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)

The major outer membrane protein of Legionella pneumophila is composed of 28- and 31-kDa subunits cross-linked by interchain disulfide bonds. The oligomer is covalently anchored to the underlying peptidoglycan via the 31-kDa subunit. We have cloned the structural gene ompS encoding both proteins. Oligonucleotide probes synthesized from the codons of the N-terminal amino acid sequence of purified 28- and 31-kDa subunits were used to identify cloned sequences. A 2.9-kb HindIII fragment cloned into pBluescript (clone H151) contained the ompS gene. Nucleotide sequence analysis revealed an open reading frame of 891 bp encoding a polypeptide of 297 amino acids. A leader sequence of 21 amino acids was identified, and the mature protein contained 276 amino acids. The deduced amino acid sequence of OmpS matched the experimentally determined amino acid sequence (32 amino acids), with the exception of two cysteine residues. The deduced amino acid sequence was rich in glycine and aromatic amino acids and contained four cysteine residues, two in the amino terminus and two in the carboxy region. Primer extension analysis (total RNA from L. pneumophila) identified the transcription start at 96 to 98 bp upstream of the translation start, but no Escherichia coli-like promoter sequences were evident. While an mRNA transcript from clone H151 was detected, no cross-reactive protein was detected by immunoblotting with either monoclonal or polyclonal antibody. Attempts to subclone the gene in the absence of the putative promoter region (i.e., under the control of the lac promoter) proved unsuccessful, possibly because of overproduction lethality in E. coli. The ompS DNA sequence was highly conserved among the serogroups of L. pneumophila, and related species also exhibited homology in Southern blot analysis at a moderately high stringency. Evidence is presented to suggest that this gene may be environmentally regulated in L. pneumophila.
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PMID:Cloning and nucleotide sequence of a gene (ompS) encoding the major outer membrane protein of Legionella pneumophila. 173 23

Investigations were undertaken to improve detection and isolation of Legionella spp. from samples containing a large number of non-legionellae isolates. The direct fluorescent antibody staining technique was used in conjunction with a sequential culturing method which was developed to improve the recovery rate of Legionella spp. from such samples. The technique for enrichment and isolation of Legionella spp. from environmental samples includes storage at 4 degrees C and repeated culture on freshly prepared media. Heat and acid treatments were included when deemed appropriate. A DNA probe was used for confirmation of Legionella. Treatment of the water samples, as described, and co-cultivation with amoebae naturally present in the samples are concluded to be responsible for increased success in recovery of Legionella isolates.
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PMID:Sequential culturing method improves recovery of Legionella spp. from contaminated environmental samples. 174 11

Whole cell DNA of Legionella pneumophila isolates was examined by small-fragment restriction endonuclease analysis (SF-REA). Fourteen serogroup 1 isolates from tap water in one hospital collected before and after eradication measures had been taken were compared with control strains of serogroup 1 and other serogroups that were not epidemiologically linked. DNA was digested with EcoRI and electrophoresed on polyacrylamide gels. The gel patterns were made visible by silver staining and analysed by direct visual comparison. All 15 epidemiologically unrelated strains of Legionella pneumophila serogroup 1 and of other serogroups exhibited different restriction fragment patterns. The isolates from the hospital could be clearly subdivided into two groups by SF-REA, suggesting that the hot water supply of the hospital was contaminated with two different strains. SF-REA performed on Legionella pneumophila serogroup 1 DNA enabled further subtyping of these organisms and thus appears to be a useful technique for investigating their epidemiology.
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PMID:Subtyping of Legionella pneumophila serogroup 1 isolates by small-fragment restriction endonuclease analysis. 174 16

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.
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PMID:Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen. 176 77

DNA coding for the 16S rRNA of an intracellular bacterium was directly amplified from lysed cells of a host amoebae using the polymerase chain reaction and primers specific for eubacteria. The amoebae had been used to recover an uncultured bacterium observed in the sputum of a patient with pneumonia. The amplified DNA was sequenced directly and compared with published 16S rRNA sequences. The analysis revealed that the intracellular bacterium is a member of the genus Legionella and that it is different from species, including L. pneumophila, for which 16S ribosomal RNA sequence data are available.
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PMID:Direct amplification and sequencing of the 16S ribosomal DNA of an intracellular Legionella species recovered by amoebal enrichment from the sputum of a patient with pneumonia. 177 31

Over a period of 3 years, Legionella pneumophila serogroup 6 strains were isolated from warm water outlets and dental units in the Dental Faculty and from the Surgery and Internal Medicine Clinics at the University of Dresden, Dresden, Germany. In the bacteriological unit of the above-mentioned facility, L. pneumophila serogroups 3 and 12 were grown from warm water specimens. The medical facilities are located in separate buildings connected with a ring pipe warm water system. All L. pneumophila serogroup 6 strains isolated from the warm water supply reacted with a serogroup-specific monoclonal antibody, but not with two other monoclonal antibodies which are subgroup specific, reacting with other serogroup 6 strains. The NotI genomic profiles obtained by pulsed-field gel electrophoresis of 25 serogroup 6 strains isolated from the Dental Faculty over a 3-year period, 1 isolate from the Internal Medicine Clinic, and 4 strains from the Surgery Clinic were identical. Furthermore, all these strains hybridized with a 300-kb NotI fragment when a legiolysin (lly)-specific DNA probe was used. The NotI pattern, however, differed from those of six serogroup 6 strains of other origins, one serogroup 12 strain from the bacteriological unit, and another six unrelated strains of serogroups other than serogroup 6. L. pneumophila serogroup 6 strains which can be divided into only two subgroups by the use of monoclonal antibodies are differentiated in at least six NotI cleavage types obtained by pulsed-field electrophoresis.
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PMID:Analysis of Legionella pneumophila serogroup 6 strains isolated from a hospital warm water supply over a three-year period by using genomic long-range mapping techniques and monoclonal antibodies. 178 83

