• 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.
    • Production of infectious genotype 1b virus particles in cell culture and impairment by replication enhancing mutations.

      Pietschmann, Thomas; Zayas, Margarita; Meuleman, Philip; Long, Gang; Appel, Nicole; Koutsoudakis, George; Kallis, Stephanie; Leroux-Roels, Geert; Lohmann, Volker; Bartenschlager, Ralf (2009-06)
      With the advent of subgenomic hepatitis C virus (HCV) replicons, studies of the intracellular steps of the viral replication cycle became possible. These RNAs are capable of self-amplification in cultured human hepatoma cells, but save for the genotype 2a isolate JFH-1, efficient replication of these HCV RNAs requires replication enhancing mutations (REMs), previously also called cell culture adaptive mutations. These mutations cluster primarily in the central region of non-structural protein 5A (NS5A), but may also reside in the NS3 helicase domain or at a distinct position in NS4B. Most efficient replication has been achieved by combining REMs residing in NS3 with distinct REMs located in NS4B or NS5A. However, in spite of efficient replication of HCV genomes containing such mutations, they do not support production of infectious virus particles. By using the genotype 1b isolate Con1, in this study we show that REMs interfere with HCV assembly. Strongest impairment of virus formation was found with REMs located in the NS3 helicase (E1202G and T1280I) as well as NS5A (S2204R), whereas a highly adaptive REM in NS4B still allowed virus production although relative levels of core release were also reduced. We also show that cells transfected with the Con1 wild type genome or the genome containing the REM in NS4B release HCV particles that are infectious both in cell culture and in vivo. Our data provide an explanation for the in vitro and in vivo attenuation of cell culture adapted HCV genomes and may open new avenues for the development of fully competent culture systems covering the therapeutically most relevant HCV genotypes.
    • Promicromonospora kermanensis sp. nov., an actinobacterium isolated from soil.

      Mohammadipanah, Fatemeh; Montero-Calasanz, Maria Del Carmen; Schumann, Peter; Spröer, Cathrin; Rohde, M; 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.
    • Proposal of Henriciella barbarensis sp. nov. and Henriciella algicola sp. nov., stalked species of the genus and emendation of the genus Henriciella.

      Abraham, Wolf-Rainer; de Carvalho, Maira Peres; da Costa Neves, Thais Souto Paula; Memoria, Marina Torquato; Tartuci, Iago Toledo; Vancanneyt, Marc; Smit, John; Rohde, M; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7,38124 Braunschweig, Germany. (2017-08)
      Two Gram-negative, heterotrophic, aerobic, prosthecated, marine bacteria, designated strains MCS23T and MCS27T, were isolated from seawater samples. NaCl was required for growth. The major polar lipid detected in strain MCS27T was phosphatidylglycerol, whereas those detected in MCS23T were phosphatidylglycerol, sulfoquinovosyl diacylglycerol and 1,2-diacyl-3-α-d-glucuronopyranosyl-sn-glycerol taurineamide. The most abundant cellular fatty acids were C18 : 1ω7 and C16 : 0, hydroxyl-fatty acids were 3-OH C12 : 0 in both strains and 3-OH C11 : 0 in MCS23T. Strains MCS23T and MCS27T had DNA G+C contents of 57.0 and 55.0 mol%, respectively. The two strains shared 99.3 % 16S rRNA gene sequence similarity; levels of similarity with the type strains of species of the genus Henriciella were 99.4-97.8 % but DNA-DNA hybridizations were 53 % or lower. Besides their 16S rRNA gene sequences, the novel strains can be differentiated from other species of the genus Henriciella by cell morphology, lipid and fatty acid patterns and enzyme activities. The data obtained led to the identification of two novel species, for which the names Henriciella barbarensis sp. nov. (type strain MCS23T=LMG 28705T=CCUG 66934T) and Henriciella algicola sp. nov. (type strain MCS27T=LMG 29152T=CCUG 67844T) are proposed. As these two novel species are the first prosthecate species in the genus Henriciella, an emended genus description is also provided.
    • Protein homeostasis-more than resisting a hot bath.

      Lee, Changhan; Wigren, Edvard; Lünsdorf, Heinrich; Römling, Ute; Helmholtz Centre for infection research, Inhoffenstr. 7,38124 Braunschweig, Germany. (2016-04)
      Maintenance of protein homeostasis is essential for survival of all organisms. In bacteria, the protein quality control system has a broad physiological impact beyond heat shock resistance, being involved in virulence, antibiotic resistance, as well as protection against environmental stresses. Its contribution to rejuvenation and growth arrest suggests interference with protein quality control to be a novel antimicrobial strategy. Remarkably, a protein quality control module originating from environmental strains has been found to be horizontally transferred to predominant clonal groups of bacteria providing exquisite thermotolerance to recently emerged global pathogens suggesting that novel features related to protein homeostasis contribute to the transition to new environments.
    • The Protein Network of the Pseudomonas aeruginosa Denitrification Apparatus.

