While formulating this medium, it has been demonstrated that cysteine was an absolute requirement for the bacterial growth and that the addition of soluble ferric pyrophosphate had stimulatory effects.
Unlike other microorganisms, L. Accordingly, microarray analyses performed during replicative growth of L. However, unexpectedly the up-regulation of genes encoding the Entner-Doudoroff ED pathway, as well as of a putative glucokinase, a sugar transporter and the myo-inositol catabolism indicated that L.
Interestingly, these analyses suggested for the first time that intracellular L. Indeed, later, it was shown that GamA is responsible for glycogen- and starch-degrading activities of L.
Hence, intracellular L. However, L. Moreover, 13 C- isotopologue profiling revealed that L. Based on the presence of a glucose transporter protein and on 13 C-tracer experiments, it was reported that glucose, metabolized through the ED and PPP pathways serves as co-substrate for L.
Isotopologue profiling of key metabolites of L. In addition, as expected from an intracellular bacterium, which engages a growth phase-dependent program to control its virulence, it was shown that also the carbon and energy sources are metabolized in dependence of the growth phase Gillmaier et al. Conversely, during the post-exponential phase, despite the availability of serine in the medium, serine-dependent protein biosynthesis appears to be reduced, whereas carbon from serine is still used for PHB and fatty acid biosynthesis until the post-exponential phase of growth.
Hence, upon entry into the stationary phase and under nutrient starvation, the PHB produced is catabolized by L. Simplified representation of exponential and post-exponential phase-dependent utilization of serine, glucose and glycerol by L. In vitro isotopologue labeling experiments using 13 C-serine, 13 C-glucose and 13 C-glycerol revealed a bipartite metabolism in which serine in red is mainly used during the exponential phase of growth and enters primarily the TCA cycle, whereas glucose in blue and glycerol in green are shuffled into anabolic processes during the post-exponential growth phase of L.
Relative carbon fluxes are depicted by the thickness of the arrows. For more detail, see the text. The other player in this bi-partite metabolism is glucose, which in L. As previously mentioned, L. Furthermore, glucose metabolism through the ED pathway is necessary for full fitness of L. Earlier studies provided the first indication that glycerol may be used by L. Indeed, glycerol is predominantly metabolized during the late and post-exponential phase of growth like the life stage dependent usage of other carbon sources.
The acquisition of nutrients within host cells is an indispensable prerequisite for L. The presence and the up-regulation of genes encoding 12 different ABC transporters, amino acid permeases, proteases and phospholipases during intracellular multiplication within host cells suggested how L. Indeed, it was shown that intracellular replication of L. Furthermore, 13 C-Isotopologue compositions of amino acids from bacterial and amoebal proteins showed that L.
In addition to the above mentioned transport systems, L. The L. Price and colleagues suggested that in this way AnkB may generate short peptides and amino acids, which represent nutrients for intracellular bacterial multiplication as these free amino acids may be imported into the LCV via different host solute carriers and transporters, such as the glucose Slc2a1, Slc2a6 and glycerol transporters Slc37a1 Price et al.
However, these two-effector families work synergistically to inhibit host translation and thereby liberate amino acids for L. Isoptopologue profiling during the replicative intracellular growth phase showed that L.
Although less is known about the intracellular metabolism in the late phase of growth, it is likely that L. In addition, the transmissive form of L. Moreover, intracellular L. Once nutrients are limited in the LCV, this may be the signal for L. After replicating within the LCV to high numbers, nutrients become limited, which triggers complex and coordinated regulation to allow the expression of transmissive traits, which provide L.
By analogy to E. Indeed, a L. Additionally, virulence traits are poorly expressed when L. The mild effects displayed by the lack of RelA on the expression of the virulent traits suggested that additional clues and redundant strategies are employed by L. Indeed L. Whereas, RelA synthesizes p ppGpp is following fluctuations in amino acid availability, the bifunctional enzyme SpoT leads to the accumulation of the alarmone p ppGpp in response to fatty acid depletion.
Thus, the L. When nutrients are abundant, virulent bacteria hydrolyze p ppGpp in a SpoT-dependent manner, allowing the bacteria to actively multiply and repress the transmission traits Molofsky and Swanson, ; Dalebroux et al. Conversely, as replicating bacteria exhaust the available nutrients within the LCV, p ppGpp is produced by RelA and additionally, the equilibrium of SpoT is shifted more toward synthesis instead degradation.
This leads to a massive accumulation of the alarmone and triggers the entry into the transmissive state Hammer and Swanson, ; Molofsky and Swanson, ; Dalebroux et al. SpoT is required throughout the entire infection cycle to mediate p ppGpp turnover via its hydrolase and synthase activities Xiao et al. In particular, DksA seems to respond to fatty acid stress by inducing bacterial differentiation in a p ppGpp-independent manner, as judged by the expression of certain transmissive traits within macrophages Dalebroux et al.
