No abstract

The Dr family of related adherence structures, some fimbriated and others afimbriated, bind to decayaccelerating factor molecules on human cells. Dr is associated with recurring urinary tract infection (UTI), but the distribution of Dr subtypes among uropathogenic Escherichia coli causing UTI among otherwise healthy women has yet to be described. A total of 787 UTI and fecal E. coli isolates from college women were screened for the presence of Dr sequences (drb). Fifteen percent of UTI strains were drb positive, compared to 5% of fecal strains. The adhesin (E gene) subtype of each drb-positive strain was determined by type-specific PCR followed by restriction enzyme analysis. Among 78 drb-positive strains, we found 14 (18%) afaE1, 1 (1.3%) afaE2, 1 (1.3%) afaE3, 9 (12%) draE, 9 (12%) draE-afaE3 hybrid, 1 (1.3%) daaE, 32 (41%) afaE5, 4 (5.1%) F131 E gene-like, and 7 untypeable strains. All untypeable E genes were cloned and sequenced, revealing four additional new classes of E genes, including two similar to the previously identified nonfimbrial E series. While a great range of diversity exists among the E genes, restriction fragment length polymorphism analysis demonstrated that all of these drb operons share a highly conserved gene structure. The most common subtype, afaE5, occurred three times as often among UTI than fecal strains. Over half of the drb-positive strains and 80% of those positive for afaE5 have the same virulence signature (positive for aer, kpsMT, ompT, and fim), suggesting an association of this profile with UTI pathogenesis.

No abstract

The recent definition of a consensus DNA binding sequence for the Ets family of transcription factors has allowed the identification of potential Ets binding sites in the promoters and enhancers of many inducible T-cell genes. In the studies described in this report, we have identified two potential Ets binding sites, EBS1 and EBS2, which are conserved in both the human and murine interleukin-2 enhancers. Within the human enhancer, these two sites are located within the previously defined DNase I footprints, NFAT-1 and NFIL-2B, respectively. Electrophoretic mobility shift and methylation interference analyses demonstrated that EBS1 and EBS2 are essential for the formation of the NFAT-1 and NFIL-2B nuclear protein complexes. Furthermore, in vitro mutagenesis experiments demonstrated that inducible interleukin-2 enhancer function requires the presence of either EBS1 or EBS2. Two well-characterized Ets family members, Ets-1 and Ets-2, are reciprocally expressed during T-cell activation. Surprisingly, however, neither of these proteins bound in vitro to EBS1 or EBS2. We therefore screened a T-cell cDNA library under low-stringency conditions with a probe from the DNA binding domain of Ets-1 and isolated a novel Ets family member, Elf-1. Elf-1 contains a DNA binding domain that is nearly identical to that of E74, the ecdysone-inducible Drosophila transcription factor required for metamorphosis (hence the name Elf-1, for E74-like factor 1). Elf-1 bound specifically to both EBS1 and EBS2 in electrophoretic mobility shift assays. It also bound to the purine-rich CD3R element from the human immunodeficiency virus type 2 long terminal repeat, which is required for inducible virus expression in response to signalling through the T-cell receptor. Taken together, these results demonstrate that multiple Ets family members with apparently distinct DNA binding specificities regulate differential gene expression in resting and activated T cells.