Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase activities releasing fatty acyl moieties from phosphatidylcholine and phosphatidylethanolamine and lysophospholipase activity releasing fatty acid from lyso-phosphatidylcholine were detected in both Mycobacterium microti and Mycobacterium avium. Fatty acyl groups were released from both the 1- and 2-positions of phosphatidylcholine. Generally, phospholipase activities of M. avium were cryptic while phospholipase activities of M. microti were located on the bacterial surface. However, intact M. microti did not release fatty acids from phospholipids faster than M. avium. Neither Mycobacterium secreted acyl-hydrolysing phospholipase activity. All phospholipase activities were stimulated by including phospholipids in growth media: generally, cell extracts contained 6- to 15-fold higher specific activities than extracts from mycobacteria grown in media without added phospholipid. However, not all phospholipase activities were stimulated to the same degree in any given set of conditions, suggesting the existence of more than one phospholipase gene in each Mycobacterium.
 ...
PMID:Control and location of acyl-hydrolysing phospholipase activity in pathogenic mycobacteria. 158 12

Three types of phospholipase activity--phospholipase A1, A2, and lysophospholipase--were detected in Mycobacterium leprae harvested from armadillo tissue at about 25% of the specific activity found in a slowly growing mycobacterium, Mycobacterium microti, which was grown in medium to optimize its phospholipase activity. The highest activity found was lysophospholipase, which released fatty acid from 2-lyso-phosphatidylcholine. Phospholipase activity was detected by using phosphatidylcholine and phosphatidylethanolamine. Differences in relative activities with these three types of substrate distinguished phospholipase activity in M. leprae extracts from armadillo liver extracts. Furthermore, retention of activity in M. leprae after NaOH treatment showed that the activity associated with M. leprae was not host derived. The specific activity of phospholipase was 20 times higher in extracts of M. leprae than in intact M. leprae organisms. Diazotization, a treatment which abolishes activities of surface enzymes exposed to the environment by the formation of covalent azide bonds with exposed amino groups, did not affect M. leprae's phospholipase activity, with one exception: release of arachidonic acid from phosphatidylcholine, which was partially inhibited. Phenolic glycolipid I, the major excreted amphipathic lipid of M. leprae, inhibited phospholipase activity, including release of arachidonic acid, for both M. leprae- and armadillo-derived activity.
 ...
PMID:Phospholipase activity of Mycobacterium leprae harvested from experimentally infected armadillo tissue. 185 94

In the macrophages (M phi) obtained from mouse peritoneal exudates, five kinds of phospholipid-deacylating activities were detected using phosphatidylethanolamine (PE) and phosphatidylcholine (PC) labeled with [1-14C]oleic acid either in 1- or 2- position and 1- [1-14C]oleoyl-lysoPE, as substrates. Two types of phospholipipase A1 with pH optima of 4 to 6 and 8, respectively, and two types of phospholipase A2 activities with pH optima of 4 to 5 and 8, respectively, were identified. A detected lysophospholipase activity exhibited a broad pH optimum between 4 and 8. Both types of the phospholipase A1 and A2 of M phi hydrolyzed PE more than PC. Exogenously added Ca2+ did not increase the enzymatic activities. A comparison was made of three kinds of the M phi-phospholipid deacylating activities at pH8, after challenging the M phi with Mycobacterium lepraemurium, Escherichia coli, zymosan, or latex beads for 17 hours at 37 degrees C. The bacteria used to the phagocytosis were autoclaved. When the M phi were challenged with M. lepraemurium, the phospholipase A1, A2 and lysophospholipase activities were stimulated by about 160%, 150% and 140%, respectively. However, when challenged with E. coli, the phospholipase A1 activity remarkably decreased by about a third, although the phospholipase A2 activity was stimulated by about 150% that is similar to the challenge with M. lepraemurium. An inflammatory substance, zymosan seemed an effective inducer of the phospholipase A2, the enzymatic activity was remarkably stimulated by 260%, when challenged with 200 micrograms of zymosan. The increase in phospholipase A2 activity of the M phi pretreated with the bacteria or zymosan seems to result in an increase in the hydrolysis of arachidonic acid from the M phi-phospholipids to synthesize its inflammatory oxygenated metabolites. The lysophospholipase activity was not stimulated by the substances used to challenge the M phi, except for M. lepraemurium. No significant increase in three kinds of phospholipid-deacylating activities was observed after challenging the M phi with latex beads. It was considered from the above results that the M phi-phospholipid-deacylating activities at pH8 might be affected by sort of the ingested substances.
 ...
PMID:[Phospholipid-deacylating activities of the mouse peritoneal macrophages during phagocytosis]. 248 84

