Plasmid-Encoded Outer Membrane Protein YadA Mediates Specific Binding of Enteropathogenic Yersiniae to Various Types of Collagen

The plasmid-encoded outer membrane protein YadA of enteropathogenic
yersiniae is associated with pathogenicity. Recently, collagen
binding of YadA-positive yersiniae was reported without detailed
characterization (L. Emödy, J. Heesemann, H. Wolf-Watz, M. Skurnik,
G. Kapperud, P. O'Toole, and T. Wadström, J. Bacteriol.
171:6674-6679, 1989). To elucidate the nature of collagen binding
to YadA, we used a recombinant Yersinia strain expressing the
cloned YadA gene. Direct binding of YadA-positive yersiniae to
collagens was demonstrated in affinity blot experiments on
nitrocellulose filters. A spectrum of collagen types in a wide
concentration range were tested for their ability to block binding
of 125I-labeled collagen type II to YadA-positive yersiniae. The
results indicate a specific binding site(s) for YadA in collagen
types I, II, III, IV, V, and XI. In contrast, collagen type VI did
not bind to YadA. To characterize the binding site(s) more
precisely, isolated collagen chains and cyanogen bromide fragments
were investigated. These studies revealed that binding of YadA to
collagen type I is confined to the alpha 1(I) chain, whereas the
binding site within collagen type XI is localized in the alpha
3(XI) chain. alpha 2(I), alpha 1(XI), and alpha 2(XI) did not bind
to YadA. Most interestingly, in the alpha 1(II) chain the specific
binding site for YadA resides in the cyanogen bromide fragment
CB10. The latter might indicate a binding site that does not depend
on conformation. Based on these findings, further fragmentation and
the synthesis of peptides may allow definition of the peptide
sequence(s) relevant for YadA binding.