Now showing items 21-40 of 3178

    • Inhibition of Respiration of Candida albicans by Small Molecules Increases Phagocytosis Efficacy by Macrophages.

      Cui, Shuna; Li, Minghui; Hassan, Rabeay Y A; Heintz-Buschart, Anna; Wang, Junsong; Bilitewski, Ursula; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstraße 7, 38124 Braunschweig, Germany. (American Society of Microbiology, 2020-04-15)
      Candida albicans adapts to various conditions in different body niches by regulating gene expression, protein synthesis, and metabolic pathways. These adaptive reactions not only allow survival but also influence the interaction with host cells, which is governed by the composition and structure of the fungal cell wall. Numerous studies had shown linkages between mitochondrial functionality, cell wall integrity and structure, and pathogenicity. Thus, we decided to inhibit single complexes of the respiratory chain of C. albicans and to analyze the resultant interaction with macrophages via their phagocytic activity. Remarkably, inhibition of the fungal bc1 complex by antimycin A increased phagocytosis, which correlated with an increased accessibility of β-glucans. To contribute to mechanistic insights, we performed metabolic studies, which highlighted significant changes in the abundance of constituents of the plasma membrane. Collectively, our results reinforce the strong linkage between fungal energy metabolism and other components of fungal physiology, which also determine the vulnerability to immune defense reactions.IMPORTANCE The yeast Candida albicans is one of the major fungal human pathogens, for which new therapeutic approaches are required. We aimed at enhancements of the phagocytosis efficacy of macrophages by targeting the cell wall structure of C. albicans, as the coverage of the β-glucan layer by mannans is one of the immune escape mechanisms of the fungus. We unambiguously show that inhibition of the fungal bc1 complex correlates with increased accessibilities of β-glucans and improved phagocytosis efficiency. Metabolic studies proved not only the known direct effects on reactive oxygen species (ROS) production and fermentative pathways but also the clear downregulation of the ergosterol pathway and upregulation of unsaturated fatty acids. The changed composition of the plasma membrane could also influence the interaction with the overlying cell wall. Thus, our work highlights the far-reaching relevance of energy metabolism, indirectly also for host-pathogen interactions, without affecting viability.
    • Human Lentiviral Gene Therapy Restores the Cellular Phenotype of Autosomal Recessive Complete IFN-γR1 Deficiency.

      Hahn, Katharina; Pollmann, Liart; Nowak, Juliette; Nguyen, Ariane Hai Ha; Haake, Kathrin; Neehus, Anna-Lena; Waqas, Syed F Hassnain; Pessler, Frank; Baumann, Ulrich; Hetzel, Miriam; et al. (Elsevier(Cell Press), 2020-04-11)
      Autosomal recessive (AR) complete interferon-γ receptor 1 (IFN-γR1) deficiency, also known as one genetic etiology of Mendelian susceptibility to mycobacterial disease (MSMD), is a life-threatening congenital disease leading to premature death. Affected patients present a pathognomonic predisposition to recurrent and severe infections with environmental mycobacteria or the Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine. Current therapeutic options are limited to antibiotic treatment and hematopoietic stem cell transplantation, however with poor outcome. Given the clinical success of gene therapy, we introduce the first lentiviral-based gene therapy approach to restore expression and function of the human IFN-γR-downstream signaling cascade. In our study, we developed lentiviral vectors constitutively expressing the human IFN-γR1 and demonstrate stable transgene expression without interference with cell viability and proliferation in transduced human hematopoietic cells. Using an IFN-γR1-deficient HeLa cell model, we show stable receptor reconstitution and restored IFN-γR1 signaling without adverse effect on cell functionality. Transduction of both SV40-immortalized and primary fibroblasts derived from IFN-γR1-deficient MSMD patients was able to recover IFN-γR1 expression and restore type II IFN signaling upon stimulation with IFN-γ. In summary, we highlight lentiviral vectors to correct the IFN-γ mediated immunity and present the first gene therapy approach for patients suffering from AR complete IFN-γR1 deficiency.
    • Vitamin C supports conversion of human γδ T cells into FOXP3-expressing regulatory cells by epigenetic regulation.

