The O75X adhesin of uropathogenic Escherichia coli: receptor-active domains in the canine urinary tract and in-vitro interaction with laminin.

The complementary binding sites for the purified O75X adhesin of uropathogenic Escherichia coli in canine urinary tract were determined by indirect immunofluorescence. The adhesin bound to the vascular basement membranes in the canine kidney, ureter, bladder and urethra. In the kidney, the adhesin bound also to the tubular basement membranes and to the Bowman's capsule and mesangium of the glomeruli. In the bladder and ureter, but not in the urethra, the O75X adhesin bound to the basal lamina of smooth muscle cells. Connective tissue was negative for the adhesin. Interestingly, considerable intraepithelial heterogeneity was revealed as the O75X adhesin bound to epithelium of the ureter but not to that of the kidney, bladder or urethra. The purified O75X adhesin bound specifically to laminin, a basement membrane glycoprotein, immobilized on nitrocellulose or polystyrene, suggesting that laminin is involved in the binding of the O75X adhesin to basement membranes.