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)

FK-506-binding proteins (FKBPs), which in T cells are supposed to mediate the immunosuppressive effects of the compounds FK-506 and rapamycin, have been isolated from Streptomyces chrysomallus, S. hygroscopicus subsp. ascomyceticus, and S. hygroscopicus. The latter two strains are producers of ascomycin (the ethyl analog of FK-506) and rapamycin, respectively. Like the 12-kDa FKBP in eukaryotic organisms such as humans, bovines, and Saccharomyces cerevisiae, or the FKBPs from gram-positive streptomycetes are peptidyl-prolyl-cis-trans isomerases. Inhibition studies using FK-506, rapamycin, or ascomycin, revealed inhibition of the peptidyl-prolyl cis-trans isomerase activity of the proteins at the nanomolar level, which is in the same range as with eukaryotic FKBPs. The M(r)s of the various FKBPs were 13,500 to 15,000, and they had the same pI of approximately 4.5. The N-terminal sequences of the three FKBPs were nearly identical in the first 20 amino acids. The amino acid sequence deduced from the gene sequence of S. chrysomallus gave a polypeptide of 124 amino acids. The homologies to FKBPs from humans, S. cerevisiae, and Neurospora crassa were 38, 39, and 50% identity in relevant positions, respectively. Significant homology of 38% was also seen with the C-terminal halves of bacterial protein surface antigens like the Mip protein of Legionella pneumophila and the 27-kDa Mip-like protein of Chlamydia trachomatis. In addition, two more open reading frames in Pseudomonas aeruginosa and Neisseria meningitidis of unknown function show regions of homology to the S. chrysomallus FKBP. In contrast to fungi, streptomycetes are resistant to macrolactones. Ascomycin-producing S. hygroscopicus subsp. ascomyceticus excretes the compound almost quantitatively into medium, which indicates that the organism has an efficient self-protection mechanism against its own secondary metabolite.
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PMID:FK-506-binding proteins from streptomycetes producing immunosuppressive macrolactones of the FK-506 type. 138 10

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

The immune response to individual major antigens of Legionella bozemanii was studied in 67 sera from 26 inpatients with febrile disease using immunoblotting techniques. All the patients had fever of unknown origin and showed strong serological reactions to L bozemanii that cross-reacted with Rickettsia typhi, as determined by a standard indirect microimmunofluorescence assay. Sera analysed by western blotting reacted with 12-14 molecular components of L bozemanii with apparent molecular weights ranging from 14,000 to 94,000 daltons. These reactions compared well with a reference system using antisera of rabbits immunised with the same strain of Legionella. The three major cross-reactive components of R typhi were polypeptide antigens of 94,000, 67,000 and 43,000 daltons. It is concluded that western blotting can help in the differential diagnosis of patients with fever of unknown origin whose sera cross-react to L bozemanii and R typhi.
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PMID:Western blot analysis of immune response to Legionella bozemanii antigens. 175 85

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

The prt1 gene encoding extracellular protease from Erwinia carotovora subsp. carotovora EC14 in cosmid pCA7 was subcloned to create plasmid pSK1. The partial nucleotide sequence of the insert in pSK1 (1,878 bp) revealed a 1,041-bp open reading frame (ORF1) that correlated with protease activity in deletion mutants. ORF1 encodes a polypeptide of 347 amino acids with a calculated molecular mass of 38,826 Da. Escherichia coli transformed with pSK1 or pSK23, a subclone of pSK1, produces a protease (Prt1) intracellularly with a molecular mass of 38 kDa and a pI of 4.8. Prt1 activity was inhibited by phenanthroline, suggesting that it is a metalloprotease. The prt1 promoter was localized between 173 and 1,173 bp upstream of ORF1 by constructing transcriptional lacZ fusions. Primer extension identified the prt1 transcription start site 205 bp upstream of ORF1. The deduced amino acid sequence of ORF1 showed significant sequence identity to metalloproteases from Bacillus thermoproteolyticus (thermolysin), B. subtilis (neutral protease), Legionella pneumophila (metalloprotease), and Pseudomonas aeruginosa (elastase). It has less sequence similarity to metalloproteases from Serratia marcescens and Erwinia chrysanthemi. Locations for three zinc ligands and the active site for E. carotovora subsp. carotovora protease were predicted from thermolysin.
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PMID:Erwinia carotovora subsp. carotovora extracellular protease: characterization and nucleotide sequence of the gene. 191 78

Prochymosin can be converted into chymosin by an action of external proteinases. Thus, thermolysin at pH 5.05 converts calf prochymosin into active Phe-chymosin, which is one amino acid longer than chymosin from the N-terminus with a yield of 73%. Even better results were achieved with prochymosin activation by Legionella pneumophila metalloproteinase. Apparently the stretch of prochymosin polypeptide chain adjacent to the normally observed activation point becomes available for an attack by an external proteinase at pH 5.0-6.0. These data indicate that the intermolecular activation pathway might be of physiological importance.
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PMID:Prochymosin activation by non-aspartic proteinases. 210 38

