The export of coat protein from enteroaggregative Escherichia coli by a specific ATP-binding cassette transporter system

J Biol Chem. 2003 Nov 14;278(46):45680-9. doi: 10.1074/jbc.M306413200. Epub 2003 Aug 21.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry*
  • ATP-Binding Cassette Transporters / metabolism
  • Adenosine Triphosphate / metabolism*
  • Amino Acid Sequence
  • Bacterial Adhesion
  • Blotting, Western
  • Cell Membrane / metabolism
  • Cloning, Molecular
  • Detergents / pharmacology
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / metabolism*
  • Escherichia coli / pathogenicity
  • Escherichia coli Proteins / chemistry
  • Microscopy, Electron
  • Microscopy, Electron, Scanning
  • Models, Biological
  • Models, Genetic
  • Models, Molecular
  • Molecular Sequence Data
  • Multigene Family
  • Mutagenesis, Site-Directed
  • Plasmids / metabolism
  • Protein Binding
  • Protein Transport
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Subcellular Fractions


  • AAP protein, E coli
  • ATP-Binding Cassette Transporters
  • Detergents
  • Escherichia coli Proteins
  • Adenosine Triphosphate

Associated data

  • GENBANK/AY351860