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Wernigerode, Germany

Andres D.,University of Potsdam | Andres D.,Harvard University | Gohlke U.,Max Delbruck Centrum fur Molekulare Medizin | Broeker N.K.,University of Potsdam | And 6 more authors.
Glycobiology | Year: 2013

Bacteriophage P22 recognizes O-antigen polysaccharides of Salmonella enterica subsp. enterica (S.) with its tailspike protein (TSP). In the serovars S. Typhimurium, S. Enteritidis, and S. Paratyphi A, the tetrasaccharide repeat units of the respective O-antigens consist of an identical main chain trisaccharide but different 3,6-dideoxyhexose substituents. Here, the epimers abequose, tyvelose and paratose determine the specific serotype. P22 TSP recognizes O-antigen octasaccharides in an extended binding site with a single 3,6-dideoxyhexose binding pocket. We have isolated S. Paratyphi A octasaccharides which were not available previously and determined the crystal structure of their complex with P22 TSP. We discuss our data together with crystal structures of complexes with S. Typhimurium and S. Enteritidis octasaccharides determined earlier. Isothermal titration calorimetry showed that S. Paratyphi A octasaccharide binds P22 TSP less tightly, with a difference in binding free energy of ∼7 kJ mol-1 at 20°C compared with S. Typhimurium and S. Enteritidis octasaccharides. Individual protein-carbohydrate contacts were probed by amino acid replacements showing that the dideoxyhexose pocket contributes to binding of all three serotypes. However, S. Paratyphi A octasaccharides bind in a conformation with an energetically unfavorable φ/ψ glycosidic bond angle combination. In contrast, octasaccharides from the other serotypes bind as solution-like conformers. Two water molecules are conserved in all P22 TSP complexes with octasaccharides of different serotypes. They line the dideoxyhexose binding pocket and force the S. Paratyphi A octasaccharides to bind as nonsolution conformers. This emphasizes the role of solvent as part of carbohydrate binding sites. © 2013 The Author 2013. Published by Oxford University Press. All rights reserved. Source

Wirtz C.,University of Tubingen | Witte W.,Robert Koch Institute Wernigerode | Wolz C.,University of Tubingen | Goerke C.,University of Tubingen
Virology | Year: 2010

Temperate bacteriophages play a critical role in the pathogenicity of the human pathogen Staphylococcus aureus by mediating positive lysogenic conversion for different virulence factors such as Panton-Valentine leukocidin (PVL) or by interrupting chromosomal virulence genes. PVL-encoding phages are integrated in the S. aureus genome within a conserved ORF which is surrounded by a cluster of tandemly repeated genes. Here we demonstrate that in S. aureus clonal complex ST80 strains PVL-phage induction led to the acquisition of host DNA into the phage genome probably due to a homologous recombination event between direct repeats of the two paralogous genes adjacent to the phage integration site. Phage excision was accompanied by an additional chromosomal deletion in this region. This so far unrecognized mechanism of DNA uptake into the phage genome may play an important role in the co-evolution of phages and bacteria. © 2010 Elsevier Inc. Source

Hamed M.,Saarland University | Nitsche-Schmitz D.P.,Helmholtz Center for Infection Research | Ruffing U.,Saarland University | Steglich M.,Robert Koch Institute Wernigerode | And 9 more authors.
Infection, Genetics and Evolution | Year: 2015

Hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) infections are frequently caused by predominant clusters of closely related isolates that cannot be discriminated by conventional diagnostic typing methods. Whole genome sequencing (WGS) and DNA microarray (MA) now allow for better discrimination within a prevalent clonal complex (CC). This single center exploratory study aims to distinguish invasive (blood stream infection) and non-invasive (nasal colonization) MRSA isolates of the same CC5 into phylogenetic- and virulence-associated genotypic subgroups by WGS and MA. A cohort of twelve blood stream and fifteen nasal MRSA isolates of CC5 (. spa-types t003 and t504) was selected. Isolates were propagated at the same period of time from unrelated patients treated at the University of Saarland Medical Center, Germany.Rooted phylotyping based on WGS with core-genome single nucleotide polymorphism (SNP) analysis revealed two local clusters of closely related CC5 subgroups (. t504 and Clade1 t003) which were separated from other local t003 isolates and from unrelated CC5 MRSA reference isolates of German origin. Phylogenetic subtyping was not associated with invasiveness when comparing blood stream and nasal isolates.Clustering based on MA profiles was not concordant with WGS phylotyping, but MA profiles may identify subgroups of isolates with nasal and blood stream origin. Among the new putative virulence associated genes identified by WGS, the strongest association with blood stream infections was shown for ebhB mutants.Analysis of the core-genome together with the accessory genome enables subtyping of closely related MRSA isolates according to phylogeny and presumably also to the potential virulence capacity of isolates. © 2015 Elsevier B.V. Source

Mietke H.,Staatliche Betriebsgesellschaft fur Umwelt und Landwirtschaft | Beer W.,Robert Koch Institute Wernigerode | Schleif J.,Staatliche Betriebsgesellschaft fur Umwelt und Landwirtschaft | Schabert G.,Biosynth AG | Reissbrodt R.,Robert Koch Institute Wernigerode
International Journal of Food Microbiology | Year: 2010

Animal feed often contains probiotic Bacillus strains used as feed additives. Spores of the non-pathogenic B. cereus var. toyoi (product name Toyocerin®) are used. Distinguishing between toxic wild-type Bacillus cereus strains and this probiotic strain is essential for evaluating the quality and risk of feed. Bacillus cereus CIP 5832 (product name Paciflor®) was used as probiotic strain until 2001. The properties of the two probiotic strains are quite similar.Differentiating between probiotic strains and wild-type B. cereus strains is not easy. ß-lactam antibiotics such as penicillin and cefamandole exhibit an inhibition zone in the agar diffusion test of probiotic B. cereus strains which are not seen for wild-type strains. Therefore, performing the agar diffusion test first may make sense before FT-IR testing.When randomly checking these strains by Fourier transform infrared spectroscopy (FT-IR), the probiotic B. cereus strains were separated from wild-type B. cereus/B. thuringiensis/B. mycoides/B. weihenstephanensis strains by means of hierarchical cluster analysis. The discriminatory information was contained in the spectral windows 3000-2800cm-1 ("fatty acid region"), 1200-900cm-1 ("carbohydrate region") and 900-700cm-1 ("fingerprint region"). It is concluded that FT-IR spectroscopy can be used for the rapid quality control and risk analysis of animal feed containing probiotic B. cereus strains. © 2010 Elsevier B.V. Source

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