• Molecular typing of Streptococcus suis strains isolated from diseased and healthy pigs between 1996-2016.

      Prüfer, T Louise; Rohde, Judith; Verspohl, Jutta; Rohde, M; de Greeff, Astrid; Willenborg, Jörg; Valentin-Weigand, Peter; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (PLOS, 2019-01-01)
      Streptococcus suis is an economically important pathogen of pigs as well as a zoonotic cause of human disease. Serotyping is used for further characterization of isolates; some serotypes seem to be more virulent and more widely spread than others. This study characterizes a collection of German field isolates of Streptococcus suis from pigs dating from 1996 to 2016 with respect to capsular genes (cps) specific for individual serotypes and pathotype by multiplex PCR and relates results to the clinical background of these isolates. The most prominent finding was the reduction in prevalence of serotype-2/serotype-1/2 among invasive isolates during this sampling period, which might be attributed to widely implemented autogenous vaccination programs in swine against serotype 2 in Germany. In diseased pigs (systemically ill; respiratory disease) isolates of serotype-1/serotype-14, serotype-2/serotype-1/2, serotype 3 to 5 and 7 to 9 were most frequent while in carrier isolates a greater variety of cps types was found. Serotype-1/serotype-14 seemed to be preferentially located in joints, serotype 4 and serotype 3 in the central nervous system, respectively. The virulence associated extracellular protein factor was almost exclusively associated with invasive serotype-1/serotype-14 and serotype-2/serotype-1/2 isolates. In contrast, lung isolates of serotype-2/serotype-1/2 mainly harbored the gene for muramidase-released protein. Serotype 4 and serotype 9 isolates from clinically diseased pigs most frequently carried the muramidase-released protein gene and the suilysin gene. When examined by transmission electron microscopy all but one of the isolates which were non-typable by molecular and serological methods showed various amounts of capsular material indicating potentially new serotypes among these isolates. Given the variety of cps types/serotypes detected in pigs, not only veterinarians but also medical doctors should consider other serotypes than just serotype 2 when investigating potential human cases of Streptococcus suis infection.
    • Multiple mechanisms mediate resistance to sorafenib in urothelial cancer.

      Knievel, Judith; Schulz, Wolfgang A; Greife, Annemarie; Hader, Christiane; Lübke, Tobias; Schmitz, Ingo; Albers, Peter; Niegisch, Günter (2014)
      Genetic and epigenetic changes in the mitogen activated protein kinase (MAPK) signaling render urothelial cancer a potential target for tyrosine kinase inhibitor (TKI) treatment. However, clinical trials of several TKIs failed to prove efficacy. In this context, we investigated changes in MAPK signaling activity, downstream apoptotic regulators and changes in cell cycle distribution in different urothelial cancer cell lines (UCCs) upon treatment with the multikinase inhibitor sorafenib. None of the classical sorafenib targets (vascular endothelial growth factor receptor 1/-receptor 2, VEGFR1/-R2; platelet-derived growth factor receptor α/-receptor β, PDGFR-α/-β; c-KIT) was expressed at significant levels leaving RAF proteins as its likely molecular target. Low sorafenib concentrations paradoxically increased cell viability, whereas higher concentrations induced G1 arrest and eventually apoptosis. MAPK signaling remained partly active after sorafenib treatment, especially in T24 cells with an oncogenic HRAS mutation. AKT phosphorylation was increased, suggesting compensatory activation of the phosphatidylinositol-3-kinase (PI3K) pathway. Sorafenib regularly down regulated the anti-apoptotic myeloid cell leukemia 1 (Mcl-1) protein, but combinatorial treatment with ABT-737 targeting other B-cell lymphoma 2 (Bcl-2) family proteins did not result in synergistic effects. In summary, efficacy of sorafenib in urothelial cancer cell lines appears hampered by limited effects on MAPK signaling, crosstalk with further cancer pathways and an anti-apoptotic state of UCCs. These observations may account for the lack of efficacy of sorafenib in clinical trials and should be considered more broadly in the development of signaling pathway inhibitors for drug therapy in urothelial carcinoma.
    • Mycoplasma hyopneumoniae resides intracellularly within porcine epithelial cells.

