Relationship between cadmium sensitivity and degree of plasma membrane fatty acid unsaturation in Saccharomyces cerevisiae.
The sensitivity of Saccharomyces cerevisiae to the redox-active metal copper has recently been found to be influenced by cellular fatty acid composition. This study sought to investigate whether fatty acid composition affected plasma membrane permeabilisation and whole-cell toxicity induced by the redox-inactive metal cadmium. S. cerevisiae NCYC 1383 was enriched with the polyunsaturated fatty acids linoleate (18:2) and linolenate (18:3) by growth in 18:2- or 18:3-supplemented medium. Incorporation of the exogenous fatty acids resulted in them comprising more than 65% of the total fatty acids in plasma membrane lipids. Inhibition of cell division in the presence of Cd(NO3)2 was accentuated by growth in the presence of a polyunsaturated fatty acid. Furthermore, susceptibility to Cd(2+)-induced plasma membrane permeabilisation increased with the degree of fatty acid unsaturation. Thus, during exposure to Cd2+, K+ efflux from 18:2- and 18:3-enriched cells was up to 2.5-fold or 3-fold greater, respectively than that from unsupplemented cells. In addition, reductions in cell viability during exposure to Cd2+ were most marked in polyunsaturated-fatty-acid-supplemented cells. At certain times, unsupplemented Cd(2+)-exposed cells displayed up to 7-fold greater viability than supplemented Cd(2+)-exposed cells. The study demonstrates that the toxicity of the redox-inactive metal Cd2+ towards S. cerevisiae becomes markedly amplified with increased cellular and plasma membrane fatty acid unsaturation.
Howlett
N G
NG
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, UK.
Avery
S V
SV
D002104:Cadmium / Q000494:pharmacology* / Q000633:toxicity; D002462:Cell Membrane / Q000737:chemistry*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004352:Drug Resistance, Microbial; D019787:Linoleic Acid / Q000032:analysis* / Q000494:pharmacology; D008563:Membrane Lipids / Q000032:analysis*; D010084:Oxidation-Reduction; D011188:Potassium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000187:drug effects*; D017962:alpha-Linolenic Acid / Q000032:analysis* / Q000494:pharmacology
D008563:Membrane Lipids; D002104:Cadmium; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid; D011188:Potassium