• Impact of biofilm matrix components on interaction of commensal Escherichia coli with the gastrointestinal cell line HT-29.

      Wang, X; Rochon, M; Lamprokostopoulou, A; Lünsdorf, H; Nimtz, M; Römling, U (2006-10-01)
      Commensal Escherichia coli form biofilms at body temperature by expressing the extracellular matrix components curli fimbriae and cellulose. The role of curli fimbriae and cellulose in the interaction of commensal E. coli with the intestinal epithelial cell line HT-29 was investigated. Expression of curli fimbriae by the typical commensal isolate E. coli TOB1 caused adherence and internalization of the bacteria and triggered IL-8 production in HT-29 cells. In particular, induction of IL-8 production was complex and involved curli-bound flagellin. While cellulose alone had no effect on the interaction of TOB1 with HT-29 cells, co-expression of cellulose with curli fimbriae decreased adherence to, internalization and IL-8 induction of HT-29 cells. Investigation of a panel of commensal isolates showed a partial correlation between expression of curli fimbriae and enhanced internalization and IL-8 production. In addition, a high immunostimulatory flagellin was identified. Thus, the consequences of expression of extracellular matrix components on commensal bacterial-host interactions are complex.
    • Novel peroxidases of Marasmius scorodonius degrade beta-carotene.

      Scheibner, M; Hülsdau, B; Zelena, K; Nimtz, M; de Boer, L; Berger, RG; Zorn, H; Zentrum Angewandte Chemie, Institut für Lebensmittelchemie der Universität Hannover, Wunstorfer Straße 14, 30453, Hannover, Germany. (2008-01)
      Two extracellular enzymes (MsP1 and MsP2) capable of efficient beta-carotene degradation were purified from culture supernatants of the basidiomycete Marasmius scorodonius (garlic mushroom). Under native conditions, the enzymes exhibited molecular masses of ~150 and ~120 kDa, respectively. SDS-PAGE and mass spectrometric data suggested a composition of two identical subunits for both enzymes. Biochemical characterisation of the purified proteins showed isoelectric points of 3.7 and 3.5, and the presence of heme groups in the active enzymes. Partial amino acid sequences were derived from N-terminal Edman degradation and from mass spectrometric ab initio sequencing of internal peptides. cDNAs of 1,604 to 1,923 bp, containing open reading frames (ORF) of 508 to 513 amino acids, respectively, were cloned from a cDNA library of M. scorodonius. These data suggest glycosylation degrees of ~23% for MsP1 and 8% for MsP2. Databank homology searches revealed sequence homologies of MsP1 and MsP2 to unusual peroxidases of the fungi Thanatephorus cucumeris (DyP) and Termitomyces albuminosus (TAP).