Involved in the persistence and virulence of M.tuberculosis. Catalyzes the reversible formation of succinate and glyoxylate from isocitrate, a key step of the glyoxylate cycle, which operates as an anaplerotic route for replenishing the tricarboxylic acid cycle during growth on fatty acid substrates. It also catalyzes the formation of pyruvate and succinate from 2-methylisocitrate, a key step in the methylcitrate cycle (propionate degradation route). D-threo-isocitrate = glyoxylate + succinate (2S,3R)-3-hydroxybutane-1,2,3-tricarboxylate = pyruvate + succinate Carbohydrate metabolism; glyoxylate cycle; (S)-malate from isocitrate: step 1/2. Deletion of icl2 in cells growing on 0.2% propionate shows a slightly decrease of both isocitrate and methylisocitrate lyase activity. Cell growing on 0.2% glucose show barely detectable isocitrate and methylisocitrate lyase activities. On 0.1% and 0.2% propionate, the lyase activities increase more than 10 and 100-fold, respectively. Belongs to the isocitrate lyase/PEP mutase superfamily. Isocitrate lyase family.