group leader: Prof. Rohde

Recent Submissions

  • Microbiome Yarns: microbiome of the built environment, paranormal microbiology, and the power of single cell genomics1,2,3,4.

    Timmis, Kenneth; Jebok, Franziska; Rohde, Manfred; Molinari, Gabriella; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-05-16)
  • Regulation of Flagellum Biosynthesis in Response to Cell Envelope Stress in Serovar Typhimurium.

    Spöring, Imke; Felgner, Sebastian; Preuße, Matthias; Eckweiler, Denitsa; Rohde, Manfred; Häussler, Susanne; Weiss, Siegfried; Erhardt, Marc (2018-05-01)
    Flagellum-driven motility of serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of , resulting in flagellated and nonflagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhDC with respect to proteolytic degradation. Information concerning the environmental cues controlling expression of and thus about the bistable flagellar biosynthesis remains ambiguous. Here, we demonstrated that RflP responds to cell envelope stress and alterations of outer membrane integrity. Lipopolysaccharide (LPS) truncation mutants of Typhimurium exhibited increasing motility defects due to downregulation of flagellar gene expression. Transposon mutagenesis and genetic profiling revealed that σ (RpoE) and Rcs phosphorelay-dependent cell envelope stress response systems sense modifications of the lipopolysaccaride, low pH, and activity of the complement system. This subsequently results in activation of RflP expression and degradation of FlhDC via ClpXP. We speculate that the presence of diverse hostile environments inside the host might result in cell envelope damage and would thus trigger the repression of resource-costly and immunogenic flagellum biosynthesis via activation of the cell envelope stress response. Pathogenic bacteria such as Typhimurium sense and adapt to a multitude of changing and stressful environments during host infection. At the initial stage of gastrointestinal colonization, uses flagellum-mediated motility to reach preferred sites of infection. However, the flagellum also constitutes a prime target for the host's immune response. Accordingly, the pathogen needs to determine the spatiotemporal stage of infection and control flagellar biosynthesis in a robust manner. We found that uses signals from cell envelope stress-sensing systems to turn off production of flagella. We speculate that downregulation of flagellum synthesis after cell envelope damage in hostile environments aids survival of during late stages of infection and provides a means to escape recognition by the immune system.
  • Genome biology of a novel lineage of planctomycetes widespread in anoxic aquatic environments.

    Spring, Stefan; Bunk, Boyke; Spröer, Cathrin; Rohde, Manfred; Klenk, Hans-Peter; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-04-26)
    Anaerobic strains affiliated with a novel order-level lineage of the Phycisphaerae class were retrieved from the suboxic zone of a hypersaline cyanobacterial mat and anoxic sediments of solar salterns. Genome sequences of five isolates were obtained and compared with metagenome-assembled genomes representing related uncultured bacteria from various anoxic aquatic environments. Gene content surveys suggest a strictly fermentative saccharolytic metabolism for members of this lineage, which could be confirmed by the phenotypic characterization of isolates. Genetic analyses indicate that the retrieved isolates do not have a canonical origin of DNA replication, but initiate chromosome replication at alternative sites possibly leading to an accelerated evolution. Further potential factors driving evolution and speciation within this clade include genome reduction by metabolic specialization and rearrangements of the genome by mobile genetic elements, which have a high prevalence in strains from hypersaline sediments and mats. Based on genetic and phenotypic data a distinct group of strictly anaerobic heterotrophic planctomycetes within the Phycisphaerae class could be assigned to a novel order that is represented by the proposed genus Sedimentisphaera gen. nov. comprising two novel species, S. salicampi gen. nov., sp. nov. and S. cyanobacteriorum gen. nov., sp. nov. This article is protected by copyright. All rights reserved.
  • Extracellular Actin Is a Receptor for Mycoplasma hyopneumoniae.

