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

Abstract

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.

BBA70 of Borrelia burgdorferi Is a Novel Plasminogen-binding Protein

“…The binding constant for BBA70 lies in a similar range of affinities reported for other plasminogen-binding proteins, such as B. burgdorferi enolase with a K d of 125 nM (34), staphylokinase from S. aureus with a reported K d of 9.3 nM (9), and DnaK and enolase from Bifidobacterium animalis with K d values of 11 and 42 nM, respectively (73,74).…”

Externalized Glycolytic Enzymes Are Novel, Conserved, and Early Biomarkers of Apoptosis

“…Surface exposure of glycolytic enzymes has been noted previously in a variety of enteric bacteria and pathogens and is responsible for specific plasminogen binding (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). This striking commonality of glycolytic enzyme externalization raises the possibility that the exposure of glycolytic enzymes on microorganisms reflects a subversion of innate apoptotic immunity though apoptotic mimicry that facilitates commensalism or pathogenesis.…”

Role of Extracellular Transaldolase from Bifidobacterium bifidum in Mucin Adhesion and Aggregation

“…To visualize the cell surface-associated Tal of B. bifidum A8, the conditions described previously were used (6). B. bifidum A8 was grown in 10 ml of MRSc for 18 h, harvested by centrifugation, washed twice with PBS, and rotated in PBS-1% BSA for 30 min.…”

“…lactis and Bifidobacterium bifidum, respectively. Under certain circumstances, these proteins could play a role in facilitating the colonization of the human gut through degradation of the extracellular matrix of cells or by facilitating a close contact with the epithelium (5,6,7,17,42). Also, a pilus-type IV mediated host colonization and persistence mechanism has recently been demonstrated in Bifidobacterium breve (30).…”