Recent Submissions

  • MAIT Cells Are Major Contributors to the Cytokine Response in Group A Streptococcal Toxic Shock Syndrome.

    Emgård, Johanna; Bergsten, Helena; McCormick, John K; Barrantes, Israel; Skrede, Steinar; Sandberg, Johan K; Norrby-Teglund, Anna; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (National Academy of Sciences, 2019-11-26)
    Streptococcal toxic shock syndrome (STSS) is a rapidly progressing, life-threatening, systemic reaction to invasive infection caused by group A streptococci (GAS). GAS superantigens are key mediators of STSS through their potent activation of T cells leading to a cytokine storm and consequently vascular leakage, shock, and multiorgan failure. Mucosal-associated invariant T (MAIT) cells recognize MR1-presented antigens derived from microbial riboflavin biosynthesis and mount protective innate-like immune responses against the microbes producing such metabolites. GAS lack de novo riboflavin synthesis, and the role of MAIT cells in STSS has therefore so far been overlooked. Here we have conducted a comprehensive analysis of human MAIT cell responses to GAS, aiming to understand the contribution of MAIT cells to the pathogenesis of STSS. We show that MAIT cells are strongly activated and represent the major T cell source of IFNγ and TNF in the early stages of response to GAS. MAIT cell activation is biphasic with a rapid TCR Vβ2-specific, TNF-dominated response to superantigens and a later IL-12- and IL-18-dependent, IFNγ-dominated response to both bacterial cells and secreted factors. Depletion of MAIT cells from PBMC resulted in decreased total production of IFNγ, IL-1β, IL-2, and TNFβ. Peripheral blood MAIT cells in patients with STSS expressed elevated levels of the activation markers CD69, CD25, CD38, and HLA-DR during the acute compared with the convalescent phase. Our data demonstrate that MAIT cells are major contributors to the early cytokine response to GAS, and are therefore likely to contribute to the pathological cytokine storm underlying STSS.
  • Labyrinthopeptins exert broad-spectrum antiviral activity through lipid-binding-mediated virolysis.

    Prochnow, Hans; Rox, Katharina; Birudukota, N V Suryanarayana; Weichert, Loreen; Hotop, Sven-Kevin; Klahn, Philipp; Mohr, Kathrin; Franz, Sergej; Banda, Dominic H; Blockus, Sebastian; et al. (ASM, 2019-10-30)
    To counteract the serious health threat posed by known and novel viral pathogens, drugs that target a variety of viruses through a common mechanism have attracted recent attention due to their potential in treating (re-)emerging infections, for which direct acting antivirals are not available. We found that labyrinthopeptins A1 and A2, the prototype congeners of carbacyclic lanthipeptides, inhibit the proliferation of diverse enveloped viruses, including Dengue virus, Zika virus, West Nile virus, Hepatitis C virus, Chikungunya virus, Karposi's Sarcoma-associated Herpes virus, Cytomegalovirus, and Herpes Simplex virus, in the low μM to nM range. Mechanistic studies on viral particles revealed that labyrinthopeptins induce a virolytic effect through binding to the viral membrane lipid phosphatidylethanolamine (PE). These effects are enhanced by a combined equimolar application of both labyrinthopeptins, and a clear synergism was observed across a concentration range corresponding to IC10-IC90 values of the compounds. Time-resolved experiments with large unilamellar vesicles (LUVs) reveal that membrane lipid raft compositions (PC/PE/Chol/SM (17:10:33:40)) are particularly sensitive to labyrinthopeptins compared to PC/PE (90:10) LUVs, even though the overall PE-amount remains constant. Labyrinthopeptins exhibited low cytotoxicity and had favorable pharmacokinetic properties in mice (t1/2= 10.0 h), which designates them as promising antiviral compounds acting by an unusual viral lipid targeting mechanism.Importance For many viral infections, current treatment options are insufficient. Because the development of each antiviral drug is time-consuming and expensive, the prospect of finding broad-spectrum antivirals that can fight multiple, diverse viruses - well-known as well as (re-)emerging species - has gained attention, especially for the treatment of viral co-infections. While most known broad spectrum agents address processes in the host cell, we found that targeting lipids of the free virus outside the host cell with the natural products labyrinthopeptin A1 and A2 is a viable strategy to inhibit the proliferation of a broad range of viruses from different families, including Chikungunya virus, Dengue virus, Zika virus, Karposi's Sarcoma-associated Herpes virus, or Cytomegalovirus. Labyrinthopeptins bind to viral phosphatidylethanolamine and induce virolysis without exerting cytotoxicity to host cells. This represents a novel and unusual mechanism to tackle medically relevant viral infections.
  • Regulation of Candida albicans Interaction with Macrophages through the Activation of HOG Pathway by Genistein