    Raymond, Benjamin B A; Madhkoor, Ranya; Schleicher, Ina; Uphoff, Cord C; Turnbull, Lynne; Whitchurch, Cynthia B; Rohde, Manfred; Padula, Matthew P; Djordjevic, Steven P; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018)
    Mycoplasma hyopneumoniae, an agriculturally important porcine pathogen, disrupts the mucociliary escalator causing ciliostasis, loss of cilial function, and epithelial cell death within the porcine lung. Losses to swine production due to growth rate retardation and reduced feed conversion efficiency are severe, and antibiotics are used heavily to control mycoplasmal pneumonia. Notably, little is known about the repertoire of host receptors that M. hyopneumoniae targets to facilitate colonization. Here we show, for the first time, that actin exists extracellularly on porcine epithelial monolayers (PK-15) using surface biotinylation and 3D-Structured Illumination Microscopy (3D-SIM), and that M. hyopneumoniae binds to the extracellular β-actin exposed on the surface of these cells. Consistent with this hypothesis we show: (i) monoclonal antibodies that target β-actin significantly block the ability of M. hyopneumoniae to adhere and colonize PK-15 cells; (ii) microtiter plate binding assays show that M. hyopneumoniae cells bind to monomeric G-actin in a dose dependent manner; (iii) more than 100 M. hyopneumoniae proteins were recovered from affinity-chromatography experiments using immobilized actin as bait; and (iv) biotinylated monomeric actin binds directly to M. hyopneumoniae proteins in ligand blotting studies. Specifically, we show that the P97 cilium adhesin possesses at least two distinct actin-binding regions, and binds monomeric actin with nanomolar affinity. Taken together, these observations suggest that actin may be an important receptor for M. hyopneumoniae within the swine lung and will aid in the future development of intervention strategies against this devastating pathogen. Furthermore, our observations have wider implications for extracellular actin as an important bacterial receptor.
  • Differential magnesium implant corrosion coat formation and contribution to bone bonding.

    Rahim, Muhammad Imran; Weizbauer, Andreas; Evertz, Florian; Hoffmann, Andrea; Rohde, Manfred; Glasmacher, Birgit; Windhagen, Henning; Gross, Gerhard; Seitz, Jan-Marten; Mueller, Peter P; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
    Magnesium alloys are presently under investigation as promising biodegradable implant materials with osteoconductive properties. To study the molecular mechanisms involved, the potential contribution of soluble magnesium corrosion products to the stimulation of osteoblastic cell differentiation was examined. However, no evidence for the stimulation of osteoblast differentiation could be obtained when cultured mesenchymal precursor cells were differentiated in the presence of metallic magnesium or in cell culture medium containing elevated magnesium ion levels. Similarly, in soft tissue no bone induction by metallic magnesium or by the corrosion product magnesium hydroxide could be observed in a mouse model. Motivated by the comparatively rapid accumulation solid corrosion products physicochemical processes were examined as an alternative mechanism to explain the stimulation of bone growth by magnesium-based implants. During exposure to physiological solutions a structured corrosion coat formed on magnesium whereby the elements calcium and phosphate were enriched in the outermost layer which could play a role in the established biocompatible behavior of magnesium implants. When magnesium pins were inserted into avital bones, corrosion lead to increases in the pull out force, suggesting that the expanding corrosion layer was interlocking with the surrounding bone. Since mechanical stress is a well-established inducer of bone growth, volume increases caused by the rapid accumulation of corrosion products and the resulting force development could be a key mechanism and provide an explanation for the observed stimulatory effects of magnesium-based implants in hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 697-709, 2017.
  • Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products.

    Sváb, Domonkos; Falgenhauer, Linda; Rohde, Manfred; Szabó, Judit; Chakraborty, Trinad; Tóth, István; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018)
    During recent years, interest in the use of bacteriophages as biocontrol agents against foodborne pathogens has increased, particularly for members of the family Enterobacteriaceae, with pathogenic Escherichia coli, Shigella, and Salmonella strains among them. Here, we report the isolation and characterisation of 12 novel T5-like bacteriophages from confiscated food samples. All bacterophages effectively lysed E. coli K-12 strains and were able to infect pathogenic E. coli strains representing enterohaemorrhagic (EHEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), and enteroinvasive (EIEC) pathotypes, Shigella dysenteriae, S. sonnei strains, as well as multidrug-resistant (MDR) E. coli and multiple strains representing different Salmonella enterica serovars. All the bacteriophages exhibited Siphoviridae morphology. Whole genome sequencing of the novel T5-like bacteriophages showed that they represent two distinct groups, with the genome-based grouping correlating to the different host spectra. As these bacteriophages are of food origin, their stability and lack of any virulence genes, as well as their broad and mutually complementary host spectrum makes these new T5-like bacteriophages valuable candidates for use as biocontrol agents against foodborne pathogenic enterobacteria.
  • Microbiome Yarns: human biome reproduction, evolution and visual acuity,,.

