Inhibition of fatty acid desaturation in sycamore cells deprived of iron.
The growth of isolated sycamore cells in a medium devoid of iron induced a marked reduction of the unsaturation level of fatty acids: the proportion of linolenic acid (C18:3) in polar lipids (phospholipids and galactolipids) decreased whereas a parallel increase in the proportions of oleic (C18:1) and linoleic (C18:2) acid was observed. In our experimental conditions, no direct effect of iron deprivation on fatty acid and glycerolipid biosynthesis could be observed. When sycamore cells were incubated in the presence of [14C]acetate, the level of unsaturation in fatty acids was very strongly reduced: no polyunsaturated fatty acids were synthesized in iron-deprived cells: only [14C]palmitic and [14C]oleic acids accumulated in glycerolipids. In contrast, sycamore cells grown in an iron-containing medium in the presence of [14C]acetate were able to synthesize glycerolipids containing 14C-labelled C18:2 and C18:3. We concluded that, in sycamore cells, iron is essential for C18:1-->C18:2-->C18:3 desaturations. In contrast, C18:0-->C18:1 desaturation is much less sensitive to iron deprivation under our experimental conditions.
Pascal
N
N
URA CNRS n. 576, Département de Biologie Moléculaire et Structurale, Grenoble, France.
Dorne
A J
AJ
D000085:Acetates / Q000378:metabolism; D002478:Cells, Cultured; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D050356:Lipid Metabolism; D014197:Trees / Q000378:metabolism*
D000085:Acetates; D005227:Fatty Acids; D007501:Iron; D044943:Fatty Acid Desaturases