      Raymond, B B A; Turnbull, L; Jenkins, C; Madhkoor, R; Schleicher, I; Uphoff, C C; Whitchurch, C B; Rohde, M; Djordjevic, S P; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (2018-12-06)
      Enzootic pneumonia incurs major economic losses to pork production globally. The primary pathogen and causative agent, Mycoplasma hyopneumoniae, colonises ciliated epithelium and disrupts mucociliary function predisposing the upper respiratory tract to secondary pathogens. Alleviation of disease is reliant on antibiotics, vaccination, and sound animal husbandry, but none are effective at eliminating M. hyopneumoniae from large production systems. Sustainable pork production systems strive to lower reliance on antibiotics but lack of a detailed understanding of the pathobiology of M. hyopneumoniae has curtailed efforts to develop effective mitigation strategies. M. hyopneumoniae is considered an extracellular pathogen. Here we show that M. hyopneumoniae associates with integrin β1 on the surface of epithelial cells via interactions with surface-bound fibronectin and initiates signalling events that stimulate pathogen uptake into clathrin-coated vesicles (CCVs) and caveosomes. These early events allow M. hyopneumoniae to exploit an intracellular lifestyle by commandeering the endosomal pathway. Specifically, we show: (i) using a modified gentamicin protection assay that approximately 8% of M. hyopneumoniae cells reside intracellularly; (ii) integrin β1 expression specifically co-localises with the deposition of fibronectin precisely where M. hyopneumoniae cells assemble extracellularly; (iii) anti-integrin β1 antibodies block entry of M. hyopneumoniae into porcine cells; and (iv) M. hyopneumoniae survives phagolysosomal fusion, and resides within recycling endosomes that are trafficked to the cell membrane. Our data creates a paradigm shift by challenging the long-held view that M. hyopneumoniae is a strict extracellular pathogen and calls for in vivo studies to determine if M. hyopneumoniae can traffic to extrapulmonary sites in commercially-reared pigs.
    • A network of trans-cortical capillaries as mainstay for blood circulation in long bones.

      Grüneboom, Anika; Hawwari, Ibrahim; Weidner, Daniela; Culemann, Stephan; Müller, Sylvia; Henneberg, Sophie; Brenzel, Alexandra; Merz, Simon; Bornemann, Lea; Zec, Kristina; et al. (Nature publishing group(NPG), 2019-01-21)
      Closed circulatory systems (CCS) underlie the function of vertebrate organs, but in long bones their structure is unclear, although they constitute the exit route for bone marrow (BM) leukocytes. To understand neutrophil emigration from BM, we studied the vascular system of murine long bones. Here we show that hundreds of capillaries originate in BM, cross murine cortical bone perpendicularly along the shaft and connect to the periosteal circulation. Structures similar to these trans-cortical-vessels (TCVs) also exist in human limb bones. TCVs express arterial or venous markers and transport neutrophils. Furthermore, over 80% arterial and 59% venous blood passes through TCVs. Genetic and drug-mediated modulation of osteoclast count and activity leads to substantial changes in TCV numbers. In a murine model of chronic arthritic bone inflammation, new TCVs develop within weeks. Our data indicate that TCVs are a central component of the CCS in long bones and may represent an important route for immune cell export from the BM.
    • New insights into the antimicrobial effect of mast cells against Enterococcus faecalis.

      Scheb-Wetzel, Matthias; Rohde, Manfred; Bravo, Alicia; Goldmann, Oliver; Helmholtz Centre for infection reseach,Inhoffenstr. 7, D-38124 Braunschweig, Germany. (2014-11)
      Enterococcus faecalis has emerged as an important cause of life-threatening multidrug-resistant bacterial infections in the hospital setting. The pathogenesis of enterococcal infections has remained a relatively neglected field despite their obvious clinical relevance. The objective of this study was to characterize the interactions between mast cells (MCs), an innate immune cell population abundant in the intestinal lamina propria, and E. faecalis. This study was conducted with primary bone marrow-derived murine MCs. The results demonstrated that MCs exerted an antimicrobial effect against E. faecalis that was mediated both by degranulation, with the concomitant discharge of the antimicrobial effectors contained in the granules, and by the release of extracellular traps, in which E. faecalis was snared and killed. In particular, the cathelicidin LL-37 released by the MCs had potent antimicrobial effect against E. faecalis. We also investigated the specific receptors involved in the recognition of E. faecalis by MCs. We found that Toll-like receptors (TLRs) are critically involved in the MC recognition of E. faecalis, since MCs deficient in the expression of MyD88, an adaptor molecule required for signaling by most TLRs, were significantly impaired in their capacity to degranulate, to reduce E. faecalis growth as well as to release tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) after encountering this pathogen. Furthermore, TLR2 was identified as the most prominent TLR involved in the recognition of E. faecalis by MCs. The results of this study indicate that MCs may be important contributors to the host innate immune defenses against E. faecalis.
    • Nocardiopsis mwathae sp. nov., isolated from the haloalkaline Lake Elmenteita in the African Rift Valley.

