The expression of the flagellum of<i>Legionella pneumophila</i>is modulated by different environmental factors

Heuner, Klaus; Brand, Bettina; Häcker, J.

doi:10.1111/j.1574-6968.1999.tb13603.x

Cited by 47 publications

(16 citation statements)

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“…Finally, since the results of the experiments with fla-gfp and fla-cat reporter gene assays were ambiguous in some aspects (see below), we constructed flaA and flaB transcriptional fusions with the luxAB operon of V. harveyi, which has been used as a highly sensitive reporter system in different bacterial species and eukaryotes, and is a good reporter for use in vivo and in infected cultures of eukaryotic cells (Baldwin et al, 1984 ; Kirchner et al, 1989 ;Heuner et al, 1999). The sensitivities of both CAT expression as measured by ELISA and luciferase activity measured in a photoncounting device were high.…”

Section: Construction and Evaluation Of Transcriptional Reporter Fusimentioning

confidence: 99%

“…Primers HPFlaANotI1\HPFlaBNotI1 and HpgfpNotI2 were used to delete the gfp gene from these constructs by inverse PCR and subsequent religation. The deleted gfp fragment was then replaced with the luxAB operon (V. harveyi) that had been amplified from MiniTn5luxAB (De Lorenzo et al, 1990 ;Heuner et al, 1999) using primers containing NotI sites (LuxABNotI1 and LuxABNotI2). The resulting plasmids pSUS1609 and pSUS1601 were used to generate allelic exchange mutants in H. pylori by natural transformation.…”

Section: Introductionmentioning

confidence: 99%

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Growth phase-dependent and differential transcriptional control of flagellar genes in Helicobacter pylori

Niehus

Suerbaum

et al. 2002

Microbiology

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INTRODUCTIONThe eubacterial genus Helicobacter comprises the gastric Helicobacter species that infect the stomach mucosa of many different kinds of mammals. All of these have developed specific adaptation mechanisms to permit persistent life in the inhospitable environment of the stomach. Helicobacter pylori, the causative agent of chronic gastritis and peptic ulcers in humans, like other Helicobacter species depends on its strong motility to move through the viscous mucus gel lining the epithelium of the human stomach, to establish chronic infection of the human gastric mucosa and to persist in the gastric mucus (Hazell et al., 1986 ; Worku et al., 1999). Flagellar filaments contain FlaA and FlaB subunits in a stoichiometric ratio of approximately ten to one (Kostrzynska et al., 1991 ;Suerbaum et al., 1993 ;Josenhans et al., 1995aJosenhans et al., , 1999. Mutants lacking the major flagellin FlaA show strongly impaired motility in vitro and possess only truncated flagella, whereas flaB mutants have moderately diminished motility and apparently normal flagella. In the gnotobiotic piglet animal model and the H. mustelae-ferret model, isogenic mutants lacking either the FlaB or the FlaA subunits were both severely impaired in their ability to colonize (Andrutis et al., 1997 ;Eaton et al., 1996). Those results demonstrated the importance of both flagellins in vivo. The H. pylori flaA and flaB genes are unlinked on the chromosome and their transcription is regulated by two different promoters (Leying et al., 1992 ;Suerbaum et al., 1993). Expression of flaA is controlled by a σ#)-dependent promoter, a class of promoters responsible for the transcriptional activation of late flagellar genes in many flagellated bacteria (class 3 ;Aizawa, 2000 ;Josenhans et al., 2002). flaB and several other flagellar (Spohn & Scarlato, 1999). Dependency of a number of flagellar genes on the ' environmentally regulated ' σ&% factor has also been observed in Caulobacter crescentus, Vibrio cholerae and Campylobacter species, (Anderson et al., 1995 ;Jagannathan et al., 2001 ;Prouty et al., 2001). However, the evolutionary, environmental and functional basis for the importance of σ&% promoters in flagellar regulation in all these bacterial species is not well established.The genetic background and global regulation of flagellar motility and signal transduction in Helicobacter species have not been thoroughly investigated yet. The complete genome sequences of two H. pylori strains have confirmed that both strains possess most motility genes known from other bacteria, but that these are much less frequently organized in operons than in most other bacteria (Alm et al., 1999 ; Tomb et al., 1997). Based on homology searches, some genes known from other bacteria to be important in motility regulation have not been identified in H. pylori (Josenhans & Suerbaum, 2001 Labigne-Roussel et al., 1988).H. pylori strains were cultured on blood agar plates (Columbia agar base II, Oxoid), supplemented with 10 % sheep blood and the following antibiotics : v...

