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Generating a Fractal Microstructure of Laminin-111 to Signal to Cells
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Published on: September 28, 2020

Two domains of cytotoxic necrotizing factor type 1 bind the cellular receptor, laminin receptor precursor protein

Beth A McNichol1, Susan B Rasmussen, Humberto M Carvalho

  • 1Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA.

Infection and Immunity
|August 22, 2007
PubMed

Insights

Cytotoxic necrotizing factor (CNF1) toxins bind to host cells via two distinct regions: one in the N-terminus (amino acids 135-164) and another in the C-terminus (amino acids 683-730). These toxins are produced by pathogenic E. coli.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Cell Biology

Background:

  • Cytotoxic necrotizing factor type 1 (CNF1) and CNF2 are homologous toxins from pathogenic Escherichia coli.
  • These toxins modify Rho GTPases, impacting cellular functions.
  • CNF1 and CNF2 possess N-terminal binding, transmembrane, and C-terminal catalytic domains.

Purpose of the Study:

  • To identify the specific regions of CNF1 responsible for binding to its cellular receptor, the laminin receptor precursor protein (LRP).
  • To investigate potential alternative cellular receptors for CNF1.

Main Methods:

  • Characterization of truncated CNF1 toxins (DeltaN63, DeltaN545, DeltaC469) for conformational integrity, enzymatic activity, and antibody reactivity.
  • Cell binding assays using LRP and HEp-2 cells with wild-type CNF1, CNF2, and truncated variants.
  • Competitive binding inhibition assays using monoclonal antibodies (MAbs) and LRP.
  • Confocal microscopy to visualize toxin-receptor interactions.

Main Results:

  • CNF1 possesses two primary binding regions for LRP: amino acids 135-164 in the N-terminus and amino acids 683-730 in the C-terminus.
  • Truncated toxins DeltaN63, DeltaN545, and DeltaC469 maintained structural and functional integrity.
  • CNF1 demonstrated binding to additional receptors on HEp-2 cells.
  • LRP was confirmed as a cellular receptor for CNF2.

Conclusions:

  • CNF1 utilizes distinct N-terminal and C-terminal regions for receptor binding.
  • The laminin receptor precursor protein (LRP) is a key receptor for CNF1 and CNF2.
  • CNF1 may interact with multiple cellular receptors for efficient cellular entry and activity.

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