Involved in the catabolism of short chain fatty acids (SCFA) via the 2-methylcitrate cycle I (propionate degradation route). Catalyzes the dehydration of 2-methylcitrate (2-MC) to yield the cis isomer 2-methyl-aconitate (PubMed:11976302). Could also catalyze the dehydration of citrate and the hydration of cis-aconitate (By similarity). (2S,3S)-2-methylcitrate = 2-methyl-cis-aconitate + H2O citrate = D-threo-isocitrate Organic acid metabolism; propanoate degradation. Carbohydrate metabolism; tricarboxylic acid cycle; isocitrate from oxaloacetate: step 1/2. Monomer. By propionate. The prpD2B2C2 operon is essential for growth on propionate as sole carbon source. Belongs to the PrpD family.