Hydrophobic domains affect the collagen-binding specificity and surface polymerization as well as the virulence potential of the YadA protein of Yersinia enterocolitica.

The YadA surface protein of enteropathogenic Yersinia species contains two highly hydrophobic regions: one close to the amino terminal, and the other at the carboxy-terminal end of the YadA polypeptide. To study the role of these hydrophobic regions, we constructed 66 bp deletion mutants of the yadA genes of Yersinia enterocolitica serotype O:3 strain 6471/76 (YeO3) and of O:8 strain 8081 (YeO8). The mutant proteins, YadAYeO3-delta 83-104 and YadAYeO8-delta 8O-101, lacked 22 amino acids from the amino-terminal hydrophobic region, formed fibrillae and were expressed on the cell surface. Bacteria expressing the mutated protein lost their auto-agglutination potential as well as their collagen-binding property. Binding to fibronectin and laminin was affected differently in the YeO3 and the YeO8 constructs. The deletion did not influence YadA-mediated complement inhibition. Loss of the collagen-binding property was associated with loss of virulence in mice. We also constructed a number of YadAYeO3 deletion mutants lacking the hydrophobic carboxy-terminal end of the protein. Deletions ranging from 19 to 79 amino acids from the carboxy terminus affected polymerization of the YadA subunits, and also resulted in the loss of the YadA expression on the cell surface. This suggests that the carboxy terminus of YadA is involved in transport of the protein to the bacterial outer surface.