    Cui, Shuna; Hassan, Rabeay; Heintz-Buschart, Anna; Bilitewski, Ursula; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI AG, 2016-01-28)
    he severity of infections caused by Candida albicans, the most common opportunistic human fungal pathogen, needs rapid and effective antifungal treatments. One of the effective ways is to control the virulence factors of the pathogen. Therefore, the current study examined the effects of genistein, a natural isoflavone present in soybeans, on C. albicans. The genistein-treated C. albicans cells were then exposed to macrophages. Although no inhibition effect on the growth rates of C. albicans was noted an enhancement of the immune response to macrophages has been observed, indicated by phagocytosis and release of cytokines TNF-α and IL-10. The effect of genistein on the enhanced phagocytosis can be mimicked by the fungicides fludioxonil or iprodione, which inhibit the histidine kinase Cos1p and lead to activation of HOG pathway. The western blot results showed a clear phosphorylation of Hog1p in the wild type strain of C. albicans after incubation with genistein. In addition, effects of genistein on the phosphorylation of Hog1p in the histidine kinase mutants Δcos1 and Δsln1 were also observed. Our results thus indicate a new bio-activity of genistein on C. albicans by activation of the HOG pathway of the human pathogen C. albicans.
  • Anti-biofilm Agents against Pseudomonas aeruginosa: A Structure-Activity Relationship Study of C-Glycosidic LecB Inhibitors

    Sommer, Roman; Rox, Katharina; Wagner, Stefanie; Hauck, Dirk; Henrikus, Sarah S; Newsad, Shelby; Arnold, Tatjana; Ryckmans, Thomas; Brönstrup, Mark; Imberty, Anne; et al. (American Chemical Society, 2019-10-24)
    Biofilm formation is a key mechanism of antimicrobial resistance. We have recently reported two classes of orally bioavailable C-glycosidic inhibitors of the Pseudomonas aeruginosa lectin LecB with antibiofilm activity. They proved efficient in target binding, were metabolically stable, nontoxic, selective, and potent in inhibiting formation of bacterial biofilm. Here, we designed and synthesized six new carboxamides and 24 new sulfonamides for a detailed structure-activity relationship for two clinically representative LecB variants. Sulfonamides generally showed higher inhibition compared to carboxamides, which was rationalized based on crystal structure analyses. Substitutions at the thiophenesulfonamide increased binding through extensive contacts with a lipophilic protein patch. These metabolically stable compounds showed a further increase in potency toward the target and in biofilm inhibition assays. In general, we established the structure-activity relationship for these promising antibiofilm agents and showed that modification of the sulfonamide residue bears future optimization potential.
  • Diversity and community composition of particle-associated and free-living bacteria in mesopelagic and bathypelagic Southern Ocean water masses: Evidence of dispersal limitation in the Bransfield Strait

    Milici, Mathias; Vital, Marius; Tomasch, Jürgen; Badewien, Thomas H.; Giebel, Helge A.; Plumeier, Iris; Wang, Hui; Pieper, Dietmar H.; Wagner-Döbler, Irene; Simon, Meinhard; et al. (Wiley-Blackwell, 2017-05-01)
    The Southern Ocean constitutes about 10% of the global oceans' volume and is characterized by high primary production. Particulate organic matter (POM) is exported from the photic zone to the deep ocean and sustains life of particle associated (PA) and free-living (FL) bacterial communities in the dark realm. Little is known about the composition and diversity of PA and FL bacterial communities below the photic zone and how they differ among various regions of the Southern Ocean. Therefore, we investigated the composition of small (3–8 μm) and large (> 8 μm) PA and FL (0.2–3 μm) bacterial communities between 500 m and 3600 m in the Bransfield Strait, Drake Passage, and the south Atlantic Ocean featuring also Southern Ocean water masses. PA bacterial communities had a higher OTU richness and evenness than FL ones. Taxonomic analysis revealed a different community composition between FL and PA bacteria. A large number of OTUs belonging to diverse phyla (Bacteroidetes, Planctomycetes, Betaproteobacteria, Deltaproteobacteria, and Verrucomicrobia) were significantly enriched on particles; in contrast very few bacterial lineages were FL specialists. Life-style (FL vs. PA) and region (Bransfield basin vs. other regions) strongly influenced bacterial communities. Depth explained only marginal fraction of the total variation (∼ 12%), suggesting that selective processes driven by depth have a smaller effect in the Southern Ocean when compared to life-style (25%) and region (31%). Overall these data indicate a strong influence of isolated water masses such as the basin of the Bransfield Strait on the composition of bacterial communities in the dark ocean. © 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography
  • Diversity of Bacteria Exhibiting Bile Acid-inducible 7α-dehydroxylation Genes in the Human Gut.