      Kouakanou, Léonce; Peters, Christian; Sun, Qiwei; Floess, Stefan; Bhat, Jaydeep; Huehn, Jochen; Kabelitz, Dieter; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Nature Publishing Group, 2020-04-16)
      Human γδ T cells are potent cytotoxic effector cells, produce a variety of cytokines, and can acquire regulatory activity. Induction of FOXP3, the key transcription factor of regulatory T cells (Treg), by TGF-β in human Vγ9 Vδ2 T cells has been previously reported. Vitamin C is an antioxidant and acts as multiplier of DNA hydroxymethylation. Here we have investigated the effect of the more stable phospho-modified Vitamin C (pVC) on TGF-β-induced FOXP3 expression and the resulting regulatory activity of highly purified human Vγ9 Vδ2 T cells. pVC significantly increased the TGF-β-induced FOXP3 expression and stability and also increased the suppressive activity of Vγ9 Vδ2 T cells. Importantly, pVC induced hypomethylation of the Treg-specific demethylated region (TSDR) in the FOXP3 gene. Genome-wide methylation analysis by Reduced Representation Bisulfite Sequencing additionally revealed differentially methylated regions in several important genes upon pVC treatment of γδ T cells. While Vitamin C also enhances effector functions of Vγ9 Vδ2 T cells in the absence of TGF-β, our results demonstrate that pVC potently increases the suppressive activity and FOXP3 expression in TGF-β-treated Vγ9 Vδ2 T cells by epigenetic modification of the FOXP3 gene
    • The Set7 Lysine Methyltransferase Regulates Plasticity in Oxidative Phosphorylation Necessary for Trained Immunity Induced by β-Glucan.

      Keating, Samuel T; Groh, Laszlo; van der Heijden, Charlotte D C C; Rodriguez, Hanah; Dos Santos, Jéssica C; Fanucchi, Stephanie; Okabe, Jun; Kaipananickal, Harikrishnan; van Puffelen, Jelmer H; Helder, Leonie; et al.
      Trained immunity confers a sustained augmented response of innate immune cells to a secondary challenge, via a process dependent on metabolic and transcriptional reprogramming. Because of its previous associations with metabolic and transcriptional memory, as well as the importance of H3 histone lysine 4 monomethylation (H3K4me1) to innate immune memory, we hypothesize that the Set7 methyltransferase has an important role in trained immunity induced by β-glucan. Using pharmacological studies of human primary monocytes, we identify trained immunity-specific immunometabolic pathways regulated by Set7, including a previously unreported H3K4me1-dependent plasticity in the induction of oxidative phosphorylation. Recapitulation of β-glucan training in vivo additionally identifies Set7-dependent changes in gene expression previously associated with the modulation of myelopoiesis progenitors in trained immunity. By revealing Set7 as a key regulator of trained immunity, these findings provide mechanistic insight into sustained metabolic changes and underscore the importance of characterizing regulatory circuits of innate immune memory.
    • Cellular Importin-α3 Expression Dynamics in the Lung Regulate Antiviral Response Pathways against Influenza A Virus Infection.

      Thiele, Swantje; Stanelle-Bertram, Stephanie; Beck, Sebastian; Kouassi, Nancy Mounogou; Zickler, Martin; Müller, Martin; Tuku, Berfin; Resa-Infante, Patricia; van Riel, Debby; Alawi, Malik; et al.
      Importin-α adaptor proteins orchestrate dynamic nuclear transport processes involved in cellular homeostasis. Here, we show that importin-α3, one of the main NF-κB transporters, is the most abundantly expressed classical nuclear transport factor in the mammalian respiratory tract. Importin-α3 promoter activity is regulated by TNF-α-induced NF-κB in a concentration-dependent manner. High-level TNF-α-inducing highly pathogenic avian influenza A viruses (HPAIVs) isolated from fatal human cases harboring human-type polymerase signatures (PB2 627K, 701N) significantly downregulate importin-α3 mRNA expression in primary lung cells. Importin-α3 depletion is restored upon back-mutating the HPAIV polymerase into an avian-type signature (PB2 627E, 701D) that can no longer induce high TNF-α levels. Importin-α3-deficient mice show reduced NF-κB-activated antiviral gene expression and increased influenza lethality. Thus, importin-α3 plays a key role in antiviral immunity against influenza. Lifting the bottleneck in importin-α3 availability in the lung might provide a new strategy to combat respiratory virus infections.
    • Presence of hepatitis B virus in synovium and its clinical significance in rheumatoid arthritis.