    Timmis, Kenneth; Jebok, Franziska; Molinari, Gabriella; Rohde, Manfred; Lahti, Leo; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-01)
  • Labrenzia salina sp. nov., isolated from the rhizosphere of the halophyte Arthrocnemum macrostachyum.

    Camacho, Maria; Redondo-Gómez, Susana; Rodríguez-Llorente, Ignacio; Rohde, Manfred; Spröer, Cathrin; Schumann, Peter; Klenk, Hans-Peter; Montero-Calasanz, Maria Del Carmen; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-12)
    A novel, halophilic, motile, rod-shaped, Gram-staining-negative and non-endospore forming bacterium, designated Cs25T, was isolated from the rhizosphere of the halophyte Arthrocnemum macrostachyum growing in a tidal flat. Strain Cs25T was observed to be catalase-negative and oxidase-positive, and to hydrolyse hypoxanthine. Growth occurred from 15 to 40 °C, at pH 7.0-10.0 and with 1-11 % (w/v) NaCl. Q-10 was identified as the dominant ubiquinone, and the major cellular fatty acids were C18 : 1ω7c, 11-methyl C18 : 1ω7c, C20 : 1ω7c and C18 : 0. The polar lipids comprised phosphatidylmonomethylethanolamine, phosphatidylcholine, sulphoquinovosyldiacylglyceride, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The 16S rRNA gene showed 99.19, 98.6 and 98.59 % sequence identity with Labrenzia alba DSM 18320T, L. aggregata DSM 13394T and L. marina DSM 17023T, respectively. Based on the phenotypic and molecular features and DNA-DNA hybridization data, it is concluded that strain Cs25T represents a novel species for which the name Labrenzia salinasp. nov. is proposed. The type strain is Cs25T (=DSM 29163T=CECT 8816T).
  • Characterization of the first cultured representative of Verrucomicrobia subdivision 5 indicates the proposal of a novel phylum.

    Spring, Stefan; Bunk, Boyke; Spröer, Cathrin; Schumann, Peter; Rohde, Manfred; Tindall, Brian J; Klenk, Hans-Peter; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
    The recently isolated strain L21-Fru-ABTrepresents moderately halophilic, obligately anaerobic and saccharolytic bacteria that thrive in the suboxic transition zones of hypersaline microbial mats. Phylogenetic analyses based on 16S rRNA genes, RpoB proteins and gene content indicated that strain L21-Fru-ABTrepresents a novel species and genus affiliated with a distinct phylum-level lineage originally designated Verrucomicrobia subdivision 5. A survey of environmental 16S rRNA gene sequences revealed that members of this newly recognized phylum are wide-spread and ecologically important in various anoxic environments ranging from hypersaline sediments to wastewater and the intestine of animals. Characteristic phenotypic traits of the novel strain included the formation of extracellular polymeric substances, a Gram-negative cell wall containing peptidoglycan and the absence of odd-numbered cellular fatty acids. Unusual metabolic features deduced from analysis of the genome sequence were the production of sucrose as osmoprotectant, an atypical glycolytic pathway lacking pyruvate kinase and the synthesis of isoprenoids via mevalonate. On the basis of the analyses of phenotypic, genomic and environmental data, it is proposed that strain L21-Fru-ABTand related bacteria are specifically adapted to the utilization of sulfated glycopolymers produced in microbial mats or biofilms.
  • Standard susceptibility testing overlooks potent azithromycin activity and cationic peptide synergy against MDR Stenotrophomonas maltophilia.

    Kumaraswamy, Monika; Lin, Leo; Olson, Joshua; Sun, Ching-Fang; Nonejuie, Poochit; Corriden, Ross; Döhrmann, Simon; Ali, Syed Raza; Amaro, Deirdre; Rohde, Manfred; Pogliano, Joe; Sakoulas, George; Nizet, Victor; Helmholtz-Zentrum für Infectionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2016-05)
    The Gram-negative bacillus Stenotrophomonas maltophilia (SM) is an emerging MDR opportunistic pathogen. Recent studies identify a potentially relevant activity of azithromycin against Gram-negative bacteria overlooked in standard bacteriological testing. We investigated azithromycin activity against SM in testing conditions incorporating mammalian tissue culture medium and host defence factors.
  • Taxonomic analyses of members of the Streptomyces cinnabarinus cluster, description of Streptomyces cinnabarigriseus sp. nov. and Streptomyces davaonensis sp. nov.

