A Processed Multidomain Mycoplasma hyopneumoniae Adhesin Binds Fibronectin, Plasminogen, and Swine Respiratory Cilia

Lisa M Seymour,Ania T Deutscher,Cheryl Jenkins,Tracey A Kuit,Linda Falconer,F Chris Minion,Ben Crossett,Matthew Padula,Nicholas E Dixon,Steven P Djordjevic,Mark J Walker

doi:10.1074/jbc.m110.104463

Abstract

Porcine enzootic pneumonia is a chronic respiratory disease that affects swine. The etiological agent of the disease, Mycoplasma hyopneumoniae, is a bacterium that 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 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 (K(D) 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 (K(D) 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.

Highlights

Porcine enzootic pneumonia is a chronic respiratory disease affecting swine populations worldwide
This 17 kDa peptide was identified during ESIMS/MS analysis of M. hyopneumoniae strain 232 proteins separated using SDS-PAGE, along with peptides that indicate the presence of two distinct C-terminal P116 fragments with observed sizes within the ranges of 45–52 kDa and 52– 68 kDa
The presence of these peptides establishes that P116 is expressed in vitro, while the peptides detected from a SDSPAGE gel and 2DGE indicates P116 is proteolytically processed and provides insight into the processing pattern

Summary

A Processed Multidomain Mycoplasma hyopneumoniae

The etiological agent of the disease, Mycoplasma hyopneumoniae, is a bacterium that adheres to cilia of the swine respiratory tract, resulting in loss of cilia and epithelial cell damage. M. hyopneumoniae cells were found to bind plasminogen in a dose-dependent and saturable manner; the C-terminal domain of P116 binds to plasminogen (KD 44 ؎ 5 nM). P116 fragments adhere to the PK15 porcine kidney epithelial-like cell line and swine respiratory cilia. These data suggest that P116 is an important adhesin and virulence factor of M. hyopneumoniae. The etiological agent, Mycoplasma hyopneumoniae, adheres to cilia in the respiratory tract of pigs, resulting in loss of cilia and epithelial cell damage [1]. □S The on-line version of this article (available at http://www.jbc.org) contains supplemental Tables S1–S5 and Fig. S6

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EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION