A processed multidomain hyopneumoniae adhesin binds fibronectin, plasminogen and swine respiratory cilia

A processed multidomain hyopneumoniae adhesin binds fibronectin, plasminogen and swine respiratory cilia

Porcine enzootic pneumonia is a chronic respiratory disease which affects swine. The aetiological agent of the disease, Mycoplasma hyopneumoniae, is a bacterium which adheres to cilia of the swine respiratory tract, resulting in loss of cilia and epithelial cell damage. A M. hyopneumoniae protein P116, encoded by mhp108, was investigated as a
potential adhesin. Examination of P116 expression using proteomic analyses observed P116 as a full length protein and also as fragments, ranging from 17 kDa to 70 kDa in
size. A variety of pathogenic bacterial species have been shown to bind the extracellular matrix component fibronectin as an adherence mechanism. M. hyopneumoniae
cells were found to bind fibronectin in a dose dependent
and saturable manner. Surface plasmon resonance was used to show that a recombinant C-terminal domain of P116 bound fibronectin at physiologically relevant concentrations (KD 24 ± 6 nM). Plasmin(ogen) binding proteins are also expressed by many bacterial pathogens, facilitating extracellular matrix degradation. M. hyopneumoniae cells
were found to also bind plasminogen in a dose-dependent and saturable manner; the C-terminal domain of P116 binds to
plasminogen (KD 44 ± 5 nM). Plasminogen binding was abolished when the C-terminal lysine of P116 was deleted, implicating this residue as part of the plasminogen binding site. P116 fragments adhere to the PK15 porcine kidney epithelial-like cell line and swine respiratory cilia. Collectively these data suggest that P116 is an important adhesin and virulence factor of M. hyopneumoniae.

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