Involved in the naphthalene upper catabolic pathway. Catalyzes the transformation of trans-O-hydroxybenzylidenepyruvate (THBPA) to salicylaldehyde and pyruvate. The reaction is reversible. Can also use substrate which carry trans-alpha,beta-unsaturated keto acid side chain and adjacent hydroxyl group such as trans-4-(3-hydroxy-2-thianaphthenyl)-2-oxo-but-3-enoate, trans-4-(3-hydroxy-2-benzofuranyl)-2-oxobut-3-enoate, and trans-4-(3-hydroxy-2-thienyl)-2-oxobut-3-enoate. (3E)-4-(2-hydroxyphenyl)-2-oxobut-3-enoate + H2O = pyruvate + salicylaldehyde Aromatic compound metabolism; naphthalene degradation. Belongs to the DapA family.