Bacterial phosphatidylglycerol and cardiolipin biosynthesis

A reusable bacterial membrane-lipid module connecting phosphatidylglycerol synthesis from CDP-diacylglycerol to phospholipase-D-family cardiolipin synthesis. PgsA forms phosphatidylglycerol phosphate, PgpA removes its terminal phosphate to form phosphatidylglycerol, and alternative Cls lineages transfer a phosphatidyl group from phosphatidylglycerol or phosphatidylethanolamine to phosphatidylglycerol to form cardiolipin.

The root is one connected route with two coherent nested parts rather than two unrelated modules. The phosphatidylglycerol part is independently useful and can terminate at phosphatidylglycerol, which is both a bulk membrane lipid and the substrate for other pathways. The cardiolipin part describes the downstream branch when cardiolipin is produced; it does not imply that all phosphatidylglycerol is committed to cardiolipin. CDP-diacylglycerol synthesis, phosphatidylethanolamine and phosphatidylcholine branches, phosphatidylglycerol modification, cardiolipin turnover, and acyl-chain remodeling are outside the boundary.