II secretion system and was activated by a factor present in the bacterial culture supernatant dependent on the zinc metalloprotease. Finally, the role of plaC in intracellular infection of Acanthamoeba castellanii and U937 macrophages with L. pneumophila was assessed, and plaC was found to be dispensable. Thus, L. pneumophila possesses another secreted lipolytic enzyme, a protein with acyltransferase, phospholipase A, and lysophospholipase A activities. This enzyme is distinguished from the previously characterized phospholipases A and lysophospholipases A by its capacity not only to cleave fatty acids from lipids but to transfer them to cholesterol. Cholesterol is an important compound of eukaryotic membranes, and an acyltransferase might be a tool for host cell modification to fit the needs of the bacterium.

scholarly journals Mycoplasma hyopneumoniae p65 Surface Lipoprotein Is a Lipolytic Enzyme with a Preference for Shorter-Chain Fatty Acids

2004 ◽  
Vol 186 (17) ◽  
pp. 5790-5798 ◽  
Author(s):  
Jono A. Schmidt ◽  
Glenn F. Browning ◽  
Philip F. Markham
Keyword(s):  
Fatty Acids ◽  
Signal Sequence ◽  
Lipolytic Activity ◽  
Mycoplasma Hyopneumoniae ◽  
Lipolytic Enzyme ◽  
Protein Cleavage ◽  
Lipolytic Enzymes ◽  
Hydrolysis Of ◽  
Chain Fatty Acids

ABSTRACT Mycoplasma hyopneumoniae is the most significant bacterial pathogen of the respiratory tract of swine. p65 is an immunodominant surface lipoprotein of M. hyopneumoniae that is specifically recognized during disease. Analysis of the translated amino acid sequence of the gene encoding p65 revealed similarity to the GDSL family of lipolytic enzymes. To examine the lipolytic activity of p65, the gene was cloned and expressed in Escherichia coli after truncation of the prokaryotic lipoprotein signal sequence and mutagenesis of the mycoplasma TGA tryptophan codons. After treatment with thrombin, the recombinant glutathione S-transferase (GST)-p65 protein yielded a 66-kDa fusion protein cleavage product corresponding in size to the mature p65 protein. The esterase activity of recombinant GST-p65 was indicated by the formation of a cleared zone on tributyrin agar plates and the hydrolysis of p-nitrophenyl esters of caproate (pNPC) and p-nitrophenyl esters of palmitate (pNPP). Lipase activity was indicated by the hydrolysis of the artificial triglyceride 1,2-O-dilauryl-rac-glycero-3-glutaric acid resorufin ester. Using pNPC and pNPP as substrates, recombinant GST-p65 had optimal activity between pHs 9.2 and 10.2 and at a temperature higher than 39°C. Calcium ions did not increase the activity of recombinant GST-p65. Rabbit anti-p65 antibodies inhibited the activity of recombinant GST-p65 and also inhibited the growth of M. hyopneumoniae in vitro. Examination of the kinetic parameters of recombinant GST-p65 for the hydrolysis of pNPC and pNPP indicated a preference for the shorter fatty acid chain of pNPC. The physiological and/or pathogenic role of mycoplasma lipolytic enzymes has not been determined, but they are likely to play an important role in mycoplasmas' nutritional requirements for long-chain fatty acids and may reduce the function of lung surfactants in mycoplasma-induced respiratory diseases. This is the first report of the lipolytic activity of a lipid-modified surface immunogen of a mycoplasma.

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