scholarly journals Identification of a Gal/GalNAc Lectin in the Protozoan Hartmannella vermiformis as a Potential Receptor for Attachment and Invasion by the Legionnaires' Disease Bacterium

1997 ◽  
Vol 186 (4) ◽  
pp. 537-547 ◽  
Author(s):  
Chandrasekar Venkataraman ◽  
Bradley J. Haack ◽  
Subbarao Bondada ◽  
Yousef Abu Kwaik
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Kinase Inhibitors ◽  
Tyrosine Phosphatase ◽  
Bacterial Attachment ◽  
Host Proteins ◽  
Hartmannella Vermiformis ◽  
Legionnaire's Disease ◽  
Legionnaire’S Disease

The Legionnaire's disease bacterium, Legionella pneumophila, is a facultative intracellular pathogen which invades and replicates within two evolutionarily distant hosts, free-living protozoa and mammalian cells. Invasion and intracellular replication within protozoa are thought to be major factors in the transmission of Legionnaire's disease. Although attachment and invasion of human macrophages by L. pneumophila is mediated in part by the complement receptors CR1 and CR3, the protozoan receptor involved in bacterial attachment and invasion has not been identified. To define the molecular events involved in invasion of protozoa by L. pneumophila, we examined the role of protein tyrosine phosphorylation of the protozoan host Hartmannella vermiformis upon attachment and invasion by L. pneumophila. Bacterial attachment and invasion were associated with a time-dependent tyrosine dephosphorylation of multiple host cell proteins. This host cell response was highly specific for live L. pneumophila, required contact with viable bacteria, and was completely reversible following washing off the bacteria from the host cell surface. Tyrosine dephosphorylation of host proteins was blocked by a tyrosine phosphatase inhibitor but not by tyrosine kinase inhibitors. One of the tyrosine dephosphorylated proteins was identified as the 170-kD galactose/N-acetylgalactosamine–inhibitable lectin (Gal/GalNAc) using immunoprecipitation and immunoblotting by antibodies generated against the Gal/GalNAc lectin of the protozoan Entamoeba histolytica. This Gal/GalNAc–inhibitable lectin has been shown previously to mediate adherence of E. histolytica to mammalian epithelial cells. Uptake of L. pneumophila by H. vermiformis was specifically inhibited by two monovalent sugars, Gal and GalNAc, and by mABs generated against the 170-kD lectin of E. histolytica. Interestingly, inhibition of invasion by Gal and GalNAc was associated with inhibition of bacterial-induced tyrosine dephosphorylation of H. vermiformis proteins. High stringency DNA hybridization confirmed the presence of the 170-kD lectin gene in H. vermiformis. We conclude that attachment of L. pneumophila to the H. vermiformis 170-kD lectin is required for invasion and is associated with tyrosine dephosphorylation of the Gal lectin and other host proteins. This is the first demonstration of a potential receptor used by L. pneumophila to invade protozoa.

scholarly journals Identification of Putative Cytoskeletal Protein Homologues in the Protozoan Host Hartmannella vermiformis as Substrates for Induced Tyrosine Phosphatase Activity upon Attachment to the Legionnaires' Disease Bacterium, Legionella pneumophila

1998 ◽  
Vol 188 (3) ◽  
pp. 505-514 ◽  
Author(s):  
Chandrasekar Venkataraman ◽  
Lian-Yong Gao ◽  
Subbarao Bondada ◽  
Yousef Abu Kwaik
Keyword(s):  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Tyrosine Phosphatase ◽  
Bacterial Attachment ◽  
Cytoskeletal Proteins ◽  
Bacterial Invasion ◽  
Receptor Mediated Endocytosis ◽  
Legionnaires Disease ◽  
Hartmannella Vermiformis ◽  
Major Factors