      Chen, Yu-Lan; Jing, Jun; Mo, Ying-Qian; Ma, Jian-Da; Yang, Li-Juan; Chen, Le-Feng; Zhang, Xiang; Yan, Tao; Zheng, Dong-Hui; Pessler, Frank; et al. (BMC, 2018-06-19)
      Previous studies have revealed that hepatitis B virus (HBV) infection may be related to rheumatoid arthritis (RA), but there are no studies on the presence of HBV antigens or nucleic acid in synovium from patients with RA with HBV infection. In the present study, we investigated the presence of HBV in the synovium and its clinical significance in RA. METHODS: Fifty-seven consecutive patients with active RA (Disease Activity Score 28-joint assessment based on C-reactive protein ≥ 2.6) and available synovial tissue who had completed 1 year of follow-up were recruited from a prospective cohort. The patients were divided into chronic HBV infection (CHB, n = 11) and non-CHB groups according to baseline HBV infection status. Clinical data were collected at baseline and at 1-, 3-, 6-, and 12-month follow-up. Radiographic changes of hand/wrist at baseline and month 12 were assessed with the Sharp/van der Heijde-modified Sharp score (mTSS). HBV in synovium was determined by immunohistochemical staining for hepatitis B virus surface antigen and hepatitis B virus core antigen (HBcAg) and by nested PCR for the HBV S gene. RESULTS: HBcAg was found in the synovium of patients with RA with CHB (7 of 11, 64%), which was confirmed by PCR for the HBV S gene. Compared with the non-CHB group, more CD68-positive macrophages, CD20-positive B cells, and CD15-positive neutrophils infiltrated the synovium in the CHB group (all p <  0.05). There were smaller improvements from baseline in most disease activity indicators mainly at month 12, and a significantly higher percentage of CHB patients experienced 1-year radiographic progression (ΔmTSS ≥ 0.5 unit/yr, 64% vs. 26%, p = 0.024). Multivariate logistic regression analysis showed that CHB status (OR 14.230, 95% CI 2.213-95.388; p = 0.006) and the density of synovial CD68-positive macrophages (OR 1.002, 95% CI 1.001-1.003; p = 0.003) were independently associated with 1-year radiographic progression. CONCLUSIONS: The presence of HBV in RA synovium may be involved in the pathogenesis of local lesions and exacerbate disease progression in RA.
    • Exhaustion and Inflation at Antipodes of T Cell Responses to Chronic Virus Infection.

      Cicin-Sain, Luka; Arens, Ramon; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2017-12-14)
      Viruses that have coevolved with their host establish chronic infections that are well tolerated by the host. Other viruses, that are partly adapted to their host, may induce chronic infections where persistent replication and viral antigen expression occur. The former induce highly functional and resilient CD8T cell responses called memory inflation. The latter induce dysfunctional and exhausted responses. The reasons compelling T cell responses towards inflationary or exhausted responses are only partly understood. In this review we compare the two conditions and describe mechanistic similarities and differences. We also provide a list of potential reasons why exhaustion or inflation occur in different virus infections. We propose that T cell-mediated transcriptional repression of viral gene expression provides a critical feature of inflation that allows peaceful virus and host coexistence. The virus is controlled, but its genome is not eradicated. If this mechanism is not available, as in the case of RNA viruses, the virus and the host are compelled to an arms race. If virus proliferation and spread proceed uncontrolled for too long, T cells are forced to strike a balance between viral control and tissue destruction, losing antiviral potency and facilitating virus persistence.
    • Assortative mating by population of origin in a mechanistic model of admixture

