• Bifidobacterial enolase, a cell surface receptor for human plasminogen involved in the interaction with the host.

      Candela, Marco; Biagi, Elena; Centanni, Manuela; Turroni, Silvia; Vici, Manuela; Musiani, Francesco; Vitali, Beatrice; Bergmann, Simone; Hammerschmidt, Sven; Brigidi, Patrizia; et al. (2009-10)
      The interaction with the host plasminogen/plasmin system represents a novel component in the molecular cross-talk between bifidobacteria and human host. Here, we demonstrated that the plasminogen-binding bifidobacterial species B. longum, B. bifidum, B. breve and B. lactis share the key glycolytic enzyme enolase as a surface receptor for human plasminogen. Enolase was visualized on the cell surface of the model strain B. lactis BI07. The His-tagged recombinant protein showed a high affinity for human plasminogen, with an equilibrium dissociation constant in the nanomolar range. By site-directed mutagenesis we demonstrated that the interaction between the B. lactis BI07 enolase and human plasminogen involves an internal plasminogen-binding site homologous to that of pneumococcal enolase. According to our data, the positively charged residues Lys-251 and Lys-255, as well as the negatively charged Glu-252, of the B. lactis BI07 enolase are crucial for plasminogen binding. Acting as a human plasminogen receptor, the bifidobacterial surface enolase is suggested to play an important role in the interaction process with the host.
    • Biofilm formation by Salmonella enterica serovar Typhimurium colonizing solid tumours.

      Crull, Katja; Rohde, Manfred; Westphal, Kathrin; Loessner, Holger; Wolf, Kathrin; Felipe-López, Alfonso; Hensel, Michael; Weiss, Siegfried (2011-08)
      Systemic administration of Salmonella enterica serovar Typhimurium to tumour bearing mice results in preferential colonization of the tumours and retardation of tumour growth. Although the bacteria are able to invade the tumour cells in vitro, in tumours they were never detected intracellularly. Ultrastructural analysis of Salmonella-colonized tumours revealed that the bacteria had formed biofilms. Interestingly, depletion of neutrophilic granulocytes drastically reduced biofilm formation. Obviously, bacteria form biofilms in response to the immune reactions of the host. Importantly, we tested Salmonella mutants that were no longer able to form biofilms by deleting central regulators of biofilm formation. Such bacteria could be observed intracellularly in immune cells of the host or in tumour cells. Thus, tumour colonizing S. typhimurium might form biofilms as protection against phagocytosis. Since other bacteria are behaving similarly, solid murine tumours might represent a unique model to study biofilm formation in vivo.
    • The FbaB-type fibronectin-binding protein of Streptococcus pyogenes promotes specific invasion into endothelial cells.

      Amelung, Silva; Nerlich, Andreas; Rohde, Manfred; Spellerberg, Barbara; Cole, Jason N; Nizet, Victor; Chhatwal, Gursharan S; Talay, Susanne R; Department of Medical Microbiology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany. (2011-08)
      Invasive serotype M3 Streptococcus pyogenes are among the most frequently isolated organisms from patients suffering from invasive streptococcal disease and have the potential to invade primary human endothelial cells (EC) via a rapid and efficient mechanism. FbaB protein, the fibronectin-binding protein expressed by M3 S. pyogenes, was herein identified as a potent invasin for EC. By combining heterologous gene expression with allelic replacement, we demonstrate that FbaB is essential and sufficient to trigger EC invasion via a Rac1-dependent phagocytosis-like uptake. FbaB-mediated uptake follows the classical endocytic pathway with lysosomal destination. FbaB is demonstrated to be a streptococcal invasin exhibiting EC tropism. FbaB thus initiates a process that may contribute to the deep tissue tropism and spread of invasive S. pyogenes isolates into the vascular EC lining.
    • Host-pathogen interactions in streptococcal immune sequelae.

      Nitsche-Schmitz, D Patric; Chhatwal, Gursharan S; Helmholtz Centre for Infection Research, Inhoffenstraße 7, D-38124 Braunschweig, Germany. Patric.Nitsche@helmholtz-hzi.de (2013)
      Otherwise uncomplicated infections with Streptococcus pyogenes can cause two insidious immune sequelae known as post-streptococcal glomerulonephritis (PSGN) and acute rheumatic fever (ARF). These diseases follow with a latency of a few weeks or months after primary infection and are responsible for high mortality and morbidity. PSGN has also been linked to infections with group C streptococci of the species S. equi ssp. zooepidemicus (SESZ). Moreover, there are some indications that infection with group C and G streptococci (GCGS) of the subspecies Streptococcus dysgalactiae ssp. equisimilis (SDSE) leads to ARF. Despite decades of research, the picture of the molecular pathogenesis of streptococcal immune sequelae resembles a jigsaw puzzle. Herein we try to put some of the puzzle bits together that have been collected till date.
    • SCM, a novel M-like protein from Streptococcus canis, binds (mini)-plasminogen with high affinity and facilitates bacterial transmigration.

      Fulde, Marcus; Rohde, Manfred; Hitzmann, Angela; Preissner, Klaus T; Nitsche-Schmitz, D Patric; Nerlich, Andreas; Chhatwal, Gursharan Singh; Bergmann, Simone; Department of Medical Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany. Marcus.Fulde@helmholtz-hzi.de (2011-02-24)
      Streptococcus canis is an important zoonotic pathogen capable of causing serious invasive diseases in domestic animals and humans. In the present paper we report the binding of human plasminogen to S. canis and the recruitment of proteolytically active plasmin on its surface. The binding receptor for plasminogen was identified as a novel M-like protein designated SCM (S. canis M-like protein). SPR (surface plasmon resonance) analyses, radioactive dot-blot analyses and heterologous expression on the surface of Streptococcus gordonii confirmed the plasminogen-binding capability of SCM. The binding domain was located within the N-terminus of SCM, which specifically bound to the C-terminal part of plasminogen (mini-plasminogen) comprising kringle domain 5 and the catalytic domain. In the presence of urokinase, SCM mediated plasminogen activation on the bacterial surface that was inhibited by serine protease inhibitors and lysine amino acid analogues. Surface-bound plasmin effectively degraded purified fibrinogen as well as fibrin clots, resulting in the dissolution of fibrin thrombi. Electron microscopic illustration and time-lapse imaging demonstrated bacterial transmigration through fibrinous thrombi. The present study has led, for the first time, to the identification of SCM as a novel receptor for (mini)-plasminogen mediating the fibrinolytic activity of S. canis.