Lipid biosynthesis by isolated plastids from greening pea, Pisum sativum.
Isolated etioplasts from 8-day-old dark-grown pea seedlings incorporated [1-(14)C]acetate into lipid at a relatively low rate. Plastids from seedlings that had been illuminated for at least 2 hr showed an enhanced incorporation provided the plastids were illuminated during incubation with the labeled acetate. Dark incubation or the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) decreased the acetate-incorporating activity of the developing chloroplasts to the level observed with etioplasts. Light had a marked effect on the type of fatty acid into which acetate was incorporated by the developing chloroplasts. Unsaturated fatty acids (mostly oleic acid) accounted for 60-80% of the incorporated label if the plastids were illuminated, but in the dark or in the presence of DCMU the unsaturated acids accounted for only 0-15% of the label incorporated into lipid. The effect of ATP on incorporation was dependent on the maturity of the chloroplasts; mature pea chloroplasts were inhibited by ATP, whereas in developing plastids there was a slight stimulation by ATP. Inhibition of acetate incorporation into lipid by DCMU appears to be due to inhibition of noncyclic phosphorylation. Incorporation was restored by reduced 2,3,5,6-tetramethylphenylenediamine, which restored phosphorylation, but not by reduced N,N,N',N'-tetramethylphenylenediamine.
D000085:Acetates / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D002250:Carbon Radioisotopes; D002734:Chlorophyll / Q000032:analysis; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D002855:Chromatography, Thin Layer; D004237:Diuron / Q000494:pharmacology; D008027:Light; D008055:Lipids / Q000096:biosynthesis*; D010655:Phenylenediamines / Q000494:pharmacology; D010944:Plants / Q000378:metabolism*
D000085:Acetates; D002250:Carbon Radioisotopes; D008055:Lipids; D010655:Phenylenediamines; D002734:Chlorophyll; D000255:Adenosine Triphosphate; D004237:Diuron