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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To enable effective use of phoA gene fusions in Legionella pneumophila, we constructed MudphoA, a derivative of the mini-Mu phage Mu dII4041, which is capable of generating gene fusions to the Escherichia coli alkaline phosphatase gene (EC 3.1.3.1). Although an existing fusion-generating transposon, TnphoA, has been a useful tool for studying secreted proteins in other bacteria, this transposon and other Tn5 derivatives transpose inefficiently in Legionella pneumophila, necessitating the construction of a more effective vector for use in this pathogen. Using MudphoA we generated fusions to an E. coli gene encoding a periplasmic protein and to an L. pneumophila gene encoding an outer membrane protein; both sets of fusions resulted in alkaline phosphatase activity. We have begun to use MudphoA to mutate secreted proteins of L. pneumophila specifically, since this subset of bacterial proteins is most likely to be involved in host-bacterial interactions. This modified transposon may be useful for studies of other bacteria that support transposition of Mu, but not Tn5, derivatives.
Mol Microbiol 1992 Jul
PMID:PhoA gene fusions in Legionella pneumophila generated in vivo using a new transposon, MudphoA. 132 25

Legionella pneumophila is an intracellular parasite which is able to survive and multiply in human monocytes and alveolar macrophages. The Mip (macrophage infectivity potentiator) protein has been shown to be an essential virulence factor. A search of translated nucleic acid data bases has shown that the Mip protein from strain Wadsworth possesses regions homologous to those found in the FK506-binding proteins (FKBPs) of several different eukaryotic organisms. FKBPs are able to bind to the immunosuppressant macrolide FK506 and possess peptidyl-prolyl cis/trans isomerase (PPIase) activity. The gene coding for the Mip protein was cloned from the chromosome of L. pneumophila strain Philadelphia I and sequenced. It was synthesized in Escherichia coli K-12 and after purification it exhibited PPIase activity catalysing the slow cis/trans isomerization of prolyl peptide bonds in oligopeptides. Mip is inhibited by FK506 and fully resistant to cyclosporin A, as was also found for the recently characterized FKBP-type PPIases of eukaryotes. However, the N-terminal extension of Mip and/or the substitutions of the variable amino acids in the C-terminal FKBP core leads to variations, when compared with eukaryotic FKBPs, in substrate specificity with the oligopeptide substrates of type Suc-Ala-Xaa-Pro-Phe-4-nitroanilide. Nevertheless, the Legionella Mip factor represents a bacterial gene product which shares some characteristics normally found in eukaryotic proteins. In view of the activity of PPIases in protein-folding reactions, such prokaryotic FKBP analogues may represent a new class of bacterial pathogenicity factors.
Mol Microbiol 1992 May
PMID:Mip protein of Legionella pneumophila exhibits peptidyl-prolyl-cis/trans isomerase (PPlase) activity. 137 19

A 27 kDa Chlamydia trachomatis Mip-like protein with homology of a 175-amino-acid C-terminal fragment to the surface-exposed Legionella pneumophila mip-gene product has previously been described. In this paper the entire chlamydia Mip-like sequence of C. trachomatis serovar L2 (lymphogranuloma venereum (LGV) biovar) is presented. The sequence shows high similarity to the legionella Mip protein and its C-terminal region, like that of the legionella Mip, has high amino acid similarity to eukaryotic and prokaryotic FK506-binding proteins. The chlamydial mip-like gene was detected by polymerase chain reaction (PCR) in other C. trachomatis serovars and by sequencing of the mip-like genes of serovars B and E (trachoma biovar) was shown to be highly conserved within the two major biovars of C. trachomatis. Monoclonal and polyclonal antibodies raised against the recombinant Mip-like protein failed to demonstrate surface-exposed epitopes on infectious elementary bodies or reproductive reticulate body forms either by immunofluorescence or immuno-gold electron microscopy. However, a complement-dependent inhibition of up to 91% of infectivity for cell cultures was observed with antibodies to the N-terminal fragment of the Mip-like protein suggesting that antibody-accessible epitopes are present on infectious EBs.
Mol Microbiol 1992 Sep
PMID:Chlamydia trachomatis Mip-like protein. 140 89

An Escherichia coli K-12 strain deleted for sodA and sodB (manganese and iron superoxide dismutases) was constructed and characterized by Southern blotting, enzyme assays, and physiological analyses. The sod deletion strain was used to clone the iron superoxide dismutase gene of Legionella pneumophila by complementation to paraquat resistance.
Mol Gen Genet 1992 Apr
PMID:Construction of an Escherichia coli K-12 strain deleted for manganese and iron superoxide dismutase genes and its use in cloning the iron superoxide dismutase gene of Legionella pneumophila. 158 12

Methods were developed for the detection of Legionella in environmental water sources, based upon the polymerase chain reaction (PCR) and gene probes. All species of Legionella, including all 15 serogroups of L. pneumophila tested, were detected by PCR amplification of a 104 bp DNA sequence that codes for a region of 5S rRNA followed by radiolabelled oligoprobe hybridization to an internal region of the amplified DNA. Strains of L. pneumophila (all serogroups) were specifically detected based upon amplification of a portion of the coding region of the macrophage infectivity potentiator (mip) gene. Pseudomonas spp. that exhibit antigenic cross-reactivity in serological detection methods did not produce positive signals in the PCR-gene probe method using Southern blot analyses. Single cell, single gene Legionella detection was achieved with the PCR-gene probe methods.
Mol Cell Probes 1990 Jun
PMID:Detection of Legionella with polymerase chain reaction and gene probe methods. 169 56

