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Outer membrane protein YadA of enteropathogenic yersiniae mediates specific binding to cellular but not plasma
H Schulze-Koops1, H Burkhardt, J Heesemann
1Max-Planck-Society, Clinical Research Unit for Rheumatology/Immunology, University Erlangen-Nürnberg, Germany.
Abstract:
The binding of bacteria or bacterial products to host proteins of tissue extracellular matrix may be a mechanism of tissue adherence. We investigated interactions of the plasmid-encoded outer membrane protein YadA, which confers pathogenic functions on enteropathogenic yersiniae, with fibronectin. Attachment of YadA-positive and YadA-negative recombinant Yersinia enterocolitica strains to cartilage-derived human cellular fibronectin and human plasma fibronectin in the solid phase revealed that YadA mediates binding of yersiniae to cellular fibronectin in a saturable, concentration-dependent manner. The interaction could be inhibited by an anti-YadA-specific anti-serum. An anti-beta 1-integrin antibody and the synthetic peptide G-R-G-D-S-P, representing the binding site for alpha 5 beta 1-integrin on fibronectin, did not block attachment of YadA-positive yersiniae to cellular fibronectin, indicating a binding site for YadA on cellular fibronectin independent of the R-G-D-S-containing site. By contrast, YadA failed to mediate binding to plasma fibronectin immobilized on nitrocellulose or plastic surfaces. These observations provide evidence for the hypothesis that the binding region for YadA in cellular fibronectin is not present in plasma fibronectin. This study is the first report on differential binding of bacteria to splicing variants of fibronectin. Further experiments might answer the question whether binding of YadA to cellular fibronectin contributes to the pathogenesis of yersiniae, both to the initial adhesion of the bacteria to the matrices of the host and to the arthritogenic potential of enteropathogenic yersiniae.
Insights
The bacterial outer membrane protein YadA mediates enteropathogenic yersiniae attachment to cellular fibronectin, but not plasma fibronectin. This interaction is independent of the integrin-binding site, suggesting a novel adhesion mechanism.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bacterial adherence to host tissues is crucial for pathogenesis.
- Extracellular matrix proteins like fibronectin are key targets for bacterial adhesion.
- The YadA outer membrane protein of enteropathogenic yersiniae is implicated in virulence.
Purpose of the Study:
- To investigate the interaction between the YadA protein and fibronectin.
- To determine if YadA mediates bacterial binding to different fibronectin variants.
- To elucidate the binding site of YadA on fibronectin.
Main Methods:
- Utilized recombinant Yersinia enterocolitica strains (YadA-positive and negative).
- Assessed bacterial attachment to purified human cellular and plasma fibronectin.
- Employed anti-YadA antibodies, anti-integrin antibodies, and synthetic peptides for inhibition studies.
Main Results:
- YadA mediates saturable, concentration-dependent binding of yersiniae to cellular fibronectin.
- This binding is inhibited by anti-YadA antibodies.
- YadA does not bind to plasma fibronectin, and the binding site on cellular fibronectin is distinct from the RGD-containing integrin-binding site.
Conclusions:
- YadA facilitates bacterial adhesion to cellular fibronectin via a novel binding mechanism.
- Differential binding to fibronectin splicing variants may play a role in yersiniae pathogenesis and tissue tropism.
- This study highlights the first reported instance of differential bacterial binding to fibronectin variants.