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Plasma-membrane Phospholipid Unsaturation Affects Expression of the General Amino-acid Permease in Saccharomyces cerevisiae Y185
Abstract
Saccharomyces cerevisiae Y185, enriched in linoleyl residues and incubated for up to 4 h in derepression buffer, more rapidly acquired general amino-acid permease (GAP) activity, as measured by the rate of accumulation of l-alanine, compared with organisms enriched in oleyl residues. A GAP-less mutant incubated under the same conditions did not acquire further l-alanine-accumulating ability, irrespective of the nature of the fatty-acyl enrichment. During derepression, K
T values for the GAP were virtually identical irrespective of the fatty-acyl enrichment, but V
max values were greater for linoleyl residue-enriched organisms, particularly after 1 h in derepression buffer. During incubation in derepression buffer, organisms with either fatty-acyl enrichment did not differ in the size of the amino-N pool, the concentration of l-alanine in that pool, rates of protein synthesis and glucose fermentation, or rate and extent of incorporation of label from 
. Under conditions used to measure rates of l-alanine accumulation, organisms with either enrichment showed no evidence of metabolism of accumulated l-alanine.
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© Society for General Microbiology 1985