Catalyzes the committed step to the synthesis of the acidic phospholipids. Transfers specifically a phosphatidyl group from CDP-diacylglycerol to glycerol-3-phosphate to form phosphatidylglycerophosphate. Cannot catalyze the phosphatidyl group transfer to inositol, serine, choline or phosphatidylglycerol. Possesses high activity with CDP-dipalmitoylglycerol and low activity with CDP-dioleoylglycerol. a CDP-1,2-diacyl-sn-glycerol + sn-glycerol 3-phosphate = 1,2-diacyl-sn-glycero-3-phospho-(1'-sn-glycero-3'-phosphate) + CMP + H(+) Optimum pH is 8.5. Phospholipid metabolism; phosphatidylglycerol biosynthesis; phosphatidylglycerol from CDP-diacylglycerol: step 1/2. Pale green plants with impaired photosynthesis. Belongs to the CDP-alcohol phosphatidyltransferase class-I family.