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)

A 67-year-old female was admitted to our hospital, because of high fever and dry cough. She had undergone semiradical hysterectomy and radiation therapy for carcinoma of the uterine cervix one year previously. Her chest roentgenograms on admission showed lobar consolidation of the left upper lobe. Antibiotics were administered but her general condition and pulmonary consolidation did not improve. As Legionellosis was highly suspected, we performed bronchoscopic examinations. Bronchial mucosa was almost normal with no secretion, and Legionella was isolated from the specimen obtained bronchoscopically. Six days later, L. pneumophila serogroup 2 was isolated and identified from an intratracheal aspiration, and serological diagnosis was made by indirect immunofluorescence antibody. We could also detect the bacteria in the BALF by immunofluorescence microscopy and in the tissue of the TBLB specimen with the ABC method.
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PMID:[Second serogroup of Legionella pneumophila isolated from a patient with fulminant pneumonia]. 221 93

Legionella pneumophila is a bacterial parasite of freshwater amoebae which also grows in alveolar macrophages and thus causes the potentially fatal pneumonia Legionnaires' disease. Intracellular growth within amoebae and macrophages is mechanistically similar and requires the Icm/Dot type IV secretion system. This paper reports the development of an assay, the amoebae plate test (APT), to analyse growth of L. pneumophila wild-type and icm/dot mutant strains spotted on agar plates in the presence of Acanthamoeba castellanii. In the APT, wild-type L. pneumophila formed robust colonies even at high dilutions, icmT, -R, -P or dotB mutants failed to grow, and icmS or -G mutants were partially growth defective. The icmS or icmG mutant strains were used to screen an L. pneumophila chromosomal library for genes that suppress the growth defect in the presence of the amoebae. An icmS suppressor plasmid was isolated that harboured the icmS and flanking icm genes, indicating that this plasmid complements the intracellular growth defect of the mutant. In contrast, different icmG suppressor plasmids rendered the icmG mutant more cytotoxic for A. castellanii without enhancing intracellular multiplication in amoebae or RAW264.7 macrophages. Deletion of individual genes in the suppressor plasmids inserts identified lcs (Legionella cytotoxic suppressor) -A, -B, -C and -D as being required for enhanced cytotoxicity of an icmG mutant strain. The corresponding proteins show sequence similarity to hydrolases, NlpD-related metalloproteases, lipid A disaccharide synthases and ABC transporters, respectively. Overexpression of LcsC, a putative paralogue of the lipid A disaccharide synthase LpxB, increased cytotoxicity of an icmG mutant but not that of other icm/dot or rpoS mutant strains against A. castellanii. Based on sequence comparison and chromosomal location, lcsB and lcsC probably encode enzymes involved in cell wall maintenance and peptidoglycan metabolism. The APT established here may prove useful to identify other bacterial factors relevant for interactions with amoeba hosts.
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PMID:The amoebae plate test implicates a paralogue of lpxB in the interaction of Legionella pneumophila with Acanthamoeba castellanii. 1563 36

The Gram-negative bacterium Legionella pneumophila elaborates the siderophore legiobactin. We previously showed that cytoplasmic LbtA helps mediate legiobactin synthesis, inner-membrane LbtB promotes export of legiobactin, and outer-membrane LbtU acts as the ferrisiderophore receptor. RT-PCR analyses now identified lbtC as an iron-repressed gene that is the final gene in an operon containing lbtA and lbtB. In silico analysis predicted that LbtC is an inner-membrane protein that belongs to the major facilitator superfamily (MFS). Although capable of normal growth in standard media, lbtC mutants were defective for growth on iron-depleted agar media. While producing normal levels of legiobactin, lbtC mutants were unable to utilize supplied legiobactin to stimulate growth on iron-depleted media and displayed an impaired ability to take up radiolabelled iron. All lbtC mutant phenotypes were complemented by reintroduction of an intact copy of lbtC. When a cloned copy of both lbtC and lbtU was introduced into a heterologous bacterium (Legionella longbeachae), the organism acquired the ability to utilize legiobactin to grow better on low-iron media. Together, these data indicate that LbtC is involved in the uptake of legiobactin, and based upon its predicted location is most likely the mediator of ferrilegiobactin transport across the inner membrane. The data are also a unique documentation of how an MFS protein can promote bacterial iron-siderophore import, standing in contrast to the vast majority of studies which have defined ABC-type permeases as the mediators of siderophore import across the Gram-negative inner membrane or the Gram-positive cytoplasmic membrane.
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PMID:The major facilitator superfamily-type protein LbtC promotes the utilization of the legiobactin siderophore by Legionella pneumophila. 2216 Apr 1

Type 1 secretion systems (T1SSs) are broadly distributed among bacteria and translocate effectors with diverse function across the bacterial cell membrane. Legionella pneumophila, the species most commonly associated with Legionellosis, encodes a T1SS at the lssXYZABD locus which is responsible for the secretion of the virulence factor RtxA. Many investigations have failed to detect lssD, the gene encoding the membrane fusion protein of the RtxA T1SS, in non-pneumophila Legionella, which has led to the assumption that this system is a virulence factor exclusively possessed by L. pneumophila. Here we discovered RtxA and its associated T1SS in a novel Legionella taurinensis strain, leading us to question whether this system may be more widespread than previously thought. Through a bioinformatic analysis of publicly available data, we classified and determined the distribution of four T1SSs including the RtxA T1SS and four novel T1SSs among diverse Legionella spp. The ABC transporter of the novel Legionella T1SS Legionella repeat protein secretion system shares structural similarity to those of diverse T1SS families, including the alkaline protease T1SS in Pseudomonas aeruginosa. The Legionella bacteriocin (1-3) secretion systems T1SSs are novel putative bacteriocin transporting T1SSs as their ABC transporters include C-39 peptidase domains in their N-terminal regions, with LB2SS and LB3SS likely constituting a nitrile hydratase leader peptide transport T1SSs. The LB1SS is more closely related to the colicin V T1SS in Escherichia coli. Of 45 Legionella spp. whole genomes examined, 19 (42%) were determined to possess lssB and lssD homologs. Of these 19, only 7 (37%) are known pathogens. There was no difference in the proportions of disease associated and non-disease associated species that possessed the RtxA T1SS (p = 0.4), contrary to the current consensus regarding the RtxA T1SS. These results draw into question the nature of RtxA and its T1SS as a singular virulence factor. Future studies should investigate mechanistic explanations for the association of RtxA with virulence.
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PMID:Whole genome sequence analysis reveals the broad distribution of the RtxA type 1 secretion system and four novel putative type 1 secretion systems throughout the Legionella genus. 3193 15