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.

Membrane Interactions of Phytochemicals as Their Molecular Mechanism Applicable to the Discovery of Drug Leads from Plants

“…Polyene antibiotic amphotericin B and imidazole antifungal miconazole specifically act on ergosterol-containing fungal cell membranes to alter membrane permeability, and both drugs also decrease the membrane fluidity of human polymorphonuclear leukocytes at antimicrobial-relevant concentrations [66]. Non-polyene antibiotic primycin with a broad antimicrobial spectrum has the property to interact with the plasma membranes of Candida albicans and rigidify them [67].…”

Effect of primycin on growth-arrested cultures and cell integrity of Staphylococcus aureus

“…This assumption is consistent with published data. Lower membrane fluidity has been observed to entail decreased primycin susceptibility of an ergosterol-less Candida albicans mutant strain possessing a more compact cell membrane compared to the wild type [14,15]. Presumably, the low membrane fluidity and the decreased diffusion rate due to low temperature hindered the integration of primycin into the cell membrane, which is necessary to exert its effect [9,15].…”

“…Lower membrane fluidity has been observed to entail decreased primycin susceptibility of an ergosterol-less Candida albicans mutant strain possessing a more compact cell membrane compared to the wild type [14,15]. Presumably, the low membrane fluidity and the decreased diffusion rate due to low temperature hindered the integration of primycin into the cell membrane, which is necessary to exert its effect [9,15]. This can also explain the more rapid killing of exponentially growing bacteria by primycin compared to that of any growtharrested cultures, as the membrane fluidity is known to be increased during the logarithmic phase [16].…”

Membrane Interactivity of Non-steroidal Anti-inflammatory Drugs: A Literature Review

“…While antibiotic amphotericin B and antifungal miconazole interact with fungal membranes to modify their permeability, both compounds decrease the fluidity of cellular membranes [120]. Non-polyene antibiotic primycin also interacts with the plasma membranes of Candida albicans to decrease their fluidity [121].…”