Structural and physiological features of sterols necessary to satisfy bulk membrane and sparking requirements in yeast sterol auxotrophs.
A variety of sterols and stanols have been analyzed for their ability to satisfy bulk membrane and high-specificity (sparking) functions in three yeast sterol auxotrophs. While many sterols and stanols satisfied bulk membrane requirements, only those possessing a C-5,6 unsaturation or capable of being desaturated at C-5 fulfilled the high-specificity sparking requirement. Unsaturation of the A-ring or beta-saturation of a C-5,6 double bond rendered both sterol and stanol unsuitable for either function. The C-28 methyl group of ergosterol, while not required for growth, allowed for greater ease of desaturation at C-5 in vivo. As a result some sterols and stanols lacking the C-28 methyl were incapable of satisfying the sparking requirement while identical compounds possessing the C-28 methyl were able to fulfill the sparking function(s). These data are extended to hypothesize a role for the C-28 methyl group of ergosterol in yeast.
D002777:Cholestanols / Q000378:metabolism; D007700:Kinetics; D008563:Membrane Lipids / Q000502:physiology*; D009154:Mutation; D010088:Oxidoreductases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development* / Q000378:metabolism; D013045:Species Specificity; D013261:Sterols / Q000378:metabolism*; D013329:Structure-Activity Relationship
D002777:Cholestanols; D008563:Membrane Lipids; D013261:Sterols; D010088:Oxidoreductases; C039306:sterol delta-5 desaturase