    Landwehr, Wiebke; Kämpfer, Peter; Glaeser, Stefanie P; Rückert, Christian; Kalinowski, Jörn; Blom, Jochen; Goesmann, Alexander; Mack, Matthias; Schumann, Peter; Atasayar, Ewelina; Hahnke, Richard L; Rohde, Manfred; Martin, Karin; Stadler, Marc; Wink, Joachim; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-12-11)
    Roseoflavin is the only known riboflavin (vitamin B2) analog with antibiotic properties. It is actively taken up by many micro-organisms and targets flavinmononucleotide riboswitches and flavoproteins. It is described as the product of the tentatively named 'Streptomyces davawensis' JCM 4913. Taxonomic analysis of this strain with a polyphasic approach showed that it is very closely related to Streptomyces cinnabarinus (DSM 40467). The two Streptomyces isolates were obtained from different geographical locations (the Philippines and the Kamchatka Peninsula, respectively), their genomes have been sequenced and the question was whether or not the two isolates were representatives of the same species. As we also worked with another isolate of Streptomyces cinnabarinus JS 360, the producer of the cinnabaramides, we wanted to clarify the taxonomic position of the three isolates by using a polyphasic approach. After analysis of the 16S rRNA gene sequence, we found in total 23 species of the genus Streptomyces that showed a similarity higher than 98.5 % to the three strains. We showed that 'S. davawensis' JCM 4913 and S. cinnabarinus DSM 40467 were very closely related but belong to two different species. Hence, we validate 'S. davawensis' as Streptomyces davaonensis sp. nov. with the type strain JCM 4913T (=DSM 101723T). In addition, the cinnabaramide producer can be clearly differentiated from S. davaonensis and this isolate is described as Streptomyces cinnabarigriseus sp. nov. with strain JS360T (=NCCB 100590T=DSM 101724T) as the type strain.
  • Genome-Scale Data Call for a Taxonomic Rearrangement of Geodermatophilaceae.

    Montero-Calasanz, Maria Del Carmen; Meier-Kolthoff, Jan P; Zhang, Dao-Feng; Yaramis, Adnan; Rohde, Manfred; Woyke, Tanja; Kyrpides, Nikos C; Schumann, Peter; Li, Wen-Jun; Göker, Markus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
    Geodermatophilaceae (order Geodermatophilales, class Actinobacteria) form a comparatively isolated family within the phylum Actinobacteria and harbor many strains adapted to extreme ecological niches and tolerant against reactive oxygen species. Clarifying the evolutionary history of Geodermatophilaceae was so far mainly hampered by the insufficient resolution of the main phylogenetic marker in use, the 16S rRNA gene. In conjunction with the taxonomic characterisation of a motile and aerobic strain, designated YIM M13156T and phylogenetically located within the family, we here carried out a phylogenetic analysis of the genome sequences now available for the type strains of Geodermatophilaceae and re-analyzed the previously assembled phenotypic data. The results indicated that the largest genus, Geodermatophilus, is not monophyletic, hence the arrangement of the genera of Geodermatophilaceae must be reconsidered. Taxonomic markers such as polar lipids and fatty-acids profile, cellular features and temperature ranges are indeed heterogeneous within Geodermatophilus. In contrast to previous studies, we also address which of these features can be interpreted as apomorphies of which taxon, according to the principles of phylogenetic systematics. We thus propose a novel genus, Klenkia, with the type species Klenkia marina sp. nov. and harboring four species formerly assigned to Geodermatophilus, G. brasiliensis, G. soli, G. taihuensis, and G. terrae. Emended descriptions of all species of Geodermatophilaceae are provided for which type-strain genome sequences are publicly available. Our study again demonstrates that the principles of phylogenetic systematics can and should guide the interpretation of both genomic and phenotypic data.
  • SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G.