    Vital, Marius; Rud, Tatjana; Rath, Silke; Pieper, Dietmar H; Schlüter, Dirk; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2019-01-01)
    The secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA), formed by gut microbiota from primary bile acids via a multi-step 7α-dehydroxylation reaction, have wide-ranging effects on host metabolism and play an important role in health and disease. A few 7α-dehydroxylating strains have been isolated, where bile acid-inducible (bai) genes were organized in a gene cluster and encoded major enzymes involved. However, only little is known on diversity and abundance of intestinal bacteria catalysing DCA/LCA formation in the human gut in situ. In this study, we took the opportunity to screen metagenome-assembled genomes (MAGs) from sequence data of stool samples provided by two recent studies along with newly available gut-derived isolates for the presence of the bai gene cluster. We revealed in total 765 and 620 MAGs encoding the potential to form DCA/LCA that grouped into 21 and 26 metagenomic species, respectively. The majority of MAGs (92.4 and 90.3%) were associated with a Ruminococcaceae clade that still lacks an isolate, whereas less MAGs belonged to Lachnospiraceae along with eight new isolates (n total = 11) that contained the bai genes. Only a few MAGs were linked to Peptostreptococcaceae. Signatures for horizontal transfer of bai genes were observed. This study gives a comprehensive overview of the diversity of bai-exhibiting bacteria in the human gut highlighting the application of metagenomics to unravel potential functions hidden from current isolates. Eventually, isolates of the identified main MAG clade are required in order to prove their capability of 7α-dehydroxylating primary bile acids.
  • Hydantoin analogs inhibit the fully assembled ClpXP protease without affecting the individual peptidase and chaperone domains.

    Fetzer, Christian; Korotkov, Vadim S; Sieber, Stephan A; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Royal Society of Chemistry, 2019-08-14)
    Proteolysis mediated by ClpXP is a crucial cellular process linked to bacterial pathogenesis. The development of specific inhibitors has largely focused on ClpP. However, this focus was challenged by a recent finding showing that conformational control by ClpX leads to a rejection of ClpP binders. Thus, we here follow up on a hit molecule from a high throughput screen performed against the whole ClpXP complex and demonstrate that stable inhibition with high potency is possible. Further investigations revealed that the small molecule binds to ClpP without affecting its activity. Likewise, the molecule does not inhibit ClpX and retains the overall oligomeric state of ClpXP upon binding. Structure activity relationship studies confirmed structural constraints in all three parts of the molecule suggesting binding into a defined stereospecific pocket. Overall, the inhibition of ClpXP without affecting the individual components represents a novel mechanism with perspectives for further optimization for in situ applications.
  • Isolation and characterisation of irinans, androstane-type withanolides from L.

    Stein, Annika; Compera, Dave; Karge, Bianka; Brönstrup, Mark; Franke, Jakob; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Beilstein Institut, 2019-01-01)
    Withanolides are steroidal lactones widespread in Nightshade plants with often potent antiproliferative activities. Additionally, the structural diversity of this compound class holds much potential for the discovery of novel biological activity. Here, we report two newly characterised withanolides, named irinans, from Physalis peruviana with highly unusual truncated backbones that resemble mammalian androstane sex hormones. Based on biomimetic chemical reactions, we propose a model that links these compounds to withanolide biosynthesis. Irinans have potent antiproliferative activities, that are however lower than those of 4ß-hydroxywithanolide E. Our work establishes androwithanolides as a new subclass of withanolides.
  • Molecular profiling of tissue biopsies reveals unique signatures associated with streptococcal necrotizing soft tissue infections