The Legionnaires' disease bacterium, Legionella pneumophila, is a facultative intracellular pathogen that invades and replicates within two evolutionarily distant hosts, free living protozoa and mammalian cells. Invasion and intracellular replication within protozoa are thought to be major factors in the transmission of Legionnaires' disease. We have recently reported the identification of a galactose/N-acetyl-d-galactosamine (Gal/GalNAc) lectin in the protozoan host Hartmannella vermiformis as a receptor for attachment and invasion by L. pneumophila (Venkataraman, C., B.J. Haack, S. Bondada, and Y.A. Kwaik. 1997. J. Exp. Med. 186:537–547). In this report, we extended our studies to the effects of bacterial attachment and invasion on the cytoskeletal proteins of H. vermiformis. We first identified the presence of many protozoan cytoskeletal proteins that were putative homologues to their mammalian counterparts, including actin, pp125FAK, paxillin, and vinculin, all of which were basally tyrosine phosphorylated in resting H. vermiformis. In addition to L. pneumophila–induced tyrosine dephosphorylation of the lectin, bacterial attachment and invasion was associated with tyrosine dephosphorylation of paxillin, pp125FAK, and vinculin, whereas actin was minimally affected. Inhibition of bacterial attachment to H. vermiformis by Gal or GalNAc monomers blocked bacteria-induced tyrosine dephosphorylation of detergent-insoluble proteins. In contrast, inhibition of bacterial invasion but not attachment failed to block bacteria-induced tyrosine dephosphorylation of H. vermiformis proteins. This was further supported by the observation that 10 mutants of L. pneumophila that were defective in invasion of H. vermiformis were capable of inducing tyrosine dephosphorylation of H. vermiformis proteins. Entry of L. pneumophila into H. vermiformis was predominantly mediated by noncoated receptor-mediated endocytosis (93%) but coiling phagocytosis was infrequently observed (7%). We conclude that attachment but not invasion by L. pneumophila into H. vermiformis was sufficient and essential to induce protein tyrosine dephosphorylation in H. vermiformis. These manipulations of host cell processes were associated with, or followed by, entry of the bacteria by a noncoated receptor-mediated endocytosis. A model for attachment and entry of L. pneumophila into H. vermiformis is proposed.

Legionnaire’s Disease

2001 ◽  
Vol 58 (10) ◽  
pp. 592-598
Author(s):  
Andreas F. Widmer
Keyword(s):  
Legionella Pneumophila ◽  
Legionnaire's Disease ◽  
Legionnaire’S Disease ◽  
Legionella Micdadei

Legionellen sind Wasserkeime und können zwei typische Krankheitsbilder auslösen: Das Pontiac-Fieber und die Legionärskrankheit. Letztere ist eine seltene (3–7%), potentiell lebensbedrohliche Pneumonie. In fast allen Fällen ist Legionella pneumophila Serogruppe I für die Pneumonie verantwortlich. Es gibt aber 42 Arten und 64 Serotypen, wobei Legionella micdadei der zweithäufigste Erreger ist. Die Letalität der Legionellenpneumonie liegt immer noch um 5% bis 10% und ist bei hospitalisierten Patienten höher. Etablierte Risiken sind Nikotinabusus, chronisch-obstruktive Pneumopathie, sowie Immunsuppression. Die Kultur bedingt Spezialnährmedien, so dass die Diagnose nicht mit Routinemethoden gestellt werden kann. Die Einführung des Antigentestes im Urin hat die Diagnostik wesentlich verbessert. Eine PCR für Sputum ergänzt die neuen diagnostischen Möglichkeiten, wobei hier die Kosten und die Spezifität die Anwendung auf Spezialfälle einschränkt. Therapie der Wahl sind neuere Makrolide oder alternativ neuere Quinolone, die sich vor allem bei transplantierten Patienten auch als Therapie der ersten Wahl durchgesetzt haben. Die Primärprävention umfasst das Halten der Warmwasserversorgung am Boiler bei 60°C, und an Hähnen zwei Minuten nach Öffnen 50°C.

scholarly journals Community-acquired pneumonia caused by Legionella pneumophila (“Legionnaire's Disease”): a brief overview and clinical observation

2020 ◽  
Vol 30 (3) ◽  
pp. 350-360
Author(s):  
I. S. Tartakovskiу ◽  
S. A. Rachin ◽  
A. I. Sinopal'nikov ◽  
S. A. Rachina ◽  
Y. A. Yanovich ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Clinical Observation ◽  
Community Acquired Pneumonia ◽  
Legionnaire's Disease ◽  
Legionnaire’S Disease

scholarly journals Outbreak of Legionnaire’s Disease Caused by Legionella pneumophila Serogroups 1 and 13

2017 ◽  
Vol 23 (2) ◽  
pp. 349-351 ◽  
Author(s):  
Toshiro Kuroki ◽  
Junko Amemura-Maekawa ◽  
Hitomi Ohya ◽  
Ichiro Furukawa ◽  
Miyuki Suzuki ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Legionnaire's Disease ◽  
Legionnaire’S Disease

scholarly journals Identification of a Gene That Affects the Efficiency of Host Cell Infection by Legionella pneumophila in a Temperature-Dependent Fashion

2003 ◽  
Vol 71 (11) ◽  
pp. 6256-6263 ◽  
Author(s):  
Dennis A. Ridenour ◽  
Suat L. G. Cirillo ◽  
Sheng Feng ◽  
Mustapha M. Samrakandi ◽  
Jeffrey D. Cirillo
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Growth Conditions ◽  
Host Cells ◽  
Secretion Systems ◽  
Cell Infection ◽  
Type Iv ◽  
Low Copy Number ◽  
Type Gene

