A Type IV Translocated Legionella Cysteine Phytase Counteracts Intracellular Growth Restriction by Phytate

Weber, Samuël; Stirnimann, Christian U.; Wieser, Mara M.; Frey, Daniel; Meier, Roger; Engelhardt, Sabrina; Li, Xiao Dan; Capitani, Guido; Kammerer, Richard A.; Hilbi, Hubert

doi:10.1074/jbc.m114.592568

Cited by 25 publications

(21 citation statements)

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“…LppA is an Icm/Dot T4SS-translocated cysteine phytase, which seems to detoxify bacteriostatic phytate within infected amoebae producing the chelator in millimolar quantities (36). The bacterial phytase LppA might promote intracellular replication not only by increasing micronutrient (iron) availability to L. pneumophila but also by production from phytate inositol phosphates or inositol, which can be used by the bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…Phytate makes up more than 80% of the organic phosphate in soil (32), serves as a major phosphorus storage compound in plants and seeds (33,34), and is a potent chelator of bivalent metal ion micronutrients, thus restricting their bioavailability (35). L. pneumophila produces the Icm/Dot T4SS-translocated phytase LppA, which appears to be implicated in detoxifying bacteriostatic phytate within amoebae (36).…”

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confidence: 99%

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Metabolism of myo -Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages

Manske

Schell

Hilbi

2016

Appl Environ Microbiol

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Legionella pneumophila is a natural parasite of environmental amoebae and the causative agent of a severe pneumonia termed Legionnaires' disease. The facultative intracellular pathogen employs a bipartite metabolism, where the amino acid serine serves as the major energy supply, while glycerol and glucose are mainly utilized for anabolic processes. The L. pneumophila genome harbors the cluster lpg1653 to lpg1649 putatively involved in the metabolism of the abundant carbohydrate myo-inositol (here termed inositol). To assess inositol metabolism by L. pneumophila, we constructed defined mutant strains lacking lpg1653 or lpg1652, which are predicted to encode the inositol transporter IolT or the inositol-2-dehydrogenase IolG, respectively. The mutant strains were not impaired for growth in complex or defined minimal media, and inositol did not promote extracellular growth. However, upon coinfection of Acanthamoeba castellanii, the mutants were outcompeted by the parental strain, indicating that the intracellular inositol metabolism confers a fitness advantage to the pathogen. Indeed, inositol added to L. pneumophila-infected amoebae or macrophages promoted intracellular growth of the parental strain, but not of the ⌬iolT or ⌬iolG mutant, and growth stimulation by inositol was restored by complementation of the mutant strains. The expression of the P iol promoter and bacterial uptake of inositol required the alternative sigma factor RpoS, a key virulence regulator of L. pneumophila. Finally, the parental strain and ⌬iolG mutant bacteria but not the ⌬iolT mutant strain accumulated [U-14 C 6 ]inositol, indicating that IolT indeed functions as an inositol transporter. Taken together, intracellular L. pneumophila metabolizes inositol through the iol gene products, thus promoting the growth and virulence of the pathogen. IMPORTANCEThe environmental bacterium Legionella pneumophila is the causative agent of a severe pneumonia termed Legionnaires' disease. The opportunistic pathogen replicates in protozoan and mammalian phagocytes in a unique vacuole. Amino acids are thought to represent the prime source of carbon and energy for L. pneumophila. However, genome, transcriptome, and proteome studies indicate that the pathogen not only utilizes amino acids as carbon sources but possesses broader metabolic capacities. In this study, we analyzed the metabolism of inositol by extra-and intracellularly growing L. pneumophila. By using genetic, biochemical, and cell biological approaches, we found that L. pneumophila accumulates and metabolizes inositol through the iol gene products, thus promoting the intracellular growth, virulence, and fitness of the pathogen. Our study significantly contributes to an understanding of the intracellular niche of a human pathogen. L egionella pneumophila is a Gram-negative ubiquitous environmental bacterium that survives in complex multispecies biofilms in natural or manmade water sources (1-3). Predominantly, however, Legionella spp. parasitize free-living protozoa and grow within these u...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Metabolism of myo -Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages

Manske

Schell

Hilbi

2016

Appl Environ Microbiol

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“…PtdIns(4)P is presumably formed on the LCV membrane by the Icm/Dot substrate SidF, a 'CX 5R' domain PI 3-phosphatase that hydrolyzes in vitro PtdIns(3,4)P2 [and also PtdIns(3,4,5)P3] (Hsu et al, 2012). The Icm/Dot substrate LppA is another effector that preferentially hydrolyzes polyphosphorylated PIs to produce PtdIns(4)P in vitro (Weber et al, 2014b). However, in infected phagocytes, LppA does not affect the LCV PI pattern, but rather functions as a hexakisphosphate inositol (phytate) phosphatase (i.e.…”

Section: Interaction With the Secretory Pathway And The Endoplasmic Rmentioning

confidence: 99%

Formation of a pathogen vacuole according toLegionella pneumophila: how to kill one bird with many stones