    Thänert, Robert; Itzek, Andreas; Hoßmann, Jörn; Hamisch, Domenica; Madsen, Martin Bruun; Hyldegaard, Ole; Skrede, Steinar; Bruun, Trond; Norrby-Teglund, Anna; Medina, Eva; et al. (Nature, 2019-08-26)
    Necrotizing soft tissue infections (NSTIs) are devastating infections caused by either a single pathogen, predominantly Streptococcus pyogenes, or by multiple bacterial species. A better understanding of the pathogenic mechanisms underlying these different NSTI types could facilitate faster diagnostic and more effective therapeutic strategies. Here, we integrate microbial community profiling with host and pathogen(s) transcriptional analysis in patient biopsies to dissect the pathophysiology of streptococcal and polymicrobial NSTIs. We observe that the pathogenicity of polymicrobial communities is mediated by synergistic interactions between community members, fueling a cycle of bacterial colonization and inflammatory tissue destruction. In S. pyogenes NSTIs, expression of specialized virulence factors underlies infection pathophysiology. Furthermore, we identify a strong interferon-related response specific to S. pyogenes NSTIs that could be exploited as a potential diagnostic biomarker. Our study provides insights into the pathophysiology of mono- and polymicrobial NSTIs and highlights the potential of host-derived signatures for microbial diagnosis of NSTIs.
  • What you see is what you get: Activity-based probes in single-cell analysis of enzymatic activities

    Lentz, Christian S.; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (DeGruyter, 2019-01-01)
    Molecular imaging methods can provide spatio-temporal information about the distribution of biomolecules or biological processes, such as certain enzymatic activities, in single cells. Within a cell, it is possible to define the subcellular location of a target, its trafficking through the cell, colocalization with other biomolecules of interest and involvement in certain cell biological processes. On the other hand, single-cell imaging promises to distinguish cells that are phenotypically different from each other. The corresponding cellular diversity comprises the presence of functionally distinct cells in a population (‘phenotypic heterogeneity’), as well as dynamic cellular responses to external stimuli (‘phenotypic plasticity’), which is highly relevant, e.g. during cell differentiation, activation (of immune cells), or cell death. This review focuses on applications of a certain class of chemical probes, the so-called activity-based probes (ABPs), for visualization of enzymatic activities in the single-cell context. It discusses the structure of ABPs and other chemical probes, exemplary applications of ABPs in single-cell studies in human, mouse and bacterial systems and considerations to be made with regard to data interpretation
  • The intriguing chemistry and biology of soraphens.

    Naini, Arun; Sasse, Florenz; Brönstrup, Mark (Royal Society of Chemistry, 2019-04-05)
    Covering: up to the end of 2018Soraphens are a class of polyketide natural products discovered from the myxobacterial strain Sorangium cellulosum. The review is intended to provide an overview on the biosynthesis, chemistry and biological properties of soraphens, that represent a prime example to showcase the value of natural products as tools to decipher cell biology, but also to open novel therapeutic options. The prototype soraphen A is an inhibitor of acetyl coenzyme A carboxylase (ACC1/2), an enzyme that converts acetyl-CoA to malonyl-CoA and thereby controls essential cellular metabolic processes like lipogenesis and fatty acid oxidation. Soraphens illustrate how the inhibition of a single target (ACC1/2) may be explored to treat various pathological conditions: initially developed as a fungicide, efforts in the past decade were directed towards human diseases, including diabetes/obesity, cancer, hepatitis C, HIV, and autoimmune disease - and led to a synthetic molecule, discovered by virtual screening of the allosteric binding site of soraphen in ACC, that is currently in phase 2 clinical trials. We will summarize how structural analogs of soraphen A have been generated through extensive isolation efforts, genetic engineering of the biosynthetic gene cluster, semisynthesis as well as partial and total synthesis.
  • Long-term Multidonor Fecal Microbiota Transfer (FMT) by Oral Capsules for Active Ulcerative Colitis.

    Steube, Arndt; Vital, Marius; Grunert, Philip; Pieper, Dietmar H; Stallmach, Andreas; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Oxford Academic, 2019-04-15)
  • Discovery pipelines for marine resources: an ocean of opportunity for biotechnology?

    Smith, D; Buddie, A G; Goss, R J M; Overmann, J; Lepleux, C; Brönstrup, M; Kloareg, B; Meiners, T; Brennecke, P; Ianora, A; et al. (Springer, 2019-07-02)
    Marine microbial diversity offers enormous potential for discovery of compounds of crucial importance in healthcare, food security and bioindustry. However, access to it has been hampered by the difficulty of accessing and growing the organisms for study. The discovery and exploitation of marine bioproducts for research and commercial development requires state-of-the-art technologies and innovative approaches. Technologies and approaches are advancing rapidly and keeping pace is expensive and time consuming. There is a pressing need for clear guidance that will allow researchers to operate in a way that enables the optimal return on their efforts whilst being fully compliant with the current regulatory framework. One major initiative launched to achieve this, has been the advent of European Research Infrastructures. Research Infrastructures (RI) and associated centres of excellence currently build harmonized multidisciplinary workflows that support academic and private sector users. The European Marine Biological Research Infrastructure Cluster (EMBRIC) has brought together six such RIs in a European project to promote the blue bio-economy. The overarching objective is to develop coherent chains of high-quality services for access to biological, analytical and data resources providing improvements in the throughput and efficiency of workflows for discovery of novel marine products. In order to test the efficiency of this prototype pipeline for discovery, 248 rarely-grown organisms were isolated and analysed, some extracts demonstrated interesting biochemical properties and are currently undergoing further analysis. EMBRIC has established an overarching and operational structure to facilitate the integration of the multidisciplinary value chains of services to access such resources whilst enabling critical mass to focus on problem resolution.
  • Firefly Bioluminescence-Based Detection of ATP

    Jarrad, Angie M,; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (CSIRO Publishing, 2019-06-04)
    Adenosine triphosphate (ATP) bioluminescence is a powerful light-producing phenomenon that occurs in nature in a variety of organisms, with ATP bioluminescence of fireflies one of the most well-known examples. The firefly ATP bioluminescence reaction has been adapted to the laboratory with a wide range of applications that include monitoring cellular processes, antimicrobial susceptibility testing, and the detection of bacterial contamination of environmental surfaces. ATP bioluminescence occurs through a multistep reaction between firefly luciferase, ATP, magnesium salt, and oxygen (Scheme 1).[1] As a simplified overview, luciferyl adenylate 2 is first formed from luciferin 1 and Mg2+-ATP. The luciferyl adenylate 2 is then oxidised with molecular oxygen to form a dioxetanone cyclic peroxide intermediate 3. Following intramolecular conversion to produce electronically excited states of oxyluciferin, the dioxetanone is decarboxylated. Finally, the return of excited oxyluciferin to the ground state 5 results in emission of visible light. For more detailed insights into the reaction mechanism, including alternative reactions and different tautomers of oxyluciferin at varying pH values, readers are referred to additional literature.
  • Species-Specific Conservation of Linear Antigenic Sites on Vaccinia Virus A27 Protein Homologs of Orthopoxviruses.

    Ahsendorf, Henrike P; Gan, Li L; Eltom, Kamal H; Abd El Wahed, Ahmed; Hotop, Sven-Kevin; Roper, Rachel L; Beutling, Ulrike; Broenstrup, Mark; Stahl-Hennig, Christiane; Hoelzle, Ludwig E; et al. (MPDI, 2019-05-29)
    The vaccinia virus (VACV) A27 protein and its homologs, which are found in a large number of members of the genus Orthopoxvirus (OPXV), are targets of viral neutralization by host antibodies. We have mapped six binding sites (epitopes #1A: aa 32-39, #1B: aa 28-33, #1C: aa 26-31, #1D: 28-34, #4: aa 9-14, and #5: aa 68-71) of A27 specific monoclonal antibodies (mAbs) using peptide arrays. MAbs recognizing epitopes #1A-D and #4 neutralized VACV Elstree in a complement dependent way (50% plaque-reduction: 12.5-200 µg/mL). Fusion of VACV at low pH was blocked through inhibition of epitope #1A. To determine the sequence variability of the six antigenic sites, 391 sequences of A27 protein homologs available were compared. Epitopes #4 and #5 were conserved among most of the OPXVs, while the sequential epitope complex #1A-D was more variable and, therefore, responsible for species-specific epitope characteristics. The accurate and reliable mapping of defined epitopes on immuno-protective proteins such as the A27 of VACV enables phylogenetic studies and insights into OPXV evolution as well as to pave the way to the development of safer vaccines and chemical or biological antivirals.
  • Deep sequencing of biofilm microbiomes on dental composite materials.