ABSTRACT The ability to infect host cells is critical for the survival and replication of intracellular pathogens in humans. We previously found that many genes involved in the ability of Legionella pneumophila to infect macrophages are not expressed efficiently under standard laboratory growth conditions. We have developed an approach using expression of L. pneumophila genes from an exogenous constitutive promoter on a low-copy-number vector that allows identification of genes involved in host cell infection. Through the use of this strategy, we found that expression of a gene, lvhB2, enhances the efficiency of L. pneumophila infection of mammalian cells. The putative protein encoded by lvhB2 has similarity to structural pilin subunits of type IV secretion systems. We confirmed that this gene plays a role in host cell infection by the construction of an in-frame deletion in the L. pneumophila lvhB2 gene and complementation of this mutant with the wild-type gene. The lvhB2 mutant does not display a very obvious defect in interactions with host cells when the bacteria are grown at 37°C, but it has an approximately 100-fold effect on entry and intracellular replication when grown at 30°C. These data suggest that lvhB2 plays an important role in the efficiency of host cell infection by L. pneumophila grown at lower temperatures.

scholarly journals Rapid Nutritional Remodeling of the Host Cell upon Attachment of Legionella pneumophila

2013 ◽  
Vol 82 (1) ◽  
pp. 72-82 ◽  
Author(s):  
William M. Bruckert ◽  
Christopher T. Price ◽  
Yousef Abu Kwaik
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Host Cell ◽  
Legionella Pneumophila ◽  
Human Monocyte ◽  
Bacterial Attachment ◽  
Content Type ◽  
Cytosolic Side ◽  
Novel Strategy ◽  
Intracellular Proliferation

ABSTRACTUpon entry ofLegionella pneumophilainto amoebas and macrophages, host-mediated farnesylation of the AnkB effector enables its anchoring to theLegionella-containing vacuole (LCV) membrane. On the LCV, AnkB triggers docking of K48-linked polyubiquitinated proteins that are degraded by the host proteasomes to elevate cellular levels of amino acids needed for intracellular proliferation. Interference with AnkB function triggersL. pneumophilato exhibit a starvation response and differentiate into the nonreplicative phase in response to the basal levels of cellular amino acids that are not sufficient to power intracellular proliferation ofL. pneumophila. Therefore, we have determined whether the biological function of AnkB is temporally and spatially triggered upon bacterial attachment to the host cell to circumvent a counterproductive bacterial differentiation into the nonreplicative phase upon bacterial entry. Here, we show that upon attachment ofL. pneumophilato human monocyte-derived macrophages (hMDMs), the host farnesylation and ubiquitination machineries are recruited by the Dot/Icm system to the plasma membrane exclusively beneath sites of bacterial attachment. Transcription and injection ofankBis triggered by attached extracellular bacteria followed by rapid farnesylation and anchoring of AnkB to the cytosolic side of the plasma membrane beneath bacterial attachment, where K48-linked polyubiquitinated proteins are assembled and degraded by the proteasomes, leading to a rapid rise in the cellular levels of amino acids. Our data represent a novel strategy by an intracellular pathogen that triggers rapid nutritional remodeling of the host cell upon attachment to the plasma membrane, and as a result, a gratuitous surplus of cellular amino acids is generated to support proliferation of the incoming pathogen.

scholarly journals Endoplasmic Reticulum Tubule Protein Reticulon 4 Associates with the Legionella pneumophila Vacuole and with Translocated Substrate Ceg9

2015 ◽  
Vol 83 (9) ◽  
pp. 3479-3489 ◽  
Author(s):  
Eva Haenssler ◽  
Vinay Ramabhadran ◽  
Connor S. Murphy ◽  
Matthew I. Heidtman ◽  
Ralph R. Isberg
Keyword(s):  
Endoplasmic Reticulum ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Early Stage ◽  
Ectopic Expression ◽  
Structural Features ◽  
Host Proteins ◽  
Tubule Formation ◽  
Content Type ◽  
Vesicular Traffic

