D-glucuronate = D-fructuronate aldehydo-D-galacturonate = keto-D-tagaturonate Carbohydrate metabolism; pentose and glucuronate interconversion. Induced by galacturonate, repressed by glucose. Member of the exu locus which is required for galacturonate utilization. Belongs to the metallo-dependent hydrolases superfamily. Uronate isomerase family.