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Section: Construction and Evaluation Of Transcriptional Reporter Fusimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Growth phase-dependent and differential transcriptional control of flagellar genes in Helicobacter pylori

Niehus

Suerbaum

et al. 2002

Microbiology

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“…The FliA-dependent transcription was determined using a reporter gene construct (luciferase) by measuring the luciferase activity. The FliA-dependent transcription was determined in the L. oakridgensis wild-type (WT) strain and the corresponding isogenic fliA mutant strain that has got either plasmid pKH23 (pFlaA-luxAB fusion) or plasmid pKH24 (promoterless luxAB construct) (31). Only the wild-type strain that harbored the pFlaA-luxAB fusion showed luciferase activity (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…As the FliA activity was successfully measured using a pflaA reporter gene fusion, further investigations of FliA were started using the pflaA-lacZ fusion (pKH12) which was used earlier to investigate FliA-dependent expression of the flagellin gene in L. pneumophila Corby (31). The levels of expression of lacZ in strains L. oakridgensis (pKH12) and L. oakridgensis ΔfliA (pKH12) at the exponential (E), postexponential (PE), and stationary (S) phases of growth at 37°C and 30°C were additionally investigated.…”

Section: Resultsmentioning

confidence: 99%

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Functional Analysis of the Alternative Sigma-28 Factor FliA and Its Anti-Sigma Factor FlgM of the Nonflagellated Legionella Species L. oakridgensis

et al. 2017

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Legionella oakridgensis causes Legionnaires' disease but is known to be less virulent than Legionella pneumophila. L. oakridgensis is one of the Legionella species that is nonflagellated. The genes of the flagellar regulon are absent, except those encoding the alternative sigma-28 factor (FliA) and its anti-sigma-28 factor (FlgM). Similar to L. oakridgensis, Legionella adelaidensis and Legionella londiniensis, located in the same phylogenetic clade, have no flagellar regulon, although both are positive for fliA and flgM. Here, we investigated the role and function of both genes to better understand the role of FliA, the positive regulator of flagellin expression, in nonflagellated strains. We demonstrated that the FliA gene of L. oakridgensis encodes a functional sigma-28 factor that enables the transcription start from the sigma-28-dependent promoter site. The investigations have shown that FliA is necessary for full fitness of L. oakridgensis. Interestingly, expression of FliA-dependent genes depends on the growth phase and temperature, as already shown for L. pneumophila strains that are flagellated. In addition, we demonstrated that FlgM is a negative regulator of FliA-dependent gene expression. FlgM seems to be degraded in a growth-phase-and temperature-dependent manner, instead of being exported into the medium as reported for most bacteria. The degradation of FlgM leads to an increase of FliA activity.IMPORTANCE A less virulent Legionella species, L. oakridgensis, causes Legionnaires' disease and is known to not have flagella, even though L. oakridgensis has the regulator of flagellin expression (FliA). This protein has been shown to be involved in the expression of virulence factors. Thus, the strain was chosen for use in this investigation to search for FliA target genes and to identify putative virulence factors of L. oakridgensis. One of the five major target genes of FliA identified here encodes the anti-FliA sigma factor FlgM. Interestingly, in contrast to most homologs in other bacteria, FlgM in L. oakridgensis seems not to be transported from the cell so that FliA gets activated. In L. oakridgensis, FlgM seems to be degraded by protease activities.KEYWORDS sigma-28 factor, anti-sigma factor, FliA, FlgM, flagella, Legionella oakridgensis L egionella oakridgensis is less virulent than L. pneumophila and is pathogenic for guinea pigs (1, 2). Recently, two human cases of Legionnaires' disease caused by L. oakridgensis were reported in France (3), showing that the bacteria are able to replicate inside human cells (1,(4)(5)(6)(7). Moreover, it was demonstrated that L. oakridgensis is able to multiply inside amoebae (4) and that the type IV secretion system is a key virulence factor; new virulence factors were also described (4). In general, no additional cysteine is needed to grow L. oakridgensis on agar plates and extracel-

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The life stage‐specific pathometabolism of Legionella pneumophila

Eisenreich

Heuner

2016

FEBS Letters

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The genus Legionella belongs to Gram-negative bacteria found ubiquitously in aquatic habitats, where it grows in natural biofilms and replicates intracellularly in various protozoa (amoebae, ciliates). L. pneumophila is known as the causative agent of Legionnaires' disease, since it is also able to replicate in human alveolar macrophages, finally leading to inflammation of the lung and pneumonia. To withstand the degradation by its host cells, a Legionellacontaining vacuole (LCV) is established for intracellular replication, and numerous effector proteins are secreted into the host cytosol using a type four B secretion system (T4BSS). During intracellular replication, Legionella has a biphasic developmental cycle that alternates between a replicative and a transmissive form. New knowledge about the host-adapted and life stagedependent metabolism of intracellular L. pneumophila revealed a bipartite metabolic network with life stage-specific usages of amino acids (e.g. serine), carbohydrates (e.g. glucose) and glycerol as major substrates. These metabolic features are associated with the differentiation of the intracellular bacteria, and thus have an important impact on the virulence of L. pneumophila.

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The expression of the flagellum ofLegionella pneumophilais modulated by different environmental factors

Cited by 47 publications

References 16 publications

Growth phase-dependent and differential transcriptional control of flagellar genes in Helicobacter pylori

Growth phase-dependent and differential transcriptional control of flagellar genes in Helicobacter pylori

Functional Analysis of the Alternative Sigma-28 Factor FliA and Its Anti-Sigma Factor FlgM of the Nonflagellated Legionella Species L. oakridgensis

The life stage‐specific pathometabolism of Legionella pneumophila

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