Function of cytidine diphosphate-diglyceride and deoxycytidine diphosphate-diglyceride in the biogenesis of membrane lipids in Escherichia coli.

摘要: Abstract CDP-diglyceride synthesized by chemical procedures is an efficient donor of phosphatidyl residues for the enzymatic synthesis phospholipids in cell-free extracts Escherichia coli. However, prior to present work, had never been isolated from living cells E. coli or any other organism. We have, therefore, and characterized cytosine-containing liponucleotide fraction find it be a mixture almost equal amounts dCDP-diglyceride. In these experiments, growing log phase were simultaneously labeled with tritiated cytosine sn-glycero-3-[32P]phosphate. Under conditions employed sn-glycero-3-[32P]phosphate was taken up without hydrolysis rapidly converted lipids. Since intracellular pools phosphatidic acid liponucleotides are very small turn over rapidly, 32P fractions may assumed reflect their relative concentrations. The radioactivity about 20 times higher than that fraction. itself less 1% lipids coli, steady state levels must exceedingly low, supporting hypothesis conversion rate-making biosynthesis membrane this activity dCDP-diglyceride phosphatidylserine phosphatidylglycerophosphate found vary considerably concentration used assay system. At concentrations greater 0.1 mm, relatively much more active phosphatidylserine. Below concentration, however, effective substrate both reactions. specificity enzymes nucleotides studied synthetic UDP-diglyceride, ADP-diglyceride, GDP-diglyceride. non-cytosine derivatives have but measurable, as donors