    Bergmann, Simone; Eichhorn, Inga; Kohler, Thomas P; Hammerschmidt, Sven; Goldmann, Oliver; Rohde, Manfred; Fulde, Marcus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017)
    The M protein of Streptococcus canis (SCM) is a virulence factor and serves as a surface-associated receptor with a particular affinity for mini-plasminogen, a cleavage product of the broad-spectrum serine protease plasmin. Here, we report that SCM has an additional high-affinity immunoglobulin G (IgG) binding activity. The ability of a particular S. canis isolate to bind to IgG significantly correlates with a scm-positive phenotype, suggesting a dominant role of SCM as an IgG receptor. Subsequent heterologous expression of SCM in non-IgG binding S. gordonii and Western Blot analysis with purified recombinant SCM proteins confirmed its IgG receptor function. As expected for a zoonotic agent, the SCM-IgG interaction is species-unspecific, with a particular affinity of SCM for IgGs derived from human, cats, dogs, horses, mice, and rabbits, but not from cows and goats. Similar to other streptococcal IgG-binding proteins, the interaction between SCM and IgG occurs via the conserved Fc domain and is, therefore, non-opsonic. Interestingly, the interaction between SCM and IgG-Fc on the bacterial surface specifically prevents opsonization by C1q, which might constitute another anti-phagocytic mechanism of SCM. Extensive binding analyses with a variety of different truncated SCM fragments defined a region of 52 amino acids located in the central part of the mature SCM protein which is important for IgG binding. This binding region is highly conserved among SCM proteins derived from different S. canis isolates but differs significantly from IgG-Fc receptors of S. pyogenes and S. dysgalactiae sub. equisimilis, respectively. In summary, we present an additional role of SCM in the pathogen-host interaction of S. canis. The detailed analysis of the SCM-IgG interaction should contribute to a better understanding of the complex roles of M proteins in streptococcal pathogenesis.
  • Determining the bacterial cell biology of Planctomycetes.

    Boedeker, Christian; Schüler, Margarete; Reintjes, Greta; Jeske, Olga; van Teeseling, Muriel C F; Jogler, Mareike; Rast, Patrick; Borchert, Daniela; Devos, Damien P; Kucklick, Martin; Schaffer, Miroslava; Kolter, Roberto; van Niftrik, Laura; Engelmann, Susanne; Amann, Rudolf; Rohde, Manfred; Engelhardt, Harald; Jogler, Christian; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017-04-10)
    Bacteria of the phylum Planctomycetes have been previously reported to possess several features that are typical of eukaryotes, such as cytosolic compartmentalization and endocytosis-like macromolecule uptake. However, recent evidence points towards a Gram-negative cell plan for Planctomycetes, although in-depth experimental analysis has been hampered by insufficient genetic tools. Here we develop methods for expression of fluorescent proteins and for gene deletion in a model planctomycete, Planctopirus limnophila, to analyse its cell organization in detail. Super-resolution light microscopy of mutants, cryo-electron tomography, bioinformatic predictions and proteomic analyses support an altered Gram-negative cell plan for Planctomycetes, including a defined outer membrane, a periplasmic space that can be greatly enlarged and convoluted, and an energized cytoplasmic membrane. These conclusions are further supported by experiments performed with two other Planctomycetes, Gemmata obscuriglobus and Rhodopirellula baltica. We also provide experimental evidence that is inconsistent with endocytosis-like macromolecule uptake; instead, extracellular macromolecules can be taken up and accumulate in the periplasmic space through unclear mechanisms.
  • Promicromonospora kermanensis sp. nov., an actinobacterium isolated from soil.

    Mohammadipanah, Fatemeh; Montero-Calasanz, Maria Del Carmen; Schumann, Peter; Spröer, Cathrin; Rohde, Manfred; Klenk, Hans-Peter; Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017-02)
    A novel strain belonging to the genus Promicromonospora, designated HM 533T, was isolated from soil in Kerman Province, Iran. It produced long and branched hyphae on ISP 2 medium that developed into a large number of irregular-shaped spores. It showed optimal growth at 25-30 °C and pH 5.0-8.0 with 0-4 % (w/v) NaCl. The peptidoglycan type of strain HM 533T was A4α l-Lys-l-Ala-d-Glu. Whole-cell hydrolysates of strain HM 533T contained the sugars ribose, glucose and galactose. The main phospholipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, two unknown glycolipids and an unknown phospholipid. MK-9(H4) and MK-9(H2) were the predominant menaquinones. The fatty acids pattern was mainly composed of the saturated branched-chain acids anteiso-C15 : 0 and iso-C15 : 0. The 16S rRNA gene sequence analysis showed the highest pairwise sequence identity (99.5-97.1 %) with the members of the genus Promicromonospora. Based on phenotypic and genotypic features, strain HM 533T is considered to represent a novel species of the genus Promicromonospora, for which the name Promicromonospora kermanensis is proposed with strain HM 533T (=DSM 45485T=UTMC 00533T=CECT 8709T) as the type strain.
  • Streptococcus equi subsp. zooepidemicus Invades and Survives in Epithelial Cells.

