A subfamily of Dr adhesins of Escherichia coli bind independently to decay-accelerating factor and the N-domain of carcinoembryonic antigen

J Biol Chem. 2006 Sep 29;281(39):29120-30. doi: 10.1074/jbc.M605681200. Epub 2006 Aug 1.

Abstract

Escherichia coli expressing the Dr family of adhesins adheres to epithelial cells by binding to decay-accelerating factor (DAF) and carcinoembryonic antigen (CEA)-related cell surface proteins. The attachment of bacteria expressing Dr adhesins to DAF induces clustering of DAF around bacterial cells and also recruitment of CEA-related cell adhesion molecules. CEA, CEACAM1, and CEACAM6 have been shown to serve as receptors for some Dr adhesins (AfaE-I, AfaE-III, DraE, and DaaE). We demonstrate that AfaE-I, AfaE-V, DraE, and DaaE adhesins bind to the N-domain of CEA. To identify the residues involved in the N-CEA/DraE interaction, we performed SPR binding analyses of naturally occurring variants and a number of randomly generated mutants in DraE and N-CEA. Additionally, we used chemical shift mapping by NMR to determine the surface of DraE involved in N-CEA binding. These results show a distinct CEA binding site located primarily in the A, B, E, and D strands of the Dr adhesin. Interestingly, this site is located opposite to the beta-sheet encompassing the previously determined binding site for DAF, which implies that the adhesin can bind simultaneously to both receptors on the epithelial cell surface. The recognition of CEACAMs from a highly diverse DrCEA subfamily of Dr adhesins indicates that interaction with these receptors plays an important role in niche adaptation of E. coli strains expressing Dr adhesins.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial / chemistry
  • Adhesins, Bacterial / physiology*
  • Animals
  • CD55 Antigens / chemistry
  • CD55 Antigens / physiology*
  • CHO Cells
  • Carcinoembryonic Antigen / chemistry*
  • Cell Adhesion
  • Cricetinae
  • Escherichia coli / metabolism*
  • Fimbriae, Bacterial / metabolism
  • Humans
  • Protein Binding
  • Protein Structure, Tertiary

Substances

  • Adhesins, Bacterial
  • CD55 Antigens
  • Carcinoembryonic Antigen