Dataset Information

IFNs Modify the Proteome of Legionella-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid.

ABSTRACT: Macrophages can be niches for bacterial pathogens or antibacterial effector cells depending on the pathogen and signals from the immune system. Here we show that type I and II IFNs are master regulators of gene expression during Legionella pneumophila infection, and activators of an alveolar macrophage-intrinsic immune response that restricts bacterial growth during pneumonia. Quantitative mass spectrometry revealed that both IFNs substantially modify Legionella-containing vacuoles, and comparative analyses reveal distinct subsets of transcriptionally and spatially IFN-regulated proteins. Immune-responsive gene (IRG)1 is induced by IFNs in mitochondria that closely associate with Legionella-containing vacuoles, and mediates production of itaconic acid. This metabolite is bactericidal against intravacuolar L. pneumophila as well as extracellular multidrug-resistant Gram-positive and -negative bacteria. Our study explores the overall role IFNs play in inducing substantial remodeling of bacterial vacuoles and in stimulating production of IRG1-derived itaconic acid which targets intravacuolar pathogens. IRG1 or its product itaconic acid might be therapeutically targetable to fight intracellular and drug-resistant bacteria.

SUBMITTER: Naujoks J

PROVIDER: S-EPMC4734697 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

IFNs Modify the Proteome of Legionella-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid.

Naujoks Jan J Tabeling Christoph C Dill Brian D BD Hoffmann Christine C Brown Andrew S AS Kunze Mareike M Kempa Stefan S Peter Andrea A Mollenkopf Hans-Joachim HJ Dorhoi Anca A Kershaw Olivia O Gruber Achim D AD Sander Leif E LE Witzenrath Martin M Herold Susanne S Nerlich Andreas A Hocke Andreas C AC van Driel Ian I Suttorp Norbert N Bedoui Sammy S Hilbi Hubert H Trost Matthias M Opitz Bastian B

PLoS pathogens 20160201 2

Macrophages can be niches for bacterial pathogens or antibacterial effector cells depending on the pathogen and signals from the immune system. Here we show that type I and II IFNs are master regulators of gene expression during Legionella pneumophila infection, and activators of an alveolar macrophage-intrinsic immune response that restricts bacterial growth during pneumonia. Quantitative mass spectrometry revealed that both IFNs substantially modify Legionella-containing vacuoles, and comparat ...[more]

PMID: 26829557

Similar Datasets

Project description:UnlabelledLegionella pneumophila is an intracellular pathogen that resides within a membrane-bound compartment that is derived from vesicles exiting the endoplasmic reticulum (ER). To create this compartment, these bacteria use a type IV secretion system to deliver effector proteins that subvert host cell functions. Several Legionella effector proteins modulate the function of the host protein Rab1, which is a GTPase that is recruited to the Legionella-containing vacuole (LCV). Here, we examined which of the Rab1-directed enzymatic activities displayed by Legionella effectors are important for localizing the Rab1 protein to the LCV membrane. The guanine nucleotide exchange factor (GEF) domain in the effector protein DrrA (SidM) was essential for Rab1 recruitment to the LCV and Rab1 AMPylation by the nucleotidyltransferase domain in DrrA was important for Rab1 retention. Legionella organisms producing mutant DrrA proteins that were severely attenuated for GEF activity in vitro retained the ability to localize Rab1 to the LCV. Rab1 localization to the LCV mediated by these GEF-defective mutants required AMPylation. Importantly, we found that efficient localization of Rab1 to the LCV occurred when Rab1 GEF activity and Rab1 AMPylation activity were provided by separate proteins. Rab1 phosphocholination (PCylation) by the effector protein AnkX, however, was unable to substitute for Rab1 AMPylation. Lastly, the defect in Rab1 localization to the LCV in AMPylation-deficient strains of Legionella was partially suppressed if the GTPase-activating protein (GAP) LepB was eliminated. Thus, our data indicate that AMPylation of Rab1 is an effective strategy to maintain this GTPase on the LCV membrane.ImportanceActivities that enable the intracellular pathogen Legionella pneumophila to subvert the function of the host protein Rab1 were investigated. Our data show that a posttranslational modification called AMPylation is critical for maintaining a pool of Rab1 on the LCV membrane. AMPylation of Rab1 led to the accumulation of GTP-bound Rab1 on the LCV membrane by protecting the protein from inactivation by GAPs. Importantly, PCylation of Rab1 by the Legionella effector protein AnkX was neither necessary nor sufficient to maintain Rab1 on the LCV, indicating that AMPylation and PCylation represent functionally distinct activities. We conclude that modification of Rab1 by AMPylation is an effective strategy to spatially and temporally regulate the function of this GTPase on a membrane-bound organelle.

