Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treponema pallidum is a pathogenic spirochete that has no known genetic exchange mechanisms. In order to identify treponemal genes encoding surface and secreted proteins, we carried out TnphoA mutagenesis of a T. pallidum genomic DNA library in Escherichia coli. Several of the resulting clones expressed enzymatically active T. pallidum-alkaline phosphatase fusion proteins. The DNA sequence of the 5' portion of a number of the treponemal genes was obtained and analyzed. A recombinant clone harboring plasmid p4A2 that encoded a treponemal protein with an approximate molecular mass of 50,000 Da was identified. Plasmid p4A2 contained an open reading frame of 1,251 nucleotides that resulted in a predicted protein of 417 amino acids with a calculated molecular mass of 47,582 Da. We have named this gene tpn50 in accordance with the current nomenclature for T. pallidum genes. A 1.9-kb HincII-ClaI fragment from p4A2 that contained the tpn50 gene was subcloned to produce p4A2HC2. Comparison of the predicted amino acid sequence of TpN50 with protein sequences in the National Center for Biotechnology Information data base indicated statistically significant homology to the Pseudomonas sp. OprF, E. coli OmpA, Bordetella avium OmpA, Neisseria meningitidis RmpM, Neisseria gonorrhoeae PIII, Haemophilus influenzae P6, E. coli PAL, and Legionella pneumophila PAL proteins. These proteins are all members of a family of outer membrane proteins that are present in gram-negative bacteria. The tpn50 gene complemented E. coli ompA mutations on the basis of two separate criteria. First, morphometry and electron microscopy data showed that E. coli C386 (ompA lpp) cells harboring plasmid vector pEBH21 were rounded while cells of the same strain harboring p4A2HC2 (TpN50+), pWW2200 (OprF+), or pRD87 (OmpA+) were rod shaped. Second, E. coli BRE51 (MC4100 delta sulA-ompA) cells harboring pEBH21 grew poorly at 42 degrees C in minimal medium, while the growth of BRE51 cells harboring p4A2HC2 was similar to that of the parental MC4100 cells. These results demonstrate that the TpN50 protein is functionally equivalent to the E. coli OmpA protein. If TpN50 functions in a similar fashion in T. pallidum, then it may be localized to the treponemal outer membrane.
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PMID:Identification and characterization of the Treponema pallidum tpn50 gene, an ompA homolog. 811 35

Legionella pneumophila is an intracellular parasite of protozoa and human phagocytes. To examine adaptation of this bacterium to parasitize protozoa, the sequence of events of the intracellular infection of the amoeba Hartmannella vermiformis was examined. The previously described uptake phenomenon of coiling phagocytosis by human monocytes was not detected. A 1 h postinfection with wild-type strain AA100, mitochondria were observed within the vicinity of the phagosome. At 2.5 h postinfection, numerous vesicles surrounded the phagosomes and mitochondria were in close proximity to the phagosome. At 5 h postinfection, the bacterium was surrounded by a ribosome-studded multilayer membrane. Bacterial multiplication was evident by 8 h postinfection, and the phagosome was surrounded by a ribosome-studded multilayer membrane until 15 h postinfection. The recruitment of organelles and formation of the ribosome-studded phagosome was defective in an isogenic attenuated mutant of L. pneumophila (strain AA101A) that failed to replicate within amoebae. At 20 h postinfection with wild-type strain AA100, numerous bacteria were present in the phagosome and ribosome were not detected around the phagosome. These data showed that, at the ultrastructural level, the intracellular infection of protozoa by L. pneumophila is highly similar to that of infection of macrophages. Immunocytochemical studies provided evidence that at 5 h postinfection the phagosome containing L. pneumophila acquired an abundant amount of the endoplasmic reticulum-specific protein (BiP). Similar to phagosomes containing heat-killed wild-type L. pneumophila, the BiP protein was not detectable in phagosomes containing the mutant strain AA101A. In addition to the absence of ribosomes and mitochondria, the BiP protein was not detected in the phagosomes at 20 h postinfection with wild-type L. pneumophila. The data indicated that the ability of L. pneumophila to establish the intracellular infection of amoebae is dependent on its capacity to reside and multiply within a phagosome surrounded by the rough endoplasmic reticulum. This compartment may constitute a rich source of nutrients for the bacteria and is probably recognized as cellular compartment. The remarkable similarity of the intracellular infections of macrophages and protozoa by L. pneumophila strongly supports the hypothesis that adaptation of the bacterium to the intracellular environment of protozoa may be the mechanism for its ability to adapt to the intracellular environment of human alveolar macrophages and causes pneumonia.
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PMID:The phagosome containing Legionella pneumophila within the protozoan Hartmannella vermiformis is surrounded by the rough endoplasmic reticulum. 878