      Goldberg, Amy; Rastogi, Ananya; Rosenberg, Noah A.; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56, 38106 Braunschweig, Germany. (Elsevier BV, 2020-04-07)
      Populations whose mating pairs have levels of similarity in phenotypes or genotypes that differ systematically from the level expected under random mating are described as experiencing assortative mating. Excess similarity in mating pairs is termed positive assortative mating, and excess dissimilarity is negative assortative mating. In humans, empirical studies suggest that mating pairs from various admixed populations-whose ancestry derives from two or more source populations-possess correlated ancestry components that indicate the occurrence of positive assortative mating on the basis of ancestry. Generalizing a two-sex mechanistic admixture model, we devise a model of one form of ancestry-assortative mating that occurs through preferential mating based on source population. Under the model, we study the moments of the admixture fraction distribution for different assumptions about mating preferences, including both positive and negative assortative mating by population. We demonstrate that whereas the mean admixture under assortative mating is equivalent to that of a corresponding randomly mating population, the variance of admixture depends on the level and direction of assortative mating. We consider two special cases of assortative mating by population: first, a single admixture event, and second, constant contributions to the admixed population over time In contrast to standard settings in which positive assortment increases variation within a population, certain assortative mating scenarios allow the variance of admixture to decrease relative to a corresponding randomly mating population: with the three populations we consider, the variance-increasing effect of positive assortative mating within a population might be overwhelmed by a variance-decreasing effect emerging from mating preferences involving other pairs of populations. The effect of assortative mating is smaller on the X chromosome than on the autosomes because inheritance of the X in males depends only on the mother's ancestry, not on the mating pair. Because the variance of admixture is informative about the timing of admixture and possibly about sex-biased admixture contributions, the effects of assortative mating are important to consider in inferring features of population history from distributions of admixture values. Our model provides a framework to quantitatively study assortative mating under flexible scenarios of admixture over time.
    • Atlas of the Immune Cell Repertoire in Mouse Atherosclerosis Defined by Single-Cell RNA-Sequencing and Mass Cytometry.

      Winkels, Holger; Ehinger, Erik; Vassallo, Melanie; Buscher, Konrad; Dinh, Huy Q; Kobiyama, Kouji; Hamers, Anouk A J; Cochain, Clément; Vafadarnejad, Ehsan; Saliba, Antoine-Emmanuel; et al. (Amercan Heart Association, 2018-03-15)
      Using single-cell RNA-sequencing of aortic leukocytes from chow diet- and Western diet-fed Apoe-/- and Ldlr-/- mice, we detected 11 principal leukocyte clusters with distinct phenotypic and spatial characteristics while the cellular repertoire in healthy aortas was less diverse. Gene set enrichment analysis on the single-cell level established that multiple pathways, such as for lipid metabolism, proliferation, and cytokine secretion, were confined to particular leukocyte clusters. Leukocyte populations were differentially regulated in atherosclerotic Apoe-/- and Ldlr-/- mice. We confirmed the phenotypic diversity of these clusters with a novel mass cytometry 35-marker panel with metal-labeled antibodies and conventional flow cytometry. Cell populations retrieved by these protein-based approaches were highly correlated to transcriptionally defined clusters. In an integrated screening strategy of single-cell RNA-sequencing, mass cytometry, and fluorescence-activated cell sorting, we detected 3 principal B-cell subsets with alterations in surface markers, functional pathways, and in vitro cytokine secretion. Leukocyte cluster gene signatures revealed leukocyte frequencies in 126 human plaques by a genetic deconvolution strategy. This approach revealed that human carotid plaques and microdissected mouse plaques were mostly populated by macrophages, T-cells, and monocytes. In addition, the frequency of genetically defined leukocyte populations in carotid plaques predicted cardiovascular events in patients.
    • Special issue: The contributions of Erio Camporesi

      Phukhamsakda, Chayanard; Wijayawardene, Nalin N.; Ariyawansa, Hiran A.; Senanayake, Indunil C.; Li, Wen-Jing; Wanasinghe, Dhanushka N.; Phookamsak, Rungtiwa; Tian, Qing; Daranagama, Dinushani A.; Thambugala, Kasun M.; et al. (Springer Science and Business Media LLC, 2020-03-23)
      [No abstract available]
    • Tutuilamides A-C: Vinyl-Chloride-Containing Cyclodepsipeptides from Marine Cyanobacteria with Potent Elastase Inhibitory Properties.

      Keller, Lena; Canuto, Kirley Marques; Liu, Chenxi; Suzuki, Brian M; Almaliti, Jehad; Sikandar, Asfandyar; Naman, C Benjamin; Glukhov, Evgenia; Luo, Danmeng; Duggan, Brendan M; et al. (AmericanChemical Society(ACS), 2020-01-28)
      Marine cyanobacteria (blue-green algae) have been shown to possess an enormous capacity to produce structurally diverse natural products that exhibit a broad spectrum of potent biological activities, including cytotoxic, antifungal, antiparasitic, antiviral, and antibacterial activities. Using mass-spectrometry-guided fractionation together with molecular networking, cyanobacterial field collections from American Samoa and Palmyra Atoll yielded three new cyclic peptides, tutuilamides A-C. Their structures were established by spectroscopic techniques including 1D and 2D NMR, HR-MS, and chemical derivatization. Structure elucidation was facilitated by employing advanced NMR techniques including nonuniform sampling in combination with the 1,1-ADEQUATE experiment. These cyclic peptides are characterized by the presence of several unusual residues including 3-amino-6-hydroxy-2-piperidone and 2-amino-2-butenoic acid, together with a novel vinyl chloride-containing residue. Tutuilamides A-C show potent elastase inhibitory activity together with moderate potency in H-460 lung cancer cell cytotoxicity assays. The binding mode to elastase was analyzed by X-ray crystallography revealing a reversible binding mode similar to the natural product lyngbyastatin 7. The presence of an additional hydrogen bond with the amino acid backbone of the flexible side chain of tutuilamide A, compared to lyngbyastatin 7, facilitates its stabilization in the elastase binding pocket and possibly explains its enhanced inhibitory potency.
    • Lignipirellula cremea gen. nov., sp. nov., a planctomycete isolated from wood particles in a brackish river estuary.