    Skive, Bolette; Rohde, Manfred; Molinari, Gabriella; Braunstein, Thomas Hartig; Bojesen, Anders M; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017)
    Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is an opportunistic pathogen of several species including humans. S. zooepidemicus is found on mucus membranes of healthy horses, but can cause acute and chronic endometritis. Recently S. zooepidemicus was found able to reside in the endometrium for prolonged periods of time. Thus, we hypothesized that an intracellular phase may be part of the S. zooepidemicus pathogenesis and investigated if S. zooepidemicus was able to invade and survive inside epithelial cells. HEp-2 and HeLa cell lines were co-cultured with two S. zooepidemicus strains (1-4a and S31A1) both originating from the uterus of mares suffering from endometritis. Cells were fixed at different time points during the 23 h infection assay and field emission scanning electron microscopy (FESEM) was used to characterize adhesion and invasion mechanisms. The FESEM images showed three morphologically different types of invasion for both bacterial strains. The main port of entry was through large invaginations in the epithelial cell membrane. Pili-like bacterial appendages were observed when the S. zooepidemicus cells were in close proximity to the epithelial cells indicating that attachment and invasion were active processes. Adherent and intracellular S. zooepidemicus, and bacteria in association with lysosomes was determined by immunofluorescence staining techniques and fluorescence microscopy. Quantification of intracellular bacteria was determined in penicillin protection assays. Both S. zooepidemicus strains investigated were able to invade epithelial cells although at different magnitudes. The immunofluorescence data showed significantly higher adhesion and invasion rates for strain 1-4a when compared to strain S31A1. S. zooepidemicus was able to survive intracellularly, but the survival rate decreased over time in the cell culture system. Phagosome-like compartments containing S. zooepidemicus at some stages fused with lysosomes to form a phagolysosome. The results indicate that an intracellular phase may be one way S. zooepidemicus survives in the host, and could in part explain how S. zooepidemicus can cause recurrent/persistent infections. Future studies should reveal the ability of S. zooepidemicus to internalize and survive in primary equine endometrial cells and during in vivo conditions.
  • Kindlin-2 recruits paxillin and Arp2/3 to promote membrane protrusions during initial cell spreading.

    Böttcher, Ralph T; Veelders, Maik; Rombaut, Pascaline; Faix, Jan; Theodosiou, Marina; Stradal, Theresia E B; Rottner, Klemens; Zent, Roy; Herzog, Franz; Fässler, Reinhard; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017-09-14)
    Cell spreading requires the coupling of actin-driven membrane protrusion and integrin-mediated adhesion to the extracellular matrix. The integrin-activating adaptor protein kindlin-2 plays a central role for cell adhesion and membrane protrusion by directly binding and recruiting paxillin to nascent adhesions. Here, we report that kindlin-2 has a dual role during initial cell spreading: it binds paxillin via the pleckstrin homology and F0 domains to activate Rac1, and it directly associates with the Arp2/3 complex to induce Rac1-mediated membrane protrusions. Consistently, abrogation of kindlin-2 binding to Arp2/3 impairs lamellipodia formation and cell spreading. Our findings identify kindlin-2 as a key protein that couples cell adhesion by activating integrins and the induction of membrane protrusions by activating Rac1 and supplying Rac1 with the Arp2/3 complex.
  • 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, Manfred; Singh, Mahavir; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (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.
  • Microbiome yarns: microbiome basis of memory,,.

    Timmis, Kenneth; Jebok, Franziska; Molinari, Gabriella; Rohde, Manfred; Timmis, James Kenneth; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-11)
  • Engineered Salmonella enterica serovar Typhimurium overcomes limitations of anti-bacterial immunity in bacteria-mediated tumor therapy

    Felgner, Sebastian; Kocijancic, Dino; Frahm, Michael; Heise, Ulrike; Rohde, Manfred; Zimmermann, Kurt; Falk, Christine; Erhardt, Marc; Weiss, Siegfried; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany.; Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Mouse-Pathology Service Unit, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Symbio Gruppe GmbH & Co KG, Herborn, Lower Saxony, Germany; Institute of Transplant Immunology, Medical School Hannover, Hannover, Hessia, Germany; Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany; Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany (2017-09-29)

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