scholarly journals Intracellular Growth of Legionella pneumophila in Dictyostelium discoideum, a System for Genetic Analysis of Host-Pathogen Interactions

2000 ◽  
Vol 68 (5) ◽  
pp. 2939-2947 ◽  
Author(s):  
Jonathan M. Solomon ◽  
Adam Rupper ◽  
James A. Cardelli ◽  
Ralph R. Isberg
Keyword(s):  
Genetic Analysis ◽  
Dictyostelium Discoideum ◽  
Legionella Pneumophila ◽  
Bacterial Pathogen ◽  
Intracellular Growth ◽  
Host Pathogen Interactions ◽  
Growth State ◽  
Myosin I ◽  
Host Pathogen ◽  
Endocytic Compartments

ABSTRACT Conditions were established in which Legionella pneumophila, an intracellular bacterial pathogen, could replicate within the unicellular organism Dictyostelium discoideum. By several criteria, L. pneumophila grew by the same mechanism within D. discoideum as it does in amoebae and macrophages. Bacteria grew within membrane-bound vesicles associated with rough endoplasmic reticulum, and L. pneumophila dot/icm mutants, blocked for growth in macrophages and amoebae, also did not grow in D. discoideum. Internalized L. pneumophila avoided degradation by D. discoideum and showed evidence of reduced fusion with endocytic compartments. The ability of L. pneumophila to grow within D. discoideum depended on the growth state of the cells. D. discoideum grown as adherent monolayers was susceptible toL. pneumophila infection and to contact-dependent cytotoxicity during high-multiplicity infections, whereas D. discoideum grown in suspension was relatively resistant to cytotoxicity and did not support intracellular growth. Some knownD. discoideum mutants were examined for their effect on growth of L. pneumophila. The coronin mutant and themyoA/B double myosin I mutant were more permissive than wild-type strains for intracellular growth. Growth of L. pneumophila in a Gβ mutant was slightly reduced compared to the parent strain. This work demonstrates the usefulness of the L. pneumophila-D. discoideum system for genetic analysis of host-pathogen interactions.

scholarly journals Investigation of the host transcriptional response to intracellular bacterial infection using Dictyostelium discoideum as a host model

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Jonas Kjellin ◽  
Maria Pränting ◽  
Frauke Bach ◽  
Roshan Vaid ◽  
Bart Edelbroek ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
High Throughput ◽  
Legionella Pneumophila ◽  
Transcriptional Response ◽  
Infection Model ◽  
Intracellular Pathogens ◽  
Host Pathogen Interactions ◽  
Human Macrophages ◽  
Wide Range ◽  
Host Pathogen

Abstract Background During infection by intracellular pathogens, a highly complex interplay occurs between the infected cell trying to degrade the invader and the pathogen which actively manipulates the host cell to enable survival and proliferation. Many intracellular pathogens pose important threats to human health and major efforts have been undertaken to better understand the host-pathogen interactions that eventually determine the outcome of the infection. Over the last decades, the unicellular eukaryote Dictyostelium discoideum has become an established infection model, serving as a surrogate macrophage that can be infected with a wide range of intracellular pathogens. In this study, we use high-throughput RNA-sequencing to analyze the transcriptional response of D. discoideum when infected with Mycobacterium marinum and Legionella pneumophila. The results were compared to available data from human macrophages. Results The majority of the transcriptional regulation triggered by the two pathogens was found to be unique for each bacterial challenge. Hallmark transcriptional signatures were identified for each infection, e.g. induction of endosomal sorting complexes required for transport (ESCRT) and autophagy genes in response to M. marinum and inhibition of genes associated with the translation machinery and energy metabolism in response to L. pneumophila. However, a common response to the pathogenic bacteria was also identified, which was not induced by non-pathogenic food bacteria. Finally, comparison with available data sets of regulation in human monocyte derived macrophages shows that the elicited response in D. discoideum is in many aspects similar to what has been observed in human immune cells in response to Mycobacterium tuberculosis and L. pneumophila. Conclusions Our study presents high-throughput characterization of D. discoideum transcriptional response to intracellular pathogens using RNA-seq. We demonstrate that the transcriptional response is in essence distinct to each pathogen and that in many cases, the corresponding regulation is recapitulated in human macrophages after infection by mycobacteria and L. pneumophila. This indicates that host-pathogen interactions are evolutionary conserved, derived from the early interactions between free-living phagocytic cells and bacteria. Taken together, our results strengthen the use of D. discoideum as a general infection model.