Project description:Interferon gamma (IFN-?) restricts the intracellular replication of many pathogens, but the mechanism by which IFN-? confers cell-intrinsic pathogen resistance remains unclear. For example, intracellular replication of the bacterial pathogen Legionella pneumophila in macrophages is potently curtailed by IFN-?. However, consistent with prior studies, no individual genetic deficiency that we tested completely abolished IFN-?-mediated control. Intriguingly, we observed that the glycolysis inhibitor 2-deoxyglucose (2DG) partially rescued L. pneumophila replication in IFN-?-treated macrophages. 2DG inhibits glycolysis and triggers the unfolded protein response, but unexpectedly, it appears these effects are not responsible for perturbing the antimicrobial activity of IFN-?. Instead, we found that 2DG rescues bacterial replication by inhibiting the expression of two key antimicrobial factors, inducible nitric oxide synthase (iNOS) and immune-responsive gene 1 (IRG1). Using immortalized and primary macrophages deficient in iNOS and IRG1, we confirmed that loss of both iNOS and IRG1, but not individual deficiency in either gene, partially reduced IFN-?-mediated restriction of L. pneumophila Further, using a combinatorial CRISPR/Cas9 mutagenesis approach, we found that mutation of iNOS and IRG1 in combination with four other genes (CASP11, IRGM1, IRGM3, and NOX2) resulted in a total loss of L. pneumophila restriction by IFN-? in primary bone marrow macrophages. Our study defines a complete set of cell-intrinsic factors required for IFN-?-mediated restriction of an intracellular bacterial pathogen and highlights the combinatorial strategy used by hosts to block bacterial replication in macrophages.IMPORTANCE Legionella pneumophila is one example among many species of pathogenic bacteria that replicate within mammalian macrophages during infection. The immune signaling factor interferon gamma (IFN-?) blocks L. pneumophila replication in macrophages and is an essential component of the immune response to L. pneumophila and other intracellular pathogens. However, to date, no study has identified the exact molecular factors induced by IFN-? that are required for its activity. We generated macrophages lacking different combinations of IFN-?-induced genes in an attempt to find a genetic background in which there is a complete loss of IFN-?-mediated restriction of L. pneumophila We identified six genes that comprise the totality of the IFN-?-dependent restriction of L. pneumophila replication in macrophages. Our results clarify the molecular basis underlying the potent effects of IFN-? and highlight how redundancy downstream of IFN-? is key to prevent exploitation of macrophages by pathogens.

Project description:LCVs purified by immuno-magnetic separation and density gradient centrifugation (fraction 4) were resolved by 1D-SDS-PAGE, the gel lanes were excised in ten equidistant pieces and subjected to trypsin digestion. For the subsequent LC-MS/MS measurements, the digests were separated by reversed phase column chromatography using an EASYnLC apparatus with self-packed columns in a one-column setup. Following loading/ desalting in 0.1% acetic acid in water at a flow rate of 700 nL/min (maximum 220 bar), the peptides were separated by applying a binary non-linear gradient from 5-50% acetonitrile in 0.1% acetic acid over 70 min. The LC was coupled online to a LTQ-Velos Orbitrap mass spectrometer (Thermo Fisher, Bremen, Germany) at a spray voltage of 2.4 kV. After a survey scan in the Orbitrap (r = 30,000), MS/MS data were recorded for the twenty most intensive precursor ions in the linear ion trap. Singly charged ions were not taken into account for MS/MS analysis. The lock mass option was enabled throughout all analyses. After mass spectrometric measurement, MS data was converted into the mzxml format (version 3.1) by ReAdW version 4.3.1 and subsequently subjected to database searching via Sorcerer using Sequest (version 27, revision 11; SageN, Milptas, CA, USA) without charge state deconvolution and deisotoping performed. Database searching was performed either with a database of combined entries of L. pneumophila strain Philadelphia-1 (NC002942) and D. discoideum, or with a database of combined entries of L. pneumophila strain Philadelphia-1 and Mus musculus. Both databases were used as target/decoy databases with a list of common contaminants added (30739 and 64993 entries, respectively). Sequest was used assuming trypsinisation with a fragment ion mass tolerance of 1.00 Da and a search tolerance of 10 ppm for the overview scans. Oxidation of methionine was specified in Sequest as a variable modification. Scaffold (version 3.5.1, Proteome Software Inc., Portland, OR, USA) was used to filter and validate MS/MS-based peptide and protein identifications. Peptide identifications were accepted when spectra exceeded Xcorr values of 2.2, 3.3 and 3.8 for doubly, triply and quadruply peptides with deltaCN values of more than 0.1. Protein identifications are based on at least 2 unique peptides. Proteins that contained similar peptides and could not be differentiated based on MS/MS analysis alone were grouped to meet the principle of parsimony.

Dataset Information

IFNs Modify the Proteome of Legionella-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid.

Publications

IFNs Modify the Proteome of Legionella-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets