Members of this protein family 4-carboxy-4-hydroxy-2-oxoadipate aldolase, also called 4-oxalocitramalate aldolase. This enzyme of the protocatechuate 4,5-cleavage pathway converts its substrate to pyruvate plus oxaloacetate. Protocatechuate is an intermediate in many pathways for degrading aromatic compounds, including lignin, fluorene, etc. Hara, et al. showed the LigK gene was not only a 4-carboxy-4-hydroxy-2-oxoadipate aldolase but also the enzyme of the following step, oxaloacetate decarboxylase.