Genomics of Legionella species
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REPOSITORIES: ENA
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Project description:Comparative analyses of Legionella species to identify genetic features of strains causing Legionnaires' disease
| PRJEB7322 | ENA
Project description:Comparative analyses of Legionella species to identify genetic features of strains causing Legionnaires' disease
| PRJEB7321 | ENA
Project description:Legionella pneumophila (Lp) is a waterborne bacterium able to infect human alveolar macrophages, causing a severe pneumonia known as Legionnaires’ disease. In water, Lp grows inside ciliates and ameoba. Lp is able to survive for several months in water, while searching for host cells. In Lp, the sigma factor RpoS is important for survival in water. Several small regulatory RNAs (sRNA) are known to regulate the expression of RpoS in other bacteria. A previous transcriptomic study showed that RpoS positively regulates the sRNA Lpr10 in Lp. Microarray analysis was performed to investigate the genes regulated by Lpr10.
2020-05-27 | GSE151162 | GEO
Project description:Legionella pneumophila, an intracellular pathogen responsible for the pneumonia-like Legionnaires’ disease in humans, inhabits aquatic environments, including man-made water systems such as water fountains, foot spas, and tap water, and exists as part of biofilms or as a protozoan parasite. As a bacterivore, Tetrahymena thermophila provides a favorable environment for Legionella to establish a replicative niche (Legionella-containing vacuole; LCV) under environmental stress. Conversely, the L. pneumophila Ofk308 strain, isolated from an Ashiyu foot spa, has been found to be cytotoxic to the ciliate T. thermophila CU427. This study aimed to identify the cytotoxicity-related genes of Legionella and elucidate their mechanisms specific to the Tetrahymena host. A comparative analysis using RNA-sequencing was conducted with two Legionella strains, Philadelphia-1 and Ofk308, to select several candidate genes. Deletion mutants of Ofk308 were constructed by homologous recombination. Eight out of ten candidate gene deletion mutants were successfully generated. These mutants were analyzed for cytotoxicity against T. thermophila and intracellular bacterial growth at 2 h, 24 h, and 48 h postinfection. Among the deletion mutants, ∆vicinal oxygen chelate (VOC) and msrB/A exhibited reduced cytotoxicity. Furthermore, LCVs formed in T. thermophila infected with ∆VOC and msrB/A were smaller in size compared to those formed by the parental strain Ofk308, suggesting a role in both cytotoxicity and intracellular growth. Multiple factors contribute to the cytotoxicity exhibited by the Ofk308 strain in protozoan host cells, and gene expression analysis may reveal additional relevant factors.
2025-08-08 | GSE304426 | GEO
Project description:Upon infection of host cells Legionella pneumophila releases a multitude of effector enzymes into the hosts cytoplasm that hijack a plethora of cellular activities, including the hosts ubiquitination pathways. Effectors belonging to the SidE-family are involved in non-canonical serine phosphoribosyl ubiquitination of host substrate proteins contributing to the formation of a Legionella-containing vacuole which is crucial in the onset of legionnaires disease. This dynamic process is reversed by effectors called Dups that hydrolyse the phosphodiester in the phosphoribosyl ubiquitinated protein. We installed reactive warheads on chemically prepared ribosylated ubiquitin to generate a set of probes targetting these Legionella enzymes. In vitro tests on recombinant DupA revealed that a vinyl sulfonate warhead was most efficient in covalent complex formation. Mutagenesis and x-ray crystallography approaches were used to identify the site of covalent crosslinking to be an allosteric cysteine residue and subsequent application of this probe highlight the potential to selective enrich Dup enzymes from Legionella infected cell lysates.
2025-05-06 | PXD049797 | Pride
Project description:Legionella pneumophila is the causative agent of Legionnaires’ disease, an acute pulmonary infection. L. pneumophila is able to infect and multiply in both phagocytic protozoan, such as Acanthamoeba castellanii, and mammalian professional phagocytes. The best-known virulence determinant used by L. pneumophila to infect host cells is a Type IVb translocation system named Icm/Dot, which is used to modify the host cell functions to the benefit of the bacteria. To date the Icm/Dot systeme is known to translocate more than 100 effectors. While the transcriptional response of Legionella to the intracellular environement of A. castelannii as already been investigated, much less is known of how Legionella reacts transcriptionnally inside human macrophages. In this study, the transcriptome of L. pneumophila was monitored during exponential and post-exponential phase in rich AYE broth and during infection of human cultured macrophages by using microarray and a RNA amplification procedure called SCOTS to allow for the study of conditions of low bacterial loads. Among the genes induced intracellularly are those involved in amino acid synthesis pathway leading to L-arginine, L-histidne and L-proline as well as many transport system involved in amino acid and iron uptake. The Icm/Dot systems is not differentially expressed inside cells compare to the E phase control but the effectors are strongly induced. The intracellular transcriptome was further used to identify putative new Icm/Dot effectors and translocation was show to occur for 3 of them. This study provides a comprehensive view of how L. pneumophila react to the human macrophages intracellular environment.