      Akhwale, Juliah Khayeli; Göker, Markus; Rohde, Manfred; Schumann, Peter; Boga, Hamadi Iddi; Klenk, Hans-Peter; German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124 Braunschweig, Germany. (2016-01-18)
      During a screening for novel and biotechnologically useful bacteria in haloalkaline lakes, strain No.156(T) was isolated from a sediment sample from lake Elmenteita in the African Rift Valley and studied by a polyphasic taxonomic approach. The strain was observed to form yellow aerial and substrate mycelia; optimal growth was found to be at 30-35 °C in salt concentrations of 6-9 % (w/v) and at pH 7-9. The DNA G+C content of the novel strain was 71 mol%. Analysis of 16S rRNA sequences indicated that the isolate belongs to the genus Nocardiopsis with sequence similarities below 98 % to the type strains of all other representatives of the genus. Mycolic acids were not detected in whole cell methanolysates. The peptidoglycan was found to contain meso-diaminopimelic acid as the diamino acid with no diagnostic sugars. The main polar lipids were identified as phosphatidylmethylethanolamine, phosphatidylcholine, phosphatidylglycerol and phosphatidylinositol but no diphosphatidylglycerol. The predominant menaquinones were MK-11(H8), MK-11(H6), MK-10(H8) and MK-10(H6). Cellular fatty acids were found to consist of saturated and monounsaturated iso- and anteiso-branched acids with 16-18 C-length, tuberculostearic acid (Me18:0), and straight-chain saturated (16:0, 18:0) acids. These characteristics match those of the genus Nocardiopsis. Based on 16S rRNA gene sequence analysis and phenotypic characteristics, a novel species with the name Nocardiopsis mwathae is proposed. The type strain is No.156(T) (=DSM 46659(T) = CECT 8552(T)). The INSDC accession number for the 16S rRNA gene sequence of strain No.156(T) is KF976731.
    • Non-Invasive Approach for Evaluation of Pulmonary Hypertension Using Extracellular Vesicle-Associated Small Non-Coding RNA.

      Lipps, Christoph; Northe, Philipp; Figueiredo, Ricardo; Rohde, Manfred; Brahmer, Alexandra; Krämer-Albers, Eva-Maria; Liebetrau, Christoph; Wiedenroth, Christoph B; Mayer, Eckhard; Kriechbaum, Steffen D; et al. (MDPI, 2019-10-29)
      Extracellular vesicles are released by numerous cell types of the human body under physiological but also under pathophysiological conditions. They are important for cell-cell communication and carry specific signatures of peptides and RNAs. In this study, we aimed to determine whether extracellular vesicles isolated from patients with pulmonary hypertension show a disease specific signature of small non-coding RNAs and thus have the potential to serve as diagnostic and prognostic biomarkers. Extracellular vesicles were isolated from the serum of 23 patients with chronic thromboembolic pulmonary hypertension (CTEPH) and 23 controls using two individual methods: a column-based method or by precipitation. Extracellular vesicle- associated RNAs were analyzed by next-generation sequencing applying molecular barcoding, and differentially expressed small non-coding RNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). We identified 18 microRNAs and 21 P-element induced wimpy testis (PIWI)-interacting RNAs (piRNAs) or piRNA clusters that were differentially expressed in CTEPH patients compared with controls. Bioinformatic analysis predicted a contribution of these piRNAs to the progression of cardiac and vascular remodeling. Expression levels of DQ593039 correlated with clinically meaningful parameters such as mean pulmonary arterial pressure, pulmonary vascular resistance, right ventricular systolic pressure, and levels of N-terminal pro-brain natriuretic peptide. Thus, we identified the extracellular vesicle- derived piRNA, DQ593039, as a potential biomarker for pulmonary hypertension and right heart disease.
    • Novel drug targets in cell wall biosynthesis exploited by gene disruption in Pseudomonas aeruginosa.

