title: The export of coat protein from enteroaggregative Escherichia coli by a specific ATP-binding cassette transporter system.
abstract: Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen characterized by aggregative adherence (AA) to cultured human mucosal epithelium cells. We have recently characterized a 10.2-kDa protein, called dispersin, which is exported from the bacteria and which promotes dispersal of EAEC across the intestinal mucosa. Here, we present evidence that dispersin is exported by a putative ABC transporter complex, which is encoded by a genetic locus of the EAEC virulence plasmid pAA2. We demonstrate that the locus comprises a cluster of five genes (designated aat-PABCD), including homologs of an inner-membrane permease (AatP), an ATP-binding cassette protein (AatC) and the outer membrane protein TolC (AatA). We show that, like TolC, AatA localizes to the outer membrane independently of its ABC partner. Dispersin appears to require the Aat complex for outer membrane translocation but not for secretion across the inner membrane. We also show that, like the dispersin gene, transcription of the aat cluster is dependent on AggR, a regulator of virulence genes in EAEC. We propose that the aat cluster encodes a specialized ABC transporter, which plays a role in the pathogenesis of EAEC by transporting dispersin out of the bacterial cell.
authors.affiliation: Center for Vaccine Development, Departments of Pediatrics, Medicine, and Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. nishi1@m2.kufm.kagoshima-u.ac.jp
authors.forename: Junichiro
authors.initials: J
authors.lastname: Nishi
authors.forename: Jalaluddin
authors.initials: J
authors.lastname: Sheikh
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizuguchi
authors.forename: Ben
authors.initials: B
authors.lastname: Luisi
authors.forename: Valerie
authors.initials: V
authors.lastname: Burland
authors.forename: Adam
authors.initials: A
authors.lastname: Boutin
authors.forename: Debra J
authors.initials: DJ
authors.lastname: Rose
authors.forename: Frederick R
authors.initials: FR
authors.lastname: Blattner
authors.forename: James P
authors.initials: JP
authors.lastname: Nataro
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions
chemical_list: C479827:AAP protein, E coli; D018528:ATP-Binding Cassette Transporters; D003902:Detergents; D029968:Escherichia coli Proteins; D000255:Adenosine Triphosphate