2011-01-01 | GSE23029 | GEO
Project description:Legionella pneumophila is a water-borne pathogen, and thus survival in the aquatic environment is central to its transmission to humans. Hence, identifying genes required for its survival in water could help prevent Legionnaires’ disease outbreaks. In the present study, we investigate for the first time the role of the sigma factor RpoS in promoting the survival in water, where L. pneumophila experiences total nutrient deprivation. The rpoS mutant showed a significant survival defect compared to the wild-type strain in defined water medium (DFM). Then, we analyzed the transcriptome of the rpoS mutant during exposure to water using whole genome microarray analysis. We found that RpoS negatively affects the expression of several genes, including genes required for replication, cell division, translation and transcription, suggesting that the mutant fails to shutdown major metabolic programs.
2014-12-04 | GSE56258 | GEO
Project description:In this report, we have developed a rapid oligonucleotide microarray detection technique to identify the most common ten Legionella spp.. The sensitivity of the detection was at 1.0 ng with genomic DNA or 13 CFU/100 mL with Legionella cultures. The microarray detected seven air conditioner-condensed water samples with 100% accuracy, validating the technique as a promising method for applications in basic microbiology, clinical diagnosis, food safety, and epidemiological surveillance. The phylogenetic study based on the ITS has also revealed interestingly that the non-pathogenic L. fairfieldensis is the closest to L. pneumophila than the nine other pathogenic Legionella spp..
2014-10-04 | GSE61962 | GEO
Project description:Legionella pneumophila is a Gram-negative, environmental bacterium, which causes the life-threatening pneumonia Legionnaires’ disease. The facultative intracellular bacterium forms biofilms and employs the Icm/Dot type IV secretion system (T4SS) to replicate in amoebae and macrophages. The Legionella quorum sensing (Lqs) system and the transcription factor LvbR form a regulatory network controlling various traits, including bacterial motility, virulence and biofilm architecture. Here we show by comparative proteomics that in biofilms formed by L. pneumophila mutant strains lacking LvbR or the response regulator LqsR, proteins encoded by the 133 kb fitness island and components of the flagellum (FlaA) are downregulated. Confocal microscopy revealed that the ∆lqsR or ∆flaA mutant strains formed biofilms of the same patchy morphology as the parental strain JR32, while the ∆lvbR mutant forms a mat-like biofilm as previously shown. Acanthamoeba castellanii amoebae migrated more slowly through biofilms formed by the ∆lvbR, ∆lqsR or ∆flaA mutant strains, and amoebae migration was impaired in biofilms formed by L. pneumophila lacking a functional Icm/Dot T4SS (∆icmT) or the secreted effector proteins LegG1 and PpgA. Amoebae migrating through biofilms formed by JR32, ∆lvbR or ∆icmT were decorated by clusters of bacteria, while amoebae in ∆lqsR or ∆flaA biofilms were not. Taken together, the Lqs system, LvbR, FlaA and the Icm/Dot T4SS regulate migration of A. castellanii through L. pneumophila biofilms, and – with the exception of the T4SS – also regulate bacterial cluster formation on the amoeba. Hence, amoebae migration through L. pneumophila biofilms is regulated by bacterial quorum sensing, virulence and motility.
2022-06-08 | PXD030337 | Pride
Project description:Legionella pneumophila is a water-borne pathogen, and thus survival in the aquatic environment is central to its transmission to humans. Hence, identifying genes required for its survival in water could help prevent Legionnaires’ disease outbreaks. In the present study, we investigate for the first time the role of the sigma factor RpoS in promoting the survival in water, where L. pneumophila experiences total nutrient deprivation. The rpoS mutant showed a significant survival defect compared to the wild-type strain in defined water medium (DFM). Then, we analyzed the transcriptome of the rpoS mutant during exposure to water using whole genome microarray analysis. We found that RpoS negatively affects the expression of several genes, including genes required for replication, cell division, translation and transcription, suggesting that the mutant fails to shutdown major metabolic programs. The WT and rpoS mutant were grown to exponential phase in rich AYE broth, washed three times in DFM (NaCl 0.5 g/L, KH2PO40.2 g/L, KCl 0.5 g/L, pH=6.9) and resuspended in DFM at an OD600 of 0.1, After 24h exposure, RNA was extracted.
2014-12-04 | E-GEOD-56258 | biostudies-arrayexpress