      Elamin, Ayssar A; Steinicke, Susanne; Oehlmann, Wulf; Braun, Yvonne; Wanas, Hanaa; Shuralev, Eduard A; Huck, Carmen; Maringer, Marko; Rohde, M; Singh, Mahavir; et al. (2017)
      For clinicians, Pseudomonas aeruginosa is a nightmare pathogen that is one of the top three causes of opportunistic human infections. Therapy of P. aeruginosa infections is complicated due to its natural high intrinsic resistance to antibiotics. Active efflux and decreased uptake of drugs due to cell wall/membrane permeability appear to be important issues in the acquired antibiotic tolerance mechanisms. Bacterial cell wall biosynthesis enzymes have been shown to be essential for pathogenicity of Gram-negative bacteria. However, the role of these targets in virulence has not been identified in P. aeruginosa. Here, we report knockout (k.o) mutants of six cell wall biosynthesis targets (murA, PA4450; murD, PA4414; murF, PA4416; ppiB, PA1793; rmlA, PA5163; waaA, PA4988) in P. aeruginosa PAO1, and characterized these in order to find out whether these genes and their products contribute to pathogenicity and virulence of P. aeruginosa. Except waaA k.o, deletion of cell wall biosynthesis targets significantly reduced growth rate in minimal medium compared to the parent strain. The k.o mutants showed exciting changes in cell morphology and colonial architectures. Remarkably, ΔmurF cells became grossly enlarged. Moreover, the mutants were also attenuated in vivo in a mouse infection model except ΔmurF and ΔwaaA and proved to be more sensitive to macrophage-mediated killing than the wild-type strain. Interestingly, the deletion of the murA gene resulted in loss of virulence activity in mice, and the virulence was restored in a plant model by unknown mechanism. This study demonstrates that cell wall targets contribute significantly to intracellular survival, in vivo growth, and pathogenesis of P. aeruginosa. In conclusion, these findings establish a link between cell wall targets and virulence of P. aeruginosa and thus may lead to development of novel drugs for the treatment of P. aeruginosa infection.
    • The novel extremely acidophilic, cell-wall-deficient archaeon Cuniculiplasma divulgatum gen. nov., sp. nov. represents a new family, Cuniculiplasmataceae fam. nov., of the order Thermoplasmatales.

      Golyshina, Olga V; Lünsdorf, Heinrich; Kublanov, Ilya V; Goldenstein, Nadine I; Hinrichs, Kai-Uwe; Golyshin, Peter N; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-01)
      Two novel cell-wall-less, acidophilic, mesophilic, organotrophic and facultatively anaerobic archaeal strains were isolated from acidic streamers formed on the surfaces of copper-ore-containing sulfidic deposits in south-west Spain and North Wales, UK. Cells of the strains varied from 0.1 to 2 μm in size and were pleomorphic, with a tendency to form filamentous structures. The optimal pH and temperature for growth for both strains were 1.0-1.2 and 37-40 °C, with the optimal substrates for growth being beef extract (3 g l- 1) for strain S5T and beef extract with tryptone (3 and 1 g l- 1, respectively) for strain PM4. The lipid composition was dominated by intact polar lipids consisting of a glycerol dibiphytanyl glycerol tetraether (GDGT) core attached to predominantly glycosidic polar headgroups. In addition, free GDGT and small relative amounts of intact and core diether lipids were present. Strains S5T and PM4 possessed mainly menaquinones with minor fractions of thermoplasmaquinones. The DNA G+C content was 37.3 mol% in strain S5T and 37.16 mol% for strain PM4. A similarity matrix of 16S rRNA gene sequences (identical for both strains) showed their affiliation to the order Thermoplasmatales, with 73.9-86.3 % identity with sequences from members of the order with validly published names. The average nucleotide identity between genomes of the strains determined in silico was 98.75 %, suggesting, together with the 16S rRNA gene-based phylogenetic analysis, that the strains belong to the same species. A novel family, Cuniculiplasmataceae fam. nov., genus Cuniculiplasma gen. nov. and species Cuniculiplasma divulgatum sp. nov. are proposed based on the phylogenetic, chemotaxonomic analyses and physiological properties of the two isolates, S5T and PM4 ( = JCM 30641 = VKM B-2940). The type strain of Cuniculiplasma divulgatum is S5T ( = JCM 30642T = VKM B-2941T).
    • Novel members of the family Micromonosporaceae, Rugosimonospora acidiphila gen. nov., sp. nov. and Rugosimonospora africana sp. nov.