The sequence of the structural gene encoding the Legionella pneumophila extracellular zinc metalloprotease has been determined and was found to possess a single large open reading frame (ORF) of 1,629 nucleotides (nt). This ORF was preceded by consensus promoter (TTAACT . . . 17 nt . . . TATAAC) and ribosome-binding (TAAGGAG) sequences. The deduced polypeptide contained a putative signal sequence and a total of 543 amino acid residues with a computed molecular size of 60,775 daltons, substantially larger than the observed 38,000 daltons of the native and recombinant proteins. A homology search revealed extensive amino acid identity with Pseudomonas aeruginosa elastase, a protein that is also encoded by an ORF substantially larger than that predicted for the mature size of the protein. The structural identity between the L. pneumophila protease and P. aeruginosa elastase was most pronounced in the regions forming the enzymatic active site of elastase. Amino acid residues constituting the active-site cleft of elastase were greater than 75% conserved. Elastase residues that interact with and mediate proteolysis of substrate peptides were 100% conserved. Competitive inhibitors of elastase and the structurally and functionally related thermolysin (phosphoramidon and a phosphoramidate analog, Z-GlyP(O)Leu-Ala), were shown to be equally potent at inhibiting the proteolytic activity of the L. pneumophila protease. These inhibitor studies along with the amino acid sequence similarities provide strong evidence that the L. pneumophila protease and P. aeruginosa elastase share a similar molecular mechanism of proteolysis.
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PMID:Legionella pneumophila zinc metalloprotease is structurally and functionally homologous to Pseudomonas aeruginosa elastase. 211 Jan 46

All Legionella species express a 60-kilodalton (kDa) protein which contains a genus-specific epitope recognized by murine monoclonal antibody GW2X4B8B2H6. A genomic cosmid library of Legionella pneumophila chromosomal DNA was constructed in pHC79 and screened for 60-kDa antigen-expressing clones with the monoclonal antibody. A 3.2-kilobase EcoRI fragment from cosmid 14B11 expressing a 60-kDa protein was subcloned into pUC19 (pSH16), and deletion of a 1.2-kilobase HindIII fragment (pSH16A) generated a 33-kDa truncated polypeptide no longer reactive with the monoclonal antibody. Southern blot analysis of chromosomal DNA from selected Legionella species restricted with EcoRI and probed with the 1.2-kilobase fragment coding for the carboxyl region of the protein revealed DNA homology which was not observed with DNA from Escherichia coli. Maxicell analysis of pSH16 identified a second polypeptide of approximately 15 kDa expressed from a gene (htpA) upstream of the gene coding the 60-kDa protein (htpB). Both proteins were preferentially synthesized by L. pneumophila following heat shock (temperature shift from 25 to 42 degrees C), and under steady-state growth conditions the relative level of 60-kDa protein was unaffected by temperature. In E. coli, expression of a 60-kDa protein from pSH16 also increased following heat shock (25 to 42 degrees C), but under steady-state conditions expression was temperature dependent. Temperature-dependent expression from pSH16 was not observed in an rpoH (htpR) mutant strain of E. coli. The Legionella 60-kDa protein appears to be a heat shock protein which shares cross-reactive epitopes with the GroEL homolog of E. coli. In addition, a region of htpB encoding the 27-kDa carboxyl portion of the protein containing the monoclonal antibody-reactive epitope also contains DNA sequences unique to and conserved within the genus.
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PMID:Cloning and temperature-dependent expression in Escherichia coli of a Legionella pneumophila gene coding for a genus-common 60-kilodalton antigen. 256 81

In a previous study, a 24-kilodalton (kDa) protein surface antigen of Legionella pneumophila was cloned into Escherichia coli and found to be expressed on the host cell surface. Subsequently, a site-directed mutation in this gene (designated mip) in L. pneumophila was found to impair the capacity of this bacterium to initiate intracellular infection in human macrophages. The work presented here indicates that the antigenic gene product is distinct from the 24- to 29-kDa major outer membrane protein of L. pneumophila. In addition, the antigen was identified as a highly basic protein on two-dimensional nonequilibrium polyacrylamide gels and on two-dimensional monoclonal antibody immunoblots. When the DNA fragment encoding this protein was sequenced, a long open reading frame of 699 base pairs was identified within a region to which antigen expression was previously mapped. mip mRNA isolated from both L. pneumophila and transformed E. coli had the same 5' end, as determined by primer extension analysis, indicating that the same promoter sequences are used in both species. A likely factor-independent transcriptional terminator was found 20 residues downstream of the stop codon, suggesting that mip is encoded on a monocistronic message. The inferred polypeptide began with a possible 20- to 24-residue signal sequence, and, as predicted by two-dimensional electrophoresis, had a molecular weight of 24,868 and was a potent polycation with an estimated pI of 9.8.
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PMID:DNA sequence of mip, a Legionella pneumophila gene associated with macrophage infectivity. 292 52

An immunoblot (Western) assay was developed employing a species-specific monoclonal antibody to a 43 kDa Mycoplasma pneumoniae membrane polypeptide and a species-specific monoclonal antibody to 29 kDa Legionella pneumophila outer membrane protein. This assay could simultaneously detect these two different antigens directly in sputum. The 43 kDa M. pneumoniae antigen was detected by this assay in each of three M. pneumoniae culture-confirmed sputum specimens. In addition, the 29 kDa L. pneumophila antigen was detected in three of three L. pneumophila culture-confirmed sputum specimens. Neither of these two specific antigens were detected in induced sputum specimens from ten normal individuals.
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PMID:The simultaneous direct detection of Mycoplasma pneumoniae and Legionella pneumophila antigens in sputum specimens by a monoclonal antibody immunoblot assay. 311 90


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