Involved in the modified meta-cleavage pathway for the 2-aminophenol catabolism. (3E)-2-oxohex-3-enedioate + H(+) = 2-oxopent-4-enoate + CO2 Strongly inhibited by Fe(2+), Fe(3+), K(3)[Fe(CN)(6)], Ag(+) and Cu(2+). Optimum pH is 7.5. Stable in the range of pH 5.0-8.0. Stable up to 35 degrees Celsius. Forms a complex with AmnF. Belongs to the hydratase/decarboxylase family.