Direct in vivo interaction of the antibiotic primycin with the plasma membrane of Candida albicans: An EPR study

Eszter Virág, Joseph Belagyi, Zoltán Gazdag, Csaba Vágvölgyi, Miklós Pesti

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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 μg ml -1 for 33erg + and 128 μg ml -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 μg ml -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.

Original languageEnglish
Pages (from-to)42-48
Number of pages7
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1818
Issue number1
DOIs
Publication statusPublished - Jan 1 2012

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Keywords

  • 5-SASL
  • Candida albicans
  • EPR
  • Membrane fluidity
  • Primycin
  • ST-EPR

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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