The expression of the flagellum of Legionella pneumophila is modulated by different environmental factors

Heuner, K

doi:10.1016/s0378-1097(99)00160-3

Cited by 25 publications

(31 citation statements)

References 16 publications

(31 reference statements)

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“…pillar-and mushroom-like structures) formed at 25 u C remained more stably attached than filamentous, mycelial-mat-like biofilms formed at 37 and 42 u C. Also, Mampel et al (2006) reported that biofilm formation at 37 u C was 30 % lower than at 23 and 30 u C. Furthermore, we have shown that adhesion is highest for late stationary phase cells. This is expected, as L. pneumophila shows increased expression of the flagellum and of type IV pili, both of which have been described in other bacteria to be involved in adhesion (O'Toole & Kolter, 1998;Pratt & Kolter, 1998;Watnick & Kolter, 1999), in stationary phase during low-temperature growth (Heuner et al, 1999;Soderberg et al, 2004). Because stationary phase mimics the transmissive phase in which bacteria are released from amoebae (Molofsky & Swanson, 2004), our observations suggest that bacteria that exit host cells in natural lowtemperature environments are in an optimal physiological state to adhere to biofilms.…”

Section: Discussionsupporting

confidence: 74%

Transcriptional profiling of Legionella pneumophila biofilm cells and the influence of iron on biofilm formation

et al. 2008

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In aquatic environments, biofilms constitute an ecological niche where Legionella pneumophila persists as sessile cells. However, very little information on the sessile mode of life of L. pneumophila is currently available. We report here the development of a model biofilm of L. pneumophila strain Lens and the first transcriptome analysis of L. pneumophila biofilm cells. Global gene expression analysis of sessile cells as compared to two distinct populations of planktonic cells revealed that a substantial proportion of L. pneumophila genes is differentially expressed, as 2.3 % of the 2932 predicted genes exhibited at least a twofold change in gene expression. Comparison with previous results defining the gene expression profile of replicative-and transmissive-phase Legionella suggests that sessile cells resemble bacteria in the replicative phase. Further analysis of the most strongly regulated genes in sessile cells identified two induced gene clusters. One contains genes that encode alkyl hydroperoxide reductases known to act against oxidative stress. The second encodes proteins similar to PvcA and PvcB that are involved in siderophore biosynthesis in Pseudomonas aeruginosa. Since iron has been reported to modify biofilm formation in other species, we further focused on iron control of gene expression and biofilm formation. Among the genes showing the greatest differences in expression between planktonic cells and biofilm, only pvcA and pvcB were regulated by iron concentration. A DpvcA L. pneumophila mutant showed no changes in biofilm formation compared to the wild-type, suggesting that the pvcA product is not mandatory for biofilm formation. However, biofilm formation by L. pneumophila wild-type and a DpvcA strain was clearly inhibited in iron-rich conditions.

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Section: Discussionsupporting

confidence: 74%

Transcriptional profiling of Legionella pneumophila biofilm cells and the influence of iron on biofilm formation

et al. 2008

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“…Error bars show SD. *Significant difference between the calibrator and the time post-infection have a contrary effect (Heuner et al 1999). Additionally, the regulatory genes of the P. salmonis flagellar cascade share similar expression profiles to those described for L. pneumophila, where rpoN (σ54) and fliA (σ28) are induced, triggering a high expression of the final genes in the cascade, such as flaA and flaB (Prouty et al 2001, McCarter 2006.…”

Section: Discussionmentioning

confidence: 68%

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Carril

Gómez²,

Marshall³

2017

Dis. Aquat. Org.

