title: Direct in vivo interaction of the antibiotic primycin with the plasma membrane of Candida albicans: an EPR study.
abstract: The direct interaction of the antibiotic primycin with the plasma membrane was investigated by employing the well-characterized ergosterol-producing, amphotericin B-sensitive parental Candida albicans strain 33erg(+) and its ergosterol-less amphotericin B-resistant plasma membrane mutant erg-2. The growth inhibition concentration in shaken liquid medium was 64 μgml(-1) for 33erg(+) and 128 μgml(-1) for erg-2, suggesting that the plasma membrane composition influences the mode of action of primycin. To determine the primycin-induced changes in the plasma membrane dynamic, electron paramagnetic resonance (EPR) spectroscopy methods were used, the spin-labeled fatty acid 5-(4,4-dimethyloxazolidine-N-oxyl)stearic acid) being applied for the in vivo measurements. The phase transition temperatures of untreated strain 33erg(+) and its mutant erg-2 were 12.5°C and 11°C, respectively. After 128 μgml(-1) primycin treatment, these values increased to 17.5°C and 16°C, revealing a significant reduction in the phospholipid flexibility. Saturation transfer EPR measurements demonstrated that, the rotational correlation times of the spin label molecule for the control samples of 33erg(+) and erg-2 were 60 ns and 100 ns. These correlation times gradually decreased on the addition of increasing primycin concentrations, reaching 8 μs and 1 μs. The results indicate the plasma membrane "rigidizing" effect of primycin, a feature that may stem from its ability to undergo complex formation with membrane constituent fatty acid molecules, causing alterations in the structures of phospholipids in the hydrophobic surface near the fatty acid chain region.
authors: Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary.
authors: Eszter
authors: E
authors: Virág
authors: Joseph
authors: J
authors: Belagyi
authors: Zoltán
authors: Z
authors: Gazdag
authors: Csaba
authors: C
authors: Vágvölgyi
authors: Miklós
authors: M
authors: Pesti
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D004875:Ergosterol / Q000737:chemistry / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D057927:Hydrophobic and Hydrophilic Interactions; D018942:Macrolides / Q000737:chemistry* / Q000494:pharmacology; D008560:Membrane Fluidity; D044367:Phase Transition; D013113:Spin Labels; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D005227:Fatty Acids; D018942:Macrolides; D013113:Spin Labels; D000666:Amphotericin B; C009041:primycin; D004875:Ergosterol