Catalyzes the formation of pyruvate and succinate from 2-methylisocitrate during the metabolism of endogenous propionyl-CoA. (2S,3R)-3-hydroxybutane-1,2,3-tricarboxylate = pyruvate + succinate Organic acid metabolism; propanoate degradation. Impairs growth with propionate as the sole carbon and energy source. Belongs to the isocitrate lyase/PEP mutase superfamily. Isocitrate lyase family.