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Biosynthesis of Triacylglycerols:- Phospholipid Synthesis in E. coli Employs CDP-Diacylglycerol

المؤلف:  David L. Nelson، Michael M. Cox

المصدر:  Lehninger Principles of Biochemistry

الجزء والصفحة:  811

2026-07-01

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Biosynthesis of Triacylglycerols:- Phospholipid Synthesis in E. coli Employs CDP-Diacylglycerol

The first strategy for head-group attachment is illustrated by the synthesis of phosphatidylserine, phos phatidylethanolamine, and phosphatidylglycerol in E. coli. The diacylglycerol is activated by condensation of phosphatidic acid with cytidine triphosphate (CTP) to form CDP-diacylglycerol, with the elimination of pyro phosphate (Fig. 21–25). Displacement of CMP through nucleophilic attack by the hydroxyl group of serine or by the C-1 hydroxyl of glycerol 3-phosphate yields phos phatidylserineor phosphatidylglycerol 3-phosphate, respectively. The latter is processed further by cleavage of the phosphate monoester (with release of Pi) to yield phosphatidylglycerol. Phosphatidylserine and phosphatidylglycerol can serve as precursors of other membrane lipids in bacteria (Fig. 21–25). Decarboxylation of the serine moiety in phosphatidylserine, catalyzed by phosphatidylserine decarboxylase, yields phosphatidylethanolamine. In E. coli, condensation of two molecules of phosphatidylglycerol, with elimination of one glycerol, yields cardiolipin, in which two diacylglycerols are joined through a common head group.

FIGURE 21–26 Synthesis of cardiolipin and phosphatidylinositol in eukaryotes. These glycerophospholipids are synthesized using strategy 1 in Figure 21-24. Phosphatidylglycerol is synthesized as in bacteria (see Fig. 21–25). PI represents phosphatidylinositol.