Catalyzes the Claisen condensation of propionyl-CoA and oxaloacetate (OAA) to yield 2-methylcitrate (2-MC) and CoA. Also catalyzes the condensation of oxaloacetate with propionyl-CoA but with a lower specificity. H2O + oxaloacetate + propanoyl-CoA = (2S,3S)-2-methylcitrate + CoA + H(+) acetyl-CoA + H2O + oxaloacetate = citrate + CoA + H(+) Carbohydrate metabolism; tricarboxylic acid cycle. Homodimer. By propionate. The prpD1B1C1 operon seems not to be involved in propionate degradation. Belongs to the citrate synthase family. Extended N-terminus.