    Conrads, Georg; Wendt, Laura Katharina; Hetrodt, Franziska; Deng, Zhi-Luo; Pieper, Dietmar; Abdelbary, Mohamed M H; Barg, Andree; Wagner-Döbler, Irene; Apel, Christian (2019-01-01)
    Background: The microbiome on dental composites has not been studied in detail before. It has not been conclusively clarified whether restorative materials influence the oral microbiome. Methods: We used Illumina Miseq next-generation sequencing of the 16S V1-V2 region to compare the colonisation patterns of bovine enamel (BE) and the composite materials Grandio Flow (GF) and Grandio Blocs (GB) after 48 h in vivo in 14 volunteers. Applying a new method to maintain the oral microbiome ex vivo for 48 h also, we compared the microbiome on GF alone and with the new antimicrobial substance carolacton (GF+C). Results: All in vitro biofilm communities showed a higher diversity and richness than those grown in vivo but the very different atmospheric conditions must be considered. Contrary to expectations, there were only a few significant differences between BE and the composite materials GB and GF either in vivo or in vitro: Oribacterium, Peptostreptococcaceae [XI][G-1] and Streptococcus mutans were more prevalent and Megasphaera, Prevotella oulorum, Veillonella atypica, V. parvula, Gemella morbillorum, and Fusobacterium periodonticum were less prevalent on BE than on composites. In vivo, such preferences were only significant for Granulicatella adiacens (more prevalent on BE) and Fusobacterium nucleatum subsp. animalis (more prevalent on composites). On DNA sequence level, there were no significant differences between the biofilm communities on GF and GF+C. Conclusion: We found that the oral microbiome showed an increased richness when grown on various composites compared to BE in vitro, but otherwise changed only slightly independent of the in vivo or in vitro condition. Our new ex vivo biofilm model might be useful for pre-clinical testing of preventive strategies.
  • New geldanamycin derivatives with anti Hsp properties by mutasynthesis.

    Hermane, Jekaterina; Eichner, Simone; Mancuso, Lena; Schröder, Benjamin; Sasse, Florenz; Zeilinger, Carsten; Kirschning, Andreas; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Royal Society of Chemistry, 2019-05-29)
    Mutasynthetic supplementation of the AHBA blocked mutant strain of S. hygroscopicus, the geldanamycin producer, with 21 aromatic and heteroaromatic amino acids provided new nonquinoid geldanamycin derivatives. Large scale (5 L) fermentation provided four new derivatives in sufficient quantity for full structural characterisation. Among these, the first thiophene derivative of reblastatin showed strong antiproliferative activity towards several human cancer cell lines. Additionally, inhibitory effects on human heat shock protein Hsp90α and bacterial heat shock protein from H. pylori HpHtpG were observed, revealing strong displacement properties for labelled ATP and demonstrating that the ATP-binding site of Hsps is the target site for the new geldanamycin derivatives.
  • Von Willebrand Factor Mediates Pneumococcal Aggregation and Adhesion in Blood Flow.

