Interaction of iturin A, a lipopeptide antibiotic, with Saccharomyces cerevisiae cells: influence of the sterol membrane composition.
The binding of the membrane-active lipopeptide antibiotic iturin A to yeast cells was studied using radioactive iturin A. Saccharomyces cerevisiae had a maximum binding capacity of 5.6 x 10(9) molecules per single cell. The Scatchard plot of binding showed a biphasic profile, with a lower dissociation constant for small concentrations of iturin A. The break of slope at 30 microM iturin A corresponds to the micellization of antibiotic in solution. The binding is also dependent on the nature of the sterol present in the membrane. A mutant yeast strain with a membrane containing cholesterol instead of ergosterol showed the highest affinity for iturin A and the highest sensitivity to this antibiotic, as measured by K+ ion release. In contrast the presence of stigmasterol increased the resistance of the cells to iturin A.
Laboratoire de Biochimie Microbienne, Université de Lyon I, Villeurbanne, France.
C
C
Latoud
F
F
Peypoux
G
G
Michel
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000032:analysis / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D010455:Peptides; D010456:Peptides, Cyclic / Q000378:metabolism / Q000494:pharmacology; D010840:Phytosterols / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013104:Spheroplasts / Q000378:metabolism; D013265:Stigmasterol / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D010455:Peptides; D010456:Peptides, Cyclic; D010840:Phytosterols; C013579:iturin A; D002784:Cholesterol; D013265:Stigmasterol; D011188:Potassium