scholarly journals Legionella Subvert the Functions of Rab1 and Sec22b to Create a Replicative Organelle

2004 ◽  
Vol 199 (9) ◽  
pp. 1201-1211 ◽  
Author(s):  
Jonathan C. Kagan ◽  
Mary-Pat Stein ◽  
Marc Pypaert ◽  
Craig R. Roy
Keyword(s):  
Endoplasmic Reticulum ◽  
Legionella Pneumophila ◽  
Molecular Mechanisms ◽  
Bacterial Pathogen ◽  
Host Cells ◽  
Intracellular Growth ◽  
Host Proteins ◽  
Morphological Studies ◽  
Bacterial Replication ◽  
Inhibition Studies

Legionella pneumophila is a bacterial pathogen that infects eukaryotic host cells and replicates inside a specialized organelle that is morphologically similar to the endoplasmic reticulum (ER). To better understand the molecular mechanisms governing transport of the Legionella-containing vacuole (LCV), we have identified host proteins that participate in the conversion of the LCV into a replicative organelle. Our data show that Rab1 is recruited to the LCV within minutes of uptake. Rab1 recruitment to the LCV precedes remodeling of this compartment by ER-derived vesicles. Genetic inhibition studies demonstrate that Rab1 is important for the recruitment of ER-derived vesicles to the LCV and that inhibiting Rab1 function abrogates intracellular growth of Legionella. Morphological studies indicate that the Sec22b protein is located on ER-derived vesicles recruited to the LCV and that Sec22b is delivered to the LCV membrane. Sec22b function was found to be important for biogenesis of the specialized organelle that supports Legionella replication. These studies demonstrate that Legionella has the ability to subvert Rab1 and Sec22b function to facilitate the transport and fusion of ER-derived vesicles with the LCV, resulting in the formation of a specialized organelle that can support bacterial replication.

scholarly journals Possible Effects of Microbial Ecto-Nucleoside Triphosphate Diphosphohydrolases on Host-Pathogen Interactions

2008 ◽  
Vol 72 (4) ◽  
pp. 765-781 ◽  
Author(s):  
Fiona M. Sansom ◽  
Simon C. Robson ◽  
Elizabeth L. Hartland
Keyword(s):  
Legionella Pneumophila ◽  
Purinergic Signaling ◽  
Extracellular Nucleotides ◽  
Microbial Pathogens ◽  
Nucleoside Triphosphate ◽  
Host Pathogen Interactions ◽  
Host Pathogen ◽  
Specific Receptors ◽  
Parasitic Pathogens

SUMMARYIn humans, purinergic signaling plays an important role in the modulation of immune responses through specific receptors that recognize nucleoside tri- and diphosphates as signaling molecules. Ecto-nucleoside triphosphate diphosphohydrolases (ecto-NTPDases) have important roles in the regulation of purinergic signaling by controlling levels of extracellular nucleotides. This process is key to pathophysiological protective responses such as hemostasis and inflammation. Ecto-NTPDases are found in all higher eukaryotes, and recently it has become apparent that a number of important parasitic pathogens of humans express surface-located NTPDases that have been linked to virulence. For those parasites that are purine auxotrophs, these enzymes may play an important role in purine scavenging, although they may also influence the host response to infection. Although ecto-NTPDases are rare in bacteria, expression of a secreted NTPDase in Legionella pneumophila was recently described. This ecto-enzyme enhances intracellular growth of the bacterium and potentially affects virulence. This discovery represents an important advance in the understanding of the contribution of other microbial NTPDases to host-pathogen interactions. Here we review other progress made to date in the characterization of ecto-NTPDases from microbial pathogens, how they differ from mammalian enzymes, and their association with organism viability and virulence. In addition, we postulate how ecto-NTPDases may contribute to the host-pathogen interaction by reviewing the effect of selected microbial pathogens on purinergic signaling. Finally, we raise the possibility of targeting ecto-NTPDases in the development of novel anti-infective agents based on potential structural and clear enzymatic differences from the mammalian ecto-NTPDases.