      Peeters, Stijn H; Wiegand, Sandra; Kallscheuer, Nicolai; Jogler, Mareike; Heuer, Anja; Jetten, Mike S M; Boedeker, Christian; Rohde, Manfred; Jogler, Christian; HZI,Helmholtz Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (Springer, 2020-04-01)
      A novel planctomycetal strain, designated Pla85_3_4T, was isolated from the surface of wood incubated at the discharge of a wastewater treatment plant in the Warnow river near Rostock, Germany. Cells of the novel strain have a cell envelope architecture resembling that of Gram-negative bacteria, are round to pear-shaped (length: 2.2 ± 0.4 µm, width: 1.2 ± 0.3 µm), form aggregates and divide by polar budding. Colonies have a cream colour. Strain Pla85_3_4T grows at ranges of 10-30 °C (optimum 26 °C) and at pH 6.5-10.0 (optimum 7.5), and has a doubling time of 26 h. Phylogenetically, strain Pla85_3_4T (DSM 103796T = LMG 29741T) is concluded to represent a novel species of a novel genus within the family Pirellulaceae, for which we propose the name Lignipirellula cremea gen. nov., sp. nov.
    • Palstimolide A: A Complex Polyhydroxy Macrolide with Antiparasitic Activity.

      Keller, Lena; Siqueira-Neto, Jair L; Souza, Julia M; Eribez, Korina; LaMonte, Gregory M; Smith, Jennifer E; Gerwick, William H; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (MDPI, 2020-03-31)
      Marine Cyanobacteria (blue-green algae) have been shown to possess an enormous potential to produce structurally diverse natural products that exhibit a broad spectrum of potent biological activities, including cytotoxic, antifungal, antiparasitic, antiviral, and antibacterial activities. Here, we report the isolation and structure determination of palstimolide A, a complex polyhydroxy macrolide with a 40-membered ring that was isolated from a tropical marine cyanobacterium collected at Palmyra Atoll. NMR-guided fractionation in combination with MS2-based molecular networking and isolation via HPLC yielded 0.7 mg of the pure compound. The small quantity isolated along with the presence of significant signal degeneracy in both the 1H and 13C-NMR spectra complicated the structure elucidation of palstimolide A. Various NMR experiments and solvent systems were employed, including the LRHSQMBC experiment that allows the detection of long-range 1H-13C correlation data across 4-, 5-, and even 6-bonds. This expanded NMR data set enabled the elucidation of the palstimolide's planar structure, which is characterized by several 1,5-disposed hydroxy groups as well as a tert-butyl group. The compound showed potent antimalarial activity with an IC50 of 223 nM as well as interesting anti-leishmanial activity with an IC50 of 4.67 µM.
    • Single-nucleotide polymorphism-based genetic diversity analysis of clinical Pseudomonas aeruginosa isolates.

      Muthukumarasamy, Uthayakumar; Preusse, Matthias; Kordes, Adrian; Koska, Michal; Schniederjans, Monika; Khaledi, Ariane; Häussler, Susanne; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (Oxford Academic, 2020-03-20)
      Extensive use of next-generation sequencing has the potential to transform our knowledge on how genomic variation within bacterial species impacts phenotypic versatility. Since different environments have unique selection pressures, they drive divergent evolution. However, there is also parallel or convergent evolution of traits in independent bacterial isolates inhabiting similar environments. The application of tools to describe population-wide genomic diversity provides an opportunity to measure the predictability of genetic changes underlying adaptation. Here we describe patterns of sequence variations in the core genome among 99 individual Pseudomonas aeruginosa clinical isolates and identified single nucleotide polymorphisms (SNPs) that are the basis for branching of the phylogenetic tree. We also identified SNPs that were acquired independently, in separate lineages, and not through inheritance from a common ancestor. While our results demonstrate that the P. aeruginosa core genome is highly conserved and in general, not subject to adaptive evolution, instances of parallel evolution will provide an opportunity to uncover genetic changes that underlie phenotypic diversity.
    • Liver-derived extracellular vesicles: A cell by cell overview to isolation and characterization practices.