Licochalcone A, extracted and purified from Chinese licorice roots, showed in vitro inhibitory effect on human pathogenic Mycobacteria species and Legionella species. M. tuberculosis, M. bovis and BCG were inhibited by < 20 mg/l licochalcone A, whereas all non- M. tuberculosis complex species were resistant to > 20 mg/l Legionella pneumophila (serogroups 1 - 7) and L. bozemanii, L. dumoffii, L. feelei, L. longbeacheae and L. wadsworthii were inhibited by licochalcone A 1 - 4 mg/l, whereas L. gormanii and L. micdadei were inhibited by licochalcone A 500 - 1000 mg/l. These data indicate that licochalcone A might be of interest as a new class of antibacterial drug in the treatment of severe lung-infections.
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PMID:In vitro antimycobacterial and antilegionella activity of licochalcone A from Chinese licorice roots. 1205 17

Lipid A of Rhizobium leguminosarum, a nitrogen-fixing plant endosymbiont, displays several significant structural differences when compared with Escherichia coli. An especially striking feature of R. leguminosarum lipid A is that it lacks both the 1- and 4'-phosphate groups. Distinct lipid A phosphatases that attack either the 1 or the 4' positions have previously been identified in extracts of R. leguminosarum and Rhizobium etli but not Sinorhizobium meliloti or E. coli. Here we describe the identification of a hybrid cosmid (pMJK-1) containing a 25-kb R. leguminosarum 3841 DNA insert that directs the overexpression of the lipid A 1-phosphatase. Transfer of pMJK-1 into S. meliloti 1021 results in heterologous expression of 1-phosphatase activity, which is normally absent in extracts of strain 1021, and confers resistance to polymyxin. Sequencing of a 7-kb DNA fragment derived from the insert of pMJK-1 revealed the presence of a lipid phosphatase ortholog (designated LpxE). Expression of lpxE in E. coli behind the T7lac promoter results in the appearance of robust 1-phosphatase activity, which is normally absent in E. coli membranes. Matrix-assisted laser-desorption/time of flight and radiochemical analysis of the product generated in vitro from the model substrate lipid IVA confirms the selective removal of the 1-phosphate group. These findings show that lpxE is the structural gene for the 1-phosphatase. The availability of lpxE may facilitate the re-engineering of lipid A structures in diverse Gram-negative bacteria and allow assessment of the role of the 1-phosphatase in R. leguminosarum symbiosis with plants. Possible orthologs of LpxE are present in some intracellular human pathogens, including Francisella tularensis, Brucella melitensis, and Legionella pneumophila.
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PMID:Expression cloning and biochemical characterization of a Rhizobium leguminosarum lipid A 1-phosphatase. 1286 41

Francisella tularensis is a highly infectious bacterial pathogen that is considered by the Centers for Disease Control and Prevention to be a potential bioterrorism weapon. Here, the crystallization of a 37.2 kDa phosphatase encoded by the genome of F. tularensis subsp. holarctica live vaccine strain is reported. This enzyme shares 41% amino-acid sequence identity with Legionella pneumophila major acid phosphatase and contains the RHGXRXP motif that is characteristic of the histidine acid phosphatase family. Large diffraction-quality crystals were grown in the presence of Tacsimate, HEPES and PEG 3350. The crystals belong to space group P4(1)2(1)2, with unit-cell parameters a = 61.96, c = 210.78 A. The asymmetric unit is predicted to contain one protein molecule, with a solvent content of 53%. A 1.75 A resolution native data set was recorded at beamline 4.2.2 of the Lawrence Berkeley National Laboratory Advanced Light Source. Molecular-replacement trials using the human prostatic acid phosphatase structure as the search model (28% amino-acid sequence identity) did not produce a satisfactory solution. Therefore, the structure of F. tularensis histidine acid phosphatase will be determined by multiwavelength anomalous dispersion phasing using a selenomethionyl derivative.
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PMID:Crystallization of a newly discovered histidine acid phosphatase from Francisella tularensis. 1651 Dec 56

A 1-month-old girl developed respiratory failure due to bilateral interstitial pneumonia after bathing in reheated and reused water. A molecular test for sputum and an environmental culture detected Legionella pneumophila serotype 1. This is the first report of infantile legionellosis contracted from a bathtub at home.
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PMID:Case of Infantile Legionella Pneumonia After Bathing in Reheated and Reused Water. 2885 16