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Blockage of cell wall receptors for yeast killer toxin KT28 with antimannoprotein antibodies

M J Schmitt1, F Radler

  • 1Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg-Universität Mainz, Federal Republic of Germany.

Antimicrobial Agents and Chemotherapy
|August 1, 1990
PubMed

Insights

Yeast killer toxin KT28 binds to specific mannoprotein structures on the cell wall. Toxin resistance in Saccharomyces cerevisiae mutants is linked to altered mannoprotein, with outer mannotriose side chains identified as key binding domains.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Yeast killer toxins are proteins secreted by certain yeast strains that exhibit toxicity towards other sensitive yeast strains.
  • The cell wall of Saccharomyces cerevisiae is a complex structure primarily composed of mannoproteins, glucans, and chitin.
  • Understanding toxin-receptor interactions is crucial for yeast biology and potential biotechnological applications.

Purpose of the Study:

  • To identify the specific receptor on the yeast cell wall responsible for binding the killer toxin KT28.
  • To elucidate the molecular basis of killer toxin resistance in Saccharomyces cerevisiae mannoprotein mutants.
  • To determine the precise structural domains of mannoprotein involved in toxin interaction.

Main Methods:

  • Utilized polyclonal antimannoprotein antibodies to block toxin binding.
  • Employed indirect immunofluorescence to visualize toxin localization on yeast cells.
  • Performed structural analysis of acetylated mannoprotein from wild-type and mutant yeast strains.

Main Results:

  • Antimannoprotein antibodies specifically blocked killer toxin KT28 binding, indicating mannoprotein as the primary receptor.
  • Indirect immunofluorescence confirmed KT28 binding to cell wall mannoprotein.
  • Mannoprotein mutants (mnn) exhibited resistance due to a deficiency in toxin-binding sites.
  • Structural analysis pinpointed outer mannotriose side chains of mannoprotein as the direct binding domains for KT28.

Conclusions:

  • Killer toxin KT28 interacts with specific mannoprotein structures on the yeast cell wall.
  • Alterations in mannoprotein, particularly the outer mannotriose side chains, confer resistance to killer toxins.
  • This study elucidates the molecular mechanism of yeast killer toxin binding and resistance.

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