      Borrero-de Acuña, José Manuel; Rohde, Manfred; Wissing, Josef; Jänsch, Lothar; Schobert, Max; Molinari, Gabriella; Timmis, Kenneth N; Jahn, Martina; Jahn, Dieter; Helmholtz Centre for infection research (HZI), Inhoffenstraße 7, 38124 Braunschweig, Germany. (2016-02-22)
      Oxidative phosphorylation using multiple component, membrane-associated protein complexes is the most effective way for a cell to generate energy. Here, we systematically investigated the multiple protein-protein interactions of the denitrification apparatus of the pathogenic bacterium Pseudomonas aeruginosa. During denitrification, nitrate (Nar), nitrite (Nir), nitric-oxide (Nor) and nitrous-oxide (Nos) reductases catalyze the reaction cascade of NO(3-) → NO(2-) → NO → N2O → N2. Genetic experiments suggested that the nitric-oxide reductase NorBC and the regulatory protein NosR are the nucleus of the denitrification protein network. We utilized membrane interactomics in combination with electron microscopy co-localization studies to elucidate the corresponding protein-protein interactions. The integral membrane proteins NorC, NorB and NosR form the core assembly platform that binds the nitrate reductase NarGHI and the periplasmic nitrite reductase NirS via its maturation factor NirF. The periplasmic nitrous-oxide reductase, NosZ, is linked via NosR. The nitrate transporter, NarK2, the nitrate regulatory system, NarXL, various nitrite reductase maturation proteins, NirEJMNQ, and the Nos assembly lipoproteins, NosFL, were also found to be attached. A number of proteins associated with energy generation, including electron donating dehydrogenases, the complete ATP synthase, almost all enzymes of the TCA cycle, and the SEC system of protein transport, among many other proteins, were found to interact with the denitrification proteins. This deduced nitrate respirasome is presumably only one part of an extensive cytoplasmic membrane-anchored protein network connecting cytoplasmic, inner membrane and periplasmic proteins, to mediate key activities occurring at the barrier/interface between the cytoplasm and the external environment.
    • Proteomic Investigation Uncovers Potential Targets and Target Sites of Pneumococcal Serine-Threonine Kinase StkP and Phosphatase PhpP.

      Hirschfeld, Claudia; Gómez-Mejia, Alejandro; Bartel, Jürgen; Hentschker, Christian; Rohde, Manfred; Maaß, Sandra; Hammerschmidt, Sven; Becher, Dörte; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2020-02-04)
      Like eukaryotes, different bacterial species express one or more Ser/Thr kinases and phosphatases that operate in various signaling networks by catalyzing phosphorylation and dephosphorylation of proteins that can immediately regulate biochemical pathways by altering protein function. The human pathogen Streptococcus pneumoniae encodes a single Ser/Thr kinase-phosphatase couple known as StkP-PhpP, which has shown to be crucial in the regulation of cell wall synthesis and cell division. In this study, we applied proteomics to further understand the physiological role of pneumococcal PhpP and StkP with an emphasis on phosphorylation events on Ser and Thr residues. Therefore, the proteome of the non-encapsulated D39 strain (WT), a kinase (ΔstkP), and phosphatase mutant (ΔphpP) were compared in a mass spectrometry based label-free quantification experiment. Results show that a loss of function of PhpP causes an increased abundance of proteins in the phosphate uptake system Pst. Quantitative proteomic data demonstrated an effect of StkP and PhpP on the two-component systems ComDE, LiaRS, CiaRH, and VicRK. To obtain further information on the function, targets and target sites of PhpP and StkP we combined the advantages of phosphopeptide enrichment using titanium dioxide and spectral library based data evaluation for sensitive detection of changes in the phosphoproteome of the wild type and the mutant strains. According to the role of StkP in cell division we identified several proteins involved in cell wall synthesis and cell division that are apparently phosphorylated by StkP. Unlike StkP, the physiological function of the co-expressed PhpP is poorly understood. For the first time we were able to provide a list of previously unknown putative targets of PhpP. Under these new putative targets of PhpP are, among others, five proteins with direct involvement in cell division (DivIVA, GpsB) and peptidoglycan biosynthesis (MltG, MreC, MacP).
    • Prothrombotic and Proinflammatory Activities of the β-Hemolytic Group B Streptococcal Pigment.

