Pathways, genes encoding the enzyme responsible and major phospholipids naturally occurring in E. coli are indicated in red. Pathways, genes encoding the enzyme responsible and the major lipid synthesized by foreign enzymes in E. coli are indicated in green. 1. cdsA, CDP-diacylglycerol synthase; 2. pssA, phosphatidylserine synthase; 3. psd, phosphatidylserine decarboxylase; 4. pgsA, phosphatidylglycerophosphate synthase; 5. pgpABC, phosphatidylglycerophosphate phosphatase (any of three gene products catalyse this step [18]); 6. cls, CL synthase; 7. mdoB, PG:pre-MDO (membrane-derived oligosaccharide) sn-glycerol-1-phosphate transferase; 8. dgk, diacylglycerol kinase; 9. mgs, GlcDAG synthase (Acholeplasma laidlawii); 10. dgs, GlcGlcDAG synthase (Acholeplasma laidlawii); 11. pcs, PC synthase (Legionella pneumophila). Modified from [9] with permission. © 2009 The American Society for Biochemistry and Molecular Biology.