Fatty acid uptake in Candida tropicalis: induction of a saturable process.
The rates of oleate uptake by Candida tropicalis cells grown on a high oleate concentration (3.5 mM oleate in the presence of 0.50% Brij 58) were higher than those observed in cells grown on glucose; however, oleate uptake was not saturable with substrate concentration. Cells grown at a low oleate concentration (1.0 mM oleate and 2.5% Brij 58) grew to a lower density and at a slightly slower rate; these cells were found to take up oleate at a rate 43-fold higher than cells grown on high oleate concentration. Furthermore, oleate uptake by the cells grown in low oleate medium was a saturable process with Kt and Vmax values of 56 microM and 15 nmol/(min.mg cell protein), respectively. The growth of C. tropicalis under low fatty acid concentration thus clearly results in the induction of a saturable process for its uptake. The total level of acyl-CoA synthetase activity in cells grown on the low oleate concentrations was only twofold higher than in high oleate or glucose grown cells; the level of this enzyme thus does not account for the saturable process and suggests that either the enzyme is regulated in vivo or else a hitherto unidentified enzyme is induced by growth in low concentrations of oleate.
Trigatti
B L
BL
Department of Biochemistry, McMaster University, Hamilton, Ont., Canada.
Baker
A D
AD
Rajaratnam
K
K
Rachubinski
R A
RA
Gerber
G E
GE
D000214:Acyl Coenzyme A / Q000378:metabolism; D002175:Candida / Q000378:metabolism*; D003066:Coenzyme A Ligases / Q000378:metabolism*; D004790:Enzyme Induction; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism*
D000214:Acyl Coenzyme A; D009829:Oleic Acids; C017585:oleoyl-coenzyme A; D019301:Oleic Acid; D003066:Coenzyme A Ligases