      Monciardini, Paolo; Cavaletti, Linda; Ranghetti, Anna; Schumann, Peter; Rohde, Manfred; Bamonte, Ruggiero; Sosio, Margherita; Mezzelani, Alessandra; Donadio, Stefano; Vicuron Pharmaceuticals, 21040 Gerenzano, Italy. paolo.monciardini@ktedogen.com (2009-11)
      Two novel Gram-positive-staining, acidophilic strains were isolated from soil samples. Both show typical features of filamentous actinomycetes. On the basis of 16S rRNA gene sequence analysis, the strains are members of the family Micromonosporaceae. The two strains contain hydroxydiaminopimelic acid, glycine, alanine and glutamic acid in the peptidoglycan. Fatty acid profiles clearly differentiate the two strains: cyclohexyl C(17 : 0), i-C(16 : 0) and ai-C(17 : 0) are predominant in Delta1(T), while the major components for Delta3(T) are ai-C(17 : 0) and i-C(16 : 0). The two strains also differ in their major menaquinones, MK-9(H(8), H(4), H(6)) for Delta1(T) and MK-9(H(8), H(6)) for Delta3(T), and in phospholipid patterns; Delta1(T) displays phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, methyl phosphatidylethanolamine and an unknown aminophospholipid, while Delta3(T) also contains minor amounts of several unknown phospholipids in addition to these phospholipids. The whole-cell sugars of both strains are galactose, arabinose and xylose. The G+C content of the DNA is 72.7 mol% for Delta1(T) and 71.9 mol% for Delta3(T). On the basis of chemotaxonomic, physiological and phylogenetic data, we propose Rugosimonospora gen. nov. to accommodate the two strains, with the description of Rugosimonospora acidiphila gen. nov., sp. nov. (the type species; type strain Delta1(T) =DSM 45227(T) =NBRC 104874(T)) and Rugosimonospora africana sp. nov. (type strain Delta3(T) =DSM 45228(T) =NBRC 104875(T)).
    • A novel protein quality control mechanism contributes to heat shock resistance of worldwide-distributed Pseudomonas aeruginosa clone C strains.

      Lee, Changhan; Wigren, Edvard; Trček, Janja; Peters, Verena; Kim, Jihong; Hasni, Muhammad Sharif; Nimtz, Manfred; Lindqvist, Ylva; Park, Chankyu; Curth, Ute; et al. (2015-11)
      Pseudomonas aeruginosa is a highly successful nosocomial pathogen capable of causing a wide variety of infections with clone C strains most prevalent worldwide. In this study, we initially characterize a molecular mechanism of survival unique to clone C strains. We identified a P. aeruginosa clone C-specific genomic island (PACGI-1) that contains the highly expressed small heat shock protein sHsp20c, the founding member of a novel subclass of class B bacterial small heat shock proteins. sHsp20c and adjacent gene products are involved in resistance against heat shock. Heat stable sHsp20c is unconventionally expressed in stationary phase in a wide temperature range from 20 to 42°C. Purified sHsp20c has characteristic features of small heat shock protein class B as it is monodisperse, forms sphere-like 24-meric oligomers and exhibits significant chaperone activity. As the P. aeruginosa clone C population is significantly more heat shock resistant than genetically unrelated P. aeruginosa strains without sHsp20c, the horizontally acquired shsp20c operon might contribute to the survival of worldwide-distributed clone C strains.
    • Occallatibacter riparius gen. nov., sp. nov. and Occallatibacter savannae sp. nov., acidobacteria isolated from Namibian soils, and emended description of the family Acidobacteriaceae.