      Zivko, Cristina; Fuhrmann, Gregor; Luciani, Paola; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Elsevier, 2020-02-19)
      BACKGROUND: Extracellular vesicles (EVs) are a diverse group of membrane-bound nanovesicles potentially released by every cell. With the liver's unique ensemble of cells and its fundamental physiological tasks, elucidating the role of EV-mediated hepatic cellular crosstalk and their role in different pathologies has been gaining the attention of many scientists. SCOPE OF REVIEW: The present review shifts the perspective into practice: we aim to critically discuss the methods used to purify and to biochemically analyse EVs from specific liver resident cells, including hepatocytes, hepatic stellate cells, cholangiocytes, liver sinusoidal endothelial cells, Kupffer cells, liver stem cells. The review offers a reference guide to current approaches. MAJOR CONCLUSIONS: Strategies for EV isolation and characterization are as varied as the research groups performing them. We present main advantages and disadvantages for the methods, highlighting common causes for concern, such as FBS handling, reporting of cell viability, EV yield and storage, differences in differential centrifugations, suboptimal method descriptions, and method transferability. We both looked at how adaptable the research between human and rodent cells in vitro is, and also assessed how well either of them translates to ex vivo settings. GENERAL SIGNIFICANCE: We reviewed methodological practices for the isolation and analysis of liver-derived EVs, making a cell type specific user guide that shows where to start, what has worked so far and to what extent. We critically discussed room for improvement, placing a particular focus on working towards a potential standardization of methods.
    • Advancing human pulmonary disease models in preclinical research: opportunities for lung-on-chips..

      Artzy-Schnirman, Arbel; Lehr, Claus-Michael; Sznitman, Josué; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Taylor&Francis, 2020-03-11)
      [No abstracr available]
    • Grad-seq in a Gram-positive bacterium reveals exonucleolytic sRNA activation in competence control.

      Hör, Jens; Garriss, Geneviève; Di Giorgio, Silvia; Hack, Lisa-Marie; Vanselow, Jens T; Förstner, Konrad U; Schlosser, Andreas; Henriques-Normark, Birgitta; Vogel, Jörg; HIRI, Helmholtz-Institut für RNA-basierte Infektionsforschung, Josef-Shneider Strasse 2, 97080 Würzburg, Germany. (EMBO Press, 2020-03-30)
      RNA-protein interactions are the crucial basis for many steps of bacterial gene expression, including post-transcriptional control by small regulatory RNAs (sRNAs). In stark contrast to recent progress in the analysis of Gram-negative bacteria, knowledge about RNA-protein complexes in Gram-positive species remains scarce. Here, we used the Grad-seq approach to draft a comprehensive landscape of such complexes in Streptococcus pneumoniae, in total determining the sedimentation profiles of ~ 88% of the transcripts and ~ 62% of the proteins of this important human pathogen. Analysis of in-gradient distributions and subsequent tag-based protein capture identified interactions of the exoribonuclease Cbf1/YhaM with sRNAs that control bacterial competence for DNA uptake. Unexpectedly, the nucleolytic activity of Cbf1 stabilizes these sRNAs, thereby promoting their function as repressors of competence. Overall, these results provide the first RNA/protein complexome resource of a Gram-positive species and illustrate how this can be utilized to identify new molecular factors with functions in RNA-based regulation of virulence-relevant pathways.
    • TLR4 abrogates the Th1 immune response through IRF1 and IFN-β to prevent immunopathology during L. infantum infection.