      Siemens, Nikolai; Oehmcke-Hecht, Sonja; Hoßmann, Jörn; Skorka, Sebastian B; Nijhuis, Roel H T; Ruppen, Corinne; Skrede, Steinar; Rohde, Manfred; Schultz, Daniel; Lalk, Michael; et al. (Karger, 2019-11-19)
      A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1β, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system.
    • R18C is a new viable P2-like bacteriophage of rabbit origin infecting Citrobacter rodentium and Shigella sonnei strains.

      Sváb, Domonkos; Horváth, Balázs; Rohde, Manfred; Maróti, Gergely; Tóth, István; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Springer-Nature, 2019-10-23)
      Here, we report a novel virulent P2-like bacteriophage, R18C, isolated from rabbit faeces, which, in addition to Escherichia coli K-12 strains, was able to be propagated on Citrobacter rodentium strain ICC169 and a range of Shigella sonnei strains with high efficiency of plating (EOP). It represents the first lytic bacteriophage originating from rabbit and the first infectious P2-like phage of animal origin. In the three characteristic moron-containing regions of P2-like phages, R18C contains genes with unknown function that have so far only been found in cryptic P2-like prophages.
    • A recently isolated human commensal Escherichia coli ST10 clone member mediates enhanced thermotolerance and tetrathionate respiration on a P1 phage derived IncY plasmid.

      Kamal, Shady Mansour; Cimdins-Ahne, Annika; Lee, Changhan; Li, Fengyang; Martin-Rodriguez, Alberto J; Seferbekova, Zaira; Afasizhev, Robert; Tesfaye Wami, Haleluya; Katikaridis, Panagiotis; Meins, Lena; et al. (Wiley, 2020-09-28)
      The ubiquitous human commensal Escherichia coli has been well investigated through its model representative E. coli K-12. In this work, we initially characterized E. coli Fec10, a recently isolated human commensal strain of phylogroup A/sequence type ST10. Compared to E. coli K-12, the 4.88 Mbp Fec10 genome is characterized by distinct single nucleotide polymorphisms and acquisition of genomic islands. In addition, E. coli Fec10 possesses a 155.86 kbp IncY plasmid, a composite element based on phage P1. pFec10 codes for a variety of cargo genes such as a tetrathionate reductase and its corresponding regulatory two-component system. Among cargo gene products is also the Transmissible Locus of Protein Quality Control (TLPQC), which mediates tolerance to lethal temperatures in bacteria. The disaggregase ClpGGI of TLPQC constitutes a major determinant of thermotolerance of E. coli Fec10. We confirm stand-alone disaggregation activity, but observe distinct biochemical characteristics of ClpGGI-Fec10 compared to the nearly identical Pseudomonas aeruginosa ClpGGI-SG17M. Furthermore, we observed a unique contribution of ClpGGI-Fec10 to the exquisite thermotolerance of E. coli Fec10 suggesting functional differences between both disaggregases in vivo. Detection of thermotolerance in 10% of human commensal E. coli isolates suggests successful establishment of food-borne heat resistant strains in the human gut.
    • Regulation of Flagellum Biosynthesis in Response to Cell Envelope Stress in Serovar Typhimurium.

      Spöring, Imke; Felgner, Sebastian; Preuße, Matthias; Eckweiler, Denitsa; Rohde, M; 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.
    • Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. isolated from natural or artificial marine surfaces in Northern Germany and California, USA, and emended description of the genus Rhodopirellula.

      Kallscheuer, Nicolai; Wiegand, Sandra; Jogler, Mareike; Boedeker, Christian; Peeters, Stijn H; Rast, Patrick; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-04)
      Expanding the collection of Planctomycetes by characterisation of novel species is key to better understanding of their complex lifestyles, uncommon cell biology and unexplored metabolism. Here, we isolated three novel planctomycetal strains from a kelp forest on the California Coastline at Monterey Bay or from plastic surfaces submerged in the Baltic Sea and the estuary of the river Warnow in the northeast of Germany. According to our phylogenetic analysis, the isolated strains Poly21T, Pla100T and CA85T represent three novel species within the genus Rhodopirellula. All three show typical planctomycetal traits such as division by budding. All are aerobic, mesophilic chemoheterotrophs and show genomic features comparable to other described Rhodopirellula species. However, strain CA85T is exceptional as it forms cream colonies, but no aggregates, which is a notable deviation from the pink- to red-pigmented and aggregate-forming Rhodopirellula species known thus far. We propose the names Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. for the novel strains Poly21T (DSM 102266T = LMG 29467T = CECT 9847T = VKM B-3435T), Pla100T (DSM 102937T = LMG 29465T) and CA85T (DSM 109595T = LMG 29699T = VKM B-3451T), respectively, which we present as the respective type strains of these novel species.