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FimH-mediated autoaggregation of Escherichia coli

M A Schembri1, G Christiansen, P Klemm

  • 1Microbial Adhesion Group, Section of Molecular Microbiology, BioCentrum-DTU, Bldg 301, Technical University of Denmark, DK-2800 Lyngby, Denmark.

Molecular Microbiology
|October 3, 2001
PubMed

Insights

Researchers identified specific changes in the FimH adhesin of Escherichia coli, leading to autoaggregation and bacterial settlement. These variants show adaptive potential in host colonization.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Autoaggregation in pathogenic bacteria is linked to host colonization.
  • Type 1 fimbriae, mediated by the FimH adhesin in Escherichia coli, facilitate host surface binding.
  • FimH's N-terminal domain is crucial for its adhesive properties.

Purpose of the Study:

  • To identify variants of the FimH adhesin that promote autoaggregation in E. coli.
  • To investigate the characteristics and implications of FimH-mediated autoaggregation.

Main Methods:

  • Random mutagenesis of the FimH adhesin.
  • Identification of autoaggregating E. coli clones.
  • Analysis of FimH variants using green fluorescent protein (GFP) and electron microscopy.
  • Testing inhibition by mannose and temperature variations.

Main Results:

  • Three autoaggregating E. coli clones were identified, each with multiple amino acid changes in the FimH N-terminal domain.
  • Autoaggregation was mannose-insensitive but temperature-dependent (inhibited below 30°C).
  • Autoaggregating cells exhibited distinct fimbrial morphology (twisted, entangled) and did not mix with wild-type cells.
  • Evidence suggests naturally occurring autoaggregating FimH variants exist.

Conclusions:

  • Specific mutations in FimH can induce bacterial autoaggregation, impacting settlement from liquid cultures.
  • The FimH adhesin demonstrates significant adaptability, potentially influencing bacterial interactions with host environments.
  • Autoaggregation represents a facultative trait of the FimH adhesin with implications for bacterial behavior and colonization.

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