      Sacramento, Laís Amorim; Benevides, Luciana; Maruyama, Sandra Regina; Tavares, Lucas; Fukutani, Kiyoshi Ferreira; Francozo, Marcela; Sparwasser, Tim; Cunha, Fernando Queiroz; Almeida, Roque Pacheco; da Silva, João Santana; et al. (PLOS, 2020-03-25)
      A striking feature of human visceral leishmaniasis (VL) is chronic inflammation in the spleen and liver, and VL patients present increased production levels of multiple inflammatory mediators, which contribute to tissue damage and disease severity. Here, we combined an experimental model with the transcriptional profile of human VL to demonstrate that the TLR4-IFN-β pathway regulates the chronic inflammatory process and is associated with the asymptomatic form of the disease. Tlr4-deficient mice harbored fewer parasites in their spleen and liver than wild-type mice. TLR4 deficiency enhanced the Th1 immune response against the parasite, which was correlated with an increased activation of dendritic cells (DCs). Gene expression analyses demonstrated that IRF1 and IFN-β were expressed downstream of TLR4 after infection. Accordingly, IRF1- and IFNAR-deficient mice harbored fewer parasites in the target organs than wild-type mice due to having an increased Th1 immune response. However, the absence of TLR4 or IFNAR increased the serum transaminase levels in infected mice, indicating the presence of liver damage in these animals. In addition, IFN-β limits IFN-γ production by acting directly on Th1 cells. Using RNA sequencing analysis of human samples, we demonstrated that the transcriptional signature for the TLR4 and type I IFN (IFN-I) pathways was positively modulated in asymptomatic subjects compared with VL patients and thus provide direct evidence demonstrating that the TLR4-IFN-I pathway is related to the nondevelopment of the disease. In conclusion, our results demonstrate that the TLR4-IRF1 pathway culminates in IFN-β production as a mechanism for dampening the chronic inflammatory process and preventing immunopathology development.
    • Aureliella helgolandensis gen. nov., sp. nov., a novel Planctomycete isolated from a jellyfish at the shore of the island Helgoland.

      Kallscheuer, Nicolai; Wiegand, Sandra; Boedeker, Christian; Peeters, Stijn H; Jogler, Mareike; Rast, Patrick; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian; et al. (Springer, 2020-03-27)
      A novel planctomycetal strain, designated Q31aT, was isolated from a jellyfish at the shore of the island Helgoland in the North Sea. The strain forms lucid white colonies on solid medium and displays typical characteristics of planctomycetal strains, such as division by budding, formation of rosettes, presence of crateriform structures, extracellular matrix or fibre and a holdfast structure. Q31aT is mesophilic (temperature optimum 27 °C), neutrophilic (pH optimum 7.5), aerobic and heterotrophic. A maximal growth rate of 0.017 h- 1 (generation time of 41 h) was observed. Q31aT has a genome size of 8.44 Mb and a G + C content of 55.3%. Phylogenetically, the strain represents a novel genus and species in the recently introduced family Pirellulaceae, order Pirellulales, class Planctomycetia. We propose the name Aureliella helgolandensis gen. nov., sp. nov. for the novel species, represented by Q31aT (= DSM 103537T = LMG 29700T) as the type strain.
    • The alarmones (p)ppGpp are part of the heat shock response of Bacillus subtilis.

      Schäfer, Heinrich; Beckert, Bertrand; Frese, Christian K; Steinchen, Wieland; Nuss, Aaron M; Beckstette, Michael; Hantke, Ingo; Driller, Kristina; Sudzinová, Petra; Krásný, Libor; et al. (PLOS, 2020-03-16)
      Bacillus subtilis cells are well suited to study how bacteria sense and adapt to proteotoxic stress such as heat, since temperature fluctuations are a major challenge to soil-dwelling bacteria. Here, we show that the alarmones (p)ppGpp, well known second messengers of nutrient starvation, are also involved in the heat stress response as well as the development of thermo-resistance. Upon heat-shock, intracellular levels of (p)ppGpp rise in a rapid but transient manner. The heat-induced (p)ppGpp is primarily produced by the ribosome-associated alarmone synthetase Rel, while the small alarmone synthetases RelP and RelQ seem not to be involved. Furthermore, our study shows that the generated (p)ppGpp pulse primarily acts at the level of translation, and only specific genes are regulated at the transcriptional level. These include the down-regulation of some translation-related genes and the up-regulation of hpf, encoding the ribosome-protecting hibernation-promoting factor. In addition, the alarmones appear to interact with the activity of the stress transcription factor Spx during heat stress. Taken together, our study suggests that (p)ppGpp modulates the translational capacity at elevated temperatures and thereby allows B. subtilis cells to respond to proteotoxic stress, not only by raising the cellular repair capacity, but also by decreasing translation to concurrently reduce the protein load on the cellular protein quality control system.