MECHANISMS OF ACTION OF THE ANTIBIOTIC FLAVIPIN ON MONILINIA-LAXA AND SACCHAROMYCES-CEREVISIAE

Different potential target sites of flavipin action such as cellular membrane permeability, ATP synthesis and protein synthesis were studied in the yeast Saccharomyces cerevisiae and the filamentous fungus Monilinia laxa. When M laxa or S. cerevisiae were treated with flavipin K+ ions were released in small amounts and the leakage increased slowly with time indicating that the antibiotic does not affect primarily membrane permeability. When flavipin was applied to spores of M. laxa or cells of S. cerevisiae in a medium without glucose (ATP production depended on the respiration of endogenous substrates) the level of ATP in the cells of the mould and the yeast suddenly dropped denoting the inhibition of respiration. When cells of S. cerevisiae in a medium with glucose were treated with flavipin a rapid inhibition of [S-35]methionine incorporation was observed showing that flavipin inhibited protein synthesis. Owing to its highly reactive chemical structure flavipin could act as a multisite inhibitor having pleiotropic effects on the cells.