Effects of hexavalent chromium on the plasma membranes of sensitive and tolerant mutants of Schizosaccharomyces pombe. An EPR study.
The interactions of chromium(VI) with the plasma membranes of chromium-sensitive (chr-51S) and chromium-tolerant (chr1-66T) mutants and their parental strain (6chr(+)) of a Schizosaccharomyces pombe strain were studied by electron paramagnetic resonance (EPR) spectroscopy. 5-doxylstearic acid (5-SASL) and 3-doxylbutyric acid (HO-185) spin probes were used to label the membranes. The order parameter S from the EPR spectra was calculated at different temperatures (0-25 degrees C) in order to characterize the internal dynamics of the membranes. In control experiments, both mutants exhibited differences in structural transitions in the both 5-SASL- and the HO-185-labeled membranes in comparison with their parental strain, suggesting differences in the membrane composition and/or rotational dynamics of these mutants. Addition of K(2)Cr(2)O(7) (225 microM) induced small decreases in the phase transition temperatures of the 5-SASL-labeled membranes of the parental and chromium-sensitive strains. More pronounced effects of the chromium compound on the HO-185-labeled membranes were detected as evidence that the membrane perturbations are mostly localized in the environment of the lipid-water interface.
Farkas
Nelli
N
Central Research Laboratory, Faculty of Medicine, University of Pécs, 12 Szigeti u, Pécs H-7624, Hungary. nelli.farkas@aok.pte.hu
Pesti
Miklós
M
Belagyi
Joseph
J
D002412:Cations; D002462:Cell Membrane / Q000187:drug effects; D002857:Chromium / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D009154:Mutation; D012568:Schizosaccharomyces / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics; D013113:Spin Labels; D013696:Temperature
D002412:Cations; D013113:Spin Labels; D002857:Chromium