However, upon p ppGpp accumulation, DksA and p ppGpp coordinately regulate the hierarchical cascade for flagellar expression. At the bottom of the hierarchical cascade governing L. Interestingly, the flagellar sigma factor FliA is not only implicated in the regulation of the flagellum production but also acts as regulator of virulence genes that are required for the expression of pathways important for cytotoxicity, lysosome evasion, and replication of L. As in many other bacterial pathogens, L.
Probably directly activated by the accumulation of the alarmone p ppGpp, LetA is regulating the expression of the small ncRNAs RmsX,Y,Z, which are required to relieve the repression exerted by the global regulator CsrA, an RNA-binding protein, on many virulence genes, thereby ensuring the expression of the transmissive traits Hovel-Miner et al.
This in turn makes the CsrA protein indispensable for L. Another player in this complex regulatory network, is the TCS LqsRS Legionella quorum sensing , whose role in the regulation of gene expression during the transmissive phase has been extensively studied Hochstrasser and Hilbi, Importantly, the production of LqsR is regulated at the post-transcriptional level by the global repressor CsrA Sahr et al.
Model the stringent response network governing L. The dashed arrows indicate suggested but not yet confirmed direct interactions. This pleiotropic regulatory element is known to modulate gene expression by facilitating the interaction between sRNA and their mRNA targets in diverse bacterial pathogens, controlling pathways related to metabolism, transport, energy production and conversion or membrane proteins Boudry et al.
Furthermore, L. The complex and hierarchical regulation of the L. Previous evidences in E. A first bioinformatics search revealed in L. However, deep RNA sequencing from exponentially replicative and post exponentially virulent in vitro grown L. This sRNA, named Anti-hfq, is transcribed antisense to the hfq transcript and controls the expression of Hfq through a base pairing mechanism during the exponential phase of L.
Moreover, it is important to mention that Hfq was reported to influence L. Taken together, L. Similarly to what has been described in other bacterial pathogens, many regulatory factors implicated in virulence gene expression are also major regulators of metabolic pathways. Indeed, L. An intriguing example of a regulator that is important for the expression of virulence and the regulation of metabolic traits is the RNA binding protein CsrA.
Interestingly, L. The combined or individual regulation of these two pathways is under the control of the RNA binding protein CsrA, whose presence ensures the efficient expression of the both parts of this operon Sahr et al. When nutrients are abundant CsrA binds within the gap transcript, and stabilizes the alternative secondary structure that covers the Rho-dependent transcription termination site. Consequently, this leads to a CsrA-dependent transcription of the glycolysis part of the operon toward gluconeogenesis, which under starvation or stress is not expressed.
Another example of how CsrA influences metabolism, is that this regulatory element affects the production of secondary metabolites, in particular thiamine pyrophosphate, ensuring the effecting functioning of central enzymes of the carbohydrate metabolism when required Sahr et al. Furthermore, this study highlighted the impact of CsrA on the bipartite metabolism of L. By contrast, CsrA has a negative impact on the incorporation and the metabolism of glycerol and glucose.
These studies also showed the important influence of CsrA on the production of the storage molecule PHB suggesting that CsrA is a major player in the utilization of the different carbon sources during the biphasic life cycle of L. The biphasic life cycle of L. Hence, CsrA is a major organizer of the biphasic life cycle of Legionella pneumophila integrating and coordinating the metabolic carbon switch and the transition between replicative and transmissive traits. In response to diverse and hostile environmental conditions encountered during its life cycle, L.
As such, this intracellular bacterium displays at least two reciprocal stages: a replicative and a transmissive form. The transition between the non-virulent replicative and the virulent non-replicative phase is governed by a complex regulatory network, in which transcriptional and post-transcriptional regulatory elements are engaged to insure an efficient infection cycle.
The trigger of this morphological stress response is mainly mediated by metabolic changes and therefore the availability of nutrients in the surroundings. Thus, within the LCV the usage of serine as carbon and energy source supports the multiplication of the bacteria in which the replicating bacteria show a high metabolic activity.
Upon amino acid depletion, the stringent response mediates the expression of the virulent traits but in parallel also enables the bacteria to survive for long term under stress and starving condition. This is ensured amongst others by the expression of stress and virulence related genes and an overall metabolic shift leading to the usage of alternative carbon sources like glucose and glycerolipids and an increased production of the storage molecule PHB.
Under these conditions, L. Taken together, the biphasic life cycle of L. Thus, during the biphasic life cycle the metabolism influences the transition between replicative and transmissive phase as well as the reciprocal expression of virulence factors and their regulators, in particular CsrA, which is implicated in the regulation of virulence and the metabolism. A comprehensive analysis of L. Continuous unrevealing of this complex interplay between metabolism and virulence of L. All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
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Abstract Legionella pneumophila is a gram-negative bacterium that inhabits freshwater ecosystems, where it is present in biofilm or as planktonic form. The bacterium Legionella pneumophila is responsible for most cases of Legionnaires' disease.
Outdoors, legionella bacteria survive in soil and water, but rarely cause infections. However, legionella bacteria can multiply in water systems made by humans, such as air conditioners. Although it's possible to get Legionnaires' disease from home plumbing, most outbreaks have occurred in large buildings, perhaps because complex systems allow the bacteria to grow and spread more easily.