2015

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SummaryLegionella species are ubiquitous, waterborne bacteria that thrive in numerous ecological niches. Yet, in contrast to many other environmental bacteria, Legionella spp. are also able to grow intracellularly in predatory protozoa. This feature mainly accounts for the pathogenicity of Legionella pneumophila, which causes the majority of clinical cases of a severe pneumonia termed Legionnaires' disease. The pathomechanism underlying L. pneumophila infection is based on macrophage resistance, which in turn is largely defined by the opportunistic pathogen's resistance towards amoebae. L. pneumophila replicates in macrophages or amoebae in a unique membranebound compartment, the Legionella-containing vacuole (LCV). LCV formation requires the bacterial intracellular multiplication/defective for organelle trafficking (Icm/Dot) type IV secretion system and involves a plethora of translocated effector proteins, which subvert pivotal processes in the host cell. Of the ca. 300 different experimentally validated Icm/Dot substrates, about 50 have been studied and attributed a cellular function to date. The versatility and ingenuity of these effectors' mode of actions is striking. In this review, we summarize insight into the cellular functions and biochemical activities of well-characterized L. pneumophila effector proteins and the host pathways they target. Recent studies not only substantially increased our knowledge about pathogen-host interactions, but also shed light on novel biological mechanisms.

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“…It has bacteriostatic effects on Legionella, potentially due to chelation of iron and other metal ions, thereby limiting the micronutrients accessible for Legionella's intracellular growth. This growth inhibition can be relieved by LppA (Weber et al 2014a). Identification of LppA as a phytate phosphatase effector revealed for the first time that Legionella defuses harmful host cell metabolites and deactivates competing nutrient sequestration mechanisms.…”

Section: Acquisition Of Nutrientsmentioning

confidence: 99%

“…Iron acquisition by IroT might be supported by the effector LppA, which acts as a phytate phosphatase (Weber et al 2014a) (Fig. 4A).…”

Section: Acquisition Of Nutrientsmentioning

confidence: 99%

Creating a customized intracellular niche: subversion of host cell signaling byLegionellatype IV secretion system effectors

Mattheis

Tate

et al. 2015

Can. J. Microbiol.

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Abstract:The Gram-negative facultative intracellular pathogen Legionella pneumophila infects a wide range of different protozoa in the environment and also human alveolar macrophages upon inhalation of contaminated aerosols. Inside its hosts, it creates a defined and unique compartment, termed the Legionella-containing vacuole (LCV), for survival and replication. To establish the LCV, L. pneumophila uses its Dot/Icm type IV secretion system (T4SS) to translocate more than 300 effector proteins into the host cell. Although it has become apparent in the past years that these effectors subvert a multitude of cellular processes and allow Legionella to take control of host cell vesicle trafficking, transcription, and translation, the exact function of the vast majority of effectors still remains unknown. This is partly due to high functional redundancy among the effectors, which renders conventional genetic approaches to elucidate their role ineffective. Here, we review the current knowledge about Legionella T4SS effectors, highlight open questions, and discuss new methods that promise to facilitate the characterization of T4SS effector functions in the future.Key words: Legionella, type IV secretion system, effectors, Legionella-containing vacuole.Résumé : Le pathogène intracellulaire facultatif à Gram négatif Legionella pneumophila infecte une large gamme de différents protozoaires environnementaux de même que les macrophages alvéolaires humains des suites de l'inhalation d'aérosols contaminés. À l'intérieur de ses hôtes, il crée un compartiment précis et unique nommé vacuole contenant Legionella (« Legionella-containing vacuole », LCV) pour sa survie et sa multiplication. Afin d'établir une LCV, L. pneumophila utilise sont système de sécrétion de type IV (SST4) Dot/Icm, rendant possible la translocation de plus de 300 protéines effectrices dans la cellule hôte. Au cours des dernières années, on a établi que ces effecteurs subvertissent une multitude de processus cellulaires et permettent à Legionella de prendre le contrôle du trafic cellulaire, de la transcription et de la traduction. Or, la fonction exacte de la grande majorité des effecteurs est toujours inconnue. L'importante redondance fonctionnelle au sein des effecteurs explique en partie cette incertitude et invalide les approches génétiques conventionnelles adoptées pour élucider leur rôle. Dans le présent ouvrage, nous passons en revue les connaissances actuelles entourant les effecteurs SST4 de Legionella, faisons ressortir certaines interrogations, et abordons de nouvelles méthodes qui promettent de faciliter la caractérisation de la fonction des effecteurs SST4. [Traduit par la Rédaction] Mots-clés : Legionella, système de sécrétion de type IV, effecteurs, vacuole contenant Legionella.

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A Type IV Translocated Legionella Cysteine Phytase Counteracts Intracellular Growth Restriction by Phytate

Cited by 25 publications

References 63 publications

Metabolism of myo -Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages

Metabolism of myo -Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages

Formation of a pathogen vacuole according toLegionella pneumophila: how to kill one bird with many stones

Creating a customized intracellular niche: subversion of host cell signaling byLegionellatype IV secretion system effectors

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