Fatty Acid Synthetase as a Thermoreceptor in Candida utilis1

Abstract

A partially purified fatty acid synthetase from Candida utilis synthesized fatty acids with varying chain lengths that depended on the assay temperature; the stearate/palmitate ratio decreased with decreasing temperature. This temperature-dependency was also observed in vivo for the newly synthesized fatty acids in cells incubated at various temperatures, although to a lesser extent than that observed in vitro. The difference in the temperature-dependencies observed in vivo and in vitro appeared to be due to the difference in the acceptors used in in vitro assays; a temperature-dependency comparable to that observed in vivo was reproduced in vitro on using microsomes rather than bovine serum albumin as the acceptor of the fatty acid synthetase products. Thus, the fatty acid synthetase was identified as a thermoreceptor in Candida cells known to possess a temperature-dependent, inducible desaturase system.

Cloning of a fatty acid synthase component FAS1 gene from Saccharomyces kluyveri and its functional complementation of S. cerevisiae fas1 mutant

“…In contrast to S. cerevisiae , the PUFA‐producing yeasts, such as S. kluyveri , C. albicans , C. utilis , and Yarrowia lipolytica are known to produce larger amounts of C 18 , including linoleic acid (C 18:2 ) and linolenic acid (C 18:3 ), than C 16 (Ratledge and Evans, 1991). The C. utilis FAS protein complex formed in vitro produced a higher amount of C 18:0 than C 16:0 at 30–35°C (Ito et al ., 1986). This indicates that the difference in fatty acid production between S. cerevisiae and the PUFA‐producing yeasts is due to the difference in the structure and function of the FAS protein complex.…”