Globoside-specific adhesins of uropathogenic Escherichia coli are encoded by similar trans-complementable gene clusters

Abstract

Uropathogenic Escherichia coli frequently express globoside-specific adhesins, shown to mediate binding to uroepithelial cells. For one gene cluster pap, it recently has been demonstrated that globoside binding is not dependent on expression of the pilus subunit gene papA. Instead, two other pap genes papF and papG are specifically required for globoside binding (F. P. Lindberg et al., EMBO J. 3:1167-1173, 1984). By restriction enzyme mapping, DNA hybridization, DNA sequencing, and protein expression in minicells, we show that three gene clusters encoding globoside binding have a very similar structure and gene organization, although they were cloned from different E. coli isolates. Major differences between the adhesin clones were restricted to the central part of the pilin gene (papA) and to one of the two adhesin gene (papG). The three functional units required for biogenesis of globoside-binding pili, i.e., pilin synthesis, pilin export, and pilin assembly, as well as expression of adhesion function, were all trans complementable among the gene clusters.