AggR, a transcriptional activator of aggregative adherence fimbria I expression in enteroaggregative Escherichia coli.

摘要: Abstract Enteroaggregative Escherichia coli (EAggEC) has been associated with persistent pediatric diarrhea in the developing world, yet pathogenetic mechanisms of EAggEC infection are unknown. Our previous data have suggested that aggregative adherence some strains to HEp-2 cells is mediated by flexible, bundle-forming fimbriae, which we termed fimbriae I (AAF/I). Genes sufficient confer expression AAF/I located on 60-MDa plasmid 17-2; genes present as two unlinked regions (regions 1 and 2), separated 9 kb DNA. Here report complete DNA sequencing region 2 identification an open reading frame involved AAF/I. One 794 bp encodes a protein (designated AggR) predicted molecular size 29.4 kDa, shows high degree amino acid sequence identity CfaR other members AraC class gene regulators. The cloned aggR (or, alternatively, cfaR gene) was complement clone expression. To further substantiate role regulation AAF/I, constructed 289-bp in-frame deletion replaced native 17-2 allelic exchange, using temperature-sensitive vector pIB307. resulting deletions were negative for expression, but restored when (cloned into pBluescript II SK) reintroduced mutant. RNA slot blot experiments probe putative pilin subunit (aggA) revealed operates transcriptional activator aggA aggA::phoA fusions delta aggR. AggR found promote under variety conditions temperature, osmolarity, oxygen tension, medium. At pH, maximal regulated both AggR-dependent AggR-independent mechanisms.