The products of yeast fatty acid synthetase, under usual assay conditions, are palmitate (60%) and stearate (40%). Addition of stearyl-CoA decreases synthetase activity and increases relative amounts of stearate formed (-64%). The ratio of palmitate to stearate produced is also altered by changing the incubation temperatures. At temperatures of 30 C or above, the ratio of palmitate to stearate is about 1.5. However, this ratio increases proportionately as the incubation temperature is lowered, approaching 5.5 at 5 C. The effect of temperature on the fatty acyl transfer reaction of the fatty acid synthetase complex showed that the activation energies of the palmityl transfer and stearyl transfer activities vary with temperature and may account, in part, for the increased production of fatty acids of C16 chain length over C18. This variation may be important as an in vivo short term regulation of fatty acid synthesis in response to variation in environmental temperature. Consistent with this conclusion are the observations that Saccharomyces cerevisiae cells produce over 4.5 times more Cl6 acids than C18 acids shortly after a shift in growth temperature from 35 C to 10 C. The newly synthesized palmitate is converted, in part, to palmitoleate and both are incorporated into membrane lipids. Protein synthesis does not appear to be necessary for the increased Cl6 acids to occur, suggesting that sufficient synthetase and desaturase are present to affect this change.

• PMID: 387785
• PubMed
• PubTator

Reference Type

Journal Article | Research Support, U.S. Gov't, Non-P.H.S. | Research Support, U.S. Gov't, P.H.S.

Authors

Okuyama H, Saito M, Joshi VC, Gunsberg S, Wakil SJ

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