Urinary tract infections, caused mainly by Escherichia coli, are among the most common infectious diseases. Most isolates of the uropathogenic E. coli can express type 1 and P fimbriae containing adhesins that recognize cell receptors. While P fimbriae recognize kidney glycolipid receptors and are involved in pyelonephritis, the urothelial receptors for type 1 fimbriae were not identifled. We show that type 1-fimbriated E. coli recognize uroplakins Ia and Ib, two major glycoproteins ofurothelial apical plaques. Anchorage of E. coli to urothelial surface via type 1 fimbriae-uroplakin I interactions may play a role in its bladder colonization and eventual ascent through the ureters, against urine flow, to invade the kidneys.Urinary tract infections are among the most common infectious diseases, accounting for almost 5 million cases annually and causing considerable morbidity and mortality (1). Increasing incidence of antibiotic-resistant E. coli, which causes up to 95% of these infections, calls for additional therapeutic considerations. One useful approach entails the inhibition of bacterial attachment to urothelial surface, a crucial initial event involving precise interactions between a group of bacterial adhesive molecules called adhesins and their cognate urinary tract receptors (2-4). Knowledge of the molecular details of the receptor-adhesin interface may provide a basis for rational drug design for preventing and treating urinary tract infections.To facilitate attachment to eukaryotic receptors, E. coli assemble fimbriae capped with adhesin molecules (5-7). Two major classes of fimbriae of uropathogenic E. coli have been functionally defined. The P fimbriae are expressed in "70% of the pyelonephritis isolates, and they bind to the Gala(1-4)Gal moiety in the glycolipid receptors (8). The type 1 fimbriae are expressed by more than 90% of the uropathogenic E. coli, and they can bind, via mannose moieties, to the urothelial surface (9-11). Immunohistochemical staining of voided urothelial cells of urinary infection patients showed adhering E. coli with type 1 fimbriae alone (12). Animal studies showed that E. coli expressing type 1 fimbriae, but not those harboring mutated ones, can cause urinary tract infections (13,14). These results clearly establish the functional importance of the mannosesensitive type 1 fimbriae in urinary tract infections. Virtually nothing is known, however, about the urothelial receptors that presumably bear the mannoses recognized by the type 1 fimbriae. Consequently, the precise role of this kind of fimbriae and their functional relationship with the P fimbriae in various types of urinary tract infections are not well understood (2-7, 15).Significant progress has recently been made to characterize biochemically the apical surface of mammalian urothelium, which is covered with nunmerous rigid-appearing, 0.3-to 0.5-,um plaques. In cross-sections, the luminal leaflet of the plaque membrane is twice as thick as the cytoplasmic leaflet, hence the term asymmetrical unit membrane (...

The transmembrane 4 (TM4) superfamily contains many important leukocyte differentiation-related surface proteins including CD9, CD37, CD53, and CD81; tumor-associated antigens including CD63/ME491, CO-029, and SAS; and a newly identified metastasis suppressor gene R2. Relatively little is known, however, about the structure and aggregation state of these four transmembrane-domained proteins. The asymmetrical unit membrane (AUM), believed to play a major role in stabilizing the apical surface of mammalian urothelium thus preventing it from rupturing during bladder distention, contains two TM4 members, the uroplakins (UPs) Ia and Ib. In association with two other (single transmembrane-domained) membrane proteins, UPII and UPIII, UPIa and UPIb form 16-nm particles that naturally form two-dimensional crystalline arrays, thus providing unique opportunities for studying membrane structure and function. To better understand how these proteins interact to form the 16-nm particles, we analyzed their nearest neighbor relationship by chemical cross-linking. We show here that UPIa and UPIb, which share 39% of their amino acid sequence, are cross-linked to UPII and UPIII, respectively. We also show that UPIa has a propensity to oligomerize, forming complexes that are stable in SDS, and that UPII can be readily crosslinked to form homodimers. The formation of UPII homodimers is sensitive, however, to octyl glucoside that can solubilize the AUMs. These data suggest that there exist two types of 16-nm AUM particles that contain UPIa/UPII or UPIb/UPIII, and support a model in which the UPIa and UPII occupy the inner and outer domains, respectively, of the UPIa/UPII particle. This model can account for the apparent "redundancy" of the uroplakins, as the structurally related UPIa and UPIb, by interacting with different partners, may play different roles in AUM formation. The model also suggests that AUM plaques with different uroplakin compositions may differ in their assembly, and in their abilities to interact with an underlying cytoskeleton. Our data indicate that two closely related TM4 proteins, UPIa and UPIb, can be present in the same cell, interacting with distinct partners. AUM thus provides an excellent model system for studying the targeting, processing, and assembly of TM4 proteins.

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A new coordination complex, aqua bis(o-phenanthroline) cadmium(II) sulfate cyanoguanidine pentahydrate, [Cd(o-phen) 2 (SO 4 )(H 2 O)](cnge) Á 5H 2 O, was synthesized and characterized. The crystal structure was solved by X-ray diffraction methods. It crystallizes in the monoclinic space group P2 1 /n with a ¼ 13.7650(2) A ˚, b ¼ 10.2796(2) A ˚, c ¼ 21.4418(3) A ˚, ¼ 90.106(2) , and Z ¼ 4 molecules per cell unit. The cadmium(II) is in a distorted octahedral environment coordinated to two nearly planar and mutually perpendicular o-phenanthrolines, one oxygen atom of sulfate, and a water molecule. Non-bonded and planar cyanoguanidine and five crystallization water molecules complete the asymmetric unit. Vibrational (FT-IR and FT-Raman) spectroscopies and thermogravimetric determinations support this structure. Intensity enhancement of the fluorescence spectrum may be a demonstration of the interaction of the metal with phenanthroline. In solution the coordination behavior is rather different, and the speciation studies point to coordination of both cnge and phenanthroline to cadmium. The improvement of the antibacterial activity of cadmium upon complexation has been determined.

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