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

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

Published on: January 3, 2012

A molecular target for viral killer toxin: TOK1 potassium channels

A Ahmed1, F Sesti, N Ilan

  • 1Department of Pediatrics, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA.

Cell
|November 11, 1999
PubMed

Insights

The K1 killer toxin from yeast activates the TOK1 potassium channel, leading to cell death. Deleting TOK1 makes yeast resistant to this toxin.

Area of Science:

  • Molecular biology
  • Yeast genetics
  • Ion channel function

Background:

  • Killer strains of Saccharomyces cerevisiae possess viruses and secrete protein toxins.
  • The K1 killer toxin targets sensitive yeast cells, disrupting potassium homeostasis and causing cell death.

Purpose of the Study:

  • To elucidate the molecular mechanism by which the K1 killer toxin induces cell death.
  • To identify the specific target of the K1 killer toxin in Saccharomyces cerevisiae.

Main Methods:

  • Genetic manipulation of Saccharomyces cerevisiae, including gene deletion and overexpression of the TOK1 gene.
  • Electrophysiological studies on yeast cells and Xenopus laevis oocytes to assess potassium flux and channel activity.
  • Expression of K1 toxin from a cDNA construct to study its direct effects.

Main Results:

  • The K1 killer toxin specifically activates the TOK1 potassium channel in the plasma membrane of Saccharomyces cerevisiae.
  • Deletion of the TOK1 gene confers resistance to the K1 killer toxin.
  • Overexpression of TOK1 increases susceptibility to the toxin.
  • Toxin-induced potassium flux was observed in cells expressing TOK1 but not in those lacking the gene.
  • The K1 toxin directly increases the open probability of TOK1 channels, independent of other cellular factors.

Conclusions:

  • The TOK1 potassium channel is the direct molecular target of the K1 killer toxin.
  • Activation of TOK1 by the K1 toxin is the primary cause of K1 toxin-induced cell death in Saccharomyces cerevisiae.

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