Catalyzes the phosphorylation of diacylglycerol (DAG) into phosphatidic acid. Is a key enzyme involved in the production of lipoteichoic acid by reintroducing DAG formed from the breakdown of membrane phospholipids into the phosphatidylglycerol biosynthetic pathway. a 1,2-diacyl-sn-glycerol + ATP = a 1,2-diacyl-sn-glycero-3-phosphate + ADP + H(+) Binds 1 Mg(2+) ion per subunit. This ion appears to have a structural role and is required for catalytic activity. Homodimer. Belongs to the diacylglycerol/lipid kinase family.