OUTER-MEMBRANE PROTEIN YADA OF ENTEROPATHOGENIC YERSINIAE MEDIATES SPECIFIC BINDING TO CELLULAR BUT NOT PLASMA FIBRONECTIN

The binding of bacteria or bacterial products to host proteins of tiss ue extracellular matrix may be a mechanism of tissue adherence. We inv estigated interactions of the plasmid-encoded outer membrane protein Y adA, which confers pathogenic functions on enteropathogenic yersiniae, with fibronectin. Attachment or YadA-positive and YadA-negative recom binant Yersinia enterocolitica strains to cartilage-derived human cell ular fibronectin and human plasma fibronectin in the solid phase revea led 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-beta1-integrin antibody and the synthetic peptide G-R-G-D-S-P, representing the bind ing site for alpha5beta1-integrin on fibronectin, did not block attach ment 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 pla sma fibronectin immobilized on nitrocellulose or plastic surfaces. The se observations provide evidence for the hypothesis that the binding r egion for YadA in cellular fibronectin is not present in plasma fibron ectin. This study is the first report on differential binding of bacte ria to splicing variants of fibronectin. Further experiments might ans wer the question whether binding of YadA to cellular fibronectin contr ibutes to the pathogenesis of yersiniae, both to the initial adhesion of the bacteria to the matrices of the host and to the arthritogenic p otential of enteropathogenic yersiniae.