Characterization of the Binding Region for the Yersinia Enterocolitica Adhesin YadA on Types I and II Collagen

Objective: The plasmid-encoded adhesin YadA confers pathogenic functions on Yersinia enterocolitica, a microorganism associated with reactive arthritis. While emerging evidence has indicated that the persistence of the bacteria in individuals with reactive arthritis is a prerequisite for the development of the disease, the tissue specificity of this immunologic disease sequela remains elusive. The present study was undertaken to investigate YadA-mediated binding of Y enterocolitica to the most abundant collagens in joints, types I and II collagen.

Methods: Binding studies were performed with recombinant Y enterocolitica strains and highly purified type II collagen and the alpha 1(I) chain of type I collagen, or fragments of these collagens generated by various enzymatic and nonenzymatic cleavage procedures. Interactions of bacteria with the proteins were determined in binding assays with radiolabeled proteins.

Results: Binding regions for YadA were identified at the 181-amino acid fragment alpha 1(I)78CBN of type I collagen and the CB10 fragment of type II collagen. From binding and blocking experiments with alpha 1(I) fragments, cyanogen bromide-derived or mammalian collagenase-derived type II collagen fragments, and synthetic peptides with collagen-like structures, it was concluded that the binding site for YadA on collagen is determined by a restricted amino acid sequence and is defined within a highly homologous 134-amino acid region. Furthermore, the binding site is not affected by mammalian collagenase digest. Binding of YadA-positive yersiniae to collagen could be inhibited by an antiserum specific for YadA.

Conclusion: This study provides the first evidence of a binding site for bacterial proteins on collagens which is not determined by the repetitive sequence Gly-X-Y of collagens. We speculate that the binding region is conserved between types I and II collagen, the most abundant collagens in the joints. Specific binding of Yersinia products to joint collagens might contribute to the arthritogenic potential of enteropathogenic yersiniae.