    Jagau, Hilger; Behrens, Ina-Kristin; Lahme, Karen; Lorz, Georgina; Köster, Reinhard W; Schneppenheim, Reinhard; Obser, Tobias; Brehm, Maria A; König, Gesa; Kohler, Thomas P; et al. (Frontiers, 2019-01-01)
    Streptococcus pneumoniae is a major cause of community acquired pneumonia and septicaemia in humans. These diseases are frequently associated with thromboembolic cardiovascular complications. Pneumococci induce the exocytosis of endothelial Weibel-Palade Bodies and thereby actively stimulate the release of von Willebrand factor (VWF), which is an essential glycoprotein of the vascular hemostasis. Both, the pneumococcus induced pulmonary inflammation and the thromboembolytic complications are characterized by a dysbalanced hemostasis including a marked increase in VWF plasma concentrations. Here, we describe for the first time VWF as a novel interaction partner of capsulated and non-encapsulated pneumococci. Moreover, cell culture infection analyses with primary endothelial cells characterized VWF as bridging molecule that mediates bacterial adherence to endothelial cells in a heparin-sensitive manner. Due to the mechanoresponsive changes of the VWF protein conformation and multimerization status, which occur in the blood stream, we used a microfluidic pump system to generate shear flow-induced multimeric VWF strings on endothelial cell surfaces and analyzed attachment of RFP-expressing pneumococci in flow. By applying immunofluorescence visualization and additional electron microscopy, we detected a frequent and enduring bacterial attachment to the VWF strings. Bacterial attachment to the endothelium was confirmed in vivo using a zebrafish infection model, which is described in many reports and acknowledged as suitable model to study hemostasis mechanisms and protein interactions of coagulation factors. Notably, we visualized the recruitment of zebrafish-derived VWF to the surface of pneumococci circulating in the blood stream and detected a VWF-dependent formation of bacterial aggregates within the vasculature of infected zebrafish larvae. Furthermore, we identified the surface-exposed bacterial enolase as pneumococcal VWF binding protein, which interacts with the VWF domain A1 and determined the binding kinetics by surface plasmon resonance. Subsequent epitope mapping using an enolase peptide array indicates that the peptide 181YGAEIFHALKKILKS195 might serve as a possible core sequence of the VWF interaction site. In conclusion, we describe a VWF-mediated mechanism for pneumococcal anchoring within the bloodstream via surface-displayed enolase, which promotes intravascular bacterial aggregation.
  • Kaposi's sarcoma-associated herpesvirus vIRF2 protein utilizes an IFN-dependent pathway to regulate viral early gene expression.

    Koch, Sandra; Damas, Modester; Freise, Anika; Hage, Elias; Dhingra, Akshay; Rückert, Jessica; Gallo, Antonio; Kremmer, Elisabeth; Tegge, Werner; Brönstrup, Mark; et al. (PLOS, 2019-05-01)
    Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) belongs to the subfamily of Gammaherpesvirinae and is the etiological agent of Kaposi's sarcoma as well as of two lymphoproliferative diseases: primary effusion lymphoma and multicentric Castleman disease. The KSHV life cycle is divided into a latent and a lytic phase and is highly regulated by viral immunomodulatory proteins which control the host antiviral immune response. Among them is a group of proteins with homology to cellular interferon regulatory factors, the viral interferon regulatory factors 1-4. The KSHV vIRFs are known as inhibitors of cellular interferon signaling and are involved in different oncogenic pathways. Here we characterized the role of the second vIRF protein, vIRF2, during the KSHV life cycle. We found the vIRF2 protein to be expressed in different KSHV positive cells with early lytic kinetics. Importantly, we observed that vIRF2 suppresses the expression of viral early lytic genes in both newly infected and reactivated persistently infected endothelial cells. This vIRF2-dependent regulation of the KSHV life cycle might involve the increased expression of cellular interferon-induced genes such as the IFIT proteins 1, 2 and 3, which antagonize the expression of early KSHV lytic proteins. Our findings suggest a model in which the viral protein vIRF2 allows KSHV to harness an IFN-dependent pathway to regulate KSHV early gene expression.
  • Microbial and Functional Profile of the Ceca from Laying Hens Affected by Feeding Prebiotics, Probiotics, and Synbiotics.

    Pineda-Quiroga, Carolina; Borda-Molina, Daniel; Chaves-Moreno, Diego; Ruiz, Roberto; Atxaerandio, Raquel; Camarinha-Silva, Amélia; García-Rodríguez, Aser; HZI, Helmholtz Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (MPDI, 2019-05-06)
    Diet has an essential influence in the establishment of the cecum microbial communities in poultry, so its supplementation with safe additives, such as probiotics, prebiotics, and synbiotics might improve animal health and performance. This study showed the ceca microbiome modulations of laying hens, after feeding with dry whey powder as prebiotics, Pediococcus acidilactici as probiotics, and the combination of both as synbiotics. A clear grouping of the samples induced per diet was observed (p < 0.05). Operational taxonomic units (OTUs) identified as Olsenella spp., and Lactobacilluscrispatus increased their abundance in prebiotic and synbiotic treatments. A core of the main functions was shared between all metagenomes (45.5%), although the genes encoding for the metabolism of butanoate, propanoate, inositol phosphate, and galactose were more abundant in the prebiotic diet. The results indicated that dietary induced-changes in microbial composition did not imply a disturbance in the principal biological roles, while the specific functions were affected.

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