Legionella pneumophila JR32 and rpoS- (LM1367) strains: Statinoary phase (stat) vs. Logarithmic (log) phase growth
Ontology highlight
ABSTRACT:
ORGANISM(S): Legionella pneumophila subsp. pneumophila str. Philadelphia 1 Legionella pneumophila
PROVIDER: GSE14830 | GEO | 2009/02/14
SECONDARY ACCESSION(S): PRJNA112069
REPOSITORIES: GEO
Similar Datasets
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
Project description:Legionella pneumophila wild-type and hfq mutant were grown to post-exponential. The wild-type strain is used as the control.
2013-05-21 | GSE42905 | GEO
Project description:Legionella pneumophila Philadelphia-1 strain was grown to stationary phase in AYE broth and starved in freshwater for 2 hours and RNA was harvested with or without sublethal heat shock via immersion in a 55 degree C hot water bath for 5 minutes
2022-02-15 | GSE196713 | 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:Legionella pneumophila is a gram-negative opportunistic human pathogen that infects and multiplies in a broad range of phagocytic protozoan and mammalian phagocytes. Based on the observation that small regulatory RNAs (sRNAs) play an important role in controlling virulence-related genes in several pathogenic bacteria, we attempted to test the hypothesis that sRNAs play a similar role in L. pneumophila. We used computational prediction followed by experimental verification to identify and characterize sRNAs encoded in the L. pneumophila genome. A 50-mer probe microarray was constructed to test the expression of predicted sRNAs in bacteria grown under a variety of conditions. This strategy successfully identified 22 expressed RNAs, out of which six were confirmed by northern blot and RACE. One of the identified sRNAs is highly expressed when the bacteria enter post exponential phase and computational prediction of its secondary structure reveals a striking similarity to the structure of 6S RNA, a widely distributed prokaryotic sRNA, known to regulate the activity of σ70-containing RNAP. A 70-mer probe microarray was used to identify genes affected by L. pneumophila 6S RNA in stationary phase. The 6S RNA encoded by the ssrS gene positively regulates expression of genes encoding type IVB secretion system effectors, stress response genes such as groES and recA as well as many genes with unknown or hypothetical functions. Deletion of 6S RNA significantly reduced L. pneumophila intracellular multiplication in both protist and mammalian host cells, but had no detectable effect on growth in rich media.
2010-01-01 | GSE19196 | GEO
Project description:Legionella pneumophila are important opportunistic pathogens for which environmental reservoirs such as protists are crucial for the infection of humans. Free-living amoebae are considered key hosts providing nutrients and shelter for highly efficient intracellular proliferation of L. pneumophila, which eventually leads to lysis of the amoeba host cell. Yet, the significance of other bacterial players for L. pneumophila ecology is poorly understood. In this study we used a ubiquitous amoeba and their bacterial endosymbiont to investigate the impact of this common association on L. pneumophila infection. We demonstrate that Acanthamoeba castellanii harboring the chlamydial symbiont Protochlamydia amoebophila were able to erase L. pneumophila and, in contrast to symbiont-free amoebae, survived the infection and were able to resume growth. Environmental amoeba isolates harboring P. amoebophila were equally well-protected, and fresh environmental isolates of L. pneumophila were equally well-erased, suggesting ecological relevance of this symbiont-mediated protection. We further show that protection was not mediated by impaired L. pneumophila uptake. Instead, we observed reduced virulence of L. pneumophila released from symbiont-containing amoebae that is strongly supported by transcriptome data. Interference with transition to the transmissive phase is thus likely the basis for this protection. Finally, our data indicate that the defensive response of amoebae harboring P. amoebophila leaves the amoebae with superior fitness reminiscent of immunological memory. Given that mutualistic associations between bacteria and amoebae are widely distributed, P. amoebophila and potentially other amoeba endosymbionts could be key elements in shaping environmental survival, abundance and virulence of this important pathogen thereby affecting frequency of human infection.
2019-04-14 | GSE125876 | GEO
Project description:Legionella pneumophila wild-type and hfq mutant were grown to post-exponential. The wild-type strain is used as the control. Two strains: wild-type (control) and hfq mutant (test). Three biological replicates. Ch1 is gDNA, use as a reference channel (Talaat, 2002, NAR)
2013-05-21 | E-GEOD-42905 | biostudies-arrayexpress
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 Lab strain (JR32) sequencing
| PRJDB4906 | 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