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The Piscirickettsia salmonis genome was screened to evaluate potential flagellarelated open reading frames, as well as their genomic organization and eventual expression. A complete and organized set of flagellar genes was found for P. salmonis, although no structural flagellum has ever been reported for this bacterium. To gain further understanding, the hierarchical flagellar cascade described for Legionella pneumophila was used as a reference model for putative analysis in P. salmonis. Specifically, 5 of the most relevant genes from this cascade were chosen, including 3 regulatory genes (fleQ, triggers the cascade; fliA, regulates the σ28-coding gene; and rpoN, an RNA polymerase-dependent gene) and 2 terminal structural genes (flaA and flaB, flagellin and a flagellin-like protein, respectively). Kinetic experiments evaluated gene expressions over time, with P. salmonis assessed in 2 liquid, cell-free media and during infection of the SHK-1 fish cell line. Under all conditions, the 5 target genes were primarily expressed during early growth/infection and were differentially expressed when bacteria encountered environmental stress (i.e. a high-salt concentration). Intriguingly, the flagellin monomer was fully expressed under all growth conditions and was located near the bacterial membrane. While no structural flagellum was detected under any condition, the recombinant flagellin monomer induced a proinflammatory response in SHK-1 cells, suggesting a possible immunomodulatory function. The potential implications of these observations are discussed in the context of P. salmonis biology and pathogenic potential.

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“…3A). As a control for the growth phases, we analyzed the expression of flagellin (FlaA) by L. pneumophila harvested at the indicated growth phase because it is known that the expression of flagellin is highly induced in PE phase of L. pneumophila (2,47). As expected, the bacteria did not express flagellin in the replicative phase (EE ϩ LE), whereas FlaA was detected in PE and S phases (Fig.…”

Section: Construction and Growth Characterization Of L Pneumophila Mmentioning

confidence: 99%

“…When nutrients become limiting, L. pneumophila differentiates into the mature intracellular form. This phase corresponds to the transmissive phase in which L. pneumophila becomes flagellated, expresses its virulence factors, and seems to be metabolically dormant (1)(2)(3)(4). This biphasic life cycle is also observed during growth in liquid medium, and therefore, in vitro experiments are considered as valid models to analyze the specific features encountered during both phases (3).…”

mentioning

confidence: 99%

Growth-related Metabolism of the Carbon Storage Poly-3-hydroxybutyrate in Legionella pneumophila

Gillmaier

Schunder

Kutzner

et al. 2016

Journal of Biological Chemistry

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Legionella pneumophila, the causative agent of Legionnaires disease, has a biphasic life cycle with a switch from a replicative to a transmissive phenotype. During the replicative phase, the bacteria grow within host cells in Legionella-containing vacuoles. During the transmissive phenotype and the postexponential (PE) growth phase, the pathogens express virulence factors, become flagellated, and leave the Legionella-containing vacuoles. Using 13 C labeling experiments, we now show that, under in vitro conditions, serine is mainly metabolized during the replicative phase for the biosynthesis of some amino acids and for energy generation. During the PE phase, these carbon fluxes are reduced, and glucose also serves as an additional carbon substrate to feed the biosynthesis of poly-3-hydroxybuyrate (PHB), an essential carbon source for transmissive L. pneumophila. Whole-cell FTIR analysis and comparative isotopologue profiling further reveal that a putative 3-ketothiolase (Lpp1788) and a PHB polymerase (Lpp0650), but not enzymes of the crotonylCoA pathway (Lpp0931-0933) are involved in PHB metabolism during the PE phase. However, the data also reflect that additional bypassing reactions for PHB synthesis exist in agreement with in vivo competition assays using Acanthamoeba castellannii or human macrophage-like U937 cells as host cells. The data suggest that substrate usage and PHB metabolism are coordinated during the life cycle of the pathogen.

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The expression of the flagellum of Legionella pneumophila is modulated by different environmental factors

Cited by 25 publications

References 16 publications

Transcriptional profiling of Legionella pneumophila biofilm cells and the influence of iron on biofilm formation

Transcriptional profiling of Legionella pneumophila biofilm cells and the influence of iron on biofilm formation

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Growth-related Metabolism of the Carbon Storage Poly-3-hydroxybutyrate in Legionella pneumophila

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