Novel class of OTU deubiquitinases regulate substrate ubiquitination upon Legionella infection

2020 ◽  
Author(s):  
Donghyuk Shin ◽  
Anshu Bhattacharya ◽  
Yi-Lin Cheng ◽  
Marta Campos Alonso ◽  
Ahmad Reza Mehdipour ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Effector Proteins ◽  
Homology Detection ◽  
Host Pathogen Interactions ◽  
Catalytic Core ◽  
Ubiquitin Binding ◽  
Structural Differences ◽  
Host Pathogen ◽  
Ubiquitination System ◽  
Structural Insights

AbstractLegionella pneumophila is a gram-negative pathogenic bacterium that causes Legionaries’ disease. The Legionella genome codes more than 300 effector proteins able to modulate host-pathogen interactions during infection. Among them are also enzymes altering the host-ubiquitination system including bacterial ligases and deubiquitinases. In this study, based on homology-detection screening on 305 Legionella effector proteins, we identified two LegionellaOTU-like deubiquitinases (LOT; LotB (Lpg1621/Ceg23) and LotC (Lpg2529), LotA (Lpg2248/Lem21) is already known). A crystal structure of LotC catalytic core (LotC14-310) was determined at 2.4 Å and compared with other OTU deubiquitinases, including LotB. Unlike the classical OTU-family, the structures of Legionella OTU-family (LotB and LotC) shows an extended helical lobe between the Cys-loop and the variable loop, which define a novel class of OTU-deubiquitinase. Despite structural differences in their helical lobes, both LotB and LotC interact with ubiquitin. LotB has an additional ubiquitin binding site (S1’) enabling specific cleavage of Lys63-linked poly-ubiquitin chains. By contrast, LotC only contains the S1 site and cleaves different species of ubiquitin chains. MS analysis of catalytically inactive LotB and LotC identified different categories of host-substrates for these two related DUBs. Together, our results provide new structural insights of bacterial OTU deubiquitinases and indicate distinct roles of bacterial deubiquitinases in host-pathogen interactions.

scholarly journals The Ubiquitination System within Bacterial Host–Pathogen Interactions

2021 ◽  
Vol 9 (3) ◽  
pp. 638
Author(s):  
Vera Vozandychova ◽  
Pavla Stojkova ◽  
Kamil Hercik ◽  
Pavel Rehulka ◽  
Jiri Stulik
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Pathogenic Bacteria ◽  
Vaccine Development ◽  
Shigella Flexneri ◽  
Effector Proteins ◽  
Deubiquitinating Enzymes ◽  
Host Pathogen Interactions ◽  
Host Pathogen ◽  
Ubiquitination System

Ubiquitination of proteins, like phosphorylation and acetylation, is an important regulatory aspect influencing numerous and various cell processes, such as immune response signaling and autophagy. The study of ubiquitination has become essential to learning about host–pathogen interactions, and a better understanding of the detailed mechanisms through which pathogens affect ubiquitination processes in host cell will contribute to vaccine development and effective treatment of diseases. Pathogenic bacteria (e.g., Salmonella enterica, Legionella pneumophila and Shigella flexneri) encode many effector proteins, such as deubiquitinating enzymes (DUBs), targeting the host ubiquitin machinery and thus disrupting pertinent ubiquitin-dependent anti-bacterial response. We focus here upon the host ubiquitination system as an integral unit, its interconnection with the regulation of inflammation and autophagy, and primarily while examining pathogens manipulating the host ubiquitination system. Many bacterial effector proteins have already been described as being translocated into the host cell, where they directly regulate host defense processes. Due to their importance in pathogenic bacteria progression within the host, they are regarded as virulence factors essential for bacterial evasion. However, in some cases (e.g., Francisella tularensis) the host ubiquitination system is influenced by bacterial infection, although the responsible bacterial effectors are still unknown.

Sign in / Sign up

Export Citation Format

Share Document