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Detection of Toxin Translocation into the Host Cytosol by Surface Plasmon Resonance
10:41

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Published on: January 3, 2012

Internalized Pseudomonas exotoxin A can exploit multiple pathways to reach the endoplasmic reticulum

Daniel C Smith1, Robert A Spooner, Peter D Watson

  • 1Molecular Cell Biology Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.

Traffic (Copenhagen, Denmark)
|March 16, 2006
PubMed

Insights

Pseudomonas exotoxin A (PEx) uses multiple cellular pathways to reach the endoplasmic reticulum (ER). This toxin exploits both lipid-dependent and protein-dependent sorting signals for ER entry, a promiscuous trafficking strategy.

Area of Science:

  • Cell Biology
  • Molecular Toxicology
  • Protein Trafficking

Background:

  • Pseudomonas exotoxin A (PEx) intoxication requires cell entry via receptor-mediated endocytosis to the endoplasmic reticulum (ER) and retro-translocation to the cytosol.
  • PEx binds to the alpha2-macroglobulin receptor/low-density lipoprotein receptor-related protein (LRP).

Purpose of the Study:

  • To investigate the intracellular trafficking pathways utilized by PEx for ER entry in mammalian cells.
  • To determine if PEx employs distinct routes depending on its association with detergent-resistant microdomains (DRMs).

Main Methods:

  • Utilized HeLa cells to study PEx trafficking.
  • Investigated receptor recruitment to DRMs.
  • Analyzed endosomal transport pathways using Rab9, Arf1, and Rab6 dependent mechanisms.
  • Perturbed retrograde transport pathways to assess PEx route selection.

Main Results:

  • PEx recruits its receptor (LRP) to detergent-resistant microdomains (DRMs).
  • PEx utilizes Rab9-dependent and independent pathways from endosomes to the trans-Golgi network (TGN).
  • PEx can access the ER via multiple retrograde pathways, including Rab6-dependent routes previously associated with lipid-sorting signals.

Conclusions:

  • PEx exhibits promiscuous intracellular trafficking, exploiting both lipid- and protein-sorting signal-controlled pathways for ER entry.
  • Partial localization of PEx within DRMs allows for a choice of trafficking routes, suggesting DRM-associated PEx uses lipid-dependent pathways while non-DRM PEx uses KDEL receptor-mediated pathways.

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