      Foesel, Bärbel U; Mayer, Susanne; Luckner, Manja; Wanner, Gerhard; Rohde, Manfred; Overmann, Jörg; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-01)
      Three Gram-negative, non-spore-forming, encapsulated bacteria were isolated from a Namibian river-bank soil (strains 277T and 307) and a semiarid savannah soil (strain A2-1cT). 16S rRNA gene sequence analyses placed them within subdivision 1 of the Acidobacteria and revealed 100 % similarity between strains 277T and 307 and 98.2 % similarity between A2-1cT and the former two strains. The closest relatives with validly published names were Telmatobacter bradus, Acidicapsa borealis and Acidicapsa ligni (94.7-95.9 % similarity to the type strains). Cells of all three strains were rod-shaped and motile and divided by binary fission. Ultrastructural analyses revealed a thick cell envelope, resulting mainly from a thick periplasmic space. Colonies of strains 277T and 307 were white to cream and light pink, respectively, while strain A2-1cT displayed a bright pink colour. All three strains were aerobic, chemoheterotrophic mesophiles with a broad temperature range for growth and a moderately acidic pH optimum. Sugars and complex proteinaceous substrates were the preferred carbon and energy sources. A few polysaccharides were degraded. The major quinone in all three strains was MK-8; MK-7 occurred in strain A2-1cT as a minor compound. Major fatty acids were iso-C15 : 0 and iso-C17 : 1ω7c. In addition, iso-C17 : 0 occurred in significant amounts. The DNA G+C contents of strains 277T, 307 and A2-1cT were 59.6, 59.9 and 58.5 mol%, respectively. Based on these characteristics, the three isolates are assigned to two novel species of the novel genus Occallatibacter gen. nov., Occallatibacter riparius sp. nov. [type strain 277T ( = DSM 25168T = LMG 26948T) and reference strain 307 ( = DSM 25169 = LMG 26947)] and Occallatibacter savannae sp. nov. [type strain A2-1cT ( = DSM 25170T = LMG 26946T)]. Together with several other recently described taxa, the novel isolates provide the basis for an emended description of the established family Acidobacteriaceae.
    • The olfactory epithelium as a port of entry in neonatal neurolisteriosis.

      Pägelow, Dennis; Chhatbar, Chintan; Beineke, Andreas; Liu, Xiaokun; Nerlich, Andreas; van Vorst, Kira; Rohde, M; Kalinke, Ulrich; Förster, Reinhold; Halle, Stephan; et al. (2018-10-15)
      Bacterial infections of the central nervous system (CNS) remain a major cause of mortality in the neonatal population. Commonly used parenteral infection models, however, do not reflect the early course of the disease leaving this critical step of the pathogenesis largely unexplored. Here, we analyzed nasal exposure of 1-day-old newborn mice to Listeria monocytogenes (Lm). We found that nasal, but not intragastric administration, led to early CNS infection in neonate mice. In particular, upon bacterial invasion of the olfactory epithelium, Lm subsequently spread along the sensory neurons entering the brain tissue at the cribriform plate and causing a significant influx of monocytes and neutrophils. CNS infection required listeriolysin for penetration of the olfactory epithelium and ActA, a mediator of intracellular mobility, for translocation into the brain tissue. Taken together, we propose an alternative port of entry and route of infection for neonatal neurolisteriosis and present a novel infection model to mimic the clinical features of late-onset disease in human neonates.
    • On the relation between filament density, force generation, and protrusion rate in mesenchymal cell motility.

      Dolati, Setareh; Kage, Frieda; Mueller, Jan; Müsken, Mathias; Kirchner, Marieluise; Dittmar, Gunnar; Sixt, Michael; Rottner, Klemens; Falcke, Martin; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Amrican Society for Cell biology, 2018-11-01)
      Lamellipodia are flat membrane protrusions formed during mesenchymal motion. Polymerization at the leading edge assembles the actin filament network and generates protrusion force. How this force is supported by the network and how the assembly rate is shared between protrusion and network retrograde flow determines the protrusion rate. We use mathematical modeling to understand experiments changing the F-actin density in lamellipodia of B16-F1 melanoma cells by modulation of Arp2/3 complex activity or knockout of the formins FMNL2 and FMNL3. Cells respond to a reduction of density with a decrease of protrusion velocity, an increase in the ratio of force to filament number, but constant network assembly rate. The relation between protrusion force and tension gradient in the F-actin network and the density dependency of friction, elasticity, and viscosity of the network explain the experimental observations. The formins act as filament nucleators and elongators with differential rates. Modulation of their activity suggests an effect on network assembly rate. Contrary to these expectations, the effect of changes in elongator composition is much weaker than the consequences of the density change. We conclude that the force acting on the leading edge membrane is the force required to drive F-actin network retrograde flow.
    • A Periplasmic Complex of the Nitrite Reductase NirS, the Chaperone DnaK, and the Flagellum Protein FliC Is Essential for Flagellum Assembly and Motility in Pseudomonas aeruginosa.

