Involved in the biosynthesis of the nonproteinogenic amino acid monomer (S)-3,5-dihydroxyphenylglycine (Dpg) responsible of the production of vancomycin and teicoplanin antibiotics. Catalyzes the Claisen condensation of four molecules of malonyl-CoA to yield 3,5-dihydroxyphenylacetyl-CoA (DPA-CoA) and three free coenzyme A (CoA). DpgA requires the presence of the dehydratases DpgB and DpgD to facilitate the aromatization of the DPA-S-DgpA or DPA-S-CoA intermediate. 4 H(+) + 4 malonyl-CoA = (3,5-dihydroxyphenyl)acetyl-CoA + 4 CO2 + 3 CoA + H2O kcat is 1 min(-1) for transferase activity with malonyl-CoA as substrate. Antibiotic biosynthesis; vancomycin biosynthesis. Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.