Also, home and car air conditioning units don't use water for cooling. Most people become infected when they inhale microscopic water droplets containing legionella bacteria. This might be from the spray from a shower, faucet or whirlpool, or water from the ventilation system in a large building. Outbreaks have been linked to:. Besides by breathing in water droplets, the infection can be transmitted in other ways, including:.
Not everyone exposed to legionella bacteria becomes sick. You're more likely to develop the infection if you:. Legionnaires' disease can be a problem in hospitals and nursing homes, where germs can spread easily and people are vulnerable to infection. Outbreaks of Legionnaires' disease are preventable, but prevention requires water management systems in buildings that ensure that water is monitored and cleaned regularly.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. Article PubMed Google Scholar. Eisenreich, W. Metabolic host responses to infection by intracellular bacterial pathogens. Gillmaier, N. James, B. Polyhydorxyburyrate in Legionella pneumophila , an energy source for survival in low-nutrient environments. Oliva, G. The Life Cycle of L. Bruggemann, H. Virulence strategies for infecting phagocytes deduced from the in vivo transcriptional program of Legionella pneumophila.
Kuriki, T. Journal of bioscience and bioengineering 87 , — Gurung, N. Herrmann, V. GamA is a eukaryotic-like glucoamylase responsible for glycogen- and starch-degrading activity of Legionella pneumophila.
Genome-scale identification of Legionella pneumophila effectors using a machine learning approach. Lifshitz, Z. Computational modeling and experimental validation of the Legionella and Coxiella virulence-related type-IVB secretion signal. Muder, R. Infection due to Legionella species other than L. Marchler-Bauer, A. Reuter, S. A pilot study of rapid whole-genome sequencing for the investigation of a Legionella outbreak. Kobayashi, M. Structural insights into the catalytic reaction that is involved in the reorientation of Trp at the substrate-binding site in GH13 dextran glucosidase.
Roy, A. Yang, J. Article Google Scholar. Truchan, H. Rossier, O. Infection and immunity 72 , — The type II secretion system of Legionella pneumophila elaborates two aminopeptidases, as well as a metalloprotease that contributes to differential infection among protozoan hosts.
Hales, L. Legionella pneumophila contains a type II general secretion pathway required for growth in amoebae as well as for secretion of the Msp protease.
DebRoy, S. Legionella pneumophila type II secretome reveals unique exoproteins and a chitinase that promotes bacterial persistence in the lung. Nagai, H. Huang, L. The E Block motif is associated with Legionella pneumophila translocated substrates. Wang, Y. Prediction of bacterial type IV secreted effectors by C-terminal features. Sory, M. Molecular microbiology 14 , — Bardill, J. Kruse-Jarres, J. Evaluation of a new alpha-amylase assay using 4. J Clin Chem Clin Biochem 27 , — Hagele, E.
Mechanism of action of human pancreatic and salivary alpha-amylase on 4,6-ethylidene-alphanitrophenyl-maltoheptaoside substrate. Clin Chem 35 , — Al-Khodor, S. The life stage-specific pathometabolism of Legionella pneumophila.
Amino acid requirements for Legionella pneumophila growth. Bachman, M. RpoS co-operates with other factors to induce Legionella pneumophila virulence in the stationary phase. Molecular microbiology 40 , — Hammer, B. Co-ordination of legionella pneumophila virulence with entry into stationary phase by ppGpp.
Molecular microbiology 33 , — Dalebroux, Z. Distinct roles of ppGpp and DksA in Legionella pneumophila differentiation. The Legionella pneumophila rpoS gene is required for growth within Acanthamoeba castellanii. Journal of bacteriology , — Li, L. Faucher, S. Quintarelli, G. The effects of alpha amylase on collagen-proteoglycans and collagen-glycoprotein complexes in connective tissue matrices. Histochemie 18 , — Stone, B. Chen, D. Efficient transformation of Legionella pneumophila by high-voltage electroporation.
Molecular mimicry by an F-box effector of Legionella pneumophila hijacks a conserved polyubiquitination machinery within macrophages and protozoa. Anisimova, M. Approximate likelihood-ratio test for branches: A fast, accurate, and powerful alternative. Dereeper, A. Santic, M. A Francisella tularensis pathogenicity island protein essential for bacterial proliferation within the host cell cytosol. Download references. DGE- You can also search for this author in PubMed Google Scholar.
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Reprints and Permissions. Best, A. A Legionella pneumophila amylase is essential for intracellular replication in human macrophages and amoebae.
Sci Rep 8, Download citation. Received : 26 February Accepted : 05 April Published : 20 April Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative.
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Subjects Bacterial pathogenesis Pathogens. Introduction The accidental human pathogen, Legionella pneumophila , causes an atypical pneumonia when water droplets, stemming from a contaminated water source such a cooling tower or humidifier, are inhaled by humans, which are considered as accidental host 1 , 2 , 3.
Results Identification of amylases in L. Figure 1. Full size image. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Materials and Methods Strains and cell lines L.
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