      Borrero-de Acuña, José Manuel; Molinari, Gabriella; Rohde, Manfred; Dammeyer, Thorben; Wissing, Josef; Jänsch, Lothar; Arias, Sagrario; Jahn, Martina; Schobert, Max; Timmis, Kenneth N; et al. (2015-10-01)
      Pseudomonas aeruginosa is a ubiquitously occurring environmental bacterium and opportunistic pathogen responsible for various acute and chronic infections. Obviously, anaerobic energy generation via denitrification contributes to its ecological success. To investigate the structural basis for the interconnection of the denitrification machinery to other essential cellular processes, we have sought to identify the protein interaction partners of the denitrification enzyme nitrite reductase NirS in the periplasm. We employed NirS as an affinity-purifiable bait to identify interacting proteins in vivo. Results obtained revealed that both the flagellar structural protein FliC and the protein chaperone DnaK form a complex with NirS in the periplasm. The interacting domains of NirS and FliC were tentatively identified. The NirS-interacting stretch of amino acids lies within its cytochrome c domain. Motility assays and ultrastructure analyses revealed that a nirS mutant was defective in the formation of flagella and correspondingly in swimming motility. In contrast, the fliC mutant revealed an intact denitrification pathway. However, deletion of the nirF gene, coding for a heme d1 biosynthetic enzyme, which leads to catalytically inactive NirS, did not abolish swimming ability. This pointed to a structural function for the NirS protein. FliC and NirS were found colocalized with DnaK at the cell surface of P. aeruginosa. A function of the detected periplasmic NirS-DnaK-FliC complex in flagellum formation and motility was concluded and discussed.
    • The planctomycete Stieleria maiorica Mal15 employs stieleriacines to alter the species composition in marine biofilms.

      Kallscheuer, Nicolai; Jeske, Olga; Sandargo, Birthe; Boedeker, Christian; Wiegand, Sandra; Bartling, Pascal; Jogler, Mareike; Rohde, Manfred; Petersen, Jörn; Medema, Marnix H; et al. (Nature publishing group(NPG), 2020-06-12)
      Bacterial strains of the phylum Planctomycetes occur ubiquitously, but are often found on surfaces of aquatic phototrophs, e.g. alga. Despite slower growth, planctomycetes are not outcompeted by faster-growing bacteria in biofilms on such surfaces; however, strategies allowing them to compensate for slower growth have not yet been investigated. Here, we identified stieleriacines, a class of N-acylated tyrosines produced by the novel planctomycete Stieleria maiorica Mal15T, and analysed their effects on growth of the producing strain and bacterial species likely co-occurring with strain Mal15T. Stieleriacines reduced the lag phase of Mal15T and either stimulated or inhibited biofilm formation of two bacterial competitors, indicating that Mal15T employs stieleriacines to specifically alter microbial biofilm composition. The genetic organisation of the putative stieleriacine biosynthetic cluster in strain Mal15T points towards a functional link of stieleriacine biosynthesis to exopolysaccharide-associated protein sorting and biofilm formation.
    • Planctomycetes do possess a peptidoglycan cell wall.

      Jeske, Olga; Schüler, Margarete; Schumann, Peter; Schneider, Alexander; Boedeker, Christian; Jogler, Mareike; Bollschweiler, Daniel; Rohde, Manfred; Mayer, Christoph; Engelhardt, Harald; et al. (2015)
      Most bacteria contain a peptidoglycan (PG) cell wall, which is critical for maintenance of shape and important for cell division. In contrast, Planctomycetes have been proposed to produce a proteinaceous cell wall devoid of PG. The apparent absence of PG has been used as an argument for the putative planctomycetal ancestry of all bacterial lineages. Here we show, employing multiple bioinformatic methods, that planctomycetal genomes encode proteins required for PG synthesis. Furthermore, we biochemically demonstrate the presence of the sugar and the peptide components of PG in Planctomycetes. In addition, light and electron microscopic experiments reveal planctomycetal PG sacculi that are susceptible to lysozyme treatment. Finally, cryo-electron tomography demonstrates that Planctomycetes possess a typical PG cell wall and that their cellular architecture is thus more similar to that of other Gram-negative bacteria. Our findings shed new light on the cellular architecture and cell division of the maverick Planctomycetes.
    • Pneumolysin induces platelet destruction, not platelet activation, which can be prevented by immunoglobulin preparations in vitro.

