Component of the methylcitrate cycle that catalyzes the synthesis of (2S,3S)-2-methylcitrate from propionyl-CoA and oxaloacetate. Plays an important role in detoxification of propionyl-CoA, an inhibitor of both primary and secondary metabolism. Has also citrate synthase activity using as substrates acetyl-CoA and oxaloacetate. H2O + oxaloacetate + propanoyl-CoA = (2S,3S)-2-methylcitrate + CoA + H(+) acetyl-CoA + H2O + oxaloacetate = citrate + CoA + H(+) Optimum pH is 8.0-9.0. Optimum temperature is 49-54 degrees Celsius. Organic acid metabolism; propanoate degradation. Homodimer. Belongs to the citrate synthase family.