title: Aggregative adherence fimbria I expression in enteroaggregative Escherichia coli requires two unlinked plasmid regions.
abstract: Adherence to HEp-2 cells by many enteroaggregative Escherichia coli (EAggEC) strains is associated with the expression of flexible, bundle-forming fimbriae 2 to 3 nm in diameter, designated aggregative adherence fimbriae I (AAF/I). We have previously reported the molecular cloning and TnphoA mutagenesis of AAF/I genes from the large plasmid of prototype EAggEC strain 17-2 (J. P. Nataro, Y. Deng, D. R. Maneval, A. L. German, W. C. Martin, and M. M. Levine, Infect. Immun. 60:2297-2304, 1992). Here, we report that further mapping and subcloning of AAF/I regions suggest that expression of the fimbriae requires two separate plasmid regions (designated regions 1 and 2). Approximately 9 kb of DNA unnecessary for fimbrial expression separates the two regions; this intervening segment encodes the EAggEC heat-stable enterotoxin (EAST1). Neither region was capable of conferring aggregative HEp-2 adherence (AA) when cloned individually; when the two regions were cloned as a single fragment or when each was cloned into a different vector and introduced into the same E. coli HB101 cell, AA was restored. AA-positive constructs also expressed human erythrocyte hemagglutination, autoagglutination in broth cultures, and the production of AAF/I as detected by immunogold electron microscopy.
authors.affiliation: Department of Pediatrics, University of Maryland School of Medicine, Baltimore 21201.
authors.forename: J P
authors.initials: JP
authors.lastname: Nataro
authors.forename: D
authors.initials: D
authors.lastname: Yikang
authors.forename: J A
authors.initials: JA
authors.lastname: Giron
authors.forename: S J
authors.initials: SJ
authors.lastname: Savarino
authors.forename: M H
authors.initials: MH
authors.lastname: Kothary
authors.forename: R
authors.initials: R
authors.lastname: Hall
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: C079725:AggA protein, E coli; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins