Bifidobacterial enolase, a cell surface receptor for human plasminogen involved in the interaction with the host.
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.
Candela
Marco
M
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
Biagi
Elena
E
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
Centanni
Manuela
M
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
Turroni
Silvia
S
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
Vici
Manuela
M
Department of Experimental Pathology, University of Bologna, Italy.
Musiani
Francesco
F
Department of Agro Environmental Science and Technology, University of Bologna, Italy.
Vitali
Beatrice
B
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
Bergmann
Simone
S
Department of Microbial Pathogenicity, Helmholtz Centre for Infection Research GmbH, Braunschweig, Germany.
Hammerschmidt
Sven
S
Department Genetics of Microorganisms, Ernst Moritz Arndt University Greifswald, Greifswald, Germany.
Brigidi
Patrizia
P
Department of Pharmaceutical Sciences, CIRB-centre for Biotechnology, University of Bologna, Italy.
D001644:Bifidobacterium / Q000201:enzymology* / Q000502:physiology*; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D054884:Host-Pathogen Interactions; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010751:Phosphopyruvate Hydratase / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D010958:Plasminogen; D010751:Phosphopyruvate Hydratase