The phospholipid deacylating enzyme was solubilized from the particulate (membrane) fraction of Mycobacterium lepraemurium with Triton X-100 and sodium cholate, and purified 1100-fold to homogeneous state by 5 steps of column chromatography: DE-52, PL-Sepharose (phosphatidylserine-attached sepharose), Mono P, heparin-Agarose and Mono Q column chromatography. The purified enzyme was composed of single polypeptide chain and molecular mass of 37 kDa was estimated for the protein by SDS-PAGE. The isoelectric point was determined about pH 4.6 and the protein was highly resistant to various kinds of proteolytic enzymes. The purified enzyme hydrolyzed both diacyl and monoacyl phospholipids showing that this enzyme was classified to phospholipase B (phospholipase A1/lysophospholipase). This phospholipase B had acidic pH optima and hydrolyzed both neutral phospholipids such as phosphatidylcholine (PC), phosphatidylethanolamine (PE) and acidic phospholipids such as phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylglycerol (PG). Various fatty acids such as 12:0, 14:0, 16:0, 18:0 and 18:1 at sn-1 position, and 18:1, 18:2, 18:3 and 16:0 at sn-2 position were liberated from PC, suggesting no strict specificity toward the fatty acyl groups of phospholipids. From the comparison of degradation patterns of phosphatidylcholine with sn-1-[1-14C]- and sn-2-[1-14C]fatty acids, this enzyme was suggested to hydrolyze sn-1 position of phospholipid first and then sn-2 position, as the phospholipase B of M. phlei. This enzyme also attacked 1-acyl- and 2-acyl-lyso-PC at about same rates. The Km values for 1-acyl-2-oleoyl-PC and 2-oleoyl-lyso-PC were estimated 1.6 and 0.75 mM, respectively.
 ...
PMID:Purification and properties of a membrane-bound phospholipase B from Mycobacterium lepraemurium. 881 50

Lysophospholipids are key intermediates in the metabolism of phospholipids. Cytoplasmic membranes of both eukaryotes and prokaryotes are made of phospholipid bilayers. Phospholipases are activated during phagocytosis. Lysophospholipids generated by phospholipase A2 or A1 degrade cell membranes and can cause cell lysis. An active lysophospholipase, that hydrolyzes lysophospholipids, was detected by the radioisotope technique in Mycobacterium leprae. About two-thirds of the enzyme was particulate and one-third cytoplasmic. Optimum activity was at 37 degrees C, and at pH 6.0. Temperatures above 70 degrees C completely inactivated the enzyme. The compound AACOCF3, a trifluromethylketone analog of arachiodonic acid, inhibited the activity; the inhibition appeared to be of the uncompetetive type. The K(m) of the enzyme was 2.5 x 10(-4)M, suggesting a fairly strong affinity for the substrate. Lysophospholipids have been shown to be microbicidal to invading organisms. Possession of lysophospholipase by M. leprae is apparently one of the methods by which the bacilli overcome the defense mechanisms of the host.
 ...
PMID:Properties of lysophospholipase in Mycobacterium leprae. 891 65

The Rv0183 gene of the Mycobacterium tuberculosis H37Rv strain, which has been implicated as a lysophospholipase, was cloned and expressed in Escherichia coli. The purified Rv0183 protein did not show any activity when lysophospholipid substrates were used, but preferentially hydrolysed monoacylglycerol substrates with a specific activity of 290 units x mg(-1) at 37 degrees C. Rv0183 hydrolyses both long chain di- and triacylglycerols, as determined using the monomolecular film technique, although the turnover was lower than with MAG (monoacyl-glycerol). The enzyme shows an optimum activity at pH values ranging from 7.5 to 9.0 using mono-olein as substrate and is inactivated by serine esterase inhibitors such as E600, PMSF and tetrahydrolipstatin. The catalytic triad is composed of Ser110, Asp226 and His256 residues, as confirmed by the results of site-directed mutagenesis. Rv0183 shows 35% sequence identity with the human and mouse monoglyceride lipases and well below 15% with the other bacterial lipases characterized so far. Homologues of Rv0183 can be identified in other mycobacterial genomes such as Mycobacterium bovis, Mycobacterium smegmatis, and even Mycobacterium leprae, which is known to contain a low number of genes involved in the replication process within the host cells. The results of immunolocalization studies performed with polyclonal antibodies raised against the purified recombinant Rv0183 suggested that the enzyme was present only in the cell wall and culture medium of M. tuberculosis. Our results identify Rv0183 as the first exported lipolytic enzyme to be characterized in M. tuberculosis and suggest that Rv0183 may be involved in the degradation of the host cell lipids.
 ...
PMID:Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids. 1778 50