The pSAM2 element of Streptomyces ambofaciens integrates site-specifically in the genome of different Streptomyces species by recombination between a 58 bp sequence common to the plasmid (attP) and the chromosome (attB). Southern hybridization analysis showed that sequences similar to the pSAM2 attB site were found in other actinomycetes (Mycobacterium, Nocardia, Micromonospora) as well as unrelated bacteria (Bacillus circulans, Escherichia coli, Clostridium botulinum, Bordetella pertussis, and Legionella pneumophila). Hybridizing fragments from B. circulans and Mycobacterium tuberculosis were cloned and sequenced. Comparison of these sequences with the sequence of the integration zone of S. ambofaciens revealed a conserved region of 76 bp which overlapped with the attB site. This conserved sequence was similar to the Salmonella typhimurium and E. coli tRNA(pro1) genes as well as a number of eucaryotic tRNA genes and had a proline-tRNA-like cloverleaf structure. Furthermore, the Streptomyces lividans attB site of the Streptomyces glaucescens element pIJ408 was also found to overlap a potential tRNA gene (tRNA(thr)). We note here that these two putative tRNA genes as well as those which overlap the attB site of the elements SLP1 of Streptomyces coelicolor and pMEA100 of Nocardia mediterranei all contain the site where integrative recombination takes place. These presumptive actinomycete tRNA genes lack the 3' terminal CCA sequence found in most procaryotic tRNA genes.
Mol Gen Genet 1990 Jul
PMID:The chromosomal integration site of the Streptomyces element pSAM2 overlaps a putative tRNA gene conserved among actinomycetes. 170 70

A prominent 19 kDa surface antigen of Legionella pneumophila, cloned in Escherichia coli, was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9 kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA+ gene fusions, gene-rated by TnphoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA+ transposon insertions were also associated with loss of the 19 kDa antigen in immunoassays using a monoclonal antibody (mAb1E9) and the replacement of the 19 kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.
Mol Microbiol 1991 Aug
PMID:Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen. 176 77

A genomic library of Legionella pneumophila, the causative agent of Legionnaires' disease in humans was constructed in Escherichia coli K12 and the recombinant clones were tested for haemolysis and other phenotypic properties. Seven clones were identified which were able to confer haemolysis of human, sheep, and canine erythrocytes but which were unable to mediate proteolytic activities or cytotoxic effects on CHO- or Vero cells. Clones that exhibited this haemolytic property were also able to produce a brown colour and a yellow-green fluorescence activity detected on M9 plates containing tyrosine. The genetic determinant encoding these properties, termed legiolysin (lly) was mapped by Tn1000 mutagenesis and by subcloning experiments. Southern hybridization with an lly-specific gene probe showed that this determinant is part of the genome of L. pneumophila but is not identical to a protease gene of L. pneumophila which also mediates haemolysis. Minicell analysis of lly-specific plasmids exhibited a protein of 39 kDa. Polyclonal antibodies generated against a LacZ-Lly hybrid protein also recognized a 39 kDa protein produced either by the recombinant legiolysin-positive E. coli K12 clones or by L. pneumophila wild-type strains.
Mol Microbiol 1991 May
PMID:Characterization of legiolysin (lly), responsible for haemolytic activity, colour production and fluorescence of Legionella pneumophila. 195 91

A 27kDa Chlamydia trachomatis L2 protein was characterized by the use of monoclonal antibodies and by two-dimensional gel electrophoresis. The protein was shown to be located in the membrane of reticulate bodies as well as elementary bodies. Its synthesis could be detected from 10 hours post-infection. Cloning and sequence analysis of the distal part of the gene revealed an open reading frame of 175 amino acids. Comparison of the deduced amino acid sequence with the NBRF data base revealed significant homology between the 27 kDa chlamydial membrane protein and the product of the macrophage infectivity potentiator (mip) gene of Legionella pneumophila.
Mol Microbiol 1991 Jan
PMID:Chlamydia trachomatis contains a protein similar to the Legionella pneumophila mip gene product. 201 97

Detection of pathogens (Legionella species) and indicator bacteria (coliform bacteria) was achieved by multiplex (simultaneous) PCR amplification of diagnostic gene sequences and by hybridization to immobilized poly-dT-tailed capture probes using a dot- or slot-blot approach. Complex manipulations of primer concentrations and staggered additions of primers were required in order to achieve equal amplification of multiple genes. Multiplex PCR amplification of two different Legionella genes, one specific for L. pneumophila (mip) and the other for the genus Legionella (5S rRNA), was achieved by staggered amplification. Multiplex PCR amplification using differing amounts of primers specific for lacZ and lamB genes permitted the detection of coliform bacteria and those associated with human faecal contamination, including the indicator bacterial species E. coli and enteric pathogens Salmonella and Shigella. Hybridization of biotin-labelled amplified DNA, in which the biotin was incorporated during PCR amplification from biotinylated-dUTP, to immobilized 400-dT-tailed capture probes permitted specific and sensitive detection of target gene sequences. The sensitivity of colorimetric detection achieved by PCR amplification of target DNA was at a level equivalent to 1-2 bacterial cells, which is the same level of sensitivity obtained with radioactive detection. The simultaneous amplification of several genes and hybridization to immobilized capture probes with colorimetric detection is an effective, efficient and rapid detection method for various human bacterial pathogens.
Mol Cell Probes 1990 Oct
PMID:Multiplex PCR amplification and immobilized capture probes for detection of bacterial pathogens and indicators in water. 228 Jul 81


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