The genus Legionella consists of 51 serogroups comprising 34 species. Biochemical reactions and cell wall fatty acid and quinone analyses may confirm that an isolate is a Legionella sp. and indicate to which species it belongs, but DNA hybridization studies have been necessary for a definitive identification. Recently, the commercially available BIOLOG identification system has offered a standardized, easily reproducible system of substrate metabolism by bacteria resuspended in multiwell plates. A tetrazolium dye acts as an electron acceptor during the oxidation of the wide range of substrates and forms an irreversible, highly colored formazan when reduced. The 95 substrate wells are read rapidly with a conventional plate reader, and the results are downloaded for comparison with a computer data base, allowing quick identification. The BIOLOG system's ability to test more diverse classes of substrates, including amino acids, peptides, carboxylic acids, and carbohydrates, was used in this study to establish a new data base and identify the asaccharolytic Legionella spp. In particular, Legionella pneumophila behaved as a microaerophile, and the fastest, most diverse metabolic activities occurred after the development of a low-oxygen incubation environment. Alternatively, bacteria could be successfully incubated in air when their concentration was double that recommended by the manufacturer. Similar results were obtained by using either Page's amoebal saline or distilled water as the resuspending and incubation medium. Type strains did not cross-identify with any of the strains already in the manufacturer's data base. The results indicate that this modified system has value in being able to identify Legionella isolates to the species level.
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PMID:Development of the BIOLOG substrate utilization system for identification of Legionella spp. 178 92

The protein PpIA (19 kD) cloned from a genomic library of Legionella pneumophila, Philadelphia 1, represents a peptido-glycan associated outer membrane protein in recombinant E. coli K-12 and L. pneumophila. It exhibits distinct sequence homology to lipoproteins of Haemophilus influenzae and E. coli. A ppIA specific DNA probe generated by PCR was used in Southern hybridizations of chromosomal DNA of Legionella strains and other Gram-negative pathogens. Under conditions of high stringency, hybridization could only be observed in L. pneumophila isolates, but all other Legionella strains tested displayed hybridization under lower stringency. No signals appeared after hybridization of chromosomal DNA from a variety of other bacteria. Using anti-PpIA monospecific polyclonal antibodies in Western blots, it was demonstrated that PpIA related proteins of nearly the same size are found in all L. pneumophila isolates and in a variety of, but not all, the Legionella species analysed here.
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PMID:Phenotype versus genotype of the 19 kD peptido-glycan associated protein of Legionella (PpIA), among Legionellae and other gram-negative bacteria. 181 89

After the demonstration of analogs of the Legionella pneumophila macrophage infectivity potentiator (Mip) protein in other Legionella species, the Legionella micdadei mip gene was cloned and expressed in Escherichia coli. DNA sequence analysis of the L. micdadei mip gene contained in the plasmid pBA6004 revealed a high degree of homology (71%) to the L. pneumophila mip gene, with the predicted secondary structures of the two Mip proteins following the same pattern. Southern hybridization experiments, with the plasmid pBA6004 as the probe, suggested that the mip gene of L. micdadei has extensive homology with the mip-like genes of several Legionella species. Furthermore, amino acid sequence comparisons revealed significant homology to two eukaryotic proteins with isomerase activity (FK506-binding proteins).
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PMID:Nucleotide sequence analysis of the Legionella micdadei mip gene, encoding a 30-kilodalton analog of the Legionella pneumophila Mip protein. 184 May 77

A genomic library of Legionella pneumophila, the causative agent of Legionnaires disease in humans, was constructed in Escherichia coli K-12, and the recombinant clones were screened by immuno-colony blots with an antiserum raised against heat-killed L. pneumophila. Twenty-three clones coding for a Legionella-specific protein of 19 kDa were isolated. The 19-kDa protein, which represents an outer membrane protein, was found to be associated with the peptidoglycan layer both in L. pneumophila and in the recombinant E. coli clones. This was shown by electrophoresis and Western immunoblot analysis of bacterial cell membrane fractions with a monospecific polyclonal 19-kDa protein-specific antiserum. The protein was termed peptidoglycan-associated protein of L. pneumophila (Ppl). The corresponding genetic determinant, ppl, was subcloned on a 1.8-kb ClaI fragment. DNA sequence studies revealed that two open reading frames, pplA and pplB, coding for putative proteins of 18.9 and 16.8 kDa, respectively, were located on the ClaI fragment. Exonuclease III digestion studies confirmed that pplA is the gene coding for the peptidoglycan-associated 19-kDa protein of L. pneumophila. The amino acid sequence of PplA exhibits a high degree of homology to the sequences of the Pal lipoproteins of E. coli K-12 and Haemophilus influenzae.
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PMID:Cloning, genetic analysis, and nucleotide sequence of a determinant coding for a 19-kilodalton peptidoglycan-associated protein (Ppl) of Legionella pneumophila. 185 72


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