Ionophoretic properties and mitochondrial effects of cereulide - The emetic toxin of B-cereus

R Mikkola, NEL Saris, PA Grigoriev, MA Andersson, MS Salkinoja-Salonen*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The emetic toxin of Bacillus cereus found to cause immobilization of spermatozoa. and swelling of their mitochondria, was purified and its structure found to be identical to the earlier known toxin cereulide. It increased the conductance in black-lipid membranes in KCI solutions in an ionophore-like manner. It formed adducts with K+. Na+, and NH4+ but the conductance was highly selective for K+ in relation to Na+ and H+ (three orders of magnitude). The increase in the kinetics of conductance indicated a stoichiometric ratio between the cereulide and K+. Its ionophoretic properties are thus similar to those of valinomycin. In addition, its effects on I at liver mitochondria were similar: it stimulated swelling and respiration in respiring mitochondria in the presence but not in the absence of K+ it reduced the transmembrane potential under these conditions. In nonrespiring mitochondria, swelling was seen in KNO3- but not in NaNO3-containing media, less in acetate. In NaNO3 media addition of the cereulide caused a transient diffusion potential which was reduced by adding K+. It is concluded that the toxic effects of cereulide are due to it being a K+ ionophore.

Original languageEnglish
Pages (from-to)112-117
Number of pages6
JournalEUROPEAN JOURNAL OF BIOCHEMISTRY
Volume263
Issue number1
Publication statusPublished - Jul 1999
MoE publication typeA1 Journal article-refereed

Keywords

  • cereulide
  • ionophore
  • mitochondria
  • spermatozoa
  • toxin
  • BACILLUS-CEREUS
  • CELLS

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