      Jahn, Kristin; Handtke, Stefan; Palankar, Raghavendra; Weißmüller, Sabrina; Nouailles, Geraldine; Kohler, Thomas P; Wesche, Jan; Rohde, Manfred; Heinz, Corina; Aschenbrenner, Axel F; et al.
      Community-acquired pneumonia by primary or superinfections with Streptococcus pneumoniae can lead to acute respiratory distress requiring mechanical ventilation. The pore-forming toxin pneumolysin alters the alveolar-capillary barrier and causes extravasation of protein-rich fluid into the interstitial pulmonary tissue, which impairs gas exchange. Platelets usually prevent endothelial leakage in inflamed pulmonary tissue by sealing inflammation-induced endothelial gaps. We not only confirm that S pneumoniae induces CD62P expression in platelets, but we also show that, in the presence of pneumolysin, CD62P expression is not associated with platelet activation. Pneumolysin induces pores in the platelet membrane, which allow anti-CD62P antibodies to stain the intracellular CD62P without platelet activation. Pneumolysin treatment also results in calcium efflux, increase in light transmission by platelet lysis (not aggregation), loss of platelet thrombus formation in the flow chamber, and loss of pore-sealing capacity of platelets in the Boyden chamber. Specific anti-pneumolysin monoclonal and polyclonal antibodies inhibit these effects of pneumolysin on platelets as do polyvalent human immunoglobulins. In a post hoc analysis of the prospective randomized phase 2 CIGMA trial, we show that administration of a polyvalent immunoglobulin preparation was associated with a nominally higher platelet count and nominally improved survival in patients with severe S pneumoniae-related community-acquired pneumonia. Although, due to the low number of patients, no definitive conclusion can be made, our findings provide a rationale for investigation of pharmacologic immunoglobulin preparations to target pneumolysin by polyvalent immunoglobulin preparations in severe community-acquired pneumococcal pneumonia, to counteract the risk of these patients becoming ventilation dependent. This trial was registered at www.clinicaltrials.gov as #NCT01420744.
    • Preclinical Assessment of Bacteriophage Therapy against Experimental Lung Infection.

      Wienhold, Sandra-Maria; Brack, Markus C; Nouailles, Geraldine; Krishnamoorthy, Gopinath; Korf, Imke H E; Seitz, Claudius; Wienecke, Sarah; Dietert, Kristina; Gurtner, Corinne; Kershaw, Olivia; et al. (MDPI, 2021-12-24)
      Respiratory infections caused by multidrug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality among critically ill hospitalized patients. Bacteriophages (phages) eliminate pathogens with high host specificity and efficacy. However, the lack of appropriate preclinical experimental models hampers the progress of clinical development of phages as therapeutic agents. Therefore, we tested the efficacy of a purified lytic phage, vB_AbaM_Acibel004, against multidrug-resistant A. baumannii clinical isolate RUH 2037 infection in immunocompetent mice and a human lung tissue model. Sham- and A. baumannii-infected mice received a single-dose of phage or buffer via intratracheal aerosolization. Group-specific differences in bacterial burden, immune and clinical responses were compared. Phage-treated mice not only recovered faster from infection-associated hypothermia but also had lower pulmonary bacterial burden, lower lung permeability, and cytokine release. Histopathological examination revealed less inflammation with unaffected inflammatory cellular recruitment. No phage-specific adverse events were noted. Additionally, the bactericidal effect of the purified phage on A. baumannii was confirmed after single-dose treatment in an ex vivo human lung infection model. Taken together, our data suggest that the investigated phage has significant potential to treat multidrug-resistant A. baumannii infections and further support the development of appropriate methods for preclinical evaluation of antibacterial efficacy of phages.