Intracellular growth ofLegionella pneumophilaoccurs in a replication vacuole constructed by host proteins that regulate vesicular traffic from the host endoplasmic reticulum (ER). This process is promoted by a combination of approximately 300 Icm/Dot translocated substrates (IDTS). One of these proteins, Ceg9, was previously identified in a screen forL. pneumophilaIDTS that manipulate secretory traffic when overexpressed in yeast. Using ectopic expression of Ceg9 in mammalian cells, we demonstrate that Ceg9 interacts with isoforms of host reticulon 4 (Rtn4), a protein that regulates ER tubule formation. Binding occurs under conditions that prevent association with other known reticulon binding proteins, arguing that Ceg9 binding is stable. A tripartite complex was demonstrated among Rtn4, Ceg9, and atlastin 1, a previously characterized reticulon interacting partner. The binding of Ceg9 to Rtn4 was not due to bridging by atlastin 1 but resulted from the two interacting partners binding independently to reticulon. When Ceg9 is ectopically expressed in mammalian cells, it shows a localization pattern that is indistinguishable from that of Rtn4, perhaps due to interactions between and similar structural features of the two proteins. Consistent with Rtn4 playing a role in the formation of theLegionella-containing vacuole, it was recruited to almost 50% of the vacuoles within 20 min postinfection. Our studies suggest thatL. pneumophilaproteins interact with ER tubules at an early stage of replication vacuole formation.

scholarly journals Evolution and Adaptation of Legionella pneumophila to Manipulate the Ubiquitination Machinery of Its Amoebae and Mammalian Hosts

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Christopher T.D. Price ◽  
Yousef Abu Kwaik
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Bacterial Pathogen ◽  
Structural Similarity ◽  
Ubiquitin Pathway ◽  
Diverse Range ◽  
E3 Ligases ◽  
Environmental Bacterium ◽  
Natural Hosts

The ubiquitin pathway is highly conserved across the eukaryotic domain of life and plays an essential role in a plethora of cellular processes. It is not surprising that many intracellular bacterial pathogens often target the essential host ubiquitin pathway. The intracellular bacterial pathogen Legionella pneumophila injects into the host cell cytosol multiple classes of classical and novel ubiquitin-modifying enzymes that modulate diverse ubiquitin-related processes in the host cell. Most of these pathogen-injected proteins, designated as effectors, mimic known E3-ubiquitin ligases through harboring F-box or U-box domains. The classical F-box effector, AnkB targets host proteins for K48-linked polyubiquitination, which leads to excessive proteasomal degradation that is required to generate adequate supplies of amino acids for metabolism of the pathogen. In contrast, the SidC and SdcA effectors share no structural similarity to known eukaryotic ligases despite having E3-ubiquitin ligase activity, suggesting that the number of E3-ligases in eukaryotes is under-represented. L. pneumophila also injects into the host many novel ubiquitin-modifying enzymes, which are the SidE family of effectors that catalyze phosphoribosyl-ubiquitination of serine residue of target proteins, independently of the canonical E1-2-3 enzymatic cascade. Interestingly, the environmental bacterium, L. pneumophila, has evolved within a diverse range of amoebal species, which serve as the natural hosts, while accidental transmission through contaminated aerosols can cause pneumonia in humans. Therefore, it is likely that the novel ubiquitin-modifying enzymes of L. pneumophila were acquired by the pathogen through interkingdom gene transfer from the diverse natural amoebal hosts. Furthermore, conservation of the ubiquitin pathway across eukaryotes has enabled these novel ubiquitin-modifying enzymes to function similarly in mammalian cells. Studies on the biological functions of these effectors are likely to reveal further novel ubiquitin biology and shed further lights on the evolution of ubiquitin.

scholarly journals Dynamic proteomics profiling of Legionella pneumophila infection unveils modulation of the host mitochondrial stress response pathway

2020 ◽  
Author(s):  
Julia Noack ◽  
David Jimenez-Morales ◽  
Erica Stevenson ◽  
Tom Moss ◽  
Gwendolyn Jang ◽  
...  
Keyword(s):  
Stress Response ◽  
Host Cell ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Bacterial Pathogen ◽  
Effector Proteins ◽  
Mitochondrial Stress ◽  
Cellular Targets ◽  
Mitochondrial Proteome ◽  
Cell Proteome

SUMMARYThe human pathogen Legionella pneumophila (L.p.) secretes ~330 bacterial effector proteins into the host cell which interfere with numerous cellular pathways and often regulate host cell proteins through post-translational modifications. However, the cellular targets and functions of most L.p. effectors are not known. In order to obtain a global overview of potential targets of these effectors, we analyzed the host cell proteome, ubiquitinome, and phosphoproteome during L.p. infection. Our analysis reveals dramatic spatiotemporal changes in the host cell proteome that are dependent on the secretion of bacterial effectors. Strikingly, we show that L.p. substantially reshapes the mitochondrial proteome and modulates mitochondrial stress response pathways such as the mitochondrial unfolded protein response (UPRmt). To our knowledge, this is the first evidence of manipulation of the UPRmt by a bacterial pathogen in mammalian cells. In addition, we have identified a previously uncharacterized L.p. effector that is targeted to host cell mitochondria and protects mitochondrial network integrity during mitochondrial stress.

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